Minitab
®
Minitab
®
Minitab
®
Minitab
®
Session Commands
Minitab
®
, Minitab Connect
®
, Minitab Model Ops
®
, Minitab Engage
®
, Minitab Workspace
®
, Salford Predictive Modeler
®
,
SPM
®
, and the Minitab
®
logo are all registered trademarks of Minitab, LLC, in the United States and other countries.
Additional trademarks of Minitab, LLC can be found at www.minitab.com. All other marks referenced remain the
property of their respective owners.
©
2024 Minitab, LLC. All rights reserved.
2
Contents
Using Session Commands............................................................................................................................................11
Alphabetical list of session commands................................................................................................................................................11
What are session commands?.................................................................................................................................................................27
Session command syntax notation........................................................................................................................................................27
Symbols to use with session commands.............................................................................................................................................27
Using a subcommand.................................................................................................................................................................................28
Using session commands in the Command Line pane and the History pane................................................................... 28
Using the History pane..............................................................................................................................................................................29
Rules for entering session command arguments.............................................................................................................................29
Rules for entering session commands..................................................................................................................................................30
Interrupting session command execution...........................................................................................................................................30
Updates for release 19.1............................................................................................................................................................................30
Commands that are unavailable in the web app..............................................................................................................................36
Opening, Saving, and Printing Files...........................................................................................................................38
END: Session command for ending data input.................................................................................................................................38
GSAVE: Session subcommand for saving a graph in a file........................................................................................................... 38
ODBC: Session command for importing data from a database file.......................................................................................... 39
OUTFILE and NOOUTFILE: Session commands for saving a Minitab session in a text file.............................................. 40
PRINT: Session command for displaying columns, constants, or matrices in the output pane..................................... 40
READ data into columns............................................................................................................................................................................41
READ data into a matrix.............................................................................................................................................................................43
RESTART: Session command for restarting.........................................................................................................................................43
RETRIEVE: Session command for retrieving a saved worksheet or project............................................................................ 44
SAVE: Session command for saving a worksheet or project........................................................................................................44
STOP: Session command for closing Minitab....................................................................................................................................45
WOPEN: Session command for opening a worksheet................................................................................................................... 45
WORKSHEET: Session command for making a worksheet active, for closing a worksheet, or for renaming a worksheet
..............................................................................................................................................................................................................................48
WRITE: Session command for writing data to the screen or a data file.................................................................................. 49
WSAVE: Session command for saving a worksheet file................................................................................................................. 51
XPPOINT: Session command for sending output to Microsoft PowerPoint.......................................................................... 53
XWORD: Session command for sending output to Microsoft Word........................................................................................53
Other Session Commands............................................................................................................................................54
PYSC: Session command for running a Python script....................................................................................................................54
RSCR: Session command for running a R script...............................................................................................................................54
NAME: Session command for assigning names to columns, stored constants, and matrices....................................... 55
ABORT: Subcommand for exiting a multi-line command.............................................................................................................56
HELP: Session command for opening this guide.............................................................................................................................56
Dynamic Data Exchange..............................................................................................................................................57
XDACTIVATE: Session command for activating a link.....................................................................................................................57
3
XDADD: Session command for adding a new link........................................................................................................................... 57
XDDEACTIVATE: Session command for deactivating a client link.............................................................................................. 59
XDEXEC: Session command for executing a command in a remote application................................................................ 60
XDGET: Session command for performing a one-time data transfer....................................................................................... 60
XDREMOVE: Session command for deleting an established link............................................................................................... 61
Manipulating and Calculating Data...........................................................................................................................63
Calculator.........................................................................................................................................................................................................63
Data..................................................................................................................................................................................................................106
Editor...............................................................................................................................................................................................................132
Basic Statistics.............................................................................................................................................................139
DESCRIBE: Session command for summarizing numeric data with statistics..................................................................... 139
STATS: Session command for storing descriptive statistics....................................................................................................... 143
GSUMMARY: Session command for displaying a graphical summary of each variable................................................ 146
ONEZ: Session command for performing a 1-sample Z-test.................................................................................................... 147
ONET: Session command for performing a 1-sample t-test..................................................................................................... 148
TWOT: Session command for performing a 2-sample t-test when samples are in one column................................ 149
TWOSAMPLE: Session command for performing a 2-sample t-test when the samples are in different columns. 150
PAIR: Session command for performing a paired t-test............................................................................................................. 151
PONE: Session command for performing a hypothesis test of the proportion................................................................ 152
PTWO: Session command for performing a hypothesis test of the difference between two proportions............ 154
ONERATE: Session command for performing a 1-sample Poisson rate test....................................................................... 155
TWORATE: Session command for performing a 2-sample Poisson rate test...................................................................... 156
ONEV: Session command for performing a 1 variance test...................................................................................................... 157
TWOVARIANCES: Session command for determining whether the variances or standard deviations of two groups
differ................................................................................................................................................................................................................158
CORRELATION: Session command for measuring the strength and direction of the association between two
variables.........................................................................................................................................................................................................160
COVARIANCE: Session command for calculating the covariance between pairs of columns...................................... 162
NORMTEST: Session command for performing a normality test............................................................................................ 163
OUTLIER: Session command for performing an outlier test...................................................................................................... 165
PGOODNESS: Session command for performing a chi-square goodness-of-fit test for Poisson distribution...... 166
Regression...................................................................................................................................................................168
INDICATOR: Session command for creating indicator variables.............................................................................................. 168
REGRESS: Session command for performing a regression analysis....................................................................................... 169
BREG: Session command for performing best subsets regression.........................................................................................178
FITLINE: Session command for creating a fitted line plot.......................................................................................................... 179
SSWORKSHEET: Session command for creating a stability study worksheet..................................................................... 182
SHELFLIFE: Session command for performing a stability study............................................................................................... 183
NLINEAR: Session command for performing nonlinear regression.......................................................................................188
OREG: Session command for performing orthogonal regression.......................................................................................... 192
PLS: Session command for performing partial least squares regression............................................................................. 194
GZLM: Session command for fitting a binary logistic model or a Poisson model........................................................... 199
BFIT: Session command for creating a binary fitted line plot................................................................................................... 210
OLOGISTIC: Session command for performing ordinal logistic regression......................................................................... 213
4
Minitab Statistical Software Contents
NLOGISTIC: Session command for performing nominal logistic regression...................................................................... 216
ANOVA.........................................................................................................................................................................219
ONEWAY: Session command for performing a one-way ANOVA........................................................................................... 219
ANOM: Session command for creating an analysis of means chart...................................................................................... 223
ANOVA: Session command for performing a balanced ANOVA............................................................................................. 224
GLM: Session command for fitting the general linear model................................................................................................... 227
REML: Session command for fitting a mixed effects model...................................................................................................... 235
COMPARE: Session command for performing multiple comparisons of means............................................................... 241
MANOVA: Session command for performing a general MANOVA........................................................................................ 244
NESTED: Session command for performing a fully-nested ANOVA....................................................................................... 248
VARTEST: Session command for performing an equal variances test................................................................................... 249
INTPLOT: Session command for creating an interval plot.......................................................................................................... 250
MAIN: Session command for creating a main effects plot........................................................................................................253
INTERACT: Session command for creating an interactions plot.............................................................................................. 254
DOE..............................................................................................................................................................................257
Screening Designs......................................................................................................................................................................................257
Factorial Designs.........................................................................................................................................................................................277
Response Surface Designs......................................................................................................................................................................342
Mixture Designs..........................................................................................................................................................................................365
Taguchi Designs..........................................................................................................................................................................................412
Modify and Display Designs..................................................................................................................................................................420
Quality and Process Improvement...........................................................................................................................425
Quality Planning Tools..............................................................................................................................................................................425
Control Charts..............................................................................................................................................................................................432
Capability Analysis.....................................................................................................................................................................................593
Tolerance Intervals.....................................................................................................................................................................................662
Measurement Systems Analysis............................................................................................................................................................666
Acceptance Sampling...............................................................................................................................................................................688
Reliability/Survival.....................................................................................................................................................695
Test Plans.......................................................................................................................................................................................................695
Distribution Analysis (Right Censoring).............................................................................................................................................703
Distribution Analysis (Arbitrary Censoring)......................................................................................................................................718
Growth Curves.............................................................................................................................................................................................729
Regression with Life Data........................................................................................................................................................................735
Cox Regression............................................................................................................................................................................................740
Probit Analysis.............................................................................................................................................................................................750
Warranty Analysis.......................................................................................................................................................................................754
Predictive Analytics....................................................................................................................................................758
CART Regression.........................................................................................................................................................................................758
CART Classification....................................................................................................................................................................................765
TreeNet Regression....................................................................................................................................................................................773
TreeNet Classification................................................................................................................................................................................784
5
Minitab Statistical Software Contents
Random Forests Regression...................................................................................................................................................................796
Random Forests Classification...............................................................................................................................................................801
MARS Regression.......................................................................................................................................................................................807
Discover Best Model (Continuous Response).................................................................................................................................814
Discover Best Model (Binary Response)............................................................................................................................................827
Multivariate Analysis.................................................................................................................................................841
PCA: Session command for performing principal components analysis.............................................................................. 841
FACTOR: Session command for performing a factor analysis................................................................................................... 842
CLUOBS: Session command for clustering observations............................................................................................................845
CLUVARS: Session command for clustering variables..................................................................................................................849
KMEANS: Session command for non-hierarchical clustering of observations................................................................... 851
DISCRIMINANT: Session command for performing discriminant analysis.......................................................................... 852
ITEMANALYSIS: Session command for performing item analysis........................................................................................... 854
CA: Session command for performing simple correspondence analysis............................................................................. 855
MCA: Session command for performing a multiple correspondence analysis.................................................................. 859
Time Series Analysis...................................................................................................................................................862
AAMODEL: Session command for the selection of an alternative model from Forecast with Best ARIMA
Model.............................................................................................................................................................................................................862
ACF: Session command for calculating autocorrelation.............................................................................................................862
ADF: Session command for conducting an augmented Dickey-Fuller test......................................................................... 863
ARIMA: Session command for modeling time series behavior and generating forecasts............................................ 864
ATARIMA: Session command for selecting parameters for an ARIMA model and generating forecasts................ 866
CCF: Session command for calculating cross correlation between two time series........................................................ 871
DECOMP: Session command for performing decomposition on a time series................................................................. 872
DES: Session command for performing double exponential smoothing............................................................................. 876
DIFFERENCES: Session command for calculating differences...................................................................................................880
LAG: Session command for calculating the lags of a column................................................................................................... 881
MLAG: Session command to calculate lags of one or more columns................................................................................... 881
MA: Session command for calculating a moving average......................................................................................................... 882
PACF: Session command for calculating partial autocorrelation............................................................................................. 886
SES: Session command for performing single exponential smoothing................................................................................ 887
TBOXCOX: Session command for performing a Box-Cox transformation on time series data................................... 891
TREND: Session command for performing a trend analysis...................................................................................................... 892
TSWINT: Session command for performing Holt-Winters seasonal exponential smoothing...................................... 896
Tables...........................................................................................................................................................................901
TABLE: Session command for creating one-way, two-way, and multi-way tables using categorical variables...... 901
TALLY: Session command for displaying a one-way table for each column....................................................................... 903
TCHISQUARE: Session command for performing a chi-square goodness-of-fit test...................................................... 904
XTABS: Session command for displaying one-way, two-way, and multi-way tables for categorical variables...... 905
Nonparametric Analysis............................................................................................................................................909
1-Sample Sign..............................................................................................................................................................................................909
1-Sample Wilcoxon....................................................................................................................................................................................909
MANN-WHITNEY: Session command for performing a Mann-Whitney test..................................................................... 910
6
Minitab Statistical Software Contents
FRIEDMAN: Session command for performing a Friedman test............................................................................................. 910
KRUSKAL-WALLIS: Session command for performing a Kruskal-Wallis test....................................................................... 911
MOOD: Session command for performing a Mood's median test......................................................................................... 911
RUNS: Session command for performing a runs test.................................................................................................................. 911
WALSH: Session command for calculating pairwise averages.................................................................................................912
WDIFF: Session command for calculating pairwise differences...............................................................................................912
WSLOPE: Session command for calculating pairwise slopes....................................................................................................912
Equivalence Test.........................................................................................................................................................914
TOST: Session command for performing an equivalence test..................................................................................................914
Power and Sample Size Analysis..............................................................................................................................919
FDESIGN: Session subcommand for power and sample size for a general full factorial design................................. 919
FFDESIGN: Session subcommand for power and sample size for a 2-level factorial design....................................... 920
ONERATE: Session subcommand for power and sample size for a 1-sample Poisson rate test................................. 921
ONEVARIANCE: Session command for power and sample size for a 1 variance test..................................................... 923
ONEWAY: Session command for power and sample size for one-way ANOVA................................................................ 924
PBDESIGN: Session subcommand for power and sample size for Plackett-Burman design........................................ 925
PONE: Session subcommand for power and sample size for a 1 proportion test........................................................... 926
POWER: Session command for power and sample size.............................................................................................................. 927
PTWO: Session subcommand for power and sample size for a 2 proportion test.......................................................... 929
SSCI: Session command for estimating sample size.................................................................................................................... 930
SSTI: Session command for sample size for tolerance intervals.............................................................................................. 931
TONE: Session command for power and sample size for a 1-sample t-test....................................................................... 933
TOST: Session command for power and sample size for an equivalence test................................................................... 934
TPAIRED: Session subcommand for power and sample size for a paired t-test................................................................ 935
TTWO: Session subcommand for power and sample size for a 2-sample t-test.............................................................. 936
TWORATE: Session subcommand for power and sample size for a 2-sample Poisson rate test................................ 938
TWOVARIANCE: Session subcommand for power and sample size for a 2 variances test........................................... 939
ZONE: Session subcommand for power and sample size for a 1-sample Z-test.............................................................. 940
Graphs..........................................................................................................................................................................942
CHART: Session command for creating a bar chart......................................................................................................................942
HMAP: Session command for creating a heatmap....................................................................................................................... 945
PLOT: Session command for creating a scatterplot......................................................................................................................947
NPLOT: Session command for creating a binned scatterplot...................................................................................................949
GCORRELATION: Session command for creating a correlogram............................................................................................ 951
MATRIXPLOT: Session command for creating a matrix of plots............................................................................................... 952
BUBBLEPLOT: Session command for creating a bubble plot..................................................................................................... 955
MARGPLOT: Session command for creating a marginal plot.................................................................................................... 957
HISTOGRAM: Session command for creating a histogram........................................................................................................ 958
DOTPLOT: Session command for creating a dotplot.................................................................................................................... 961
STEM-AND-LEAF: Session command for creating a stem-and-leaf plot.............................................................................. 963
PPLOT: Session command for creating a probability plot.......................................................................................................... 963
ECDF: Session command for creating an empirical CDF plot................................................................................................... 968
DPLOT: Session command for creating a probability distribution plot................................................................................. 970
BOXPLOT: Session command for creating a boxplot....................................................................................................................975
7
Minitab Statistical Software Contents
INTPLOT: Session command for creating an interval plot.......................................................................................................... 978
INDPLOT: Session command for creating an individual value plot........................................................................................ 980
LPLOT: Session command for creating a line plot.........................................................................................................................983
PIECHART: Session command for creating a pie chart................................................................................................................ 985
TSPLOT: Session command for creating a time series plot........................................................................................................ 987
PARPLOT: Session command for creating a parallel plot............................................................................................................ 989
ARGRAPH: Session command for creating an area graph......................................................................................................... 990
CONTOURPLOT: Session command for creating a contour plot............................................................................................. 992
PLTX: Session command for creating a 3D scatterplot................................................................................................................995
SURFACEPLOT: Session command for creating a surface plot................................................................................................. 996
Graph Options.............................................................................................................................................................................................999
Model-Based Commands........................................................................................................................................1094
FACPLOT: Session command for creating a factorial plot........................................................................................................ 1094
MFFCUBE: Session command for creating a cube plot for fitted means........................................................................... 1095
MMOPT: Session command for the Response Optimizer........................................................................................................ 1095
MOVERCONT: Session command for creating an overlaid contour plot........................................................................... 1098
MSURFACE: Session command for creating a surface plot..................................................................................................... 1099
PREDICT: Session command for predicting response values................................................................................................. 1101
MMPREDICT: Session command to calculate predictions from multiple models.......................................................... 1105
RMCONTOUR: Session command for creating a contour plot.............................................................................................. 1107
Macros Session Commands.....................................................................................................................................1109
Structure Commands..............................................................................................................................................................................1109
Declaration Statements.........................................................................................................................................................................1109
Local Macro Variables.............................................................................................................................................................................1112
Control Statements..................................................................................................................................................................................1115
Using DOS Commands..........................................................................................................................................................................1121
Labeling Macro Output.........................................................................................................................................................................1121
Debugging Tools......................................................................................................................................................................................1123
Additional Local Macro Features.......................................................................................................................................................1124
Commands that Affect Output...........................................................................................................................................................1125
Communicating with Macro Users....................................................................................................................................................1128
Execs Commands.....................................................................................................................................................................................1129
Supporting Concepts...............................................................................................................................................1131
Add your own function..........................................................................................................................................................................1131
Adding comments to a macro............................................................................................................................................................1131
Array table for OADESIGN....................................................................................................................................................................1131
Assigning attributes to groups...........................................................................................................................................................1132
Assigning attributes with multiple graphs and groups.............................................................................................................1132
Bar chart functions..................................................................................................................................................................................1133
Base position for project lines, area, and bar................................................................................................................................1134
Box-Behnken designs.............................................................................................................................................................................1135
Calculating a chi-square statistic for a goodness-of-fit test using session commands............................................... 1135
Calculations for FFACTORIAL...............................................................................................................................................................1136
Central composite designs...................................................................................................................................................................1136
8
Minitab Statistical Software Contents
Computing weights, or smoothed values......................................................................................................................................1138
Data requirements and formats for attribute agreement analysis....................................................................................... 1138
Default date/time formats....................................................................................................................................................................1140
Designs generated by FFDESIGN.......................................................................................................................................................1141
Entering data for factor variables......................................................................................................................................................1142
Entering data for response variables................................................................................................................................................1142
Entering patterned data for the SET session command........................................................................................................... 1143
Restricted and unrestricted mixed models....................................................................................................................................1144
Examples of entering response data for logistic regression................................................................................................... 1144
A comparison of MSURFACE and RMCONTOUR plots............................................................................................................. 1148
Graphics options for MIXCONTOUR.................................................................................................................................................1148
Graphics options for MIXOVER..........................................................................................................................................................1150
Graphics options for MIXSURFACE...................................................................................................................................................1150
Graphics options for MSURFACE.......................................................................................................................................................1152
Graphics options for SIMPLEX............................................................................................................................................................1154
Graphics options for SPCONT.............................................................................................................................................................1155
Graphics options for SPSIMP..............................................................................................................................................................1157
Graphs that use groups with the data display subcommands ............................................................................................. 1158
How to enter data for ANOVA and GLM........................................................................................................................................1158
How to enter data for CCHART..........................................................................................................................................................1159
How to enter data for GCHART..........................................................................................................................................................1159
How to enter data for NPCHART.......................................................................................................................................................1160
How to enter data for PDIAGNOSTIC, PCHART, and PPRIMECHART.................................................................................. 1161
How to enter data for TCHART...........................................................................................................................................................1161
How to enter data for UDIAGNOSTIC, UCHART, and UPRIMECHART................................................................................. 1163
How to enter subgroup data...............................................................................................................................................................1163
How to specify the model for ATCLASS, GZLM, OLOGISTIC and NLOGISTIC.................................................................. 1165
How to specify the model for factorial designs...........................................................................................................................1166
How to specify the model for GLM...................................................................................................................................................1167
How to specify the model for response surface designs.........................................................................................................1168
How to specify the model in ANOVA...............................................................................................................................................1169
How to specify the model in MGAGE..............................................................................................................................................1170
Missing values in exponential smoothing......................................................................................................................................1171
Missing values in factorial, response surface, and mixture designs..................................................................................... 1171
Notes on subcommands that store descriptive statistics (STATS command).................................................................. 1172
Numbers for colors to use in session commands.......................................................................................................................1172
Numbers for fill types to use in session commands..................................................................................................................1173
Numbers for line types to use in session commands................................................................................................................1173
Numbers to use for symbols and markers in session commands........................................................................................ 1174
Overview of DDE session commands..............................................................................................................................................1175
Pearson residuals.....................................................................................................................................................................................1175
Plackett-Burman designs......................................................................................................................................................................1176
Prompting a user for information.....................................................................................................................................................1177
Reading in data from a text file..........................................................................................................................................................1177
Generalized linear model diagnostics and residual analysis................................................................................................... 1177
Residual analysis and regression diagnostics...............................................................................................................................1178
9
Minitab Statistical Software Contents
Restrictions on GLM models................................................................................................................................................................1179
Session commands that are not allowed in macros...................................................................................................................1179
Simplex lattice design descriptions..................................................................................................................................................1180
Time unit subcommands......................................................................................................................................................................1180
Using groups in graphs.........................................................................................................................................................................1182
Using READ with FORMAT...................................................................................................................................................................1183
Using READ without subcommands.................................................................................................................................................1183
Using the SYMBOL and COLOR subcommands for PLOT........................................................................................................ 1183
Using the POSITION and MODEL subcommands.......................................................................................................................1185
Valid format items....................................................................................................................................................................................1186
10
Minitab Statistical Software Contents
Using Session Commands
Alphabetical list of session commands
A
AASA: Session command for acceptance sampling by attributes on page 688
ACF: Session command for calculating autocorrelation on page 862
ADD: Session command for addition on page 63
ALTTESTPLAN: Session command for creating an accelerated life test plan on page 699
ANOM: Session command for creating an analysis of means chart on page 223
ANOVA: Session command for performing a balanced ANOVA on page 224
ARDECISION: Session command for accepting or rejecting an entire lot on page 694
AREA: The session subcommand for shading the area below the data values to the base on page 999
ARGRAPH: Session command for creating an area graph on page 990
ARIMA: Session command for modeling time series behavior and generating forecasts on page 864
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
B
BAR: Session subcommand for representing data values with bars on page 1003
BASE: Session command for fixing a starting number for the random number generator on page 86
BBDESIGN: Session command for creating a Box-Behnken design on page 342
BCAPA: Session command for performing binomial capability analysis on page 656
BFFACTORIAL: Session command for analyzing a full or fractional factorial design with a binary response on page
296
BFIT: Session command for creating a binary fitted line plot on page 210
BGFACTORIAL: Session command for analyzing a general full factorial design with a binary response. on page 312
BOXCOX: Session command for performing a Box-Cox transformation on page 432
BOXPLOT: Session command for creating a boxplot on page 975
BTFT: Session command for calculating a 1-sample bootstrap confidence interval of a function on page 96
BTPR: Session command for calculating a 1-sample bootstrap confidence interval of a proportion on page 97
BTTM: Session command for calculating a 2-sample bootstrap confidence interval for the difference of means on
page 99
BREAK: Session command for transferring control from a DO- or WHILE-loop on page 1118
BREG: Session command for performing best subsets regression on page 178
11
Minitab Statistical Software Using Session Commands
BRIEF: Session command for controlling the amount of output on page 1125
BUBBLEPLOT: Session command for creating a bubble plot on page 955
BRSREG: Session command for analyzing a response surface design with a binary response on page 353
BSCREEN: Session command for analyzing a screening design with a binary response on page 268
BWCAPA: Session command for performing between/within capability analysis on page 596
BWCHART: Session command for creating an I-MR-R/S chart on page 446
BWSIXPAC: Session command for Between/Within Capability Sixpack on page 641
C
CA: Session command for performing simple correspondence analysis on page 855
CALL and RETURN: Session commands for passing control to another macro on page 1119
CAPA: Session command for performing a normal capability analysis on page 604
CCDESIGN: Session command for creating a central composite design on page 343
CCF: Session command for calculating cross correlation between two time series on page 871
CCHART: Session command for creating a C chart on page 531
CD: Session command for displaying or changing the current directory on page 1121
CDF: Session command for calculating the cumulative probability of an x-value on page 91
CENTER: Session command for centering data on page 80
CFAUTOMATICALLY: Session command for automatically recalculating values on page 135
CFMANUALLY: Session command for manually recalculating values on page 136
CFNOW: Session command for recalculating values now on page 136
CFORMAT: Session command for conditional formatting of worksheet cells on page 132
CHART: Session command for creating a bar chart on page 942
CIBOX: The session subcommand for displaying a median confidence interval box on a boxplot on page 1005
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CLUOBS: Session command for clustering observations on page 845
CLUVARS: Session command for clustering variables on page 849
CMEAN: Session subcommand for connecting means with lines on a boxplot on page 1010
CMEDIAN: Session subcommand for connecting means with lines on a boxplot on page 1011
CODE: Session command for changing values in columns to new values on page 119
COFFSET and GAPWIDTH: Session subcommands for the space between clusters and items in a cluster on page 1028
COMPARE: Session command for performing multiple comparisons of means on page 241
CONCATENATE: Session command for combining text columns on page 119
CONNECT: Session subcommand for connecting points with lines on page 1012
12
Minitab Statistical Software Using Session Commands
CONTOURPLOT: Session command for creating a contour plot on page 992
%CONTPROC: Session command for creating a contour plot
CONVERT: Session command for converting text data to numeric data, and numeric data to text data on page 121
COPY: Session command for copying data on page 130
CORRELATION: Session command for measuring the strength and direction of the association between two variables
on page 160
COUNT: Session command for counting the number of values in a column on page 76
COVARIANCE: Session command for calculating the covariance between pairs of columns on page 162
CTPREDICT: Session command for predicting responses for new observations for a classification tree on page 771
CTREE: Session command for creating a classification tree on page 765
CUSUM: Session command for creating a CUSUM chart on page 550
CUTPOINT, MIDPOINT, and NINTERVAL: Session subcommands for specifying cutpoints and midpoints on page
1014
D
DATA: Session subcommand for controlling the data region within the figure region on page 1015
DATE: Session command for changing data type to date/time on page 113
DATLAB: Session command for labeling data values on page 1016
DCAPA: Session command for performing individual distribution identification on page 593
DEBUG and NODEBUG: Session commands for finding problems in macros on page 1124
DECOMP: Session command for performing decomposition on a time series on page 872
DEFAULT: Session command for assigning default values to subcommand arguments on page 1112
DEFINE: Session command for defining a constant matrix on page 104
DEFTEST: Session command for defining the sensitivity of the tests for special causes on page 592
DELETE: Session command for deleting rows of data on page 111
DES: Session command for performing double exponential smoothing on page 876
DESCRIBE: Session command for summarizing numeric data with statistics on page 139
DIAGONAL: Session command for creating a matrix from a column on page 104
DIFFERENCES: Session command for calculating differences on page 880
DISCRIMINANT: Session command for performing discriminant analysis on page 852
DISTRIBUTION: Session command for fitting a distribution on page 1018
DOT: Session subcommand for displaying a symbol for each data value on page 1021
DOTPLOT: Session command for creating a dotplot on page 961
DPLOT: Session command for creating a probability distribution plot on page 970
DSDESIGN: Session command for creating a definitive screening design on page 257
13
Minitab Statistical Software Using Session Commands
DROUND: Session command for rounding date/time values on page 122
DSET: Session command for making patterned data on page 82
DTESTPLAN: Session command for creating a demonstration test plan on page 695
DTYPE: Session command for determining the data type of a column or a constant on page 1114
E
ECDF: Session command for creating an empirical CDF plot on page 968
EIGEN: Session command for calculating eigenvalues on page 63
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
ELSE, ELSEIF, IF, ENDIF: Session commands for executing code depending on a logical condition on page 1115
END: Session command for ending data input on page 38
ENDLAYOUT and LAYOUT: Session subcommands for specifying where a graph appears on a page on page 1043
ENDMACRO, GMACRO, and MACRO: Session commands for marking the beginning and ending of a macro on
page 1109
ENDWHILE and WHILE: Session commands for repeating a block of commands depending on a logical expression
on page 1116
ERASE: Session command for erasing variables on page 113
ETESTPLAN: Session command for creating an estimation test plan on page 697
EVDESIGN: Session command for creating an extreme vertices design on page 365
EWMACHART: Session command for creating an EWMA chart on page 543
EXCLUDE and INCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
EXECUTE: Session command for running an Exec file on page 1130
EXIT: Session command for transferring control back to Minitab or for closing Minitab on page 1120
F
FACPLOT: Session command for creating a factorial plot on page 276
FACTOR: Session command for performing a factor analysis on page 842
FDATE/TIME: Session command for changing the format of date/time columns on page 136
FDESIGN: Session command for creating a general full factorial design on page 277
FDESIGN: Session subcommand for power and sample size for a general full factorial design on page 919
FFACTORIAL: Session command for analyzing a full or fractional factorial design on page 288
FFCUBE: Session command for creating a cube plot on page 340
FFDESIGN: Session command for creating a full or fractional factorial design on page 279
FFDESIGN: Session subcommand for power and sample size for a 2-level factorial design on page 920
FFINT: Superseded by FACPLOT except for mixture designs on page 336
FFMAIN: Superseded by FACPLOT except for mixture designs on page 338
14
Minitab Statistical Software Using Session Commands
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
FISHBONE: Session command for creating a cause-and-effect diagram on page 425
FITD: Session command for fitting a distribution to the data on a probability plot on page 1024
FITLINE: Session command for creating a fitted line plot on page 179
FNUMERIC: Session command for changing columns to numeric format on page 136
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
%FORM: Session command for creating a data collection form for a 3-factor design
FORMULA: Session command for assigning a formula to a column on page 137
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
FRIEDMAN: Session command for performing a Friedman test on page 910
FTEXT: Session command for changing the format of text columns on page 137
G
GAGERR: Session command for performing a crossed gage R&R study on page 675
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
GAPWIDTH and COFFSET: Session subcommands for the space between clusters and items in a cluster on page 1028
GAWORKSHEET: Session command for creating a gage R&R study worksheet on page 667
GCHART: Session command for creating a G chart on page 582
GENVAR: Session command for creating a generalized variance chart on page 572
GFACTORIAL: Session command for fitting a general full factorial design on page 305
GLM: Session command for fitting the general linear model on page 227
GMACRO, MACRO, and ENDMACRO: Session commands for marking the beginning and ending of a macro on
page 1109
GOTO and MLABEL: Session commands for branching to any line in a macro on page 1118
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
GSAVE: Session subcommand for saving a graph in a file on page 38
GSCALE: Session command to determine appropriate scaling for a graph on page 1127
GSUMMARY: Session command for displaying a graphical summary of each variable on page 146
GZLM: Session command for fitting a binary logistic model or a Poisson model on page 199
H
HISTOGRAM: Session command for creating a histogram on page 958
HLABEL: Session subcommand for labeling histogram bars on a marginal plot with y-axis values on page 1030
15
Minitab Statistical Software Using Session Commands
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
I
ICHART: Session command for creating an I chart on page 490
IDIDENTIFICATION: Session command for creating probability plots of arbitrarily-censored, failure (or survival) data
on page 718
IDOVIEW: Session command for creating a layout of distribution plots on page 720
IF, ELSEIF, ELSE, ENDIF: Session commands for executing code depending on a logical condition on page 1115
ILABEL: Session subcommand for labeling individual values on a boxplot or interval plot on page 1033
IMRCHART: Session command for creating an I-MR chart on page 479
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
INDICATOR: Session command for creating indicator variables on page 85
INDIVIDUAL: Session subcommand for displaying a symbol for each individual data value on a boxplot or an
individual value plot on page 1036
INDPLOT: Session command for creating an individual value plot on page 980
INFO: Session command for summarizing the current worksheet on page 106
INTBAR: Session subcommand for displaying a vertical line with horizontal lines at the endpoints of the confidence
interval for the mean on page 1037
INTERACT: Session command for creating an interactions plot on page 254
INTLAB: Session subcommand for labeling interval bar endpoints on an interval plot on page 1039
INTPLOT: Session command for creating an interval plot on page 250
INVCDF: Session command for calculating the variable for a cumulative probability on page 94
INVERT: Session command for replacing a matrix value with its inverse on page 105
IQRBOX: Session subcommand for displaying an interquartile range box on a boxplot on page 1041
ITEMANALYSIS: Session command for performing item analysis on page 854
J
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
JOHNSON: Session command for applying the Johnson transformation on page 596
K
KKCAT, KKNAME, and KKSET: Session commands for using text on page 1112
KMEANS: Session command for non-hierarchical clustering of observations on page 851
KRUSKAL-WALLIS: Session command for performing a Kruskal-Wallis test on page 911
16
Minitab Statistical Software Using Session Commands
L
LAG: Session command for calculating the lags of a column on page 63
LAYOUT and ENDLAYOUT: Session subcommands for specifying where a graph appears on a page on page 1043
LBRIGHT: Session subcommand for specifying the brightness of the lights that illuminate a surface plot on page
1044
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
LET: Session command for correcting a number in a worksheet or performing arithmetic on page 63
LIGHT: Session subcommand for specifying the position, color, and visibility of the lights that illuminate a surface
plot on page 1047
LINE: The session subcommand for constructing a line from points on a graph on page 1048
LNGAGE: Session command for performing a gage linearity and bias study on page 673
LONGMETHOD: Session command for performing an attribute gage study (analytic method) on page 684
LOWESS: Session subcommand for fitting a LOWESS smoother to a scatterplot, a matrix plot, a histogram, or a time
series plot on page 1049
LPLOT: Session command for creating a line plot on page 983
LREGRESSION: Session command for performing a regression analysis when the error distribution is Weibull, smallest
extreme value, exponential, log-normal, normal, logistic, or log-logistic on page 735
LTABLE: Session command for fitting a distribution to arbitrarily-censored data on page 722
LTEST: Session command for parametric or nonparametric distribution analysis on page 709
M
MA: Session command for calculating a moving average on page 882
MACHART: Session command for creating a moving average chart on page 536
MACRO, ENDMACRO, and GMACRO: Session commands for marking the beginning and ending of a macro on
page 1109
MAIN: Session command for creating a main effects plot on page 253
MANN-WHITNEY: Session command for performing a Mann-Whitney test on page 910
MANOVA: Session command for performing a general MANOVA on page 244
MARGPLOT: Session command for creating a marginal plot on page 957
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
MATRIXPLOT: Session command for creating a matrix of plots on page 952
MCA: Session command for performing a multiple correspondence analysis on page 859
MCAPA: Session command for performing a normal capability analysis for multiple variables on page 626
MCONSTANT, MCOLUMN, MMATRIX, and MTYPE: Session commands for declaring variables on page 1109
MDESIGN: Session command to modify the design properties or display of a design in the worksheet on page 420
MEALAB: Session subcommand for labeling means on a boxplot or an interval plot on page 1051
MEAN: Session command for calculating the arithmetic mean of a column on page 76
17
Minitab Statistical Software Using Session Commands
MEAN: Session subcommand for displaying symbol for each mean on a boxplot, interval plot, or individual value
plot on page 1053
MEDIAN: Session command for identifying the median of a column on page 76
MEDIAN: Session subcommand for displaying a symbol for each median on a boxplot, interval plot, or individual
value plot on page 1054
MEDLAB: Session subcommand for labeling medians on a boxplot on page 1055
MERGE: Session command for merging two worksheets into one worksheet on page 106
MESH: Session command for making mesh data on page 84
MEWMA: Session command for creating a multivariate EWMA chart on page 577
MFFCUBE: Session command for creating a cube plot for fitted means on page 335
MFREE: Session command for declaring a free variable on page 1110
MGAGE: Session command for performing an expanded gage R&R study on page 670
MGRID, GRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
MIDPOINT, CUTPOINT, and NINTERVAL: Session subcommands for specifying cutpoints and midpoints on page
1014
MIXCONTOUR: Session command for creating a contour plot on page 391
MIXOVER: Session command for creating an overlaid contour plot on page 399
MIXREG: Session command for analyzing a mixture design on page 375
MIXSURFACE: Session command for creating a surface plot on page 397
MLABEL and GOTO: Session commands for branching to any line in a macro on page 1118
MLAG: Session command to calculate lags of one or more columns on page 881
MMATRIX, MCONSTANT, MCOLUMN, and MTYPE: Session commands for declaring variables on page 1109
MMOPT: Session command for the Response Optimizer on page 1095
MNCAPA: Session command for performing nonnormal capability analysis for multiple variables on page 636
MOOD: Session command for performing a Mood's median test on page 911
MOVERCONT: Session command for creating an overlaid contour plot on page 1098
MRCHART: Session command for creating an MR chart on page 497
MROPT: Session command for the Response Optimizer on page 409
MSURFACE: Session command for creating a surface plot on page 1099
MTITLE: Session command for adding a title above output on page 1121
MTYPE, MMATRIX, MCONSTANT, and MCOLUMN: Session commands for declaring variables on page 1109
MULTIPLY: Session command for multiplication on page 75
MVARCHART: Session command for creating a multi-vari chart on page 427
N
N: Session command for counting the nonmissing values in a column on page 76
18
Minitab Statistical Software Using Session Commands
NESTED: Session command for performing a fully-nested ANOVA on page 248
NEXT: Session command for transferring control from a loop to the beginning of the block on page 1117
NGROWTH: Session command for performing a nonparametric analysis using a nonparametric growth curve on
page 732
NINTERVAL, CUTPOINT, and MIDPOINT: Session subcommands for specifying cutpoints and midpoints on page
1014
NLINEAR: Session command for performing nonlinear regression on page 188
NLOGISTIC: Session command for performing nominal logistic regression on page 216
NMISS: Session command for counting the missing values in a column on page 76
NMVARCHART: Session command for creating variability charts on page 427
NNCAPA: Session command for performing a nonnormal capability analysis on page 612
NNSIXPACK: Session command for Nonnormal Capability Sixpack on page 651
NNTINTERVALS: Session command for calculating tolerance intervals on page 664
NOBRUSH: Session subcommand for disabling brushing on a graph on page 1128
NODEBUG and DEBUG: Session commands for finding problems in macros on page 1124
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOECHO and ECHO: Session commands for displaying Minitab commands in the output on page 1123
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
NOGRID, GRID, MGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
NOJITTER and JITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
NOLEGEND and LEGEND Session subcommands for controlling the legend on a graph on page 1045
NOMGRID GRID, MGRID, and NOGRID, and: Session subcommands for controlling the grid on a graph on page
1029
NOMISS and NOEMPTY: Session subcommands for excluding missing data from graphs on page 1057
NOOUTFILE and OUTFILE: Session commands for saving a Minitab session in a text file on page 40
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOPROPORTIONAL and PROPORTIONAL: Session subcommands for making the boxes on a boxplot proportional
to the square root of the number of observations in the boxes on page 1066
NORMTEST: Session command for performing a normality test on page 163
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
NOTABLE and TABLE: Session subcommand for controlling the table within the figure region on page 1085
NOTE: Session command for adding comments that are displayed in the output on page 1129
19
Minitab Statistical Software Using Session Commands
NOTRANSPOSE and TRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
NPCHART: Session command for creating a chart for the number of defectives on page 514
NTGAGE: Session command for performing a nested gage R&R study on page 680
NUMERIC: Session command for changing the data format of a date/time column or extracting date/time components
on page 123
O
OADESIGN: Session command for creating a Taguchi orthogonal array design on page 412
OAPREDICT: Session command for calculating predicted response values on page 418
ODBC: Session command for importing data from a database file on page 39
OLAB: Session subcommand for labeling outliers on a boxplot on page 1058
OLOGISTIC: Session command for performing ordinal logistic regression on page 213
ONERATE: Session command for performing a 1-sample Poisson rate test on page 155
ONERATE: Session subcommand for power and sample size for a 1-sample Poisson rate test on page 921
ONET: Session command for performing a 1-sample t-test on page 148
ONEV: Session command for performing a 1 variance test on page 157
ONEVARIANCE: Session command for power and sample size for a 1 variance test on page 923
ONEWAY: Session command for power and sample size for one-way ANOVA on page 924
ONEWAY: Session command for power and sample size for one-way ANOVA on page 924
ONEZ: Session command for performing a 1-sample Z-test on page 147
OPTDES: Session command for selecting an optimal design on page 361
OREG: Session command for performing orthogonal regression on page 192
OUTFILE and NOOUTFILE: Session commands for saving a Minitab session in a text file on page 40
OUTLIER: Session command for performing an outlier test on page 165
OUTLIER: Session subcommand for displaying a symbol for each outlier on a boxplot on page 1060
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
P
PACF: Session command for calculating partial autocorrelation on page 886
PAIR: Session command for performing a paired t-test on page 151
PANEL: Session subcommand for paneling graphs on page 1061
PARETO: Session command for creating a Pareto chart on page 428
PAUSE and RESUME: Session commands for pausing and resuming a macro on page 1121
PBDESIGN: Session command for creating a Plackett-Burman design on page 258
PBDESIGN: Session subcommand for power and sample size for Plackett-Burman design on page 925
20
Minitab Statistical Software Using Session Commands
PCA: Session command for performing principal components analysis on page 841
PCAPA: Session command for performing a Poisson capability analysis on page 659
PCHART: Session command for creating a P chart on page 503
PDF: Session command for calculating the probability distribution of a continuous random variable on page 89
PDIAGNOSTIC: Session command for determining whether to use a P chart or a Laney P' chart on page 502
PGOODNESS: Session command for performing a chi-square goodness-of-fit test for Poisson distribution on page
166
PGROWTH: Session command for performing a parametric analysis using a parametric growth curve on page 729
PIECHART: Session command for creating a pie chart on page 985
PLOT: Session command for creating a scatterplot on page 947
PLS: Session command for performing partial least squares regression on page 194
PLTX: Session command for creating a 3D scatterplot on page 995
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
PONE: Session command for performing a hypothesis test of the proportion on page 152
PONE: Session subcommand for power and sample size for a 1 proportion test on page 926
POWER: Session command for power and sample size on page 927
PPLOT: Session command for creating a probability plot on page 963
PPRIMECHART: Session command for creating a Laney P' chart on page 509
PREDICT: Session command for predicting response values on page 1101
PRINT: Session command for displaying columns, constants, or matrices in the output pane on page 40
PROBIT: Session command for performing probit analysis on page 750
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
PROPORTIONAL and NOPROPORTIONAL: Session subcommands for making the boxes on a boxplot proportional
to the square root of the number of observations in the boxes on page 1066
PTILES: Session subcommand for specifying the location of the percentile lines on a graph on page 1066
PTWO: Session command for performing a hypothesis test of the difference between two proportions on page 154
PTWO: Session subcommand for power and sample size for a 2 proportion test on page 929
PYSC: Session command for running a Python script on page 54
R
RANDOM: Session command for generating random data on page 87
RANGE: Session command for calculating a range of values in a column on page 77
RANK: Session command for ranking values in a column on page 110
RBOX: Session subcommand for displaying a range box on a boxplot on page 1070
RCHART: Session command for creating an R chart on page 461
21
Minitab Statistical Software Using Session Commands
RCOUNT: Session command for counting missing and nonmissing values in a row on page 77
RDIDENTIFICATION: Session command for creating a distribution ID plot on page 703
RDOVIEW: Session command for creating a layout of distribution plots on page 706
READ data into columns on page 41
READ data into a matrix on page 43
READ, TSET, and SET: Session command for asking users questions and using the answers in a macro on page 1128
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
REGRESS: Session command for performing a regression analysis on page 169
REGRESS: Session subcommand for fitting a regression line to data on a graph on page 1075
RESTART: Session command for restarting on page 43
RESUME and PAUSE: Session commands for pausing and resuming a macro on page 1121
RETRIEVE: Session command for retrieving a saved worksheet or project on page 44
RETURN and CALL: Session commands for passing control to another macro on page 1119
RFORMULA: Session command for removing formulas on page 137
RMAXIMUM: Session command for identifying the maximum value in each row on page 77
RMCONTOUR: Session command for creating a contour plot on page 1107
RMEAN: Session command for calculating the arithmetic mean in each row on page 78
RMEDIAN: Session command for identifying the median in each row on page 78
RMERGE: Session command for merging worksheets on page 131
RMINIMUM: Session command for identifying the minimum value in each row on page 78
RN: The session command for counting the nonmissing values in a row on page 78
RNGAGE: Session command for creating gage run chart on page 669
RNMISS: Session command for counting the missing values in a row on page 78
RNMN: Session command for performing a 1-sample randomization test of a mean on page 100
RNPR: Session command for performing a 1-sample randomization test of a proportion on page 101
RNTM: Session command for performing a 2-sample randomization test of means on page 102
ROBUST: Session command for analyzing a Taguchi design on page 414
ROWTOC: Session command for stacking multiple columns into one column on page 113
RRANGE: Session command for calculating the range in each row on page 79
RSCR: Session command for running a R script on page 54
RSREG: Session command for analyzing a response surface design with least squares regression on page 346
RSSQ: Session command for calculating the uncorrected sum of squares on page 79
RSTDEV: Session command for calculating the standard deviation in each row on page 79
22
Minitab Statistical Software Using Session Commands
RSUM: Session command for adding the values in each row on page 79
RTPREDICT: Session command for predicting responses for new observations for a regression tree on page 763
RTREE: Session command for creating a regression tree on page 758
RUNCHART: Session command for creating a run chart on page 430
RUNS: Session command for performing a runs test on page 911
S
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SAMPLE: Session command for generating rows of random data from specified columns on page 89
SAVE: Session command for saving a worksheet or project on page 44
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
SCDESIGN: Session command for creating a simplex centroid design on page 369
SCHART: Session command for creating an S chart on page 467
SCREEN: Session command for analyzing a screening design on page 260
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
SES: Session command for performing single exponential smoothing on page 887
SET: Session command for entering data into a column on page 80
SFIT: Session subcommand for specifying the attributes of the surface on a 3D surface plot on page 1079
SHELFLIFE: Session command for performing a stability study on page 183
SIMPLEX: Session command for creating a simplex design plot on page 383
%SIMPROC: Session command for creating a simplex plot on page 388
SINTERVAL: Session command for calculating a sign confidence interval on page 909
SIXPACK: Session command for Normal Capability Sixpack on page 646
SLABEL: Session subcommand for labeling the slices on a pie chart on page 1080
SLDESIGN: Session command for creating a mixture design on page 372
SLICE: Session subcommand for specifying the attributes of slices on a pie chart on page 1081
SOFFSET: Session subcommand for offsetting points from the center on page 1082
SORT: Session command for sorting columns on page 108
SPCONT: Session command for creating a contour design plot on page 394
SPDESIGN: Session command for creating a 2-level split-plot design on page 284
SPFACTORIAL: Session command for analyzing a 2-level split-plot design on page 321
SPLIT: Session command for splitting a worksheet into multiple worksheets on page 112
SPSIMP: Session command for creating a simplex design plot on page 385
SSCI: Session command for estimating sample size on page 930
23
Minitab Statistical Software Using Session Commands
SSQ: Session command for calculating the uncorrected sum of squares on page 77
SSTI: Session command for sample size for tolerance intervals on page 931
SSWORKSHEET: Session command for creating a stability study worksheet on page 182
STACK: Session command for stacking blocks of columns and constants on top of each other on page 126
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
STATS: Session command for storing descriptive statistics on page 143
STDEV: Session command for calculating the standard deviation of all the values in a column on page 77
STEM-AND-LEAF: Session command for creating a stem-and-leaf plot on page 963
STEST: Session command for performing a 1-sample sign test on page 909
STOP: Session command for closing Minitab on page 45
SUBSET: Session command for copying specified rows to a new worksheet on page 114
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
SUM: Session command for adding the values in a column on page 77
SURFACEPLOT: Session command for creating a surface plot on page 996
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
SYMPLOT: Session command for creating a symmetry plot on page 432
T
TABLE and NOTABLE: Session subcommand for controlling the table within the figure region on page 1085
TABLE: Session command for creating one-way, two-way, and multi-way tables using categorical variables on page
901
TALLY: Session command for displaying a one-way table for each column on page 903
TCHART: Session command for creating a T chart on page 587
TCHISQUARE: Session command for performing a chi-square goodness-of-fit test on page 904
TEXT: Session command for changing the data type of a column to text on page 124
TEXT: Session subcommand for displaying text on a graph on page 1088
TITLE: Session subcommand for adding a title to a graph on page 1089
TOGAGE: Session command for performing a Type 1 gage study on page 666
TOLINTERVALS: Session command for calculating tolerance intervals on page 662
TONE: Session command for power and sample size for a 1-sample t-test on page 933
TOST: Session command for performing an equivalence test on page 914
TOST: Session command for power and sample size for an equivalence test on page 934
TPAIRED: Session subcommand for power and sample size for a paired t-test on page 935
TRACE: Session command for creating a response trace plot on page 389
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
24
Minitab Statistical Software Using Session Commands
TRANSPOSE: Session command for changing rows to columns, and columns to rows on page 105
TREND: Session command for performing a trend analysis on page 892
TSET: Session command for creating data that follow complicated patterns on page 81
TSGV: Session command for creating a Tsquared-generalized variance chart on page 562
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
TSPLOT: Session command for creating a time series plot on page 987
TSQUARED: Session command for creating a Tsquared chart on page 567
TSWINT: Session command for performing Holt-Winters seasonal exponential smoothing on page 896
TTWO: Session subcommand for power and sample size for a 2-sample t-test on page 936
TWORATE: Session command for performing a 2-sample Poisson rate test on page 156
TWORATE: Session subcommand for power and sample size for a 2-sample Poisson rate test on page 938
TWOSAMPLE: Session command for performing a 2-sample t-test when the samples are in different columns on
page 150
TWOT: Session command for performing a 2-sample t-test when samples are in one column on page 149
TWOVARIANCES: Session command for determining whether the variances or standard deviations of two groups
differ on page 158
TWOVARIANCE: Session subcommand for power and sample size for a 2 variances test on page 939
U
UCHART: Session command for creating a U chart on page 525
UDIAGNOSTIC: Session command for determining whether to use a U chart or a Laney U' chart on page 530
UNSTACK: Session command for separating a column into multiple columns on page 127
UPRIMECHART: Session command for creating a Laney U' chart on page 519
V
VARTEST: Session command for performing an equal variances test on page 249
VASAMPLING: Session command for creating or comparing variables acceptance plans on page 691
VASPECT: Session subcommand for specifying the aspect ratio of the data box on page 1091
VBOX: Session subcommand for specifying the display of the box that surrounds the data on a graph on page 1092
VFACTORIAL: Session command for analyzing variability in a 2-level factorial design on page 327
VFIELD: Session subcommand for specifying the dimensions of the field of view in object units on page 1092
VMASK: Session command for creating a two-sided CUSUM chart on page 556
VORDER: Session command for controlling the order for text categories to be processed by Minitab commands
on page 137
VPOSITION: Session subcommand for specifying the view position as a ratio on page 1092
VPREPROCESS: Session command to preprocess responses for analyze variability on page 326
25
Minitab Statistical Software Using Session Commands
VUP: Session subcommand for specifying which direction is up in relation to the data box on page 1092
W
WALSH: Session command for calculating pairwise averages on page 912
WDIFF: Session command for calculating pairwise differences on page 912
WHILE and ENDWHILE: Session commands for repeating a block of commands depending on a logical expression
on page 1116
WHISKER: Session subcommand for controlling the display of whiskers on a boxplot on page 1093
WINTERVAL: Session command for calculating a Wilcoxon confidence interval on page 910
WOPEN: Session command for opening a worksheet on page 45
WORKSHEET: Session command for making a worksheet active, for closing a worksheet, or for renaming a worksheet
on page 48
WPREDICTIONS: Session command for performing warranty predictions on page 755
WRITE: Session command for writing data to the screen or a data file on page 49
WSAVE: Session command for saving a worksheet file on page 51
WSLOPE: Session command for calculating pairwise slopes on page 912
WSTACK: Session command for stacking worksheets on page 128
WTEST: Session command for performing a 1-sample Wilcoxon test on page 909
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
X
XBARCHART: Session command for creating an Xbar chart on page 454
XDACTIVATE: Session command for activating a link on page 57
XDADD: Session command for adding a new link on page 57
XDDEACTIVATE: Session command for deactivating a client link on page 59
XDEXEC: Session command for executing a command in a remote application on page 60
XDGET: Session command for performing a one-time data transfer on page 60
XDREMOVE: Session command for deleting an established link on page 61
XPPOINT: Session command for sending output to Microsoft PowerPoint on page 53
XRCHART: Session command for creating an Xbar-R chart on page 433
XSCHART: Session command for creating an Xbar-S chart on page 439
XTABS: Session command for displaying one-way, two-way, and multi-way tables for categorical variables on page
905
XWORD: Session command for sending output to Microsoft Word on page 53
Z
ZMRCHART: Session command for creating a Z-MR chart on page 485
26
Minitab Statistical Software Using Session Commands
ZONE: Session command for creating a zone chart on page 473
ZONE: Session subcommand for power and sample size for a 1-sample Z-test on page 940
What are session commands?
Session commands are a command language that you use, instead of the menus and interface, to access most functions
in Minitab. Session commands are especially useful in macros.
You can type session commands in the Command Line pane.
Session command syntax notation
Generally, the syntax of a command includes the command name, and then one or more arguments upon which the
command operates.
Usually a command operates on one or more arguments (also called parameters) that you specify; they can be columns,
constants, matrices, numbers, file names, or text strings. For example, "C1" is the argument in the following command,
which tells Minitab to draw a histogram of the data in column C1:
HISTOGRAM C1
Minitab Help uses the following typographical conventions for describing the syntax of individual commands.
K
Denotes a constant such as 8.3 or K14.
C
Denotes a column such as C13 or 'Height'.
C...C
Denotes a list of one or more columns separated by spaces.
M
Denotes a matrix such as M5.
E
Denotes either a constant or column, and sometimes a matrix.
[ ]
Denotes an optional argument, for example [K1].
Symbols to use with session commands
Use the following symbols with any session commands or subcommands.
Comment symbol (#)
Place the comment symbol # anywhere on the line to tell Minitab to ignore the rest of the line. For example:
DESCRIBE C1 #This is a comment
27
Minitab Statistical Software Using Session Commands
Missing value symbol (*)
Place the missing values symbol * anywhere a number would normally interact, to represent values that could be
missing. The asterisk should be enclosed in single quotation marks ('*' ). You could use the following command
to copy data from one column to another, omitting rows that have missing values:
COPY C1 C2;
OMIT C1 = '*'.
Using a subcommand
Many session commands have subcommands. To use a subcommand, complete the following steps.
Note When you use a command with no subcommands, you do not have to type any punctuation mark after the command line.
1. Type the main command and end the main command line with a semicolon (;).
2. Press Enter to move to the next line.
3. Type as many subcommands as you need, ending each with a semicolon (;) and pressing Enter after each.
4. End the last subcommand with a period (.).
If you forget to end the last subcommand with a period, you can type the period all by itself on the next line.
Using session commands in the Command Line
pane and the History pane
Sometimes, it is convenient to copy a previously executed session command (or sequence of session commands) from
the Command Line pane or the History pane, make minor changes if necessary, then execute the changed command(s).
Use the Command Line pane to type, edit, and enter commands.
The Command Line pane and the History pane can be viewed together, docked on the right side of the application
frame. If the Command Line pane and the History pane are not visible, then do one of the following:
Choose View > Command Line/History.
Use Ctrl+K shortcut to open the Command Line/History panes.
Note If the panes are already in view, Ctrl+K puts focus into the Command Line pane, but will not toggle the pane closed.
Executing session commands in the Command Line pane
There are several ways to enter command language into the Command Line pane. For instance, you can:
Type the commands and subcommands directly into the pane. Use the Enter key to go to the next line. For
information on arguments, go to Session command syntax notation on page 27 or Using a subcommand on page
28.
Highlight the commands in the History pane and either copy and paste to the Command Line pane, or click Copy
to Command Line.
Paste text from other applications.
Press Run to execute the command language.
28
Minitab Statistical Software Using Session Commands
Using the History pane
The History pane provides a convenient list of the commands that you have used in your project.
You can select commands and subcommands as list items and can multi select both contiguous and non-contiguous
items in the list. Selected items can be copied to clipboard or dragged to the Command Line pane. When pasted into
the Command Line pane, you can edit the command language before running it.
You can also create a Minitab macro file for a routine analysis by first working through the steps using the menus,
highlighting portions of session commands, and saving them as a macro or text file type.
Print the contents of the History pane
You can print the contents of the History pane. Right-click the selected text, then choose Print History.
Save the contents of the History pane
You can save the contents of the History pane in a text file. Right-click the selected text, then choose Save History
As. Choose your file name and file type.
Rules for entering session command arguments
Arguments specify data characteristics, such as location or titles. They can be variables (columns, constants, matrices)
as well as text strings or numbers. For information on argument notation, go to Session command syntax notation on
page 27.
Variables
Enclose variable names in single quotation marks (for example, HISTOGRAM 'Salary'). Certain commands, such as
ANOVA, GLM, and the high-resolution graphics commands do not require quotation marks, but all commands
work properly when quotes are used.
In arguments, variable names and variable numbers can be used interchangeably. For example, the two following
commands do the same thing (if C1 is named 'Sales'):
DESCRIBE C1 C2
DESCRIBE 'Sales' C2
You can abbreviate a consecutive range of columns, stored constants, or matrices with a dash. For example, PRINT
C2-C5 is equivalent to PRINT C2 C3 C4 C5.
You can use a stored constant (such as K20) in place of any constant. You can even use stored constants to form
a range such as K20:15, which represents all integers from the value of K20 to 15.
Text strings
Enclose text strings, such as labels or file names, in double quotes (for example, TITLE "This is My Title"). In earlier
versions of Minitab, text was enclosed in single quotes. Although this still works, it is no longer recommended, and
can cause a conflict with column and constant names.
Numbers
Do not enclose numbers in quotes unless you want the numbers to appear as text.
29
Minitab Statistical Software Using Session Commands
To specify a range of numbers, abbreviate the sequence using these conventions:
1:4 expands to 1 2 3 4
4:1 expands to 4 3 2 1
1:3/.5 expands to 1.0 1.5 2.0 2.5 3.0
The session command SET on page 80 includes additional abbreviation conventions.
Rules for entering session commands
A session command consists of one main command, and may have one or more subcommands. Arguments and
symbols may also be included in the command.
Subcommands, which further define how the main command should be carried out, are optional unless otherwise
specified.
Arguments, which specify data characteristics, may be included one or more times for both the main command
and subcommands.
Symbols, which assist in controlling the session language, can also be included in session commands.
Commands and column names are not case-sensitive. You can type them in lowercase, uppercase, or any combination.
You can abbreviate any session command or subcommand by using the first four letters.
Enter only one command or subcommand per line.
Close all but the last line of a command with semicolons. Close the last line with a period.
Some subcommands have their own subcommands. The order in which you give these subcommands determines
what subcommand or command they modify. You can use many subcommands more than once in a command.
Note Some commands, called %macros, are macros that are invoked by typing % followed by the full macro name (you cannot abbreviate
macro names).
Interrupting session command execution
To interrupt the display of data from a command or the execution of a macro, type Ctrl+Break. In a macro, Minitab
finishes executing the current command, then exits the macro. Display of data is halted as soon as possible.
Updates for release 19.1
The following section includes the session commands that are new, changed or obsolete for Minitab 19.
Input and history
In Minitab 19.1, choose View > Command Line/History to open the Command Line pane and the History pane. In
the Command Line pane, enter session commands and run macros. Use the History pane to see session commands
that ran and to copy those session commands.
30
Minitab Statistical Software Using Session Commands
Obsolete continuation character (&)
In previous versions the & symbol indicated that a command continued on the next line, for example:
PLS C18 = C1-C17 c1*c2 c1*c3 c1*c4 c1*c5 c1*c6 c1*c7 c1*c8 c1*c9 c1*c10 c1*c11&
c1*c12 c1*c13 c1*c14 c1*c15 c1*c16 c1*c17;
In Minitab 19.1, session commands with an & symbol create errors. Instead, type everything on 1 line.
PLS C18 = C1-C17 c1*c2 c1*c3 c1*c4 c1*c5 c1*c6 c1*c7 c1*c8 c1*c9 c1*c10 c1*c11 c1*c12
c1*c13 c1*c14 c1*c15 c1*c16 c1*c17;
Adding comments and notes
In Minitab 19.1, each instance of the NOTE command creates a new output tab. To keep different notes together,
surround all of the notes and output that you want on one output tab with MTITLE and ENDMTITLE.
New commands
Resampling commands
BTFT
Bootstrapping for 1-sample function
BTPR
Bootstrapping for 1 proportion
BTTM
Bootstrapping for 2-sample means
RNMN
Randomization test for 1-sample mean
RNPR
Randomization test for 1-sample proportion
RNTM
Randomization test for 2-sample means
Design of experiments
BFFA
Analyze a binary response variable for a 2-level factorial design.
BGFA
Analyze a binary response variable for a general full factorial design.
BRSREG
Analyze a binary response variable for a response surface design.
BSCREEN
Analyze a binary response variable for a screening design.
31
Minitab Statistical Software Using Session Commands
MDESIGN
Modify a design that is in the worksheet.
VPREPROCESS
Pre-process responses for analyzing the variability of repeat or replicate measurements for a factorial design.
Obsolete commands
CONSTANT/NOCONSTANT
Use subcommands to for an individual analysis to control the estimation of the constant term.
DIR
List the names of files in a directory.
GPAUSE
Specify the number of graphs to display before you are prompted to save or discard open graphs. In Minitab
19.1, the number of graphs does not have a fixed limit.
GPRINT
Print a graph window. In Minitab 19.1, all output is in tabs instead of windows.
GVIEW
Open a .MGF format image. Minitab does not save images in this format anymore.
INSERT
Insert rows of data into the worksheet. Consider WOPEN and READ.
IW
Set the maximum width for input to the session window. Minitab 19.1 does not limit the input width in the
Command pane.
JOURNAL/NOJOURNAL
Save session window lines to a text file. In Minitab 19.1, save the History pane.
MRESET
Restore environment settings to pre-macro conditions. In Minitab 19.1, restoration occurs at the end of every
macro.
OW
Set the width of output in the session window. In Minitab 19.1, the output pane does not have a fixed width by
number of characters.
PLUG/NOPLUG
Respond to errors from the macro processor. In Minitab 19.1, the macro processor stops when it encounters an
error.
TITLE/NOTITLE
Display a title above session window output. In Minitab 19.1, use MTITLE/ENDMTITLE to add a title for an output
tab and to group output on a single output tab.
32
Minitab Statistical Software Using Session Commands
Changes to subcommands
Opening and saving files
READ
The FORMAT subcommand does not use the T format.
RETRIEVE
The PORTABLE subcommand is obsolete. MTP format files are not compatible with Minitab 19.1.
The REPLACE/NOREPLACE subcommands are obsolete. If you save a file with the same filename, Minitab overwrites
the file.
The GRAPH does not support the parameter MGF. Minitab no longer saves images in this format.
The PROJECT subcommand saves the project in the MPX format. The subsubcommand PASSWORD specifies a
password that protects the file.
SAVE
The RELEASE subcommand accepts only 19 as a value. The tabbed output and other changes cannot be saved
to an earlier version of Minitab.
The REPLACE/NOREPLACE subcommands are obsolete. If you save a file with the same filename, Minitab overwrites
the file.
The GRAPH does not support the parameter MGF. Minitab does not save images in this format anymore.
The PROJECT subcommand saves the project in the MPX format. The subsubcommand PASSWORD specifies a
password that protects the file.
Analysis of linear models
NLOG
OLOG
The TOLERANCE subcommand uses 1 parameter. Minitab uses the same value for all tolerances.
REGRESSION
The GPARETO subcommand makes a Pareto chart of the effects.
Changes to correlation
CORRELATION
The NOPVALUES subcommand is obsolete. P-values are in the new pairwise correlation table.
The following subcommands control the amount of output:
TMETHOD
TCORRELATION
TPCORRELATION
NODEFAULT
GMPLOT
The following subcommands are for storage:
SCORRELATION
33
Minitab Statistical Software Using Session Commands
SCIS
The CONFIDENCE subcommand sets the confidence level for confidence intervals.
New subcommands
Creation of designed experiments
BBDESIGN
CCDESIGN
EVDESIGN
FDESIGN
FFDESIGN
MIXREG
OADESIGN
OPTDES
PBDESIGN
SCDESIGN
SLDESIGN
SPDESIGN
The DESIGN subcommand stores the design columns in the worksheet. The new subcommand replaces
subcommands that required individual specification.
OPTDES
The COPY subcommand moves columns that are not part of the design, such as COVARIATES, to the new worksheet
where you store rows for an optimal design.
ROBUST
The DOE subcommand stores the model information in a Minitab design object.
34
Minitab Statistical Software Using Session Commands
Analysis of linear models
FFAC
GFAC
GLM
GZLM
REGRESS
RSREGRESS
SCREEN
VFAC
The FINFORMATION subcommand specifies forward stepwise selection with information criterion.
Capability analysis
BWCAPA
CAPA
MCAPA
The UCPM and LCPM subcommands store one-sided confidence limits of the Cpm statistic.
The ONECI sub-subcommand to the CONFIDENCE subcommand specifies one-sided confidence intervals for the
capability metrics.
The PPM subcommand replaces the percentage calculations with parts per million (PPM).
Changes to subcommands
FORMAT
The FORMAT subcommand, for commands such as READ, does not use the T format.
GSAVE
REPLACE is obsolete.
NOREPLACE is obsolete.
RELEASE
The RELEASE subcommand to SAVE accepts values of 19 or higher.
WOPEN
Changes to the subsubcommands of the subcommand FTYPE:
XLSX is new.
REPLACE is obsolete.
NOREPLACE is obsolete.
35
Minitab Statistical Software Using Session Commands
WSAVE
Changes to the subsubcommands of the subcommand FTPYE:
MINITAB accepts values of 19 or higher.
XLSX is new.
U8TEXT is new.
U8CSV is new.
REPLACE is obsolete.
NOREPLACE is obsolete.
WEBPAGE is obsolete.
Obsolete subcommands
FNUMERIC
The subsubcommand CULTURE to the subcommand CURRENCY is obsolete.
READ
The subcommand TAB is obsolete. Use WOPEN instead of READ to open tab-delimited data.
WSAVE
REPLACE and NOREPLACE are obsolete. If you save with the same filename, Minitab overwrites the file.
Commands that are unavailable in the web app
The following commands are not currently supported in exec or macro files in the Minitab web app:
DescriptionCommand
Display current directory or change current directory to another pathCD
Run a MTB fileEXEC
In macros, transfer control back to interactive Minitab; in execs, exit MinitabEXIT
Save a graph fileGSAVE
Invoke commands specified on customized My MenuMYME
Create new projectNEW
Stop writing output to an open/active text fileNOOU
Import data from a database fileODBC
Save output to a text fileOUTF
Set character width of outputOW
Shift control to keyboard for interactive user inputPAUS
Change profilePROF
Python script commandPYSC
Exit MinitabQUIT
36
Minitab Statistical Software Using Session Commands
DescriptionCommand
Import data from a text file into a worksheet (READ is allowed without FILE)READ; FILE
Restart MinitabREST
Resume macro execution from interactive keyboard entryRESU
Retrieve a project file in local macrosRETR
Import data from a text file (TSET is allowed without FILE)TSET; FILE
Save a project file in local macrosSAVE
Import data from an ASCII file (SET is allowed without FILE)SET; FILE
Exit MinitabSTOP
Open worksheetWOPE
Save worksheetWSAV
Writes data in the specified columns or constants to a data file (WRITE is allowed without FILE)WRITE; FILE
Send output to Microsoft
®
PowerPointXPPO
Send output to Microsoft
®
WordXWOR
37
Minitab Statistical Software Using Session Commands
Opening, Saving, and Printing Files
END: Session command for ending data input
END
Ends data input.
Type END following the last data line typed after READ (for information, go to READ data into a matrix on page
43 or READ data into columns on page 41), or SET on page 80. This ensures that any diagnostic messages
concerning data lines will be printed before the next operation is carried out.
GSAVE: Session subcommand for saving a graph in
a file
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
38
Minitab Statistical Software Opening, Saving, and Printing Files
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
ODBC: Session command for importing data from
a database file
ODBC
Imports data from a database file, such as one saved by Microsoft Access, Oracle, dBASE, Sybase, or SAS, into the
Minitab worksheet.
With ODBC (open database connectivity), you can import a subset of data, such as data collected during a certain
month, into the Minitab worksheet. ODBC adds data to the worksheet to the right of existing columns.
To use the ODBC session commands (for example, in a macro) use this method to identify the correct syntax:
1. Choose File > Query Database (ODBC) to query data.
2. When you have successfully retrieved the data you want, copy the corresponding command language from
the History pane. (Open the History pane by pressing Ctrl+K.)
3. The COLUMNS subcommand is not created when you use the ODBC dialog boxes. If you are creating a local
macro, add this subcommand yourself. Remember that in a local macro, columns must be declared before
they are used as arguments in any commands. The ODBC session command can also query more than one
table at a time.
CONNECT "connection string"
CONNECT specifies complete information pointing to the data source you want to query on your network.
The text string argument can be very long.
SQLSTRING "sqlstring"
SQL specifies the query that selects a subset of the data. The text string can be up to 16384 characters in
length.
COLUMNS k...k
COLUMNS specifies which columns of the Minitab worksheet should hold the data. k can be an integer from
1 to 4000.
39
Minitab Statistical Software Opening, Saving, and Printing Files
The COLUMNS subcommand is required in local macros. In global macros or Execs, or when using Minitab
interactively, executing the ODBC command without the COLUMNS subcommand places new data at the
end of the global worksheet.
Note You can specify a range of columns with a colon, for example: 1:5. Within Minitab or in a global macro you can also
use stored constants that contain integers, for example 1:k1 where k1=5.
OUTFILE and NOOUTFILE: Session commands for
saving a Minitab session in a text file
OUTFILE "filename"
OUTFILE K
OUTFILE saves your Minitab output in a text file. You can specify the filename as either the name of the file in
double quotation marks, or as a stored text constant.
After OUTFILE is typed, Minitab sends a copy of the commands and output that you see in the History pane to
a text file. OUTFILE is in effect until you type NOOUTFILE or you exit Minitab. If you type OUTFILE again, with the
same file name, output is appended to the end of this file.
The file is a standard text file, which can be printed and edited by any editor or word processor. Unless you specify
a different file extension, Minitab adds the extension LIS to the file name.
You can use OUTFILE to get a printout of your worksheet. Suppose your current worksheet contains data in the
first 10 columns. For example, the following commands save a copy of your worksheet is to a file named Sales.LIS
in your default directory.
OUTFILE "Sales"
PRINT C1-C10
NOOUTFILE
Closing the outfile
NOOUTFILE
NOOUTFILE closes an open outfile. If you type OUTFILE again with the same file name, input lines are appended
to the same file.
PRINT: Session command for displaying columns,
constants, or matrices in the output pane
PRINT E...E
Displays data in the output pane. You can display one or more (or any mixture of) columns, stored constants, or
matrices.
40
Minitab Statistical Software Opening, Saving, and Printing Files
If you mix columns, constants, and matrices in one PRINT command, they are listed in the following order: first
all matrices and constants (in the order you specified), then all columns (in the order you specified). For example,
the following command prints M1, K2, K1, and M2, then C1, C4, and C3.
PRINT C1 C4 M1 K2 C3 K1 M2
If a number is too large to fit in the space allowed (and FORMAT is not used), the number is displayed in exponential
format.
FORMAT (format statement)
The FORMAT subcommand specifies where and how to print data on the output line. If you PRINT columns
using FORMAT, only the data in columns is displayed, not column names. For more information, go to Valid
format items on page 1186.
Minitab chooses the output format (i.e., number of decimal digits printed). If you want to control this yourself,
use the FORMAT subcommand, or you can right-click on the output and select Decimal Places.
The following command prints numbers single-spaced, five numbers on each line, each number in a field of
ten spaces.
PRINT C11-C15;
FORMAT (5F10).
READ data into columns
READ C...C
Reads in data, row by row, that you type from the keyboard, or that you import from a text file. You cannot type
comments on a data line when the FORMAT subcommand is used.
READ enters new data into columns, replacing any data already in those columns, if it exists. For information on
entering data into a matrix, go to READ data into a matrix on page 43.
When you enter data manually, type END. after you enter your final value.
When you use READ, you can use a space or a comma to separate data entries. For example:
READ C1 C5.
1 2
3,4
END.
For details on using this command without subcommands to select data entry options, go to Using READ without
subcommands on page 1183.
FILE "filename"
Inserts data from the specified text file. You may specify the filename as either the name of the file in double
quotes, or a stored text constant. If the file has an extension other than DAT and/or if it is not in your current
directory, include the file extension and the path within the single quotation marks. For example, use the
following command to read a copy of the file SALES.ASC stored in the subdirectory JANUARY underneath
the directory SMITH on the C drive.
READ C1-C5;
FILE "C:\SMITH\JANUARY\SALES.ASC".
FORMAT (format statement)
Include a format statement, within parentheses to specify precisely how to enter data into the worksheet.
The entire expression within the parentheses is repeated once for each record. For more information, go to
Using READ with FORMAT on page 1183.
41
Minitab Statistical Software Opening, Saving, and Printing Files
The FORMAT subcommand is useful when you want to skip over spaces, read data that have no spaces
between them, insert decimal points in numbers, or read in text data, date/time data, or currency data.
Format items may be combined together. For example, the following command reads the name in the first
20 spaces of each data line into Name (C12), skips the next 10 spaces (spaces 21 through 30), then reads the
number in space 31 into C1, the number in space 32 into C2, ..., the number in space 40 into C10.
NAME C12 'Name'
READ 'Name' C1-C10;
FILE "MYDATA";
FORMAT(A20, 10X, 10F1).
Minitab has a special date/time (DT) format which works as shown below. This says to read the date/time
value in the first 8 spaces in the file into C1, and that the format of the date/time data in the file is m/d/yy.
READ C1;
FILE "DATEDATA";
FORMAT(DT8m/d/yy).
The following example shows the use of a decimal indicator, repeat factor in front of parentheses, and the
slash.
READ C11-C15;
FILE "EMPLOYEEDATA";
FORMAT (F2.1, 2(1X,F3), F4/F2).
This example uses two data lines for every row read. From the first line, the value of C11 is in spaces 1 and
2. The first value is a whole number and the second value is in the tenths place. The format skips space 3.
Then, C12 is read from spaces 4 to 6. The format skips space 7. Then, C13 is read from spaces 8 to 10, which
repeats the pattern inside of the parentheses. C14 is read from spaces 11 to 14. In response to the /, reading
moves to the second data line, and C15 is read from spaces 1 and 2. For more information, go to Valid format
items on page 1186.
NOBS K
The NOBS subcommand specifies the number of observations (rows) to be inserted. If an END on page 38
subcommand or end-of-file is encountered before K observations are inserted, NOBS is ignored. NOBS is
useful when you want to insert just the first portion of a file. It is also useful for Prompting a user for
information on page 1177.
SKIP K
Tells Minitab to skip K lines at the top of the data file before beginning to add data into the file. This is most
useful when you have one or more lines of text, such as column names and titles, at the top of a data file
that you want to import into Minitab.
With READ; FILE only
DECIMAL works with READ when only when reading a file. DECIMAL does not work with READ if you type data.
DECIMAL ","
DECIMAL "."
Specifies a comma or period as a decimal separator.
42
Minitab Statistical Software Opening, Saving, and Printing Files
READ data into a matrix
READ K K M
Puts numbers into a matrix. To input data to columns, go to READ data into columns on page 41. You can specify
the filename as either the name of the file in double quotes, or a stored text constant. If the file has an extension
other than DAT and/or if it is not in your current directory, include the file name extension and the path within
quotation marks.
You can use either spaces or commas to separate the data in the matrix.
You must specify the dimension of the matrix in the READ command. The first K gives the number of rows, the
second K the number of columns. The M is the matrix identifier for storage. If a file name is not used, READ is
followed by data lines, each containing one row of the matrix. The following command creates the following
matrix.
Command
READ 3 4 M2
1 2 3 4
5 6 7 8
9 10 11 12
END
Matrix
1 2 3 4
5 6 7 8
9 10 11 12
FILE "filename"
FILE K
Reads or inserts data from the specified text file.
RESTART: Session command for restarting
RESTART
Note You cannot use RESTART in a global macro. For more information, go to Session commands that are not allowed in macros
on page 1179.
Allows you to start over again.
RESTART erases the worksheet, cancels any controls in effect. RESTART also closes all open files such as OUTFILE.
43
Minitab Statistical Software Opening, Saving, and Printing Files
RETRIEVE: Session command for retrieving a saved
worksheet or project
RETRIEVE "filename"
RETRIEVE K
Note The menu command File > Open and the session command WOPEN on page 45 also open Minitab saved worksheets and
Excel files (and many other types of files). They provide several useful options that are not available with RETRIEVE.
Use the main command by itself to retrieve a saved worksheet and add the file to the current project. With
subcommands you can open a project or add one or more worksheets from a project to the current project. You
can specify the filename as either the name of the file in double quotes or as a stored text constant.
If you omit the file name and the current folder contains a file named Minitab.MWX or Minitab.MTW, then Minitab
opens that file.
Note You cannot use RETRIEVE in a local macro. For more information, go to Session commands that are not allowed in macros on
page 1179.
PROJECT
Note You cannot use PROJECT in a global macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
Specifies that the file after RETRIEVE is a Minitab project file (MPX, MPJ). If you do not want the prompt,
use the SAVE command with the PROJECT subcommand before you use the RETRIEVE command.
PASS "password"
To retrieve a password-protected file, specify the password.
SAVE: Session command for saving a worksheet or
project
SAVE [K]
Note You cannot use SAVE in a local macro. For more information, go to Session commands that are not allowed in macros on page
1179.
Saves a worksheet or project. You can specify the filename as either the name of the file in double quotation
marks, or a stored text constant. When no subcommands are specified, worksheet (MWX) is the default file type
for SAVE.
A saved worksheet file contains all data, stored constants, matrices, column names, and missing value information.
Minitab automatically replaces an existing file if you save with the same filename.
You can open saved worksheets with RETRIEVE on page 44 or WOPEN on page 45.
PROJECT
Specifies to save as a Minitab Project file (MPX).
44
Minitab Statistical Software Opening, Saving, and Printing Files
WSONLY
Use the subcommand WSONLY to save only worksheets with the saved project.
PASSWORD "password"
Specify a password to use to open the file. Enter the password within double quotation marks. To remove
password protection, use the argument "".
RELEASE K
Specifies the earliest version of Minitab that can open the file. For Minitab 19 and higher, 19 is the earliest
valid argument. You cannot specify a version newer than the version of Minitab that you have.
STOP: Session command for closing Minitab
STOP
Closes Minitab.
WOPEN: Session command for opening a worksheet
WOPEN K
Note You cannot use WOPEN in a local macro. For more information, go to Session commands that are not allowed in macros on
page 1179.
Opens a worksheet. For example, to open a data set named PULSE, enter the following command.
WOPEN "PULSE"
When you open a file, you copy the contents of the file into the current Minitab project. Any changes that you
make to the worksheet while in the project do not affect the original file.
FTYPE
Specifies the type of the file to open. Use one of the following subcommands for FTYPE:
MINITAB
XLSX (For Excel files with a .xlsx extension)
EXCEL (For Excel files with a .xls extension)
XMLEXCEL
TEXT
CSV
You must specify the file type, such as EXCEL, to use some of the other subcommands, such as VNAMES. If
you do not specify the file type, then Minitab considers the file extension. For example, if you enter WOPEN
"Mywork.xls" but do not specify a file type, then Minitab opens the file as an Excel file. However, if that
Excel file were saved with the name Mywork.abc, Minitab would not recognize the file as an Excel file, and
would display an error message or open the file incorrectly.
When you open a Minitab worksheet (with FTYPE; MINITAB), you do not need to specify a release number.
45
Minitab Statistical Software Opening, Saving, and Printing Files
FIELD
FIELD allows you to specify how fields are delimited.
Use one of the following subcommands to specify what character denotes the sections of data to be placed
into each field. If FIELD is not specified, Minitab uses the default the default delimiter for the file type.
TAB
COMMA
SEMICOLON
SPACE
PERIOD
CUSTOM "K"
TDELIMITER
Specifies how text fields are delimited.
DOUBLEQUOTE
Use when the columns of data are separated by a double quotation mark.
SINGLEQUOTE
Use when the columns of data are separated by a single quotation mark.
NONE
Use to have text that is separated by a blank entered into its own column.
CUSTOM K
Use if the columns are separated by a character other than those listed above and enter the character
as K.
DECSEP
Specifies how decimals are separated.
COMMA
Specifies that decimals are separated by a comma.
PERIOD
Specifies that decimals are separated by a period.
MISSING
Specifies how to write out a missing value.
TEXT K K
Denotes text columns, with the first K as the "missing" marker in the file's original form, and the second
K as the one or more words, characters, or spaces that you want Minitab to replace these markers with.
The default Minitab marker for missing text is a space.
NUMERIC 'K' K
Denotes numeric columns, with the first K as the missing marker in the file's original form, and the
second K as the digits, characters, or spaces that you want Minitab to replace these markers with. The
default Minitab marker for missing numeric data is an asterisk (*). The missing value symbol (first K)
must be enclosed in single quotation marks.
46
Minitab Statistical Software Opening, Saving, and Printing Files
DATA
Specifies where to begin reading data in the file to be opened.
IGNOREBLANKROWS
Skips over blank data rows. If you don't use this command, Minitab reads blank data rows as missing
values.
EQUALCOLUMNS
Adds missing values (*) to shorter columns to so that all columns have the same number of rows.
CLEAN
Removes nonprintable characters and extra spaces from text columns.
CASE
Corrects case mismatches in text columns by applying the capitalization of the first occurrence of a text
value to all matching values in the column.
SHEET K
Controls the way the K
th
worksheet in the file is read. SHEET can be used one time for each worksheet in the
file.
EXCLUDE
Stops the worksheet from being imported.
VNAMES K
Specifies the row number K that contains the variable names. −1 indicates no variable names. 0 indicates
that the first row that is being imported is the variable names row.
FIRST K
Specifies the row number K to begin reading the data. If you do not choose a variable names row,
Minitab begins reading data from the first available row in the file.
NROWS K
Specifies the number of data rows. Enter a number to read a portion of the file. For example, if you enter
50, Minitab reads only the first 50 rows beginning with the first row of data. By default, Minitab reads
all rows from the file into the current worksheet.
VARIABLE K
Controls the way the K
th
variable in the worksheet is read. It can be used once for each variable in the
worksheet.
EXCLUDE
Do not import this variable.
NAME K
Assigns a name to the variable. Names can be up to 31 characters long, and can include any letters
and numbers except the symbol ' (single quotation mark) or # (pound sign). Names cannot begin
or end with a blank or consist entirely of the symbol * (asterisk). You also can name your variables
directly after the worksheet is open.
TEXT
Specifies that the data type is text.
NUMERIC
Specifies that the data type is numeric.
47
Minitab Statistical Software Opening, Saving, and Printing Files
DATETIME
Specifies that the data type is date/time.
COLUMN C
Specifies which column of the worksheet (C) the variable is placed in.
WORKSHEET: Session command for making a
worksheet active, for closing a worksheet, or for
renaming a worksheet
WORKSHEET K
You cannot use WORKSHEET in a local macro. For more information, go to Session commands that are not allowed
in macros on page 1179.
Specifies K as the active worksheet. If no worksheet is specified, then session commands work on the active
worksheet.
When you are working in Minitab, any session command you use works on the active worksheet. The active
worksheet is the worksheet associated with the active Data tab.
You can also click a worksheet to activate it. If no worksheet is active, the session command acts on the worksheet
that was most recently active.
Note A worksheet can contain up to 4000 columns, 1000 constants, and up to 10,000,000 rows depending on how much memory
your computer has.
If you run subcommands, only the last subcommand works. To rename and close a worksheet, you must use more
than one instance of the main session command.
CLOSE
Closes the worksheet.
NOPROMPT
Specifies not to prompt to save when saving the worksheet.
CURRENT
Specifies to make the named worksheet active.
RENAME K
RENAME "text"
Renames the worksheet.
48
Minitab Statistical Software Opening, Saving, and Printing Files
WRITE: Session command for writing data to the
screen or a data file
WRITE E...E
Writes data in the specified columns or constants to the screen or to a data file (also called text or ASCII file). You
can specify the filename as either the name of the file in double quotes, or a stored text constant.
WRITE exports your data to a data file which you can import into other applications, print on your printer, or enter
into Minitab with READ (for more information, go to READ data into columns on page 41 or READ data into a
matrix on page 43) or SET on page 80. WRITE prints the columns vertically, very close together, with no column
names or row numbers and prints constants horizontally, whether they are stored numeric or text constants.
If you omit the file name, WRITE displays the columns or constants on your screen. If you specify a file name but
omit the extension, WRITE adds the default extension DAT.
Use the FORMAT subcommand to write data with a fixed format, for example, columns not separated by spaces.
By default, if you WRITE to a file that already exists, Minitab asks you whether or not you want to replace the file
before proceeding. You can use the subcommands REPLACE and NOREPLACE to override Minitab's default
behavior.
WRITE normally creates a data file. It can also be used to print columns or constants on your screen or on paper.
The output is very compact. With columns, there is no header giving the column name, and there are no row
numbers on the left. Columns are always output vertically. Constants are output horizontally, whether they are
stored numeric or text constants.
A data file created with the WRITE command can be transferred to different computer types and read by other
programs. On most computers, the default file name extension is DAT.
The format of the output is adjusted to make the data as compact as possible. Thus, the number of columns
that can be put on one line varies with the data.
If a format is not specified, and if very wide text items are to be printed (e.g., 80 wide), and if the output width
is not wide enough to print the entire item, the items will be truncated on the right.
When writing columns of unequal length to a file, Minitab makes them equal by adding missing value symbols
(*) to the short columns.
Note The menu command File > Save Worksheet As and the session command WSAVE on page 51 can also save the current
Minitab worksheet as a text file, and many other file types as well. It also provides several useful options not available with WRITE.
FILE "filename"
Specify to write to a data file (also called text or ASCII file). You may specify the filename as either the name
of the file in double quotes, or a stored text constant. If you specify a file name but omit the extension, WRITE
adds the default extension DAT. Use the subcommands UTEXT and TEXT to specify Unicode or ANSI text for
the file.
UTEXT
Saves the file in Unicode format.
TEXT
Saves the file in text format.
FORMAT
A format specification, similar to a Fortran format, may be given on this subcommand. For more information,
go to Valid format items on page 1186.
49
Minitab Statistical Software Opening, Saving, and Printing Files
The format specifies where the data will appear on the output lines, and the number of decimal places printed.
FORMAT works the same way with WRITE as it does with READ (with the exception of the currency format,
which works with READ but not WRITE). For more information, go to READ data into columns on page 41
or READ data into a matrix on page 43.
The following table shows how 123.456 is output with different formats.
OutputFormat
123.456F7.3
123.46F7.2
123I7
1.23456E+02E11.6
123.456G7
If you create a file with WRITE, using a FORMAT, then the READ command (for more information, go to READ
data into columns on page 41 or READ data into a matrix on page 43) can read the file with the same format.
To create a file that READ can read without a format (or other programs can read without a format), make
sure that there is at least one space between numbers. One way to do this is with the X format item. For
example, the following command creates a file which can be read without a format.
WRITE C1-C5;
FILE "FileA";
FORMAT ( 5(1x, F11) ).
Missing numeric data are output as * in the right-most space of the field. Missing text data are output as
blanks.
You must WRITE columns of equal length.
You can write columns that contain text data with or without using a FORMAT subcommand. You must,
however, use a FORMAT subcommand to READ the file.
Column format
TAB
TAB saves the specified columns, separated by tabs, in a data (also called text or ASCII) file. Do not use FORMAT
with tab-delimited data.
NONAMES
If you do not want to include the column names in the file, use the NONAMES subcommand in addition to
TAB.
File instructions
REPLACE and NOREPLACE allow you to bypass the "REPLACE?" prompt and are most useful in macros.
REPLACE
When you specify REPLACE, Minitab always overwrites the file.
NOREPLACE
When you specify NOREPLACE and you have an existing file with the same name, Minitab generates an error
message and aborts the command or exits the macro.
50
Minitab Statistical Software Opening, Saving, and Printing Files
WSAVE: Session command for saving a worksheet
file
WSAVE "filename"
Saves all the worksheet data in a file. Use this command to rename your worksheet or save it to a new location.
If your current worksheet is untitled ("Worksheet1" appears in the tab of the worksheet), you can use WSAVE to
specify a name for your saved worksheet file.
FTYPE
Specifies a file format. The sub-subcommands (MINITAB, XLSX, and so on) are the file formats.
You must specify an FTYPE; FORMATNAME combination to use some of the other subcommands, such as
VNAMES.
If you do not use FTYPE when saving a file, Minitab saves the file as a Minitab worksheet for the version that
you have.
MINITAB K
Specifies the Minitab worksheet file type.
When you use the MINITAB file type, specify the earliest version of Minitab that can open the worksheet.
For Minitab 19 and higher, 19 is the earliest valid argument. You cannot specify a version newer than
the version of Minitab that you have.
XLSX
Specifies the Excel file type with a .xlsx extension.
EXCEL
Specifies the Excel file type with a .xls extension.
XMLEXCEL
Specifies the XML Excel file type.
TEXT
Specifies the text file type.
UTEXT
Specifies the unicode text file type.
CSV
Specifies the comma-separated file type.
UCSV
Specifies the unicode comma-separated file type.
NOVNAMES
Saves a file from Minitab into another format without saving the variable names within the file.
DECSP
Specifies the form of decimal separation when you save a text file. The sub-subcommands give the decimal
separator.
51
Minitab Statistical Software Opening, Saving, and Printing Files
COMMA
Specifies a comma decimal separator.
PERIOD
Specifies a period decimal separator.
FIELD
Specifies how fields are delimited. Choosing one of the options chooses what character denotes the sections
of data to be put into each field. If FIELD is not specified, Minitab uses the default delimiter for the file type.
The sub-subcommands give the delimiter.
TAB
Specifies the tab as the delimiter.
COMMA
Specifies the comma as the delimiter.
SEMICOLON
Specifies the semicolon as the delimiter.
PERIOD
Specifies the period as the delimiter.
SPACE
Specifies the space as the delimiter.
CUSTOM K
Specifies a custom delimiter.
TDELIMITER
Specifies how text fields are delimited.
DOUBLEQUOTE
Use when the columns of data are separated by a double quotation mark.
SINGLEQUOTE
Use when the columns of data are separated by a single quotation mark.
NONE
Use to have text that is separated by a blank entered into its own column.
CUSTOM K
Use if the columns are separated by a character other than those listed above and enter that character
as K.
MISSING
Specifies how to write out a missing value. The sub-subcommands give the values.
TEXT K K
TEXT denotes text columns, with the first K as the "missing" value symbol in the file's original form, and
the second K as the word(s), character(s), or space(s) you want Minitab to replace these symbols with.
The default Minitab symbol for missing text is a space.
52
Minitab Statistical Software Opening, Saving, and Printing Files
NUMERIC K K
NUMERIC denotes numeric columns, with the first K as the "missing" value symbol in the file's original
form. The default Minitab symbol for missing numeric data is an asterisk (*). The missing value symbol
(first K) must be enclosed in single quotation marks, '*'. The second K can be a number or '*' and is how
the symbol appears in the output file. In Excel files, the missing value symbol becomes an empty cell.
XPPOINT: Session command for sending output to
Microsoft PowerPoint
XPPOINT
Sends Minitab output and graphs to Microsoft PowerPoint so that you can create reports and presentations.
All of Minitab's graphs and output can be sent to a PowerPoint presentation. In PowerPoint, text and titles appear
in the font that is used in Minitab.
Note When you send a graph to PowerPoint, Minitab's Embedded Graph Editor is not available.
APPEND
Exports output into an open Microsoft PowerPoint presentation. The output is starts on a new slide after the
currently active slide.
XWORD: Session command for sending output to
Microsoft Word
XWORD
Sends Minitab output and graphs to Microsoft Word so that you can create reports and presentations.
All of Minitab's graphs and output can be sent to a Word document. In Word, text and titles appear in the font
that is used in Minitab.
Note When you send a graph to Word, Minitab's Embedded Graph Editor is not available.
APPEND
Exports output into an open Microsoft Word document. The output is placed after the cursor location in the
Word document.
53
Minitab Statistical Software Opening, Saving, and Printing Files
Other Session Commands
PYSC: Session command for running a Python script
PYSC ["filename.py"] ["Args"...]
Runs the Python script that you specify.
The default file extension for Python scripts is .PY. If the file extension is .PY, you do not need to type the file
extension.
The optional argument Args lets you pass arguments to the Python script through sys.argv[1:]. Args can
be any text values separated by a space. Enclose arguments in quotation marks. The default value is None, which
means that the script does not receive any arguments.
For more information on integrating Python and Minitab, go to the Minitab Support Center.
NOSERR
Specifies not to display text from the stderr file in the Output pane in Minitab. For example:
PYSC "test.py";
NOSERR.
SOUT
Specifies to display text from the stdout file in the Output pane in Minitab. For example:
PYSC "test.py";
SOUT.
RSCR: Session command for running a R script
RSCR ["filename.R"] ["Args"...]
Runs the R script that you specify.
The default file extension for R scripts is .R. If the file extension is .R, you do not need to type the file extension.
The optional argument Args lets you pass arguments to the R script through commandArgs(trailingOnly
= TRUE). Args can be any text values separated by a space. Enclose arguments in quotation marks. The default
value is Null, which means that the script does not receive any arguments.
For more information on integrating R and Minitab, go to the Minitab Support Center.
NOSERR
Specifies to not display text from the standard error (message(), warning(), or stop()) console output
in the Output pane in Minitab. The warning console output is where R error messages display when you run
your code in an R integrated development environment. For example:
RSCR "test.R";
NOSERR.
54
Minitab Statistical Software Other Session Commands
SOUT
Specifies to display text from the standard console output in the Output pane in Minitab. The standard
console output is where the results of commands like print() display in an R integrated development
environment. For example:
RSCR "test.R";
SOUT.
NAME: Session command for assigning names to
columns, stored constants, and matrices
NAME E "name"...E "name"
Assigns names to columns, stored constants, and matrices.
Names must not do the following:
Contain more than 31 characters
Begin or end with a blank
Include the symbols ' or #
Start with or consist entirely of the symbol *
Be repeated. You cannot use the same name for two variables (columns, stored constants or matrices) in the
same worksheet.
You can refer to a named column, constant, or matrix by either number or name, for example, M1 or "Inverse".
Any time you use a name, enclose the name in double quotation marks. Minitab always prints variable names, if
they exist, on all output involving that variable. You can change the name of a variable by using another NAME
command.
The following example names C1, K1, and K2.
NAME C1"Height" K1"Min" K2"Max"
The following example erases the name of C1.
NAME C1 " "
You can use both upper and lower case letters in a name. When you use the name in a Minitab command, Minitab
considers upper and lower case letters equivalent. When a name is printed in the output, however, the upper and
lower case letters are used. For example, the following commands name the C1 column Height and print the data.
NAME C1"HEIGHT"
PRINT "HEIGHT"
Note You also can type column names into the worksheet as an alternative to the NAME command.
55
Minitab Statistical Software Other Session Commands
ABORT: Subcommand for exiting a multi-line
command
ABORT
Use ABORT as the next subcommand to exit from a multi-line command without executing it.
HELP: Session command for opening this guide
HELP
Opens the Session Commands guide. The Session Commands guide provides summaries of commands and
specific information on each command and subcommand. You can use session commands as an alternative to
using menu commands, or as a way to build macros for repetitive functions.
56
Minitab Statistical Software Other Session Commands
Dynamic Data Exchange
XDACTIVATE: Session command for activating a link
XDACTIVATE "application" "topic" "item"
Activates a previously deactivated client link. When you deactivate a link using XDDEACTIVATE on page 59, Minitab
ignores/discards any queued transactions or incoming transactions until you reactivate the link.
You can use XDACTIVATE in execs and global macros, but not in local macros.
You also can pause activity globally.
application
Application is the name of a program that can participate in a DDE transaction. Usually, application is the
name of an EXE file that starts the program, without the .exe extension. For example, in the case of Minitab,
Mtb.exe starts the program, so for the application argument use Mtb.
topic
Topic is a name that depends on the type of application. In applications that use documents or data files,
the topic is often the name of the file. For example, the topic for a Microsoft Word document might be
mywork.doc. The file name can also include a path, as in c:\mywork\mywork.doc.
If one file can contain many documents or subwindows, the Topic can be the name of the file in brackets,
followed by the name of the document or window. For example, Minitab projects can contain many worksheet,
so a typical Topic would be [Minitab] worksheet 1.
Other applications have their own names for topics.
Tip It is a good idea to save files from other applications before establishing any links to or from them. If you establish a link
before saving the file, you may need to change the link name from something like "untitled" to a file name. Likewise, before
linking from Minitab, rename a new worksheet from the default of "Worksheet 1" to something meaningful, such as "First Quarter."
item
Item is a name that depends on the type of application. In Minitab, the item always specifies a row/column
location or rectangular area in the form R4C1:R4C2. You can use all of Minitab column 1 as an item by
specifying C1. A single cell (row 4, column 1) is R4C1. Most spreadsheets use close variants of the R4C1:R3C2
format for items.
XDADD: Session command for adding a new link
XDADD "application" "topic" "item"
Establishes a new DDE link between the specified application program and Minitab. With this command, Minitab
acts as a client, receiving data from the other application.
You often specify XDADD with either the APPEND or REPLACE subcommands to tell where to put the data in the
Minitab worksheet, as shown below.
XDADD "Minitab" "[myproj.mpj]pulse" "C1";
REPLACE C2;
PERFORM 2;
COMMAND "LET C2=4*C1".
57
Minitab Statistical Software Dynamic Data Exchange
When another program supports Edit > Paste Link, you can find out the application, topic, and item names by
copying a range from the other application and pasting it into the worksheet in Minitab. The type of link established
by XDADD is often referred to as a hot link.
You can use XDADD in global macros and exec macros, but not in local macros.
Data
DATA
Specifies whether to add (append) the data to the end of the columns that you specify or to replace the entire
contents of the columns in the worksheet with new data from the item you specify in the XDADD or XDGET
command. The column argument specifies the starting, or anchor column for the data in the item. When the item
has more than one column, other columns are also included.
APPEND [C]
Specifies to add the data to the end of the columns that you specify.
REPLACE [C] (default)
Specifies to replace the entire contents of the columns in the worksheet with new data from the item you
specify in the XDADD or XDGET command.
Link status
ACTIVE
Specifies to open the new link in the active state. An active link starts receiving data from the other application
immediately.
INACTIVE
Specifies to open the new link in the inactive state. An inactive link does not receive data until you activate it.
Command arguments
PERFORM K
Specifies the action to take on each occurrence of a data transfer from the server application. The argument values
and associated actions are shown in the following table.
DescriptionValue of K
Update data and execute commands.0
Update data only.1
Execute commands only.2
COMMAND "command"
Specifies one Minitab command to execute upon each occurrence of a data transfer from the server application.
The command string can contain up to 128 characters (without line breaks) and include one Minitab command
or %macro. Do not use a period at the end.
Use a %macro or the dialog box if you need to use multiple commands.
If the command includes single quotation marks ('), enclose the single quotation marks with double quotation
marks ("). You can only use a single COMMAND subcommand for each link.
58
Minitab Statistical Software Dynamic Data Exchange
This subcommand works differently than the Commands field in the Add New Links dialog box.
Link priority
PRIORITY K
Specifies the priority of the link relative to other links. The priority can be any integer from 1 (the highest priority)
to 32 (the lowest priority). Priority matters when more than one link attempts a transfer at the same time, or when
several queued transactions are waiting for processing. Minitab always completes transfers on links that have
higher priority first, then processes data from links with lower priority. Links with the same priority are transferred
on a first-in first-out basis. The default priority is 16.
XDDEACTIVATE: Session command for deactivating
a client link
XDDEACTIVATE "application" "topic" "item"
Allows you to pause (deactivate) activity on a client link. When you deactivate a link, Minitab ignores/discards any
queued transactions or incoming transactions until you use XDACTIVATE on page 57 to reactivate the link.
You can use XDDEACTIVATE in execs and global macros, but not in local macros.
You can also pause activity globally.
application
Application is the name of a program that can participate in a DDE transaction. Usually, application is the
name of an EXE file that starts the program, without the .exe extension. For example, in the case of Minitab,
Mtb.exe starts the program, so for the application argument use Mtb.
topic
Topic is a name that depends on the type of application. In applications that use documents or data files,
the topic is often the name of the file. For example, the topic for a Microsoft Word document might be
mywork.doc. The file name can also include a path, as in c:\mywork\mywork.doc.
If one file can contain many documents or subwindows, the Topic can be the name of the file in brackets,
followed by the name of the document or window. For example, Minitab projects can contain many worksheets,
so a typical Topic would be [Minitab] worksheet 1.
Other applications have their own names for topics.
Tip It is a good idea to save files from other applications before establishing any links to or from them. If you establish a link
before saving the file, you may need to change the link name from something like "untitled" to a file name. Likewise, before
linking from Minitab, rename a new worksheet from the default of "Worksheet 1" to something meaningful, such as "First Quarter."
item
Item is a name that depends on the type of application. In Minitab, the item always specifies a row/column
location or rectangular area in the form R4C1:R4C2. You can use all of Minitab column 1 as an item by
specifying C1. A single cell (row 4, column 1) is R4C1. Most spreadsheets use close variants of the R4C1:R3C2
format for items.
59
Minitab Statistical Software Dynamic Data Exchange
XDEXEC: Session command for executing a
command in a remote application
XDEXEC "application" "command"
Allows you to execute a command in a remote application.
You can use XDEXEC in any type of macro.
application
The application argument is the DDE application name that is defined by the other application.
Application is the name of a program that can participate in a DDE transaction. Usually, application is the
name of an EXE file that starts the program, without the .exe extension.
command
If the other application allows more than one command per line, you can use more than one command in
the command string. If the server does not allow more than one command, consider writing a macro in the
server language, or using several XDEXEC commands in a row to achieve the same result. Use double quotation
marks inside the command string if single quotation marks are required in the remote application.
Note If the command that you want to execute already contains double quotation marks, then put the command and application
in single quotation marks. For example, because the syntax for executing an Excel macro requires double quotation marks, the
correct syntax is XDEXEC 'EXCEL' '[Run("macro")]'.
XDGET: Session command for performing a
one-time data transfer
XDGET "application" "topic" "item"
Allows you to do a one time data transfer (often referred to as a cold link). You can use XDGET in place of copying
and pasting or in any type of macro.
application
Application is the name of a program that can participate in a DDE transaction. Usually, application is the
name of an EXE file that starts the program, without the .exe extension. For example, in the case of Minitab,
Mtb.exe starts the program, so for the application argument use Mtb.
topic
Topic is a name that depends on the type of application. In applications that use documents or data files,
the topic is often the name of the file. For example, the topic for a Microsoft Word document might be
mywork.doc. The file name can also include a path, as in c:\mywork\mywork.doc.
If one file can contain many documents or subwindows, the Topic can be the name of the file in brackets,
followed by the name of the document or window. For example, Minitab projects can contain many worksheets,
so a typical Topic would be [Minitab] worksheet 1.
60
Minitab Statistical Software Dynamic Data Exchange
Other applications have their own names for topics.
Tip It is a good idea to save files from other applications before establishing any links to or from them. If you establish a link
before saving the file, you may need to change the link name from something like "untitled" to a file name. Likewise, before
linking from Minitab, rename a new worksheet from the default of "Worksheet 1" to something meaningful, such as "First Quarter."
item
Item is a name that depends on the type of application. In Minitab, the item always specifies a row/column
location or rectangular area in the form R4C1:R4C2. You can use all of Minitab column 1 as an item by
specifying C1. A single cell (row 4, column 1) is R4C1. Most spreadsheets use close variants of the R4C1:R3C2
format for items.
APPEND and REPLACE
Specifies whether to add (append) the data to the end of the columns that you specify or to replace the entire contents
of the columns in the worksheet with new data from the item you specify in the XDADD or XDGET command. The
column argument specifies the starting, or anchor column for the data in the item. When the item has more than one
column, other columns are also included.
APPEND [C]
Specifies to add the data to the end of the columns that you specify.
REPLACE [C] (default)
Specifies to replace the entire contents of the columns in the worksheet with new data from the item you specify
in the XDADD or XDGET command.
XDREMOVE: Session command for deleting an
established link
XDREMOVE "application" "topic" "item"
Deletes an established client link.
This command deletes the specified client link immediately when Minitab accepts the command. When a link is
deleted, all existing queued requests are processed (that is transferred into the worksheet), but no new ones are
added.
You can use XDREMOVE in execs and global macros, but not in local macros.
application
Application is the name of a program that can participate in a DDE transaction. Usually, application is the
name of an EXE file that starts the program, without the .exe extension. For example, in the case of Minitab,
Mtb.exe starts the program, so for the application argument use Mtb.
topic
Topic is a name that depends on the type of application. In applications that use documents or data files,
the topic is often the name of the file. For example, the topic for a Microsoft Word document might be
mywork.doc. The file name can also include a path, as in c:\mywork\mywork.doc.
If one file can contain many documents or subwindows, the Topic can be the name of the file in brackets,
followed by the name of the document or window. For example, Minitab projects can contain many worksheets,
so a typical Topic would be [Minitab] worksheet 1.
61
Minitab Statistical Software Dynamic Data Exchange
Other applications have their own names for topics.
Tip It is a good idea to save files from other applications before establishing any links to or from them. If you establish a link
before saving the file, you may need to change the link name from something like "untitled" to a file name. Likewise, before
linking from Minitab, rename a new worksheet from the default of "Worksheet 1" to something meaningful, such as "First Quarter."
item
Item is a name that depends on the type of application. In Minitab, the item always specifies a row/column
location or rectangular area in the form R4C1:R4C2. You can use all of Minitab column 1 as an item by
specifying C1. A single cell (row 4, column 1) is R4C1. Most spreadsheets use close variants of the R4C1:R3C2
format for items.
62
Minitab Statistical Software Dynamic Data Exchange
Manipulating and Calculating Data
Calculator
Calculations
ADD: Session command for addition
ADD E...E E
Adds E and E and stores in E. E can be any column, any constant, or matrix. For columns and constants, ADD allows
up to 50 arguments. If any element of a row is missing, the result is set to missing *. If the operation is impossible,
the result is also set to missing.
EIGEN: Session command for calculating eigenvalues
EIGEN M C [M]
Calculates eigenvalues (also called characteristic values or latent roots) and eigenvectors for a symmetric matrix.
The eigenvalues are stored in decreasing order of magnitude down the column. The eigenvectors are stored as
columns of the matrix. The first column corresponds to the first eigenvalue (largest magnitude), the second column
to the second eigenvalue, and so on.
LAG: Session command for calculating the lags of a column
LAG [K] C C
Calculates the lags of a column and stores them in a new column.
Moves the row elements of a column down K rows, where K is the lag specified, storing the result in a new column
of the same length. There will be K missing value symbols, *, at the top of the output column. The output column
has the same number of rows as the input column, so the last K values from the input column are not lagged. If
K is omitted, then K = 1 is used.
If C1 contains Z1, Z2, ..., Zn, then LAG K C1 C2 puts asterisks (*) into rows 1 through K of C2, and puts Z
i
Z
i-k
into row i, K + 1 < i < n.
LET: Session command for correcting a number in a worksheet or performing arithmetic
LET C [K] = K
Use to correct a number in the worksheet. You can change a single number with the LET command. For example,
LET C1[5] = 28.6 puts 28.6 into row 5 of C1. The rest of C1 remains the same.
63
Minitab Statistical Software Manipulating and Calculating Data
LET = expression
Use to perform arithmetic with an algebraic expression. The expression can contain arithmetic operations,
comparison operations, logical operations, and functions. The functions that you can use with LET are described
below.
Note In an expression, you cannot use a hyphen to specify a range of columns or constants. For example, Minitab would interpret
C1-C4 as C1 minus C4 and 1-10 as 1 minus 10.
You can also access an individual row in a column. For arguments, you can use columns, stored constants, or
numbers. You cannot use matrices. You cannot use extra text on any session command, including LET, except
after the # symbol.
For arithmetic operations, if any element of a row is missing, the result is set to missing. If an operation is impossible,
such as division by zero, the result is set to missing. You can have up to nine nested parentheses.
Examples of LET
LET C1 = (C2 + C3)*10 - 60
LET C1 = C1 - MEAN(C1)
LET K1 = 5.3
LET K2 = MEAN(C10)/STDEV(C1)
LET C5 = (C1 < 5)
LET K2 = C1[28]
LET C1[28] = 2.35
LET C5[15] = "blue"
Arithmetic functions to use with LET
CEIL (E, K)
Rounds numbers up. In the first argument, specify the number you want rounded. In the second argument, specify
the number of decimals to round to. If K = 0 (the default), the number is rounded to the nearest integer greater
than or equal to the number. If K > 0, the number is rounded up to the specified number of decimal places after
the decimal point. If K < 0, the number is rounded up to 1- the specified number of place values to the left of the
decimal point.
For example:
CEILING (2.136, 0) equals 3
CEILING (2.136, 1) equals 2.2
CEILING (2.136, 2) equals 2.14
CEILING (–2.136, 1) equals –2.1
CEILING (253.6, –1) equals 260
CEILING (253.6, –2) equals 300
64
Minitab Statistical Software Manipulating and Calculating Data
COMBINATIONS (E, E)
Calculates the number of combinations of n items chosen k at a time. In the first argument, specify the number
of items. In the second argument, specify the number to choose. The number of items must be greater than or
equal to 1, and the number to choose must be greater than or equal to 0. Arguments can be columns or constants.
Missing values are not allowed.
FACTORIAL (E)
Calculates the factorial of a number, the product of all the consecutive integers from 1 to the number, inclusive.
The value of the number must be greater than or equal to 0. Missing values are not allowed.
FLOOR (E, K)
Rounds numbers down. In the first argument, specify the number you want rounded. In the second argument,
specify the number of decimals to round to. If K = 0 (the default), the number is rounded to the nearest integer
less than or equal to the number. If K > 0, the number is rounded down to the specified number of decimal places
after the decimal point. If K < 0, the number is rounded down to 1- the specified number of place values to the
left of the decimal point.
For example:
FLOOR (2.136, 0) equals 2
FLOOR (2.136, 1) equals 2.1
FLOOR (2.136, 2) equals 2.13
FLOOR (–2.136, 1) equals –2.2
FLOOR (253.6, –1) equals 250
FLOOR (253.6, –2) equals 200
FTC (E)
Performs the Freeman Tukey transformation to stabilize variance for Poisson data. Requires one argument, which
must be a column or stored constant that contains nonnegative integers.
FTP (E, E)
Performs the Freeman Tukey transformation to stabilize variance for binomial data. Requires one argument for
number of trials and one for number of successes. Each argument can be a column or stored constant. Trials must
be a positive integer, and successes must be an integer between 0 and n inclusive.
GAMMA (E)
Calculates the gamma function where E is the specified shape parameter (the number you want to take the function
of).
IGAMMA (E, E)
Calculates the incomplete gamma function. In the first argument, specify the upper limit of the integral. In the
second argument, specify the shape parameter (the number you want to take the function of).
LNGAMMA (E)
Calculates the natural log of the gamma function. E is the shape parameter.
MOD (E, E)
Stores the remainder after a number is divided by a divisor. In the first argument, specify the number. In the
second argument, specify the divisor. Minitab calculates the value using the formula: m (n * FLOOR (m/n)) where
m is a number and n is the divisor.
65
Minitab Statistical Software Manipulating and Calculating Data
PERMUTATIONS (E, E)
Calculates the number of permutations of n things taken k at a time. In the first argument, specify the number of
items. In the second argument, specify the number to choose. The number of items must be greater than or equal
to 1, and the number to choose must be greater than or equal to 0. Missing values are not allowed.
Column functions to use with LET
DIFFERENCES (C, K)
Calculates row-by-row differences between the numeric values in a column. In the first argument, specify the
column. Minitab subtracts from each row the element K rows above, where K is the lag you specify, and stores
the differences in a new column. If you don't specify a value for lag, the differences are computed between
consecutive rows (lag = 1). The first K rows of the new column will contain the missing value symbol, *.
LAG (C, K)
Moves the row elements of a column down K rows, storing the result in a new column of the same length. If no
value is specified, the default lag (K =1) is used. There will be K missing value symbols, *, at the top of the output
column. The output column has the same number of rows as the input column, so the last value from the input
column is not lagged.
NSCORES (C)
Calculates and stores normal scores. This command is used mainly to produce normal probability plots and
perform various tests. Here is an example of normal scores.
LET C2 = NSCORES(C1)
Loosely speaking, -1.18 is the smallest value you would expect to get if you took a sample of size 5 from a standard
normal (i.e., the expected value of the first order statistic), and -0.50 is the second smallest value you would expect
to get (i.e., the expected value of the second order statistic), and so on.
C2C1
0.01.1
-1.180.1
1.182.3
0.501.8
-0.500.9
Minitab does not calculate the expected values of the order statistics exactly, but uses percentage points as an
approximation. Thus, if there are n data values, Minitab puts f - 1[ (i - 3 / 8) / (n + 1 / 4)] next to the ith smallest
data value, where f -1(x) is the inverse cumulative distribution function of the standard normal.
If several observations are equal, they are all given the same normal score. This is calculated using the average
of their ranks. The command NORMPLOT provides additional information. The output from NORMTEST includes
a normal probability plot, relevant statistics about the data, and test statistics useful for testing a hypothesis of
normality.
RANK (C)
Calculates and stores the ranks of the input column. Assigns the numeral 1 to the smallest value, the numeral 2
to the second smallest value, the numeral 3 to the third smallest value, and so on. Ties are assigned the average
rank.
Note RANK works only with numeric columns.
The following command language ranks the values in C1 and puts the ranked values in C2.
RANK C1 C2
66
Minitab Statistical Software Manipulating and Calculating Data
Before ranking
C1
0.5
1.0
1.5
1.0
2.0
0.0
After ranking
C2C1
2.00.5
3.51.0
5.01.5
3.51.0
6.02.0
1.00.0
SORT (C)
Sorts the numerical values in a column in ascending order. Specify the column. Data must be numerical.
Date/time functions to use with LET
CTIME ()
Returns the current time, for example, 9:26:20 AM.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
DATE ("text")
DATE (E)
Returns the date portion corresponding to the argument. The argument should be a text string, such as "3/6/99
10:23", a column, or a stored constant. Text columns and constants should be in one of the Default date/time
formats on page 1140.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
ELAPSED (E)
Returns the elapsed time, given the start and end times. Enter the column with the end times minus the column
with the start times. The columns or values must be in numeric or date/time format. The elapsed time in the
output is in minutes and seconds (mm:ss) if the maximum value of the output column is less than one hour; the
elapsed time in the output is in hours, minutes, and seconds (hh:mm:ss) if the maximum of the output column is
an hour or more.
67
Minitab Statistical Software Manipulating and Calculating Data
NETWORKDAYS (E, E, [E])
Returns the number of workdays between two dates, inclusive. Specify the start date and end date in the first two
arguments. You can enter a column of dates. You can also specify a column of holidays to skip for the optional
third argument. If the dates include time portions, Minitab ignores the times. You can also enter single dates in
double quotes with the additional use of DATE. For example, to find out the number of workdays between 1/1/09
and 1/31/09, use LET c1 = NETWORKDAYS(date("1/1/09"), date("1/31/09")). Text columns and constants should
be in one of the Default date/time formats on page 1140.
NOW ()
Returns the current date and time, for example, 3/8/2003 9:24.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
TIME ("text")
TIME (E)
Returns the time portion corresponding to the argument. The argument should be a text string, such as "3/6/99
10:23", a column, or a stored constant. Text columns and constants should be in one of the Default date/time
formats on page 1140.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
TODAY ()
Returns today's date, for example, 3/8/2003.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
WHEN ("text")
WHEN (E)
Returns the date and time corresponding to the argument. The argument should be a text string, such as "3/6/99
10:23", or a column or stored constant. Text columns and constants should be in one of the Default date/time
formats on page 1140.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
WDAYS ("text", K, ["text"])
WDAYS (E, E, [E] )
Offsets the date by the given number of workdays. Enter the start date and the number of workdays to add to
the date. Minitab returns the date that is the number of working days (defined as Monday through Friday) from
the start date you specify. You can also choose to skip holidays by entering a date or column or dates for the
optional third argument. When you enter single dates in double quotes, you need to also use DATE. For example,
to find out the date of tenth workday after 1/5/09, use LET c1 = WORKDAYS(date("1/5/09"),10). Text columns and
constants should be in one of the Default date/time formats on page 1140.
Note If stored in a column, the result is in a date/time format. If stored in a constant, the result is the numeric representation of the
date/time value. Currently, stored constants in Minitab do not have date/time formats.
68
Minitab Statistical Software Manipulating and Calculating Data
Logical functions to use with LET
ANY (E, K...)
Returns a 1 if a value equals any value from a set of values, returns a 0 otherwise. Use to flag specified values in
a column. In the first argument, specify the column. In the subsequent arguments, specify the values for which to
return a 1.
IF (C <>=K, "text", ["text"])
IF (C<>=C, C, [C])
Chooses which of two values to return based on whether a condition is true or false. Conditions can be any
numerical or logical expressions. For the first argument, specify the column and the condition using >, <, or =.
For the second argument, specify the value to return if the condition is true. The third argument is optional and
allows you to specify a value to return if the condition is false. If nothing is specified, Minitab returns a missing
value. For example, IF(c1 = 1, "male", "female") returns "male" for values in c1 equal to 1 and returns "female" for
the other values in c1.
IF (C<>=K,"text", C<>= "text"...["text"])
IF (C<>=K, C, C<>= C...[C])
Chooses a value to return for each of multiple conditions evaluated sequentially. Conditions can be any numerical
or logical expressions. For the first argument, specify the column and the condition using >, <, or =. For the second
argument, specify the value to return if the condition is true. You can enter multiple conditions and values. All
values must be the same data type (numeric or text). Minitab returns the value corresponding to the first true
condition, working from left to right. The final argument is optional and allows you to specify a value to return if
all the conditions are false. If nothing is specified, Minitab returns a missing value.
For example, IF(c1 <= 2, "low", c1 <=4, "medium", "high") returns "low" for c1 values less than or equal to 2,
"medium" for values less than or equal to 4 but greater than 2, and "high" for the remaining data in c1.
Statistics functions to use with LET
COUNT (C)
Counts the number of nonmissing and missing values in a column.
GMEAN (C)
Calculates the geometric mean, the nth root of the product of the n values. All values must be greater than 0.
MAXIMUM (C)
Calculates the maximum value in a column. Missing values are omitted from the calculation.
MEAN (C)
Calculates the arithmetic mean of all the values in a column. Missing values are omitted from the calculation.
MEDIAN (C)
Calculates the median of the values in a column. Missing values are omitted from the calculation.
MINIMUM (C)
Identifies the minimum value in a column. Missing values are omitted from the calculation.
N (C)
Counts the number of nonmissing values in a column.
NMISS (C)
Counts the number of missing values in a column.
69
Minitab Statistical Software Manipulating and Calculating Data
NSCORES (C)
Calculates normal scores.
PERC (C, E)
Calculates the sample percentiles For the first argument, enter the column of data. For the second argument,
enter the column or constant specifying the desired percentiles, from 0 to 1. Missing values are ignored. For
example, to find the first quartile (25
th
percentile) of a column of data, enter the column number and the percentile
0.25.
RANGE (C)
Calculates the range of the values in a column. Missing values are omitted from the calculation.
SSQ (C)
Calculates the uncorrected sum of squares for a column. Missing values are omitted from the calculations.
STDEV (C)
Calculates the standard deviation for all the values in a column. Missing values are omitted from the calculation.
SUM (C)
Adds all the values in a column. Missing values are omitted from the calculation.
Text functions to use with LET
CLEAN ("text")
CLEAN (E)
Removes all nonprintable characters. Specify the text, column, or stored constant.
CONCATENATE ("text", "text"...)
CONCATENATE (E, E...)
Combines two or more columns or values side-by-side. Specify the text, columns, or stored constants. Minitab
treats numbers appearing in a text column (as in a street address or date/time) as text characters and will convert
numeric values to text.
FIND (E, E, [E])
Identifies the starting position of a string of text within another string of text. For the first argument, specify the
text string or the column of text that you want to find. For the second argument, specify the text value or column
of text to search. FIND is case-sensitive.
By default, Minitab searches from the first position of each text entry. You can also specify another starting position
(the location in the string from where to start the search) by inserting a number for K, the optional third argument.
For example, if c1 contains 234b75, FIND("b7",c1) returns 4, because b7 begins at the 4
th
position in the text.
Minitab returns a missing value * if the string of text is not found.
FIXED (E, K, [1])
Rounds a number to the specified number of decimals and converts it to text with or without commas. For the
first argument, specify the number or the column of numeric data you want to convert. For the second argument,
specify the number of decimals to retain. If K = 1, Minitab rounds to the nearest tenth. If K = 0 Minitab rounds
to the nearest integer. If K = –1, Minitab rounds to a multiple of ten. If you don't enter a second argument, Minitab
rounds to 2 decimal places by default.
70
Minitab Statistical Software Manipulating and Calculating Data
Minitab inserts commas to separate some place values (hundreds and thousands, hundred-thousands and millions,
etc.) in the converted text. If you don't want the commas to appear, enter a value of 1 for the optional third
argument.
HTOD (E)
Converts hexadecimal values to their equivalent decimal form. The original hexadecimal data must be in text
format.
ITEM ("text", E, [E])
ITEM E, E, [E])
Extracts the nth word from a string of text. For the first argument, specify the text or column of text. For the second
argument, specify the position of the word to extract.
By default, one or more spaces define where each word begins and ends. If you want to specify other criteria for
determining the separation between the words, such as a comma, specify the separator using the optional third
argument.
The ITEM function is similar to the WORD function, except that ITEM extracts empty text that occurs between
consecutive separators (such as ,,) while WORD ignores the empty string and extracts the text that follows
consecutive separators.
LAG (C, [K])
Copies the text in the input column to the storage column, moving each value down by the numbers of rows you
specify. For the first argument, specify the input column. For the second argument, specify the number of rows
the text values should be moved down. By default, if no value is specified, Minitab moves the text values down
one row (lag = 1).
LEFT ("text", E)
LEFT (C, E)
Returns the specified number of characters from the beginning of a string of text. For the first argument, specify
the text or the column of text values. For the second argument, indicate how many characters from the left you
want to retain.
LEN ("text")
LEN (C)
Identifies the number of characters in a string of text. Specify the text or the column of text values.
LOWER ("text")
LOWER (C)
Converts all letters to lowercase. Specify the text or the column of text values.
MID ("text", E, [E])
MID (C, E, [E])
Returns the characters from the middle part of a string of text, given the starting position and the length. For the
first argument, specify the text or the column of text values. For the second argument, specify the position of the
first character to return.
You can specify an integer for the optional third argument to limit the number of characters that Minitab returns.
If you don't enter the third argument, Minitab returns all the characters that follow the starting position.
71
Minitab Statistical Software Manipulating and Calculating Data
PAD ("text", E)
PAD (C, E)
Pads text with trailing spaces. For first argument, specify the text or the column of text values. For the second
argument, enter the total number of characters needed for the text and the trailing spaces. The padding is indicated
by total number of characters minus the number of characters in the text.
PROPER ("text")
PROPER (C)
Capitalizes the first letter in each word and converts all other characters to lowercase. Specify the text or the
column of text values.
REPT ("text", E)
REPT (C, E)
Repeats text a given number of times. For the first argument, specify the text or the column of text. For the second
argument, specify how many times to repeat the text.
REPLACE ("text", E, E, E)
REPLACE (C, E, E, E)
Replaces a substring of text within a string of text. For the first argument, specify the original text or column of
text values. For the second argument, specify the position of the first character to replace. For the third argument,
specify how many characters to replace. For the last argument, enter the new text that you want to replace the
old text with.
RIGHT ("text", E)
RIGHT (C, E)
Returns the specified number of characters from the end of a string of text. For the first argument, specify the
text or the column of text values. For the second argument, indicate how many characters from the right you want
to retain.
SEARCH (E, E, E)
Identifies the starting position of a string of text within another string of text. For the first argument, specify the
text string you want to find. For the second argument, specify the column of text to search. FIND is case-sensitive
(distinguishes between b and B).
By default, Minitab searches from the first position of each text entry. You can also specify another starting position
(the location in the string from where to start the search) by inserting a number for K, the optional third argument
of the function.
SEARCH is similar to FIND, except that SEARCH is not case-sensitive (does not distinguish between b and B).
SUBSTITUTE ("text", E, E, [E])
SUBSTITUTE (C, E, E, [E])
Replaces existing text with new text and allows you to specify which occurrence of the old text you want to replace
if the text occurs more than once in a single entry. For the first argument, specify the text or column of text. For
the second argument, specify the text that you want to replace. For the third argument, specify the new text you
want to substitute. For the last (optional) argument, you can specify which occurrence of the old text you want
to replace, if the old text occurs more than once. For example, If c1 contains 600 Pine Lane SUBSTITUTE (c1, "0",
"2", 1) returns 620 Pine Lane.
TEXT (E)
Converts a numeric value to text. Converting numeric values to text allows you to edit and manipulate the values
using text manipulation functions. Specify the number or the column of numeric values.
72
Minitab Statistical Software Manipulating and Calculating Data
TRIM ("text")
TRIM (C)
Removes all spaces except single spaces between words. Specify the text or column of text.
WORD ("text", E, [E])
WORD (C, E, [E]
Extracts the n
th
word from a string of text. For the first argument, specify the text or column of text. For the second
argument, specify the position of the word to extract.
By default, one or more spaces define where each word begins and ends. If you want to specify other criteria for
determining the separation between the words, such as a comma, specify the separator using the optional third
argument.
The WORD function is similar to the ITEM function, except that ITEM extracts the empty text that occurs between
consecutive separators (such as the comma and space) while WORD ignores the empty string and extracts the
text that follows the consecutive separators.
Trigonometry functions to use with LET
ACSH (E)
Calculates the hyperbolic arccosine of a value. Specify the value or the column of values.
ASNH (E)
Calculates the hyperbolic arcsine of a value. Specify the value or the column of values.
ATNH (E)
Calculates the hyperbolic arctangent of a value. Specify the value or the column of values.
COSH (E)
Calculates the hyperbolic cosine of a value. Specify the value or the column of values.
DEGREES (E)
Changes radians to degrees. Specify the value or the column of values.
RADIANS (E)
Changes degrees to radians. Specify the value or the column of values.
SINH (E)
Calculates the hyperbolic sine of a value. Specify the value or the column of values.
TANH (E)
Calculates the hyperbolic tangent of a value. Specify the value or the column of values.
73
Minitab Statistical Software Manipulating and Calculating Data
Constants functions to use with LET
E ( )
Calculates e = 2.71828...
MISS ( )
Returns the * = missing value symbol in the specified column.
PI ( )
Calculates pi = 3.14159...
Row statistics functions to use with LET
RCOUNT (E, E...)
Counts the number of missing and nonmissing values in the row. You cannot use a hyphen to specify a range of
columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RCOUNT on page 77 to count the number of values in each row
while specifying a range of columns, such as C1-C4.
RMAXIMUM (E, E...)
Identifies the maximum value in each row. Missing values are omitted from the calculation. You cannot use a
hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RMAXIMUM on page 77 to calculate the maximum value in each
row while specifying a range of columns, such as C1-C4.
RMEAN (E, E...)
Calculates the arithmetic mean of the values in each row. Missing values are omitted from the calculation. You
cannot use a hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RMEAN on page 78 to calculate the mean of each row while specifying
a range of columns, such as C1-C4.
RMEDIAN (E, E...)
Identifies the median of the values in each row. Missing values are omitted from the calculation. You cannot use
a hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RMEDIAN on page 78 to calculate the median of each row while
specifying a range of columns, such as C1-C4.
RMINIMUM (E, E...)
Identifies the minimum value in each row. Missing values are omitted from the calculation. You cannot use a
hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RMINIMUM on page 78 to calculate the minimum value in each row
while specifying a range of columns, such as C1-C4.
RN (E, E...)
Counts the number of nonmissing values in the row. You cannot use a hyphen to specify a range of columns. For
example, Minitab would interpret C1-C4 as C1 minus C4.
74
Minitab Statistical Software Manipulating and Calculating Data
However, you can use the session command RN on page 78 to count the number of nonmissing values in each
row while specifying a range of columns, such as C1-C4.
RNMISS (E, E...)
Counts the number of missing entries in the row. You cannot use a hyphen to specify a range of columns. For
example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RNMISS on page 78 to count the number of missing values in each
row while specifying a range of columns, such as C1-C4.
RRANGE (E, E...)
Calculates the range of values in each row. Missing values are omitted from the calculation. You cannot use a
hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RRANGE on page 79 to calculate the range of each row while
specifying a range of columns, such as C1-C4.
RSSQ (E, E...)
Calculates the uncorrected sum of squares of the values in each row. Missing values are omitted from the calculation.
You cannot use a hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus
C4.
However, you can use the session command RSSQ on page 79 to calculate the uncorrected sum of squares for
each row while specifying a range of columns, such as C1-C4.
RSTDEV (E, E...)
Calculates the standard deviation of the values in each row. Missing values are omitted from the calculation. You
cannot use a hyphen to specify a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RSTDEV on page 79 to calculate the standard deviation of each row
while specifying a range of columns, such as C1-C4.
RSUM (E, E...)
Adds the values in each row. Missing values are omitted from the calculation. You cannot use a hyphen to specify
a range of columns. For example, Minitab would interpret C1-C4 as C1 minus C4.
However, you can use the session command RSUM on page 79 to add values in each row while specifying a range
of columns, such as C1-C4.
MULTIPLY: Session command for multiplication
MULTIPLY E...E E
Note This functionality is available only as a session command, and not in a menu.
Multiplies E by E and stores the result in E. E can be any column, any constant, or any matrix. For columns and
constants, MULTIPLY allows up to 50 arguments. If any element of a row is missing, the result is set to missing. If
the operation is impossible, the result is also set to missing, *.
75
Minitab Statistical Software Manipulating and Calculating Data
Column Statistics
COUNT: Session command for counting the number of values in a column
COUNT C [K]
Counts and optionally stores the number of nonmissing and missing values in a column. (Equivalent to N total
in the menu command dialog box.)
You can also use this command as a function with LET on page 63.
MEAN: Session command for calculating the arithmetic mean of a column
MEAN
Calculates the arithmetic mean of all the values in a column and optionally stores the result. Missing values are
omitted from the calculation.
You can also use this command as a function with LET on page 63.
MEDIAN: Session command for identifying the median of a column
MEDIAN C [K]
Identifies the median of the values in a column and optionally stores the result. Missing values are omitted from
the calculation.
You can also use this command as a function with LET on page 63.
N: Session command for counting the nonmissing values in a column
N C [K]
Counts and optionally stores the number of nonmissing values in a column. (Equivalent to N nonmissing in the
menu command dialog box.)
You can also use this command as a function with LET on page 63.
NMISS: Session command for counting the missing values in a column
NMISS C [K]
Counts and optionally stores the number of missing values in a column. (Equivalent to N missing in the menu
command dialog box.)
You can also use this command as a function with LET on page 63.
76
Minitab Statistical Software Manipulating and Calculating Data
RANGE: Session command for calculating a range of values in a column
RANGE C [K]
Calculates the range of values in a column and optionally stores the result. Missing values are omitted from the
calculation.
You can also use this command as a function with LET on page 63.
SSQ: Session command for calculating the uncorrected sum of squares
SSQ C [K]
Calculates the uncorrected sum of squares for a column and optionally stores the result. Missing values are omitted
from the calculations.
You can also use this command as a function with LET on page 63.
STDEV: Session command for calculating the standard deviation of all the values in a column
STDEV C [K]
Calculates the standard deviation for all the values in a column and optionally stores the result. Missing values
are omitted from the calculation.
You can also use this command as a function with LET on page 63.
SUM: Session command for adding the values in a column
SUM C [K]
Adds all the values in a column and optionally stores the result. Missing values are omitted from the calculation.
You can also use this command as a function with LET on page 63.
Row Statistics
RCOUNT: Session command for counting missing and nonmissing values in a row
RCOUNT E...E C
Counts and stores the number of missing and nonmissing values in the row. (Equivalent to N total in the menu
command dialog box.)
Note You can also use this command as a function with LET on page 63. If you use this command as an argument of LET, you cannot
use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1 minus C4.
RMAXIMUM: Session command for identifying the maximum value in each row
RMAXIMUM E...E C
Identifies and stores the maximum value in each row. Missing values are omitted from the calculation.
77
Minitab Statistical Software Manipulating and Calculating Data
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RMINIMUM: Session command for identifying the minimum value in each row
RMINIMUM E...E C
Identifies and stores the minimum value in each row. Missing values are omitted from the calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RMEAN: Session command for calculating the arithmetic mean in each row
RMEAN
Calculates and stores the arithmetic mean of the values in each row. Missing values are omitted from the calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RMEDIAN: Session command for identifying the median in each row
RMEDIAN
Identifies and stores the median of the values in each row. Missing values are omitted from the calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RN: The session command for counting the nonmissing values in a row
RN E...E C
Counts and stores the number of nonmissing values in the row. (Equivalent to N nonmissing in the menu command
dialog box.)
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RNMISS: Session command for counting the missing values in a row
RNMISS E...E C
Counts and stores the number of missing entries in the row. (Equivalent to N missing in the menu command
dialog box.)
78
Minitab Statistical Software Manipulating and Calculating Data
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RRANGE: Session command for calculating the range in each row
RRANGE E...E C
Calculates and stores the range of values in each row. Missing values are omitted from the calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RSSQ: Session command for calculating the uncorrected sum of squares
RSSQ E...E C
Calculates and stores the uncorrected sum of squares of the values in each row. Missing values are omitted from
the calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RSTDEV: Session command for calculating the standard deviation in each row
RSTDEV E...E C
Calculates and stores the standard deviation of the values in each row. Missing values are omitted from the
calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
RSUM: Session command for adding the values in each row
RSUM E...E C
Adds and stores the values in each row. Missing values are omitted from the calculation.
You can also use this command as a function with LET on page 63. If you use this command as an argument of
LET, you cannot use a hyphen to specify a range of values. For example, Minitab would interpret C1-C4 as C1
minus C4.
79
Minitab Statistical Software Manipulating and Calculating Data
Standardize
CENTER: Session command for centering data
CENTER C...C, C...C
Centers the data in C...C and stores the results in C...C. Allows you to center and scale columns of data.
When you do not include subcommands, Minitab transforms each input column by subtracting its mean and then
dividing by its standard deviation. This is often called standardizing a variable.
LOCATION [K...K]
When you do not include Ks, Minitab transforms each column by subtracting its mean. When you specify
one K, Minitab subtracts that value from each column. Otherwise, you must list one K for each column to be
centered. Then Minitab subtracts each K from the corresponding column.
SCALE [K...K]
When you use LOCATION, Minitab first subtracts the location. When you do not specify Ks on SCALE, Minitab
divides each column by its standard deviation. When you specify one K, Minitab divides each column by K.
Otherwise, you must list one K for each column to be centered. Then Minitab divides each column by the
corresponding K.
You must specify K as greater than 0.
MINMAX [K K]
When you do not specify Ks, Minitab transforms all columns (linearly) to have minimum –1 and maximum
+1. When you specify both Ks, Minitab transforms all columns (linearly) to have the first K as minimum and
the second K as maximum.
Make Patterned Data
SET: Session command for entering data into a column
SET C
Inputs data, from the keyboard or from an ASCII file, into one column.
If there is any data in the column you list, SET erases that data and replaces it with the new data you enter. SET
is especially useful for entering data that follow a pattern, such as the numbers 1 through 10, into a column. For
more information, go to Entering patterned data for the SET session command on page 1143.
If you execute SET from the menu, the FORMAT and NOBS options are not available, the form of the data is
restricted, and data cannot be read from a file.
As a simple example, the following command language puts the numbers 2, 7, 9, 3.8, and 22 in column C7.
SET C7
2 7 9
3.8 22
END
FILE 'filename'
Enters data from the specified ASCII file. If the file has an extension other than DAT and/or if it is not in your
current directory, include the file name extension and the path within the quotation marks.
80
Minitab Statistical Software Manipulating and Calculating Data
FORMAT
The FORMAT subcommand for SET is similar to that for READ (for information, go to READ data into a
matrix on page 43 or READ data into columns on page 41). For example, the following command
language reads 10 numbers from each data line-the first from spaces 1 and 2, the second from spaces
3 and 4, and so on.
SET C1;
FILE "MYFILE";
FORMAT (10F2).
Text data can be input using the FORMAT subcommand. The field width can be up to 80 characters.
You cannot mix text and numeric data in a single column.
Here is an example that inputs four "words" using A format into C1.
SET C1;
FORMAT (A11, T16, A2).
ABCDEFGHIJK LM
abcdefghijk lm
END
For more information, go to Valid format items on page 1186.
NOBS K
Specifies the number of observations (rows) to be read. If an END on page 38 subcommand or end-of-file
is encountered before K observations are read, NOBS is ignored. NOBS is useful when you want to read
just the first portion of a file. NOBS is also useful when you prompt the user for information. For more
information, go to Prompting a user for information on page 1177.
SKIP K
Tells Minitab to skip K lines at the top of the data file before beginning to READ or SET data into the
file. This is most useful when you have one or more lines of text, such as column names and titles, at
the top of a data file that you want to import into Minitab.
DECIMAL "." or ","
Specifies a period or comma as the decimal separator.
TSET: Session command for creating data that follow complicated patterns
TSET
Using TSET, you can create data that follow more complicated patterns. You can also use TSET to import text files.
TSET is the same as SET except there is no through construct, and you list text constants, stated or stored, instead
of numbers. Repeat factors are integers, stated or stored. A text string must be enclosed in double quotes as in
LET.
As in SET, you can input data from a file in addition to typing it from the keyboard.
FILE "filename"
Enters data from the specified file. If the file has an extension other than DAT and/or if it is not in your current
directory, include the file name extension and the path within the quotation marks.
81
Minitab Statistical Software Manipulating and Calculating Data
Examples
This example contains text constants and repeat factors.
TSET C1
5("Red" "Green") 2("Yellow") 3("Green")
END
LET K1 = "Low"
LET K2 = 10
TSET C1
5(K1 "Medium" "High")K2 K1 K1
END
DSET: Session command for making patterned data
DSET C
Creates a new column of dates and/or times that follow a pattern.
For example, the commands store the dates 1/1/15, 1/2/15, ..., 1/31/15 into C1.
DSET C1;
DSTART "1/1/15";
DEND "1/31/15";
DAY 1.
Note Minitab's default date/time formats can change depending on the Regional Settings of your device. For more information, go
to Default date/time formats on page 1140.
LIST
Date/time K...K or "text" ..."text".
FORMAT K
The format statement can be used for two purposes. It provides the format for the resulting patterned data.
If no format is given then the resulting column will be in the format of the last date/time value given either
on the DSTART or DEND subcommand lines. Also, it can be utilized as a user-defined format for specifying
the input format of the start and end date/time value. If no format statement is given, the date/time values
on the DSTART and DEND subcommands must be in a default format. For example:
DSET C1;
DSTART "1/1/15";
DEND "1/31/15";
FORMAT (DTm-d-yy);
DAY 1.
The format statement must begin with the characters DT followed by the desired date/time format. The
preceding example displays dates in the form 1-1-15.
Note Minitab's default date/time formats can change depending on the Regional Settings of your device. For more information,
go to Default date/time formats on page 1140.
DSTART K
DSTART specifies the beginning date/time value. The argument can be either a stored text constant or a text
string in double quotation marks. If you want to use a non-default date/time format for the text given with
DSTART and DEND, you must use the FORMAT subcommand. (If you are using a default date/time format,
FORMAT is not necessary.)
Note Minitab's default date/time formats can change depending on the Regional Settings of your device. For more information,
go to Default date/time formats on page 1140.
82
Minitab Statistical Software Manipulating and Calculating Data
DEND K
DEND specifies the ending date/time value. The argument can be either a stored text constant or a text string
in double quotation marks. If you want to use a non-default date/time format for the text given with DSTART
and DEND, you must use the FORMAT subcommand. (If you are using a default date/time format, FORMAT
is not necessary.)
Note Minitab's default date/time formats can change depending on the Regional Settings of your device. For more information,
go to Default date/time formats on page 1140.
RLIST K
RLIST specifies the number of times to repeat the list. K must be a positive integer greater than or equal to
1.
RVALUE K
RVALUE specifies the number of times to repeat each value. K must be a positive integer greater than or
equal to 1.
Subcommands for incrementing the date/time data
You must use one (and only one) of the following subcommands with DSET to indicate how to increment the date/time
data. K must be a positive integer greater than or equal to 1.
The patterned data ends when a date/time value is greater than or equal to the end date/time value (DEND). The end
date/time value is part of the column only if the pattern equals the end date/time value.
Note Minitab's default date/time formats can change depending on the Regional Settings of your device. For more information, go to
Default date/time formats on page 1140.
DAY
Increments day by K units.
WDAY
Increments workday (M–F) by K units.
WEEK
Increments week by K units.
MONTH
Increments month by K units.
QUARTER
Increments quarter by K units.
YEAR
Increments year by K units.
HOUR
Increments hour by K units.
MINUTE
Increments minute by K units.
SECOND
Increment second by K units.
83
Minitab Statistical Software Manipulating and Calculating Data
HUNDREDTH
Increment hundredth by K units.
THOUSANDTHS
Increment thousandths by K units.
Make Mesh Data
MESH: Session command for making mesh data
MESH C C
Creates a mesh of regular x-y data and stores the data in C and C. (Data with a regular shape form a grid with
evenly spaced intervals. Data with an irregular shape are not located on evenly spaced intervals.)
You can use the mesh data for drawing surface and wireframe plots, with an option to create the z-data at the
same time.
XMESH K K K (optional)
Specifies the lowest x-value, the highest x-value, and the number of x-values. The default is 5 5 11.
YMESH K K K (optional)
Specifies the lowest y-value, the highest y-value, and the number of y-values. The default is 5 5 11.
%USERFUNC K C C C (optional)
Specifies your own function as indicated by function number K in the macro %USERFUNC. For instructions
to add your own function, go to Add your own function on page 1131.
PARAMS K...K (optional)
Specifies parameters for the functions. See the table below for formulas and the number of parameters.
Functions for z-values (optional)
The function subcommands in the following table generate Z-values for the mesh and store them in C.
Parameters (in order)EquationSubcommand
μ
1
= MU1, σ
1
= S1, μ
2
= MU2, σ
2
= S2, ρ = RHO
1
0, σ
2
0, −1 < ρ < 1)
BVNORMAL C C
The following variables are derived from the
above variables, as follows:
A, B, CBOWL C
(A 0, B 0, C 0)
84
Minitab Statistical Software Manipulating and Calculating Data
Parameters (in order)EquationSubcommand
A, B, CCONE C
(A 0, B 0, C 0)
A, B, CCOWBOYHAT C
(A 0, B 0, C 0)
A, B, CEGGCARTON C
(A 0, B 0, C 0)
A, B, C, R
where if z < 0, set z = 0
HEMISPHERE C
(A 0, B 0, C 0, R 0)
A, B, CHILLANDDALE C
(A 0, B 0, C 0)
A, B, CSADDLE C
(A 0, B 0, C 0)
A, B, CWAVE C
(A 0, B 0, C 0)
Make Indicator Variables
INDICATOR: Session command for creating indicator variables
INDICATOR C C...C
Creates indicator variables (also called dummy variables) that you can use in a regression analysis. If you use
REGRESS on page 169, you do not need to create indicator variables.
The smallest number in C2 is 2 and the largest is 6. INDICATOR creates one indicator variable for each unique
value.
C11 is the indicator variable for the value 2. C11 contains a 1 in every row where C2 contains a 2, and 0
otherwise.
C12 is the indicator variable for the value 3. C12 contains a 1 in every row where C2 contains a 3, and 0
otherwise.
C13 is the indicator variable for 5. C13 contains a 1 in every row where C2 contains 5, and 0 otherwise.
C14 is the indicator variable for 6. C13 contains a 1 in every row where C2 contains 6, and 0 otherwise.
If C2 contains an * (missing data code), then all indicator variables are also set to *.
The number of storage columns must be equal to the number of distinct values (not including *) in the input
column. Up to 100 storage columns are allowed on INDICATOR.
85
Minitab Statistical Software Manipulating and Calculating Data
The following command language is an example of using INDICATOR.
INDICATOR C2, C11-C14
Before using INDICATOR
C1
2
2
5
3
6
5
*
After using INDICATOR
C14C13C12C11...C1
0001...2
0001...2
0100...5
0010...3
1000...6
0100...5
****...*
Random Data
BASE: Session command for fixing a starting number for the random number generator
BASE K
Fixes a starting point for Minitab's random number generator.
Minitab has a long string of random numbers available. Minitab normally chooses its own starting point for this
process. If Minitab always started at the beginning of the list, you would always get the same data. To avoid this,
Minitab uses the time of day to choose a random starting point in the string.
However, you might want to control where Minitab starts the string. For example, you may wish to repeat a
sequence by generating the same set of random data. In this case, the BASE command tells the random number
generator where to start. The generator will use this base until you set a new BASE or exit Minitab.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
86
Minitab Statistical Software Manipulating and Calculating Data
RANDOM: Session command for generating random data
RANDOM E [E]
Use RANDOM to generate and store a random sample of one or more observations from a specified distribution.
The subcommand specifies the distribution. If no subcommand is given, data are simulated from a normal
distribution with mu = 0 and sigma = 1.
Use the BASE on page 86 command to generate the same set of data more than once.
Suppose you want 50 random samples, each containing 20 observations, from a binomial distribution with number
of trials n = 5, and probability of success p = 0.3. To place each sample in a separate column, type the following
commands.
RANDOM 20 C1-C50;
BINOMIAL 5 0.3.
CHISQUARE K
Specifies distribution to sample, with degrees of freedom = K.
NORMAL [K [K]]
Specifies distribution to sample. Generates data from a standard normal. Optionally, specify mean = K, and
standard deviation = K.
MNORMAL C M
Specifies distribution to sample, with mean column = C, and variance-covariance matrix = M.
F K K
Specifies distribution to sample, with numerator degrees of freedom = K, denominator degrees of freedom
= K.
T K
Specifies distribution to sample, with degrees of freedom = K.
UNIFORM [K K]
Specifies distribution to sample. Generates data using lower endpoint = 0.0 and upper endpoint = 1.0.
Optionally, specify lower endpoint = K and upper endpoint = K.
BERNOULLI K
Specifies distribution to sample, with probability of success = K.
BINOMIAL K K
Specifies distribution to sample, with number of trials = K and event probability = K.
GEOMETRIC K
Specifies distribution to sample, with event probability = K.
NONEVENT
Models the number of nonevents before the first event occurs.
TOTAL
Models the total number of trials needed to produce one event.
NEGBINOMIAL K K
Specifies distribution to sample, with event probability = K and number of events needed = K.
87
Minitab Statistical Software Manipulating and Calculating Data
NONEVENT
Models the number of nonevents before the specified number of events occurs.
TOTAL
Models the total number of trials needed to produce the specified number of events.
HYPERGEOMETRIC K K K
Specifies distribution to sample, with population size = K, event count in population = K, and sample size =
K.
DISCRETE C C
Specifies distribution to sample, with values in C and probabilities in C.
INTEGER K K
Specifies distribution to sample, with discrete uniform on integers from minimum value = K to maximum
value = K.
POISSON K
Specifies distribution to sample, with mean = K.
BETA K K
Specifies distribution to sample, with first shape parameter = K and second shape parameter = K.
CAUCHY [K [K]]
Specifies distribution to sample. Generates data using location = 0.0 and scale = 1.0. Optionally, specify
location = K and scale = K.
EXPONENTIAL [K [K]]
Specifies distribution to sample. Generates data using mean = 1.0 and threshold = 0.0. Optionally, specify
mean = K and threshold = K.
GAMMA K K [K]
Specifies distribution to sample, with shape = K, scale = K, and optionally, threshold = K.
LAPLACE [K [K]]
Specifies distribution to sample. Generates data using location = 0.0 and scale = 1.0. Optionally, specify
location = K and scale = K.
LEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LOGISTIC [K [K]]
Specifies distribution to sample. Generates data using location = 0.0 and scale = 1.0. Optionally, specify
location = K and scale = K.
LLOGISTIC [K [K [K]]]
Specifies distribution to sample. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0.
Optionally, specify location = K, scale = K, and threshold = K.
LNORMAL [K [K [K]]]
Specifies distribution to sample. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0.
Optionally, specify location = K, scale = K, and threshold = K.
88
Minitab Statistical Software Manipulating and Calculating Data
SEXTREME [K [K]]
Specifies distribution to sample. Generates data using location = 0.0 and scale = 1.0. Optionally, specify
location = K and scale = K.
TRIANGULAR K K K
Specifies distribution to sample, with lower endpoint = K, mode = K, and upper endpoint = K.
WEIBULL K K [K]
Specifies distribution sample, with shape = K, scale = K, and optionally, threshold = K.
SAMPLE: Session command for generating rows of random data from specified columns
SAMPLE K C...C
Generates K rows of random data from specified input columns, C...C, and stores in specified storage columns,
C...C.
Takes a random sample of rows. If you use REPLACE, you can select the same row more than once. If you use
NOREPLACE, you cannot select the same row more than once. If you do not use a subcommand, Minitab samples
without replacement.
Tip If there are K rows in C...C columns, you can randomize their order by sampling all K rows and storing in the original input columns.
For example, SAMPLE K C1 C1.
REPLACE
When you sample with replacement, a selected observation goes back into the pool of possible choices and
can be selected again.
NOREPLACE
When you sample without replacement, a selected observation can be chosen only once.
Probability Distributions
PDF: Session command for calculating the probability distribution of a continuous random
variable
PDF E [E]
Calculates density values or probabilities for the specified values in E from a standard normal distribution or
another specified distribution and stores in E.
For a discrete distribution, the probability distribution function (pdf) calculates probabilities for the specified
values (sometimes called the discrete probability distribution function). If you specify a discrete distribution
(BINOMIAL, GEOMETRIC, NEGBINOMIAL, HYPERGEOMETRIC, DISCRETE, INTEGER, POISSON), the arguments
on the PDF line are optional. If you do not specify arguments, Minitab displays a table of the distribution. If
you execute PDF from the menu, you must supply the input columns.
For a continuous distribution, pdf calculates the continuous probability density function (often called the
density function).
If you do not specify a distribution, results are generated for a normal distribution with mu = 0 and sigma =
1.
Storage is optional. If you specify a storage column, pdf values are stored there and are not displayed. If you do
not specify a storage column, Minitab displays pdf values.
89
Minitab Statistical Software Manipulating and Calculating Data
CHISQUARE K [K]
Specifies distribution with degrees of freedom = K.
NORMAL [K [K]]
Specifies distribution. Generates data from a standard normal; optionally specify mean = K, and standard
deviation = K.
F K K
Specifies distribution, with numerator degrees of freedom = K, denominator degrees of freedom = K.
T K
Specifies distribution, with degrees of freedom = K.
UNIFORM [K K]
Specifies distribution. Generates data using lower endpoint = 0.0 and upper endpoint = 1.0. Optionally,
specify lower endpoint = K and upper endpoint = K.
BINOMIAL K K
Specifies distribution, with number of trials = K and event probability = K.
GEOMETRIC K
Specifies distribution, with event probability = K.
NONEVENT
Models the number of nonevents before the first event occurs.
TOTAL
Models the total number of trials needed to produce one event.
NEGBINOMIAL K K
Specifies distribution, with event probability = K and number of events needed = K.
NONEVENT
Models the number of nonevents before the specified number of events occurs.
TOTAL
Models the total number of trials needed to produce the specified number of events.
HYPERGEOMETRIC K K K
Specifies distribution, with population size = K, event count in population = K, and sample size = K.
DISCRETE C C
Specifies distribution, with values in C and probabilities in C.
INTEGER K K
Specifies distribution, with discrete uniform on integers from minimum value = K to maximum value = K.
POISSON K
Specifies distribution, with mean = K.
BETA K K
Specifies distribution, with first shape parameter = K and second shape parameter = K.
90
Minitab Statistical Software Manipulating and Calculating Data
CAUCHY [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
EXPONENTIAL [K [K]]
Specifies distribution. Generates data using mean = 1.0 and threshold = 0.0. Optionally, specify mean = K
and threshold = K.
GAMMA K K [K]
Specifies distribution, with shape = K, scale = K, and optionally, threshold = K.
LAPLACE [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LOGISTIC [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LLOGISTIC [K [K [K]]]
Specifies distribution. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0. Optionally, specify
location = K, scale = K, and threshold = K.
LNORMAL [K [K [K]]]
Specifies distribution. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0. Optionally, specify
location = K, scale = K, and threshold = K.
SEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
TRIANGULAR K K K
Specifies distribution, with lower endpoint = K, mode = K, and upper endpoint = K.
WEIBULL K K [K]
Specifies distribution, with shape = K, scale = K, and optionally, threshold = K.
CDF: Session command for calculating the cumulative probability of an x-value
CDF E [E]
Calculates probabilities for the specified values in E from a standard normal distribution or another specified
distribution and stores the probabilities in E.
The cumulative distribution function, cdf, for any value x is the probability that a random variable with the specified
distribution has a value less than or equal to x. That is:
CDF (x) = Pr (X < x)
91
Minitab Statistical Software Manipulating and Calculating Data
If you specify a discrete distribution (BINOMIAL, GEOMETRIC, NEGBINOMIAL, HYPERGEOMETRIC, DISCRETE,
INTEGER, POISSON), then the arguments on the CDF line are optional. If you do not specify an argument, then
Minitab displays a table of the distribution. (Entries where the cdf is less than 0.00005 or greater than 0.99995
might not be displayed in this table.) If you execute CDF from the menu, you must supply the input columns.
If you do not specify a distribution, then the results are generated for a normal distribution with mu = 0 and
sigma = 1.
Storage is optional. If you specify a storage column, the cdf values are stored there and are not displayed. If you
do not specify a storage column, Minitab displays the cdf values.
CHISQUARE K [K]
Specifies distribution with degrees of freedom = K, and, optionally, noncentrality parameter = K.
NORMAL [K [K]]
Specifies distribution. Generates data from a standard normal. Optionally, specify mean = K and standard
deviation = K.
F K K [K]
Specifies distribution, with numerator degrees of freedom = K, denominator degrees of freedom = K, and,
optionally, noncentrality parameter = K.
T K [K]
Specifies distribution, with degrees of freedom = K and, optionally, noncentrality parameter = K.
UNIFORM [K K]
Specifies distribution. Generates data using lower endpoint = 0.0 and upper endpoint = 1.0. Optionally,
specify lower endpoint = K and upper endpoint = K.
BINOMIAL K K
Specifies distribution, with number of trials = K and event probability = K.
GEOMETRIC K
Specifies distribution, with event probability = K.
NONEVENT
Models the number of nonevents before the first event occurs.
TOTAL
Models the total number of trials that are needed to produce one event.
NEGBINOMIAL K K
Specifies distribution, with event probability = K and number of events that are needed = K.
NONEVENT
Models the number of nonevents before the specified number of events occurs.
TOTAL
Models the total number of trials that are needed to produce the specified number of events.
HYPERGEOMETRIC K K K
Specifies distribution, with population size = K, event count in population = K, and sample size = K.
DISCRETE C C
Specifies distribution, with values in C and probabilities in C.
92
Minitab Statistical Software Manipulating and Calculating Data
INTEGER K K
Specifies distribution, with discrete uniform on integers from minimum value = K to maximum value = K.
POISSON K
Specifies distribution, with mean = K.
BETA K K
Specifies distribution, with first shape parameter = K and second shape parameter = K.
CAUCHY [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
EXPONENTIAL [K [K]]
Specifies distribution. Generates data using mean = 1.0 and threshold = 0.0. Optionally, specify mean = K
and threshold = K.
GAMMA K K [K]
Specifies distribution, with shape = K, scale = K, and optionally, threshold = K.
LAPLACE [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LOGISTIC [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LLOGISTIC [K [K [K]]]
Specifies distribution. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0. Optionally, specify
location = K, scale = K, and threshold = K.
LNORMAL [K [K [K]]]
Specifies distribution. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0. Optionally, specify
location = K, scale = K, and threshold = K.
SEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
TRIANGULAR K K K
Specifies distribution, with lower endpoint = K, mode = K, and upper endpoint = K.
WEIBULL K K [K]
Specifies distribution, with shape = K, scale = K, and optionally, threshold = K.
93
Minitab Statistical Software Manipulating and Calculating Data
INVCDF: Session command for calculating the variable for a cumulative probability
INVCDF E [E]
Calculates the inverse of the cdf for the specified values in E from a standard normal distribution or another
specified distribution and stores in E.
INVCDF returns the inverse of the cumulative distribution function (cdf), meaning that for a given probability, p,
INVCDF finds a value of x such that p = CDF(x).
For discrete distributions, INVCDF (p) = min {x such that CDF(x) > p}.
If you do not specify a distribution, results are generated for a normal distribution with mu = 0 and sigma = 1.
Storage is optional. If you specify a storage column, the INVCDF values are stored there and are not displayed. If
you do not specify a storage column, Minitab displays the INVCDF values.
CHISQUARE K [K]
Specifies distribution with degrees of freedom = K, and, optionally, noncentrality parameter = K.
NORMAL [K [K]]
Specifies distribution. Generates data from a standard normal distribution. Optionally, specify mean = K, and
standard deviation = K.
F K K [K]
Specifies distribution, with numerator degrees of freedom = K, denominator degrees of freedom = K, and,
optionally, noncentrality parameter = K.
T K [K]
Specifies distribution, with degrees of freedom = K and, optionally, noncentrality parameter = K.
UNIFORM [K K]
Specifies distribution. Generates data using lower endpoint = 0.0 and upper endpoint = 1.0. Optionally,
specify lower endpoint = K and upper endpoint = K.
BINOMIAL K K
Specifies distribution, with number of trials = K and event probability = K.
GEOMETRIC K
Specifies distribution, with event probability = K.
NONEVENT
Models the number of nonevents before the first event occurs.
TOTAL
Models the total number of trials that are needed to produce one event.
NEGBINOMIAL K K
Specifies distribution, with event probability = K and number of events needed = K.
NONEVENT
Models the number of nonevents before the specified number of events occurs.
TOTAL
Models the total number of trials that are needed to produce the specified number of events.
94
Minitab Statistical Software Manipulating and Calculating Data
HYPERGEOMETRIC K K K
Specifies distribution, with population size = K, event count in population = K, and sample size = K.
DISCRETE C C
Specifies distribution, with values in C and probabilities in C.
INTEGER K K
Specifies distribution, with discrete uniform on integers from minimum value = K to maximum value = K.
POISSON K
Specifies distribution, with mean = K.
BETA K K
Specifies distribution, with first shape parameter = K and second shape parameter = K.
CAUCHY [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
EXPONENTIAL [K [K]]
Specifies distribution. Generates data using mean = 1.0 and threshold = 0.0. Optionally, specify mean = K
and threshold = K.
GAMMA K K [K]
Specifies distribution, with shape = K, scale = K, and, optionally, threshold = K.
LAPLACE [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LOGISTIC [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
LLOGISTIC [K [K [K]]]
Specifies distribution. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0. Optionally, specify
location = K, scale = K, and threshold = K.
LNORMAL [K [K [K]]]
Specifies distribution. Generates data using location = 0.0, scale = 1.0, and threshold = 0.0. Optionally, specify
location = K, scale = K, and threshold = K.
SEXTREME [K [K]]
Specifies distribution. Generates data using location = 0.0 and scale = 1.0. Optionally, specify location = K
and scale = K.
TRIANGULAR K K K
Specifies distribution, with lower endpoint = K, mode = K, and upper endpoint = K.
WEIBULL K K [K]
Specifies distribution, with shape = K, scale = K, and optionally, threshold = K.
95
Minitab Statistical Software Manipulating and Calculating Data
Resampling Analyses
BTFT: Session command for calculating a 1-sample bootstrap confidence interval of a function
BTFT C K
BTFT calculates a confidence interval for a function in a population. The C specifies the column that contains a
sample from the population. The K specifies the number of resamples. The number of resamples can be from 1
to 10,000. The available functions are mean, median, sum, variance, and standard deviation.
Use the appropriate subcommand to choose the function. Specify only one of MEAN, MEDIAN, SUM, VARIANCE,
and STDEV.
MEAN
Calculates a confidence interval for the mean.
MEDIAN
Calculates a confidence interval for the median.
SUM
Calculates a confidence interval for the sum.
VARIANCE
Calculates a confidence interval for the variance.
STDEV
Calculates a confidence interval for the standard deviation.
Options
ITYPE K
Enter K to specify the type of confidence interval.
Format of the alternative hypothesisValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
BASE K
Fixes a starting point for Minitab's random number generator.
96
Minitab Statistical Software Manipulating and Calculating Data
Normally, Minitab uses the time of day to start the random number generator. Instead, you can use the BASE
subcommand to specify a number to use to start the generator. Use the BASE subcommand so that you can
generate the same sample repeatedly.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
SSAMPLE C
Stores the statistics from the resampling process.
Results
Use the following subcommands to control what output Minitab produces.
TSTATISTICS
Displays summary statistics for the sample: mean, standard deviation, variance, sum, minimum, median, and
maximum.
TBOOTSTRAP
Displays the confidence interval and the associated statistics.
GHISTOGRAM
Displays a histogram of the resampled statistics. GHISTOGRAM does not work if the number of resamples is 1 or
if you specify GINDIVIDUAL.
GINDIVIDUAL
Displays an individual value plot that compares the resample to the original sample. GINDIVIDUAL does not work
if the number of resamples is greater than 1 or if you specify GHISTOGRAM.
BTPR: Session command for calculating a 1-sample bootstrap confidence interval of a
proportion
BTPR C K
BTPR K K K
BTPR calculates a confidence interval for a proportion in a population. In the first parameterization, the C specifies
the column that contains a sample from the population. The column must contain 1 or 2 unique, non-missing
values. The K specifies the number of resamples. The number of resamples can be from 1 to 10,000.
In the second parameterization, the first K represents the number of events. The first K must be greater than or
equal to 1. The second K represents the number of trials. The number of trials must be greater than the number
of events and less than 100,000. The third K is the number of resamples. The number of resamples must be from
1 to 10,000.
EVENT K
When the sample data are in a column, use EVENT to specify the value in the column that the proportion should
be for. The value of K matches one of the values in the sample column. Enclose text values in quotation marks.
For example, to calculate an interval for the proportion of a "Fail" in the sample column, enter EVENT "Fail".
97
Minitab Statistical Software Manipulating and Calculating Data
Options
ITYPE K
Enter K to specify the type of confidence interval.
Format of the alternative hypothesisValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
BASE K
Fixes a starting point for Minitab's random number generator.
Normally, Minitab uses the time of day to start the random number generator. Instead, you can use the BASE
subcommand to specify a number to use to start the generator. Use the BASE subcommand so that you can
generate the same sample repeatedly.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
SSAMPLE C
Stores the proportions from the resampling process.
Results
Use the following subcommands to control what output Minitab produces.
TSTATISTICS
Displays summary statistics for the sample: sample size and proportion.
TBOOTSTRAP
Displays the confidence interval and the associated statistics.
GHISTOGRAM
Displays a histogram of the resampled proportions. GHISTOGRAM does not work if the number of resamples is
1 or if you specify GINDIVIDUAL.
GBARCHART
Displays a bar chart that compares the resample to the original sample. GBARCHART does not work if the number
of resamples is greater than 1 or if you specify GHISTOGRAM.
98
Minitab Statistical Software Manipulating and Calculating Data
BTTM: Session command for calculating a 2-sample bootstrap confidence interval for the
difference of means
BTTM C C K
BTTM calculates a confidence interval for the difference between the means of two populations. The columns can
have one of two formats:
The first column contains the measurements. The second column identifies which population each observation
is from.
Each column contains a sample from a different population. Use UNSTACKED to specify that the data are in
this format.
The value of K is the number of resamples. The number of resamples must be from 1 to 10,000.
The difference is the first sample minus the second sample. When the data are stacked, the first sample depends
on the values in the identification column. The first value is the lowest number, the first value alphabetically, the
earliest date, or the earliest value in a previously-specified value order. When the data are unstacked, the first
sample is in the first C after BTTM.
UNSTACKED
Indicates that the columns after BTTM contain different samples.
Options
ITYPE K
Enter K to specify the type of confidence interval.
Format of the alternative hypothesisValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
BASE K
Fixes a starting point for Minitab's random number generator.
Normally, Minitab uses the time of day to start the random number generator. Instead, you can use the BASE
subcommand to specify a number to use to start the generator. Use the BASE subcommand so that you can
generate the same sample repeatedly.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
SDIFFERENCES C
Stores the differences from the resampling process.
99
Minitab Statistical Software Manipulating and Calculating Data
Results
Use the following subcommands to control what output Minitab produces.
TOBSERVED
Displays summary statistics for the samples: mean, standard deviation, variance, sum, minimum, median, and
maximum.
TDIFFERENCES
Displays the difference between the sample means.
TBOOTSTRAP
Displays the confidence interval and the associated statistics.
GHISTOGRAM
Displays a histogram of the resampled differences. GHISTOGRAM does not work if the number of resamples is 1
or if you specify GINDIVIDUAL.
GINDIVIDUAL
Displays an individual value plot that compares the resamples to the original samples. GINDIVIDUAL does not
work if the number of resamples is greater than 1 or if you specify GHISTOGRAM.
RNMN: Session command for performing a 1-sample randomization test of a mean
RNMN C K K
RNMN performs a hypothesis test that the mean of the population equals the second K. The C specifies the column
that contains a sample from the population. The first K specifies the number of resamples. The number of resamples
can be from 1 to 10,000.
Options
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
BASE K
Fixes a starting point for Minitab's random number generator.
100
Minitab Statistical Software Manipulating and Calculating Data
Normally, Minitab uses the time of day to start the random number generator. Instead, you can use the BASE
subcommand to specify a number to use to start the generator. Use the BASE subcommand so that you can
generate the same sample repeatedly.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
SMEAN C
Stores the means from the resampling process.
Results
Use the following subcommands to control what output Minitab produces.
TOBSERVED
Displays summary statistics for the sample: mean, standard deviation, variance, sum, minimum, median, and
maximum.
TRANDOMIZATION
Displays the results of the hypothesis test.
GHISTOGRAM
Displays a histogram of the resampled means. GHISTOGRAM does not work if the number of resamples is 1 or if
you specify GINDIVIDUAL.
GINDIVIDUAL
Displays an individual value plot that compares the resample to the original sample. GINDIVIDUAL does not work
if the number of resamples is greater than 1 or if you specify GHISTOGRAM.
RNPR: Session command for performing a 1-sample randomization test of a proportion
RNPR C K K
RNPR K K K K
RNPR performs a hypothesis test on a proportion in a population. In the first parameterization, the C specifies
the column that contains a sample from the population. The column must contain 1 or 2 unique, non-missing
values. The first K specifies the number of resamples. The number of resamples can be from 1 to 10,000. The last
K is the hypothesized proportion. The hypothesized proportion must be a value between 0 and 1.
In the second parameterization, the first K represents the number of events. The first K must be greater than or
equal to 1. The second K represents the number of trials. The number of trials must be greater than the number
of events and less than 1 million. The third K is the number of resamples. The number of resamples must be from
1 to 10,000. The last K is the hypothesized proportion. The hypothesized proportion must be a value between 0
and 1.
Options
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
101
Minitab Statistical Software Manipulating and Calculating Data
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
BASE K
Fixes a starting point for Minitab's random number generator.
Normally, Minitab uses the time of day to start the random number generator. Instead, you can use the BASE
subcommand to specify a number to use to start the generator. Use the BASE subcommand so that you can
generate the same sample repeatedly.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
SPROPORTION C
Stores the proportions from the resampling process.
Results
Use the following subcommands to control what output Minitab produces.
TOBSERVED
Displays summary statistics for the sample: sample size and proportion.
TRANDOMIZATION
Displays the results of the hypothesis test.
GHISTOGRAM
Displays a histogram of the resampled proportions. GHISTOGRAM does not work if the number of resamples is
1 or if you specify GINDIVIDUAL.
GBARCHART
Displays a bar chart that compares the resample to the original sample. GBARCHART does not work if the number
of resamples is greater than 1 or if you specify GHISTOGRAM.
RNTM: Session command for performing a 2-sample randomization test of means
RNTM C C K
RNTM performs a hypothesis test that the means of two populations are equal. The columns can have one of two
formats:
The first column contains the measurements. The second column identifies which population each observation
is from.
Each column contains a sample from a different population. Use UNSTACKED to specify that the data are in
this format.
The value of K specifies the number of resamples. The number of resamples must be from 1 to 10,000.
102
Minitab Statistical Software Manipulating and Calculating Data
The difference is the first sample minus the second sample. When the data are stacked, the first sample depends
on the values in the identification column. The first value is the lowest number, the first value alphabetically, the
earliest date, or the earliest value in a previously-specified value order. When the data are unstacked, the first
sample is in the first C after RNTM.
UNSTACKED
Indicates that the columns after RNTM contain different samples.
Options
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
The mean of the first sample is less than the mean of the second sample.–1
The mean of the first sample is not equal to the mean of the second sample.0 (default)
The mean of the first sample is greater than the mean of the second sample.1
BASE K
Fixes a starting point for Minitab's random number generator.
Normally, Minitab uses the time of day to start the random number generator. Instead, you can use the BASE
subcommand to specify a number to use to start the generator. Use the BASE subcommand so that you can
generate the same sample repeatedly.
Note If you use the same base on different platforms or different versions of Minitab, you might not get the same random number
sequence.
SDIFFERENCES C
Stores the differences from the resampling process.
Results
Use the following subcommands to control what output Minitab produces.
TOBSERVED
Displays summary statistics for the samples: mean, standard deviation, variance, sum, minimum, median, and
maximum.
TRANDOMIZATION
Displays the results of the hypothesis test.
TDIFFERENCES
Displays the difference between the sample means.
GHISTOGRAM
Displays a histogram of the resampled differences. GHISTOGRAM does not work if the number of resamples is 1
or if you specify GINDIVIDUAL.
103
Minitab Statistical Software Manipulating and Calculating Data
GINDIVIDUAL
Displays an individual value plot that compares the resamples to the original samples. GINDIVIDUAL does not
work if the number of resamples is greater than 1 or if you specify GHISTOGRAM.
Matrices
READ data into a matrix
READ K K M
Puts numbers into a matrix. To input data to columns, go to READ data into columns on page 41. You can specify
the filename as either the name of the file in double quotes, or a stored text constant. If the file has an extension
other than DAT and/or if it is not in your current directory, include the file name extension and the path within
quotation marks.
You can use either spaces or commas to separate the data in the matrix.
You must specify the dimension of the matrix in the READ command. The first K gives the number of rows, the
second K the number of columns. The M is the matrix identifier for storage. If a file name is not used, READ is
followed by data lines, each containing one row of the matrix. The following command creates the following
matrix.
Command
READ 3 4 M2
1 2 3 4
5 6 7 8
9 10 11 12
END
Matrix
1 2 3 4
5 6 7 8
9 10 11 12
FILE "filename"
FILE K
Reads or inserts data from the specified text file.
DEFINE: Session command for defining a constant matrix
DEFINE K K K M
Defines a constant matrix where K is the value, K is the number of rows, K is the number of columns, and M is the
stored matrix. For example, the following command language creates a matrix, M1, has 4 rows and 3 columns,
and all of whose entries are 1.
DEFINE 1 4 3 M1
DIAGONAL: Session command for creating a matrix from a column
DIAGONAL C M
Forms a matrix out of a column. If C has n entries, then M will be an n x n matrix with C as its diagonal and zeros
elsewhere.
104
Minitab Statistical Software Manipulating and Calculating Data
DIAGONAL M C
Takes the diagonal of a matrix and puts it into a column.
INVERT: Session command for replacing a matrix value with its inverse
INVERT M M
Replaces each value in the matrix with its inverse. The first M is the matrix to be replaced. The second M is the
new inverted matrix. The matrix must be square.
TRANSPOSE: Session command for changing rows to columns, and columns to rows
TRANSPOSE C...C
TRANSPOSE C M
TRANSPOSE M C
TRANSPOSE M [M]
TRANSPOSE reconfigures data so that rows become columns and columns become rows.
TRANSPOSE C...C transposes the values in the columns.
TRANSPOSE C M transposes the values in a column to a matrix.
TRANSPOSE MC transposes the values in a single row matrix to a column.
TRANSPOSE M [M] transposes the values in a matrix to another matrix.
VARNAMES C
Specifies a column that contains variable names for the transposed columns.
STORE C...C
STORE M
Specifies where the transposed data are to be written. You can store the data in columns or a matrix. When
you transpose data to columns, the number of columns specified must equal the number of rows in the
original columns.
If you do not use STORE, the data are stored in a new worksheet.
LABELS C
Specifies the column in which the labels of the transposed column or columns or matrix are stored.
NEWWS
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in "text" or in a constant (K)
argument, then Minitab uses the default naming of worksheets.
Important You cannot use NEWWS in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
105
Minitab Statistical Software Manipulating and Calculating Data
AFTER
Appends the transposed data into empty columns after the last column of data in the current worksheet.
Important You cannot use AFTER in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
EIGEN: Session command for calculating eigenvalues
EIGEN M C [M]
Calculates eigenvalues (also called characteristic values or latent roots) and eigenvectors for a symmetric matrix.
The eigenvalues are stored in decreasing order of magnitude down the column. The eigenvectors are stored as
columns of the matrix. The first column corresponds to the first eigenvalue (largest magnitude), the second column
to the second eigenvalue, and so on.
Data
INFO: Session command for summarizing the current worksheet
INFO [C...C]
Summarizes the current worksheet.
If no columns are specified, INFO prints a list of all columns used with their names and counts, all stored constants,
all matrices. If there are missing observations, a count of these is also given. If a column contains text data, the
letter T is printed to the left of the column. If columns have assigned formulas, these are printed along with the
method selected for updating the calculations (manual or automatic). If you list columns, information is given on
just those columns.
MERGE: Session command for merging two worksheets into one
worksheet
MERGE
Merges two worksheets into one new worksheet. You can combine any two open worksheets using MERGE. Unlike
the merging option available when opening additional worksheets, MERGE duplicates, and then combines, the
information from two original worksheets into a new worksheet. The default setting combines the worksheets,
side by side and with their existing attributes, into the new worksheet, named Merge Worksheet by default.
You can also customize the merged worksheet using the optional subcommands. You can use BY to combine the
worksheets according to the order and length of one or more columns. In addition, you can specify whether or
not to include unmatched values, missing values or multiple values from one or both of the BY columns. You can
also specify which columns will be included from each original worksheet using INCLUDE.
Note Stored constants, matrices, DOE objects, and worksheet descriptions do not transfer into the merged worksheet.
106
Minitab Statistical Software Manipulating and Calculating Data
NAME K
Specifies the name K for the new worksheet. The argument is a text constant, stated or stored. By default,
the name is Merge Worksheet.
WORKSHEET K
Specifies the name of one of the worksheets to be merged. The argument is a text constant, stated or stored.
This subcommand must be given twice.
BY C...C
Standardizes the combination of two worksheets. The order of the data within the BY columns becomes
ascending. The length and order of the remaining columns in the merged worksheet are manipulated
according to the BY column adjustments, no matter the order or length of the original columns.
The length of the columns also depends on how you would like to handle multiple, unmatched, and
missing observations within the BY columns. The adjusted length of the BY column or columns is still
applied to the order and length of the remaining columns.
Requirements for BY columns are as follows:
The column names for each of the two worksheets do not have to be unique. Minitab will create a
unique name for the columns in the merged worksheet based on the original worksheet names.
You must specify at least one pair of BY columns (one column from each worksheet) in the BY Columns
sub-dialog box. Additional BY columns must also come in pairs.
BY columns must have the same data type (numeric, date/time, or text).
When merging columns with value ordered text, the value orders in the BY columns must be the
same for both worksheets. For more information on value ordering, go to VORDER: Session command
for controlling the order for text categories to be processed by Minitab commands on page 137.
Column lengths must be the same between multiple BY columns.
Columns that are not the same lengths as the BY columns are excluded from the merged worksheet.
A note in the output documents the number of columns excluded.
NOMULTIPLES
Ignores all but the first row with the same values for the BY columns. If more than one row in a worksheet
has values for the BY columns, then only the first such row is used.
Including multiple observations indicates that you wish to keep the observations of the BY column that
are repeated within the column, regardless of the BY column values in the other worksheet. However,
the values can still be matched to multiple observations in the BY columns of the other worksheet,
depending on whether or not NOMULTIPLES is used for the other worksheet. Therefore, you could end
up with longer columns in the merged worksheet. For example, if there are two rows in one worksheet
and three rows in the other, all with the same values of the BY columns, then six rows would result.
NOMULTIPLES is available for each of the worksheets to be merged.
NOUNMATCHED
Removes unmatched BY column rows from the merged worksheet. If any row in a worksheet has values
for the BY columns that are not matched in the BY columns for the other worksheet, then that row is
not used.
By default, unmatched values are included which means that all of the rows in the opposite worksheet
that do not have matching BY column values are included. Missing value symbols would be added to
the cells for the entire row associated with the unmatched BY column values for the opposite worksheet.
Consequently, padding rows with missing values will make all of the columns for both of the worksheets
the same length as the BY columns.
107
Minitab Statistical Software Manipulating and Calculating Data
NOUNMATCHED is available for each of the worksheets to be merged.
INCLUDE C...C
Specifies which columns to include from the worksheet, whether you merge worksheets using the default
settings or using BY Columns. By default, all columns are included.
MISSINGS
Includes missing values within BY columns for both worksheets. The missing observations will be treated as
distinct values. The missing BY column value will be matched with a missing BY column value in the other
worksheet.
Note Missing values in text columns are represented by blanks and missing values in numeric and date/time columns are
represented by an asterisk.
SORT: Session command for sorting columns
SORT [C...C C...C]
Sorts one or more columns.
The default is to sort by the first column and carry along additional columns. Sorting by multiple columns is done
with the BY subcommand. SORT handles any combination of alpha or numeric columns.
The following is a simple example of the default method. Sorting is done based on the first column specified, C2.
The next two columns, C3 and C4, are carried along. Sorting is done in ascending order unless you use the
subcommand DESCENDING.
SORT C2 C3 C4 C12 C13 C14
Before sorting
C4C3C2
-1102
-1113
-3121
-1134
-1145
After sorting
C14C13C12
-3121
-1102
-1113
-1134
-1145
108
Minitab Statistical Software Manipulating and Calculating Data
BY C...C
Specifies the columns to use to sort the worksheet. Rows are first sorted by the first column listed following
BY, then, within that, by the second column, then, within that, by the third, and so on.
SORT C2 C3 C4 C12 C13 C14;
BY C2.
Before sorting with BY
C4C3C2
-1102
-1113
-3121
-1134
-1145
After sorting with BY
C14C13C12
-3121
-1102
-1113
-1134
-1145
DESCENDING C...C
Requests that sorting be done in descending, rather than the default ascending, order. Columns listed on
DESCENDING must also be listed on BY, or must be the first column listed on SORT if no BY is used.
SORT C3 C23;
BY C2;
DESCENDING C2.
Before sorting with DESCENDING
C3C2
102
113
121
134
145
After sorting with DESCENDING
C23
14
109
Minitab Statistical Software Manipulating and Calculating Data
C23
13
11
10
12
UNEQUAL
If the columns to be sorted have different numbers of rows, adds missing values so that the columns have an
equal number of rows.
Storage
Important You cannot use NEWWS and AFTER local macros. For more information, go to Session commands that are not allowed in
macros on page 1179.
Note These subcommands are optional, and are mutually exclusive. If you do not use one of these subcommands, results are stored in
the columns that you specify with the main command.
NEWWS
Stores the results in a new worksheet, with the default name.
NEWWS ["text"]
NEWWS [K]
Stores the results in a new worksheet. If you do not specify a worksheet name in a "text" argument or in a constant
(K) argument, then Minitab uses the default naming of worksheets.
AFTER ["text"]
Stores the results at the end of the specified worksheet. If you do not specify a worksheet name in a "text" argument
or in a constant (K) argument, then Minitab stores the copied data at the end of the active worksheet.
ORIGINAL
Stores the results in the original columns.
RANK: Session command for ranking values in a column
RANK
Calculates and stores the ranks of the input column. Assigns the numeral 1 to the smallest value, the numeral 2
to the second smallest value, the numeral 3 to the third smallest value, and so on. Ties are assigned the average
rank.
Note RANK works only with numeric columns.
The following command language ranks the values in C1 and puts the ranked values in C2.
RANK C1 C2
110
Minitab Statistical Software Manipulating and Calculating Data
Before ranking
C1
0.5
1.0
1.5
1.0
2.0
0.0
After ranking
C2C1
2.00.5
3.51.0
5.01.5
3.51.0
6.02.0
1.00.0
DELETE: Session command for deleting rows of data
DELETE K...K C...C
Deletes rows K...K from columns C...C, and moves the remaining rows up to close the gap. DELETE works with both
text and numeric columns.
For example, the following command language changes the worksheet as shown below.
DELETE 2 5 6 C2-C4
Before DELETE
C4C3C2
154423
175531
143422
153326
167632
158630
155424
111
Minitab Statistical Software Manipulating and Calculating Data
After DELETE
C4C3C2
154423
143422
153326
155424
You can abbreviate a list of consecutive rows by using a colon. For example, to delete rows 1 through 10 and
rows 25 through 30 from C1, use the following command language.
DELETE 1:10 25:30 C1
SPLIT: Session command for splitting a worksheet into multiple
worksheets
SPLIT
Important SPLIT cannot be used in local macros. For more information, go to Session commands that are not allowed in macros on
page 1179.
The SPLIT command splits a worksheet into multiple new worksheets, one for each combination of a set of BY
variables. Each new worksheet is automatically named to reflect the combination of the BY variables.
Use SUBSET on page 114 to copy specified rows from the active worksheet to a new worksheet. With this command,
you can specify the subset based on row numbers, brushed points on a graph, or a condition such as unmarried
males under 50 years old.
BY C...C (required)
Specifies the columns to use to subset the worksheet. A new worksheet will be created for each unique value
or combination of values in the columns. Columns must be non-empty, all the same length, and can be of
any data type.
COLUMNS C...C
Specifies the columns to be copied to the new worksheet. Columns must be the same length as the BY
columns. Columns other than these are not copied.
MATRICES M...M
Specifies the matrices to be copied to the new worksheet. Matrices must has the same number of rows as
the BY columns. Matrices other than these are not copied.
NOMATRICES
Prevents matrices from being copied to the new worksheets.
NOCONSTANTS
Prevents stored constants from being copied to the new worksheets.
MISSINGS
Specifies that missing values are treated as a distinct value of the BY variable.
112
Minitab Statistical Software Manipulating and Calculating Data
DATE: Session command for changing data type to date/time
DATE C...C C...C
Changes data type of C...C to date/time and places results in C...C.
FORMAT
Indicates the format of the new date/time column or columns. For example:
FORMAT (DTm/d/yy) formats a new column as 5/25/16
FORMAT (DTm-d-yy) formats a new column as 5-25-16
For multiple columns, add the number of columns to the format statement. For example, for 2 columns, use
FORMAT (2DTm-d-yy).
For more information on date/time formats, go to Default date/time formats on page 1140.
ERASE: Session command for erasing variables
ERASE E...E
Erases any combination of columns (including their names), constants, and matrices.
Erasing all variables that you no longer need is a good practice.
ROWTOC: Session command for stacking multiple columns into
one column
ROWTOC C...C C
Stacks rows in C...C and places them in C. Enter the columns that contain the data you want to appear in a single
column, and then enter a column number or name in which to store the stacked data.
EXPAND C...C
Expands the specified column or columns, while stacking the rows.
EXSTORE C...C
Stores the expanded columns in the specified column.
SUBSCRIPTS C
Stores row subscripts in the specified column.
CSUBS C
Stores column subscripts in the specified column.
113
Minitab Statistical Software Manipulating and Calculating Data
SUBSET: Session command for copying specified rows to a new
worksheet
SUBSET
Important You cannot use SUBSET in a local macro. For more information, go to Session commands that are not allowed in macros
on page 1179.
Use SUBSET to copy specified rows from the active worksheet to a new worksheet. With this command, you can
specify the subset based on rows that match conditions, row numbers, formatted rows, brushed points on a graph,
or a formula that you specify, such as unmarried males under 50 years old.
One of INCLUDE and EXCLUDE must be used.
One of BRUSHED, WHERE, ROWS, conditions for values in a column, or conditions for row numbers, must be used.
If more than one is used, only the last valid one is honored.
Use SPLIT on page 112 to split, or unstack, the active worksheet into two or more new worksheets based on one
or more "By" variables. SUBSET and SPLIT always copy data to new worksheets.
INCLUDE
Includes the specified rows.
INCLUDE and EXCLUDE are mutually exclusive: the last one issued is honored. Choose INCLUDE or EXCLUDE
based on the degree of subsetting. For example, if you wish to use all but a few select rows in creating your
graph, it is more efficient to use EXCLUDE and name a small number of rows with the ROWS subsubcommand.
EXCLUDE
Excludes the specified rows.
INCLUDE and EXCLUDE are mutually exclusive: the last one issued is honored. Choose INCLUDE or EXCLUDE
based on the degree of subsetting. For example, if you wish to use all but a few select rows in creating your
graph, it is more efficient to use EXCLUDE and name a small number of rows with the ROWS subsubcommand.
MINCLUDE
Includes rows that contain missing values in the subset column.
MINCLUDE and MEXCLUDE are mutually exclusive: the last one issued is honored.
MEXCLUDE
Excludes rows that contain missing values in the subset column.
MINCLUDE and MEXCLUDE are mutually exclusive: the last one issued is honored.
AND
Allows you to specify multiple conditions. For example, LT C1 50 AND EQUAL C2 'Blue' denotes rows that
contain 50 or less in C1 and contain 'Blue' in C2.
OR
Allows you to specify multiple conditions.
Conditions for values in a column
These subcommands specify values in a column. For example:
114
Minitab Statistical Software Manipulating and Calculating Data
ANY C1 22 23 27 specifies the rows in C1 that contain 22, 23, and 27.
NEQUALS C1 'male' specifies the rows in C! that do not contain 'male'.
ANY C K...K
Values in C that equal any of the specified values.
EQUALS C K
Values in C that equal the specified value.
NEQUALS C K
Values in C that do not equal the specified value.
Conditions for values in a numeric or date/time column
These subcommands specify values in a numeric or date/time column. For example:
GT C1 30 specifies the values in C1 that are greater than 30.
LTLT C1 30 70 specifies the values in C1 that are greater than 30 and less than 70.
LT C K
Values in C that are less than K.
LE C K
Values in C that are less than or equal to K.
GT C K
Values in C that are greater than K.
GE C K
Values in C that are greater than or equal to K.
LELE K C K
Values in C that are greater than or equal to K and less than or equal to K.
LELT K C K
Values in C that are greater than or equal to K and less than K.
LTLE K C K
Values in C that are greater than K and less than or equal to K.
LTLT K C K
Values in C that are greater than K and less than K.
Conditions for values in a text column
These commands specify values in a text column. The text value must be in single quotation marks. For example:
BEGINS C1 'm' specifies all values in C1 that begin with "m".
NCONTAINS C1 'non' specifies all values in C1 that contain "non".
BEGINS C K
Values in C that begin with K (text columns only).
115
Minitab Statistical Software Manipulating and Calculating Data
ENDS C K
Values in C that end with K (text columns only).
CONTAINS C K
Values in C that contain K (text columns only).
NCONTAINS C K
Values in C that do not contain K (text columns only).
Conditions for row numbers
ROWS K...K
Specifies row numbers K through K. List all row numbers to be included or excluded with a space between each.
Denote a patterned range by K:K/K. For example, 10:50/5 denotes all values from 10 to 50 by intervals of 5.
ROWLE K
The row number is less than or equal to K.
ROWGE K
The row number is greater than or equal to K. For example, ROWGE 12 denotes row numbers that are greater
than or equal to 12.
ROWBETWEEN K K
The row number is between K and K inclusive. The first value must be less than or equal to the second.
Other conditions
BRUSHED
Specifies the rows that are currently brushed.
WHERE expression
Specify a formula for subsetting. This formula must be in quotes. For example:
To subset where C1 is 2, enter WHERE "C1 = 2".
To subset where C2 = a, enter WHERE "C2 = ""a""".
To subset where C3 = 3/3/16, enter WHERE "C3 = DATE(""3/3/98"")".
CFORMAT C
Specifies a column that includes formatted rows.
Options for the new worksheet
NAME "text"
NAME K
Specifies the name of the new worksheet in a "text" argument or in a constant (K).
COLUMNS C...C
Specifies one or more columns of the appropriate length to be copied to the new worksheet. Columns other than
these are not copied.
116
Minitab Statistical Software Manipulating and Calculating Data
EQLN
Includes in the subset only columns that are the same length as the column with the condition. If this subcommand
is not used, all columns in the worksheet are included in the subset.
MATRICES M...M
Specifies one or more matrices with the appropriate number of rows to be copied to the new worksheet. Matrices
other than these are not copied.
NOMATRICES
Prevents matrices from being copied to the new worksheet.
NOCONSTANTS
Prevents stored constants from being copied to the new worksheet.
READ data into columns
READ C...C
Reads in data, row by row, that you type from the keyboard, or that you import from a text file. You cannot type
comments on a data line when the FORMAT subcommand is used.
READ enters new data into columns, replacing any data already in those columns, if it exists. For information on
entering data into a matrix, go to READ data into a matrix on page 43.
When you enter data manually, type END. after you enter your final value.
When you use READ, you can use a space or a comma to separate data entries. For example:
READ C1 C5.
1 2
3,4
END.
For details on using this command without subcommands to select data entry options, go to Using READ without
subcommands on page 1183.
FILE "filename"
Inserts data from the specified text file. You may specify the filename as either the name of the file in double
quotes, or a stored text constant. If the file has an extension other than DAT and/or if it is not in your current
directory, include the file extension and the path within the single quotation marks. For example, use the
following command to read a copy of the file SALES.ASC stored in the subdirectory JANUARY underneath
the directory SMITH on the C drive.
READ C1-C5;
FILE "C:\SMITH\JANUARY\SALES.ASC".
FORMAT (format statement)
Include a format statement, within parentheses to specify precisely how to enter data into the worksheet.
The entire expression within the parentheses is repeated once for each record. For more information, go to
Using READ with FORMAT on page 1183.
The FORMAT subcommand is useful when you want to skip over spaces, read data that have no spaces
between them, insert decimal points in numbers, or read in text data, date/time data, or currency data.
Format items may be combined together. For example, the following command reads the name in the first
20 spaces of each data line into Name (C12), skips the next 10 spaces (spaces 21 through 30), then reads the
number in space 31 into C1, the number in space 32 into C2, ..., the number in space 40 into C10.
NAME C12 'Name'
READ 'Name' C1-C10;
117
Minitab Statistical Software Manipulating and Calculating Data
FILE "MYDATA";
FORMAT(A20, 10X, 10F1).
Minitab has a special date/time (DT) format which works as shown below. This says to read the date/time
value in the first 8 spaces in the file into C1, and that the format of the date/time data in the file is m/d/yy.
READ C1;
FILE "DATEDATA";
FORMAT(DT8m/d/yy).
The following example shows the use of a decimal indicator, repeat factor in front of parentheses, and the
slash.
READ C11-C15;
FILE "EMPLOYEEDATA";
FORMAT (F2.1, 2(1X,F3), F4/F2).
This example uses two data lines for every row read. From the first line, the value of C11 is in spaces 1 and
2. The first value is a whole number and the second value is in the tenths place. The format skips space 3.
Then, C12 is read from spaces 4 to 6. The format skips space 7. Then, C13 is read from spaces 8 to 10, which
repeats the pattern inside of the parentheses. C14 is read from spaces 11 to 14. In response to the /, reading
moves to the second data line, and C15 is read from spaces 1 and 2. For more information, go to Valid format
items on page 1186.
NOBS K
The NOBS subcommand specifies the number of observations (rows) to be inserted. If an END on page 38
subcommand or end-of-file is encountered before K observations are inserted, NOBS is ignored. NOBS is
useful when you want to insert just the first portion of a file. It is also useful for Prompting a user for
information on page 1177.
SKIP K
Tells Minitab to skip K lines at the top of the data file before beginning to add data into the file. This is most
useful when you have one or more lines of text, such as column names and titles, at the top of a data file
that you want to import into Minitab.
With READ; FILE only
DECIMAL works with READ when only when reading a file. DECIMAL does not work with READ if you type data.
DECIMAL ","
DECIMAL "."
Specifies a comma or period as a decimal separator.
READ data into a matrix
READ K K M
Puts numbers into a matrix. To input data to columns, go to READ data into columns on page 41. You can specify
the filename as either the name of the file in double quotes, or a stored text constant. If the file has an extension
other than DAT and/or if it is not in your current directory, include the file name extension and the path within
quotation marks.
You can use either spaces or commas to separate the data in the matrix.
You must specify the dimension of the matrix in the READ command. The first K gives the number of rows, the
second K the number of columns. The M is the matrix identifier for storage. If a file name is not used, READ is
118
Minitab Statistical Software Manipulating and Calculating Data
followed by data lines, each containing one row of the matrix. The following command creates the following
matrix.
Command
READ 3 4 M2
1 2 3 4
5 6 7 8
9 10 11 12
END
Matrix
1 2 3 4
5 6 7 8
9 10 11 12
FILE "filename"
FILE K
Reads or inserts data from the specified text file.
CONCATENATE: Session command for combining text columns
CONCATENATE C...C C
Combines text columns C...C and places into C, to form longer words.
In the following example, portions of numbers were originally entered into columns C1–C3. CONCATENATE
combines C1-C3 into one column, C4.
READ C1-C3;
FORMAT (A4, A3, A4).
192-42-7777
123-45-6789
END
CONCATENATE C1-C3 C4
The worksheet is changed as follows.
C4-TC3-TC2-TC1-T
192-42-7777777742-192-
123-45-6789678945-123-
CODE: Session command for changing values in columns to new
values
CODE (K...K K ... (K...K)K C...C [C...C]
Copies columns, changing the indicated values. For example, the following command language codes every –1
and –2 to 100.
CODE (-1 -2)100 C1 C2;
AFTER.
The command language places the results at the end of the worksheet (C2), as follows.
C2C1
100.0-1.0
119
Minitab Statistical Software Manipulating and Calculating Data
C2C1
3.03.0
1.11.1
100.0-1.0
0.00.0
100.0-2.0
2.42.4
An interval can be abbreviated with a colon. For example, the following command language changes all values
in the range 1 to 1.5, and the value 2 into a 5.
CODE (1:1.5, 2)5 C1-C3 C11-C15
You can make several changes at one time. For example, suppose the data in columns C1–C5 include integers 1
through 10. In this case, the following command language changes all values in C1–C5 that are from 1 to 5 into
10, and all values that are from 6 to 10 into 20, and stores the results in C11–C15.
CODE (1:5)10 (6:10)20 C1-C5 C11-C15
CODE can change values into the missing data code. For example, to change –99 to *, use the following command
language.
CODE (–99) '*' C1-C10;
ORIGINAL.
You can also code text data. Enclose text values with double quotation marks. Denote a missing text value as two
double quotation marks, with no space in between, as "". For example, use the following command language to
code 1, 2, and 3 to low, medium, and high.
CODE (1) "low" (2) "medium" (3) "high" C1 C2
You can also use CONVERT on page 121 to recode text data.
ENDPOINTS K
For coding ranges of values, the value of K controls inclusion of the endpoints.
Endpoints that are included in the rangeValue of K
Lower endpoint only1
Upper endpoint only2
Both endpoints3 (default)
Neither endpoint4
TSUMMARY
Shows the summary table in the output.
TSUMMARY and NODEFAULT are mutually exclusive.
NODEFAULT
Suppresses the summary table in the output.
TSUMMARY and NODEFAULT are mutually exclusive.
120
Minitab Statistical Software Manipulating and Calculating Data
LFPERCENT K K
Recodes the unique values (of the input columns specified in the CODE command) above the K
th
percentile
in count to K, and places the recoded values into output columns specified in the CODE command.
LFVALUE K K
Recodes the unique values (of the input columns specified in the CODE command) that occur less than K
times to K, and places the recoded values into output columns specified in the CODE command.
Storage
The following subcommands are optional, and are mutually exclusive. If you do not use one of these subcommands,
results are stored in the columns that you specify with the main command.
Note You cannot use NEWWS and AFTER in a local macro.
NEWWS
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in a "text" argument or in a constant
(K) argument, then Minitab uses the default naming of worksheets.
AFTER
AFTER "text"
Stores the results at the end of the specified worksheet. If you do not specify a worksheet name in a "text"
argument, then Minitab stores the copied data at the end of the active worksheet.
ORIGINAL
Stores the results in the original columns.
CONVERT: Session command for converting text data to numeric
data, and numeric data to text data
CONVERT C C C C
Using the conversion table in C C, converts C to C.
A conversion table, assigning a numeric value to each text value, must be put into two columns before CONVERT
is used. Then, using these matching values, CONVERT changes all corresponding numeric values to the correct
text values (or vice versa). If no match is found, a missing value is stored. Missing values are denoted by * in a
numeric column and a blank in a text column. CONVERT can also be used to convert from numeric to numeric or
from text to text.
Use the following commands to store a conversion table in C1–C2. For more information on entering data using
format statements, go to READ data into a matrix on page 43 or READ data into columns on page 41.
READ C1 C2;
FORMAT (F1, 1X, A6).
1 RED
2 YELLOW
END
121
Minitab Statistical Software Manipulating and Calculating Data
Use the conversion table to do two conversions. The first CONVERT converts numbers in C3 to colors in C10. The
second converts colors in C4 to numbers in C11.
CONVERT C1 C2 C3 C10
CONVERT C2 C1 C4 C11
The worksheet is changed as follows.
C11C10-TC4-TC3C2-TC1
1REDRED1RED1
1YELLOWRED2YELLOW2
2REDYELLOW1
1RED3
*YELLOWBLUE2
NODEFAULT
Suppresses the summary table in the output.
DROUND: Session command for rounding date/time values
DROUND C C
Rounds the original date/time values in the first C and stores them in the second C.
For example, suppose you have sales data for each day of the year, but you want to summarize sales for each
quarter of the year. You can use Round Date/Time to round the dates down to the nearest quarter.
Units for rounding
Specify the unit to round to. You must use one of these mutually exclusive subcommands.
YEAR
QUARTER
MONTH
WEEK
DAY
HOUR
MINUTE
SECOND
TENTH
HUNDREDTH
THOUSANDTH
Options
DROUND rounds down to the nearest whole unit.
122
Minitab Statistical Software Manipulating and Calculating Data
UP
Use UP to round up to the nearest whole unit.
NEAREST
Use NEAREST to round up or down to the nearest whole unit.
NUMERIC: Session command for changing the data format of a
date/time column or extracting date/time components
NUMERIC C C
The NUMERIC command serves two functions:
To change a date/time or a text column to a numeric column. (Use with a date/time or text input column.)
To extract one or more components (such as the day, quarter, or hour) from a date/time column, and save
those components in a numeric column. (Use with a date/time input column.)
Note When the input column is text, no subcommands are available.
Date/time input
WKDAY
Extracts the day of the week (Sun, Mon, Tue, Wed, Thu, Fri, Sat).
DAY
Extracts the day of the month (01, 02, ..., 31).
WEEK
Extracts the week of the year number (Wk01 - Wk53).
MONTH
Extracts the month (Jan, Feb, Mar, Apr, ..., Dec).
QUARTER
Extracts the quarter (Q1, Q2, Q3, Q4).
YEAR
Extracts the year.
TWODIGIT
Uses the two digit format (00, 01, ..., 99).
FOURDIGIT
Uses the four digit format (2000, 2001, ..., 2099).
HOUR
Extracts the hour (00, 01, ..., 23).
MINUTE
Extracts the minute (00, 01, ..., 59).
123
Minitab Statistical Software Manipulating and Calculating Data
SECOND
Extracts the second (00, 01, ..., 59).
TENTHS
Extracts the tenths of a second (0, 1, 2, ..., 9).
HUNDREDTHS
Extracts the hundredths of a second (0, 1, ..., 99).
THOUSANDTHS
Extracts the thousandths of a second (0, 1, 2, ..., 999).
TEXT: Session command for changing the data type of a column
to text
TEXT C...C C...C
Changes data type of C...C to text and places results in C...C. The TEXT command serves the following functions:
Use TEXT to change a date/time or a numeric column to a text column. (Use with a date/time or numeric input
column.)
Use TEXT to extract one or more components (such as the day, quarter, or hour) from a date/time column,
and save those components in a text column. (Use with a date/time input column.)
Use TEXT to format the width of a text column. (Use with a text input column.)
Minitab automatically formats the new alpha column up to 8 characters wide. Use WIDTH or MAXWIDTH (you
cannot use both) to override this default.
Date/time input column
WKDAY
Extracts the day of the week (Sun, Mon, Tue, Wed, Thu, Fri, Sat).
DAY
Extracts the day of the month (01, 02, ..., 31).
WEEK
Extracts the week of the year number (Wk01 - Wk53).
MONTH
Extracts the month (Jan, Feb, Mar, Apr, ..., Dec).
QUARTER
Extracts the quarter (Q1, Q2, Q3, Q4).
YEAR
Extracts the year.
TWODIGIT
Uses the two digit format (00, 01, ..., 99).
124
Minitab Statistical Software Manipulating and Calculating Data
FOURDIGIT
Uses the four digit format (2000, 2001, ..., 2099).
HOUR
Extracts the hour (00, 01, ..., 23).
MINUTE
Extracts the minute (00, 01, ..., 59).
SECOND
Extracts the second (00, 01, ..., 59).
TENTHS
Extracts the tenths of a second (0, 1, 2, ..., 9).
HUNDREDTHS
Extracts the hundredths of a second (00, 01, ..., 99).
THOUSANDTHS
Extracts the thousandths of a second (000, 001, 002, ..., 999).
WIDTH K
Fixes the width (in characters) of the output column.
MAXWIDTH K
Fixes the maximum width (in characters) of the output column.
MISSING "text"
Converts missing values to "text".
Numeric input column
WIDTH K
Fixes the width (in characters) of the output column.
MAXWIDTH K
Fixes the maximum width (in characters) of the output column.
SIGNIFICANT K
Specifies the number of significant digits to maintain (up to a maximum of 6). You cannot use both SIGNIFICANT
and DECIMALS with one command.
DECIMALS K
Specifies the number of decimal digits to maintain. You cannot use both SIGNIFICANT and DECIMALS with one
command.
MISSING "text"
Converts the missing value symbol * to a specified character string. Unless you specify the width of your output
with WIDTH or MAXWIDTH, the default length for the string is 8 characters.
125
Minitab Statistical Software Manipulating and Calculating Data
Text input column
WIDTH K
Fixes the width (in characters) of the output column.
MAXWIDTH K
Fixes the maximum width (in characters) of the output column.
STACK: Session command for stacking blocks of columns and
constants on top of each other
STACK (E...E) C
STACK (E...E) ... (E...E) (C...C)
Stacks blocks of columns and constants on top of each other.
The following command language stacks C3 and C4 on C1 and C2.
STACK (C3 C4) (C1 C2) (C5 C6)
Columns to stack
C4C3C2C1
1557013066
1456612564
1606911565
Stacked columns
C6C5
15570
14566
16069
13066
12564
11565
The following command language puts 66, 64, 65, 70, 66, 69, 67, and 63 into C10. The last column (or block of
columns) specified is the target column.
STACK C1 C3 67 63 C10
SUBSCRIPTS C
Creates a column of subscripts in the original worksheet. The first block is given the subscript 1, the second
block the subscript 2, and so on.
USENAMES
Creates subscripts based on variable names.
126
Minitab Statistical Software Manipulating and Calculating Data
NEWWS
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in a "text" argument or in a
constant (K) argument, then Minitab uses the default naming of worksheets. Minitab automatically creates
a subscripts column in the new worksheet.
Important You cannot use NEWWS in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
USENAMES
Creates subscripts based on variable names.
UNSTACK: Session command for separating a column into multiple
columns
UNSTACK (C...C) (E...E)...(E...E)
Separates one or more columns into several blocks of columns and stored constants, based on subscript values
stored in an associated column.
Unstack is useful for subsetting data.
SUBSCRIPTS C...C
Uses columns to unstack data. The rows with the smallest subscript are stored in the first block, the rows
with the second smallest subscript in the second block, and so on. If you do not use SUBSCRIPTS, each row
is stored in a separate block.
In general, each block must be enclosed in parentheses. However, if a block contains just one argument, you
may omit the parentheses.
For most applications, the subcommand SUBSCRIPTS is needed.
MISSINGS
Includes rows subscripted with missing data as part of the unstacked data.
NEWWS
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in "text" or in a constant (K)
argument, then Minitab uses the default naming of worksheets.
Important You cannot use NEWWS in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
VARNAMES
Labels the columns for the unstacked data with the source variable name (the source column's label or
number if no label exists) and the corresponding row entries from the subscript column or columns. If you
do not use SUBSCRIPT, the text strings "Row1", "Row2", and so on are used.
127
Minitab Statistical Software Manipulating and Calculating Data
AFTER
Appends the unstacked data into empty columns after the last column of data in the current worksheet.
Important You cannot use AFTER in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
WSTACK: Session command for stacking worksheets
WSTACK
Important You cannot use WSTACK in a local macro. For more information, go to Session commands that are not allowed in macros
on page 1179.
Use WSTACK to stack two or more worksheets. The argument is the names of the worksheets. For example,
WSTACK "Worksheet1" "Worksheet 2" stacks Worksheet 1 on top of Worksheet 2. Minitab stacks columns with
the same names. Columns that don't have the matching names are kept as separate columns.
Within this command, you can specify that the results are placed in a new worksheet (NEWWS) or appended to
an existing worksheet (APPEND). NEWWS and APPEND subcommands are mutually exclusive. If neither is specified,
NEWWS is assumed.
You can use MERGE on page 106 to combine worksheets side-by-side.
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in "text" or in a constant (K)
argument, then Minitab uses the default naming of worksheets.
APPEND
Appends the data to the bottom of the first worksheet that you specified in WSTACK.
SOURCE ["column name"]
SOURCE appends the source worksheet name to the bottom of the specified column. If you do not
specify the column, the command creates a new ID column in the output sheet.
TSUMMARY (default)
TSUMMARY and NODEFAULT are mutually exclusive. TSUMMARY shows the summary table in the output.
NODEFAULT
TSUMMARY and NODEFAULT are mutually exclusive. NODEFAULT suppresses the summary table in the
output.
128
Minitab Statistical Software Manipulating and Calculating Data
TRANSPOSE: Session command for changing rows to columns,
and columns to rows
TRANSPOSE C...C
TRANSPOSE C M
TRANSPOSE M C
TRANSPOSE M [M]
TRANSPOSE reconfigures data so that rows become columns and columns become rows.
TRANSPOSE C...C transposes the values in the columns.
TRANSPOSE C M transposes the values in a column to a matrix.
TRANSPOSE MC transposes the values in a single row matrix to a column.
TRANSPOSE M [M] transposes the values in a matrix to another matrix.
VARNAMES C
Specifies a column that contains variable names for the transposed columns.
STORE C...C
STORE M
Specifies where the transposed data are to be written. You can store the data in columns or a matrix. When
you transpose data to columns, the number of columns specified must equal the number of rows in the
original columns.
If you do not use STORE, the data are stored in a new worksheet.
LABELS C
Specifies the column in which the labels of the transposed column or columns or matrix are stored.
NEWWS
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in "text" or in a constant (K)
argument, then Minitab uses the default naming of worksheets.
Important You cannot use NEWWS in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
AFTER
Appends the transposed data into empty columns after the last column of data in the current worksheet.
Important You cannot use AFTER in a local macro. For more information, go to Session commands that are not allowed in
macros on page 1179.
129
Minitab Statistical Software Manipulating and Calculating Data
COPY: Session command for copying data
COPY [E...E E...E]
Copy specified columns, constants, and matrices, or a subset thereof, into a similar or compatible format in a
specified worksheet.
In addition to format, the source and destination must be compatible in size. For example, you cannot copy a
column with 100 rows into a set of 50 constants. You can subset the source data to accommodate the size of the
destination.
If you don't specify an argument, COPY copies the entire contents of the current worksheet to another worksheet.
You can specify an argument to do the following:
Copy columns into columns, constants, or a matrix.
Copy constants into constants or columns.
Copy a matrix into columns or a matrix.
Specify a subset
INCLUDE and EXCLUDE are mutually exclusive. The last one issued is honored. Choose INCLUDE or EXCLUDE based
on the degree of subsetting. For example, if you want to use all rows, except a few, use EXCLUDE and specify a small
number of rows with the ROWS subsubcommand.
INCLUDE
Includes the specified rows.
BRUSHED
Use to specify all brushed rows for subsetting.
WHERE "expression"
Specify a condition to be met for subsetting. This condition must be in double quotation marks. For example:
To subset where C1 is 2, enter WHERE "C1 = 2".
To subset where C2 = a, enter WHERE "C2 = ""a"".
To subset where C3 = 3/3/16, enter WHERE "C3 = DATE(""3/3/16"")".
ROWS K:K
List all row numbers to be included or excluded with a space between each. Denote a patterned range by
K:K/K. For example, 10:50/5 denotes all values from 10 to 50 by intervals of 5.
EXCLUDE
Excludes the specified rows.
BRUSHED
Use to specify all brushed rows for subsetting.
WHERE "expression"
Specify a condition to be met for subsetting. This condition must be in double quotation marks. For example:
To subset where C1 is 2, enter WHERE "C1 = 2".
To subset where C2 = a, enter WHERE "C2 = ""a"".
To subset where C3 = 3/3/16, enter WHERE "C3 = DATE(""3/3/16"")".
130
Minitab Statistical Software Manipulating and Calculating Data
ROWS K:K
List all row numbers to be included or excluded with a space between each. Denote a patterned range by
K:K/K. For example, 10:50/5 denotes all values from 10 to 50 by intervals of 5.
USE [C] K...K
Selects rows to copy.
Specify target location
Important NEWWS, AFTER, and STORE cannot be used in local macros. For more information, go to Session commands that are not
allowed in macros on page 1179.
Note You can use only one NEWWS, AFTER, or STORE subcommand.
NEWWS
NEWWS "text"
NEWWS K
Stores the results in a new worksheet. If you do not specify a worksheet name in "text" or in a constant (K) argument,
then Minitab uses the default naming of worksheets.
AFTER
AFTER "text"
AFTER K
Stores the results at the end of the specified worksheet. If you do not specify a worksheet name in a "text" argument
or in a constant (K) argument, then Minitab stores the copied data at the end of the active worksheet.
STORE K E...E
STORE "text" E...E
Stores the copied data in the specified columns constants, or matrices of the worksheet named in a "text" argument
or in a constant (K).
Naming
VARNAMES
Gives default names to the stored columns, constants, or matrix.
RMERGE: Session command for merging worksheets
RMERGE K...K
Use RMERGE to combine two or more worksheets side-by-side into a new worksheet. The argument is the names
of the worksheets. For example, RMERGE "Worksheet1" "Worksheet 2" merges Worksheet 2 to the right
of Worksheet 1.
Note Stored constants, matrices, DOE objects, and worksheet descriptions do not transfer into the merged worksheet.
131
Minitab Statistical Software Manipulating and Calculating Data
NAME K (optional)
Specifies the name K for the new worksheet.
Editor
CFORMAT: Session command for conditional formatting of
worksheet cells
CFORMAT C...C
Formats cells in the specified columns based on the specified rule.
You can specify only one rule subcommand (and possibly its sub-subcommands) with the CFORMAT command
at a time. However, you can run CFORMAT on the same column multiple times, and the rules accumulate. If a cell
is affected by multiple rules, the formatting of the most recent rule is used.
The availability of a specific rule might depend on the data type of the column specified in CFORMAT.
Attribute subcommands
The following subcommands define the cell format for cells that meet the condition.
TCOLOR K
Specifies the text color with a number value in K, which is a number from Numbers for colors to use in session
commands on page 1172.
BOLD
Applies bold style to text in the cells to format.
NOBOLD
Removes bold style from text in the cells to formats.
ITALIC
Applies italic style to text in the cells to format.
NOITALIC
Removes italic style from text in the cells to format.
UNDERLINE
Underlines text in the cells to format.
NOUNDERLINE
Removes underline from text in the cells to format.
COLOR K
Specifies the fill color of the cells with a number value in K, which is a number from Numbers for colors to use in
session commands on page 1172.
132
Minitab Statistical Software Manipulating and Calculating Data
Rules for highlighting cells
MISSING
Formats cells that contain missing observations (available for columns with any data type).
GT K
Formats cells that are greater than K (available for columns with any data type).
LT K
Formats cells that are less than K (available for columns with any data type).
BETWEEN K K
Formats cells between K and K, inclusive (available for columns with any data type).
NOTBETWEEN K K
Formats cells that are not between K and K, inclusive (available for columns with any data type).
EQUALS K
Formats cells that are equal to K (available for columns with any data type).
TEXT "text"
Formats cells that contain the text string, 'text" (available for text columns) The text string may be found within a
larger text string. For example, if the rule is to format cells that contain "abc", a cell that contains dabcd would
be formatted.
VALUES C
VALUES K...K
Formats cells that match any of the values in C or in K...K (available for columns with any data type) C or K...K have
the same data type as the columns specified in CFORMAT.
NOVALUES C
NOVALUES K...K
Formats cells that do not match any of the values in C or in K...K (available for columns with any data type) C or
K...K have the same data type as the columns specified in CFORMAT.
YESTERDAY
Formats cells that contain yesterday's date (available for date/time columns).
TODAY
Formats cells that contain today's date (available for date/time columns).
LAST K
Formats cells that contain a date that occurred within the last K days (available for date/time columns).
LWEEK
Formats cells that contain a date that occurred last week (available for date/time columns).
TWEEK
Formats cells that occur this week (available for date/time columns).
LMONTH
Formats cells that occurred last month (available for date/time columns).
133
Minitab Statistical Software Manipulating and Calculating Data
TMONTH
Formats cells that occur this month (available for date/time columns).
Hi low rules
HVALUE K
Formats cells that contain the highest K values in the column (available for numeric and date/time columns). If
there are ties at the K
th
location, all tied values will be formatted.
HPERCENT K
Formats cells that contain the highest K percentage of values in the column (available for numeric and date/time
columns).
LVALUE K
Formats cells that contain the lowest K values in the column (available for numeric and date/time columns) If
there are ties at the K
th
location, all tied values will be formatted.
LPERCENT K
Formats cells that contain the lowest K percentage of values in the column (available for numeric and date/time
columns).
Pareto rules
MFREQUENT K
Formats cells that contain the K most frequent values (available for columns with any data type).
MPERCENT K
Formats cells that contain the top K% of values (available for columns with any data type).
BFREQUENT
Formats cells that contain the K least frequent values (available for columns with any data type).
BPERCENT K
Formats cells that contain the bottom K% of values (available for columns with any data type).
Statistical rules
OUTLIER
Formats cells that are outliers (available for columns with any data type) Columns can be different data types.
Outliers are determined based on one of the following sub-subcommands:
BOXPLOT
Observations that meet the conditions for outliers on a boxplot are formatted.
STDEV K
Observations that are more than K standard deviations away from the mean are formatted.
CONTROL K K
Formats cells that contain values that are out of control (available for numeric and date/time data).
134
Minitab Statistical Software Manipulating and Calculating Data
The first K specifies the rule:
K = 1 if data are continuous.
K = 2 if the data are attribute.
The second K specifies the subgroup size. K > 0.
Examples of subcommand syntax:
CONTROL 1 1 specifies to use I chart test 1.
CONTROL 1 K, where K > 1, specifies to use XBar chart test 1.
CONTROL K K, where K > 0, specifies to use P chart test 1.
The CONTROL subcommand honors preferences (File > Options) settings to determine the Test 1 rule criteria
and to determine the estimate of standard deviation used.
SPECIFICATION
Formats cells that are outside of the specification limits (available for numeric and date/time data)
Specify one or both of the following:
LSPEC K
Specifies the lower specification limit. Cells with values less than K are out of specification.
K for LSPEC can be any numeric or date/time value, but K for LSPEC must be less that K for USPEC. Both Ks
must match the type for the argument to CFORMAT.
USPEC K
Specifies the upper specification limit. Cells with values greater than K are out of specification.
K for USPEC can be any numeric or date/time value, but K for LSPEC must be less that K for USPEC. Both Ks
must match the type for the argument to CFORMAT.
RESIDUAL
Formats cells that are unusual observations from a model because of large standardized residual (available for
response columns that have a model associated with them).
UNUSUAL
Formats cells that are unusual observations from a model because they exhibit high leverage (available for response
columns that have a model associated with them).
CFAUTOMATICALLY: Session command for automatically
recalculating values
CFAUTOMATICALLY
Updates the data by automatically recalculating the values in columns or stored constants with assigned formulas
whenever you change the corresponding data for variables. To update formulas manually, use CFMANUALLY on
page 136.
This command cannot be used in a local macro.
135
Minitab Statistical Software Manipulating and Calculating Data
CFMANUALLY: Session command for manually recalculating values
Allows you to manually recalculate the values in columns or stored constants with assigned formulas only when
using the command CFNOW on page 136 (Calculate All Formulas Now). To update formulas automatically whenever
the data they depend on changes, use CFAUTOMATICALLY on page 135.
This command cannot be used in a local macro.
CFNOW: Session command for recalculating values now
CFNOW
Recalculates the values in columns or stored constants with assigned formulas using the current data for variables.
Can be used only when Calculate All Formulas Automatically is deselected. For more information about
calculating formulas manually with command language, go to CFMANUALLY on page 136.
This command cannot be used in a local macro.
FDATE/TIME: Session command for changing the format of
date/time columns
FDATE/TIME C...C
Changes the format of a date/time columns C...C. You can use FDATE/TIME for columns that are empty.
For more information on date/time formats, go to Default date/time formats on page 1140.
FORMAT (format statement)
Indicates the format of the date/time column. For example, use the subcommand FORMAT (DTm/d/yy) to
format the column as 5/25/18. Use the subcommand FORMAT (DTm-d-yy) to format the new column as
5-25-18.
For multiple columns, add the number of columns to the format statement. For example, for 2 columns, use
FORMAT (2DTm-d-yy).
FNUMERIC: Session command for changing columns to numeric
format
FNUMERIC C...C
Changes the format of columns C...C to the specified numeric format. You can use FNUMERIC for columns that
are empty.
AUTO
The values in the column determine the format of the column, for example, the number of decimal places
and the currency symbol (if entered).
FIXED K
Displays numeric data to K decimal places.
136
Minitab Statistical Software Manipulating and Calculating Data
EXPONENTIAL [K]
Displays numeric data using exponential notation. The optional argument K specifies the number of decimal
places.
CURRENCY [K]
Displays currency data. The optional argument K specifies the number of decimal places, from 0 to 30 inclusive.
SYMBOL "text"
Specifies the currency symbol as a text value.
NEGATIVE K
Displays negative values using a minus sign (K = 1) or parentheses (K = 2).
PERCENTAGE K
Displays percentage data to K decimal places.
FTEXT: Session command for changing the format of text columns
FTEXT
Changes the format of text columns C...C. You can use FTEXT for empty columns.
FORMULA: Session command for assigning a formula to a column
FORMULA E = expression
Assigns a formula to a column or stored constant. The expression that defines the formula may contain arithmetic
operations, comparison operations, logical operations, and functions. For a list of the functions you can use, go
to LET: Session command for correcting a number in a worksheet or performing arithmetic on page 63.
This command cannot be used in a local macro.
RFORMULA: Session command for removing formulas
RFORMULA E...E
Removes formulas from the columns or constants that you specify. Removing a formula from a column does not
remove the data from the column.
You cannot use this command in a local macro.
VORDER: Session command for controlling the order for text
categories to be processed by Minitab commands
VORDERC...C
Use VORDER to control the order in which you would like text categories to be processed by Minitab commands.
By default, text categories are processed in alphabetical order. However, alphabetical order might not always be
the most convenient way to process your data.
137
Minitab Statistical Software Manipulating and Calculating Data
VALUES K...K
VALUES C
Specifies the value order using either stored or stated text constants or a single text column.
If you use the VALUES subcommand more than one time, the last one with valid arguments wins. In the first
form, stored or stated text constants are used to specify the values in order. In the second form, the rows of
a single text column are used to specify the values in order. In either form, it is an error for values to be
repeated. Note that the command language does not provide access to standard orderings.
WORKSHEET
Specifies to order data based on the first occurrence in the worksheet.
ALPHABETICAL
Specifies to order data in alphabetical order.
138
Minitab Statistical Software Manipulating and Calculating Data
Basic Statistics
DESCRIBE: Session command for summarizing
numeric data with statistics
DESCRIBE C...C
Produces descriptive statistics for each column. You can do the calculations and display graphs separately for
each level of a BY variable.
For information on storing many different statistics, go to STATS on page 143.
Control of grouping
BY
Use BY to produce separate statistics and graphs for each unique value in C. The values in the BY column may
contain numeric, text, or date/time data and may be any value. When the BY column is text, the first entry (row
1) is level 1, the next entry that is different is level 2, and so on. Column lengths must be equal to use BY.
Statistics
MEAN
Calculates the arithmetic mean, or average. The mean is a commonly used measure of the center of a batch of
numbers.
Note Missing values are omitted from the calculation of the function Mean.
SEMEAN
Gives the standard error of the mean. It is calculated as StDev / SQRT (N).
STDEV
Calculates the sample standard deviation, which provides a measure of how spread out the data are. To calculate
the variance, simply square the standard deviation value.
If the column contains x1, x2, ..., xn, with mean x, then the standard deviation is calculated as follows:
Note Missing values are omitted from the calculation of the function Standard deviation.
VARIANCE
Variance is a measure of how far the data are spread about the mean. Sample variance equals the standard
deviation squared. It can also be computed with this formula:
139
Minitab Statistical Software Basic Statistics
CVARIATION
Displays the coefficient of variation, a measure of relative variability. It is calculated as: 100 (s / x).
MEDIAN
Stores the median of a column. The median is in the middle of the data: half the observations are less than or
equal to it. Suppose the column contains n values. If n is odd, the median is the value in the middle. If n is even,
the median is the average of the two middle values.
Note Missing values are omitted from the calculation of the function Median.
MODE
Displays the mode of a column. The mode of a data set is the value that occurs most frequently. For example, the
mode for data set {1, 3, 4, 4, 7} is 4.
Note For data sets that have multiple mode values, Minitab displays only the four smallest modes.
TRMEAN
A 5% trimmed mean is calculated. Minitab removes the smallest 5% and the largest 5% of the values (rounded
to the nearest integer).
SUM
Calculates the sum.
Note Missing values are omitted from the calculation of the function Sum.
MIN
Stores the smallest number in a column.
Note Missing values are omitted from the calculation of the function MIN.
MAX
Stores the largest number in a column.
Note Missing values are omitted from the calculation of the function MAX.
RANGE
Calculates the difference between the largest and smallest data value.
SSQ
Squares each value in the column, and computes the sum of those squared values. That is, if the column contains
x
1
, x
2
, ..., x
n
, then sum of squares calculates (x
1
2
+ x
2
2
+ ... + x
n
2
).
Note Missing values are omitted from the calculation of the function the function Sum of Squares (corrected).
SKEWNESS
Skewness is a measure of asymmetry. A value more than or less than zero indicates skewness in the data. But a
zero value does not necessarily indicate symmetry.
KURTOSIS
Kurtosis is one measure of how different a distribution is from the normal distribution. A positive value characterizes
a distribution with heavier tails than the normal distribution. A negative value characterizes a distribution with
lighter tails than the normal distribution.
140
Minitab Statistical Software Basic Statistics
MSSD
MSSD computes half the Mean of the Squared Successive Differences of a batch of numbers. For example, suppose
a column contains 1, 2, 4, and 10. The successive differences are 2 - 1 = 1, 4 - 2 = 2, and 10 - 4 = 6. Then:
MSSD = mean(1-squared, 2-squared, and 6-squared) / 2 = 6.83333
N
Returns the number of nonmissing observations in a column.
NMISS
Returns the number of missing observations in a column.
COUNT
Returns the total number of observations in a column.
When used as an option with TALLY on page 903 (Stat > Tables > Tally > Tally Individual Variables) or the
STATS on page 143, COUNT computes the number of observations in each group. For example, if you tally a column
containing 1s, 2s and 3s, COUNT tells you how many of each there are. Using COUNTS with STATS, you can store
these counts, which is useful if you want to generate a frequency plot.
CUMN
CUMN, or cumulative n, computes a cumulative frequency count of the number of non-missing observations in
each group listed in the BY columns. If there are no BY columns listed, CUMN simply counts the non-missing
observations in the columns listed with DESCRIBE or STATS. CUMN counts observations for non-missing groups
only, unless you include the MISSING subcommand.
PERCENT
If you want statistics for different groups listed in one or more BY columns, PERCENT computes what percentage
of the whole is accounted for by each group.
For example, suppose you list one BY column containing five 1s, one 2, and four 3s. PERCENT computes 50% for
the first group, 10% for the second, and 40% for the third.
If you omit the BY subcommand, then PERCENT and CUMPERCENT calculate the value 100 (for 100%).
If you include columns on the main DESCRIBE or STAT command line, then PERCENT and CUMPERCENT calculate
percentages for only the non-missing values in those columns.
CUMPERCENT
If you want statistics for different groups listed in one or more BY columns, CUMPERCENT computes the cumulative
percentage represented by each group.
For example, suppose you list one BY column containing five 1s, one 2, and four 3s.
If you omit the BY subcommand, then PERCENT and CUMPERCENT calculate the value 100 (for 100%).
If you include columns on the main DESCRIBE or STAT command line, then PERCENT and CUMPERCENT calculate
percentages for only the non-missing values in those columns.
Graphs
Each graph subcommand displays a separate graph for each variable listed on the command line.
If you use the BY subcommand, Minitab generates one graph for each column listed on the command line.
141
Minitab Statistical Software Basic Statistics
GHISTOGRAM
Displays a histogram for each variable.
GHISTOGRAM and GNHISTOGRAM display a histogram for each level of the BY variable in a separate panel of
the graph. The histograms for one variable are on the same scale to facilitate comparisons between the levels.
GNHISTOGRAM
Displays a histogram with a normal curve for each variable. GNHISTOGRAM bases each normal curve on the
sample mean and standard deviation of the data in the corresponding histogram.
GHISTOGRAM and GNHISTOGRAM display a histogram for each level of the BY variable in a separate panel of
the graph. The histograms for one variable are on the same scale to facilitate comparisons between the levels.
GINDPLOT
Displays an individual value plot for each variable.
GINDPLOT and GBOXPLOT display side-by-side plots in a single graph, one for each level of the BY variable. This
allows you to easily compare the different levels of the BY variable.
GBOXPLOT
Displays a boxplot for each variable.
GINDPLOT and GBOXPLOT display side-by-side plots in a single graph, one for each level of the BY variable. This
allows you to easily compare the different levels of the BY variable.
GSUMMARY
Displays a graphical summary for each variable.
Quartiles
Every group of data has three quartiles. To calculate quartiles, use Sort (Data > Sort) to order the data from smallest
to largest. The first quartile (Q1) is the observation at position (n+1) / 4. The second quartile is the median. The third
quartile (Q3) is the observation at position 3(n+1) / 4, where n is the number of observations. If the position is not an
integer, interpolation is used.
For example, suppose n=10. Then (10 + 1)/4 = 2.75, and Q1 is between the second and third observations (call them
x2 and x3), three-fourths of the way up. Thus, Q1 = x2 + 0.75(x3 x2). Since 3(10 + 1)/4 = 8.25, Q3 = x8 + 0.25(x9
x8), where x8 and x9 are the eight and ninth observations.
QONE
The first quartile is also referred to as the 25
th
percentile because data from 25% of the observations are less than
or equal to this value.
IQRANGE
The interquartile range equals Q3 Q1.
QTHREE
The third quartile is also referred to as the 75
th
percentile because data from 75% of the observations are less
than or equal to this value.
142
Minitab Statistical Software Basic Statistics
STATS: Session command for storing descriptive
statistics
STATS [C...C]
STATS computes a wide range of statistics on entire columns or subsets of columns and stores those statistics in
the worksheet.
STATS is similar to the commands TALLY on page 903, TABLE on page 901, and DESCRIBE on page 139. TALLY, TABLE,
and DESCRIBE compute many of these statistics and display them in an easy-to-read table format. But TABLE and
DESCRIBE cannot store the values of these statistics for use in further analysis as STATS can.
Here is an example using the PULSE.MTW data set. This data set includes three columns named Height, Weight,
and Sex (containing 1's for males, 2's for females). The NAME command names the three new columns that STATS
will store its results in. GVALUES will store the numbers 1 and 2 into C11, because these are the distinct values in
the BY column named Sex. MEAN will store the mean height for males and the mean height for females in C12,
and the mean weight for males and the mean weight for females in C13.
NAME C11 'SexID' C12 'MeanHt' C13 'MeanWt'
STATS 'Height' 'Weight';
BY 'Sex';
GVALUES C11;
MEAN C12 C13.
When there is no BY subcommand, you must list at least one column on the main STATS command line. In that
case, STATS computes the requested statistics for the entire column.
When you omit columns from the main STATS command line, you must use the BY subcommand. In that case,
you may store these statistics: N, NMISS, COUNT, CUMN, PERCENT, and CUMPERCENT. For more information,
go to Notes on subcommands that store descriptive statistics (STATS command) on page 1172.
You can use either the GLABELS, GVALUES, or GIDS subcommand so that you know which group each row of
statistics belongs to. Use the NAME on page 55 command to name each column so that you know what you
stored.
Control of grouping
BY C...C
BY lists the columns that contain the group variables (such as a column named Temp containing the values Low,
Medium, and High). Columns listed with BY may contain numeric, text, or date/time data. When you include the
BY subcommand, STATS computes statistics for each group listed in the BY columns or columns. When you omit
the BY subcommand, STATS computes statistics for whole columns rather than for subgroups.
NOEMPTY
NOEMPTY omits empty cells.
MISSINGS
MISSINGS includes missing as a distinct value of the BY column (when the BY column includes a missing value).
Otherwise, rows with missing values in BY columns are omitted.
Options
These subcommands store each distinct value listed in each BY column. Therefore, use the same number of columns
as you list with BY. It is a good idea to include at least one of these subcommands so you will know which group each
row of statistics belongs to.
143
Minitab Statistical Software Basic Statistics
GLABELS C...C
GLABELS stores the actual labels from your BY columns (such as 10, 20, 30, or Low, Medium, High). GLABELS
always stores the labels as text.
GVALUES C...C
GVALUES also stores the actual labels from your BY columns, but it stores them as the same data type (numeric
or text) as the BY variable.
GIDS C...C
GIDS stores a 1 for the first value in your BY column, a 2 for the second value, and so on, in a numeric column. If
the BY column is numeric, GIDS stores a 1 for the smallest number in the BY column, a 2 for the next largest
number, and so on. If the BY column contains text, GIDS stores a 1 for the first entry (row 1), a 2 for the next entry
that is different, and so on.
EXPAND
Stores a row of the desired statistic for each row of input instead. If you do not issue EXPAND, Minitab stores the
statistic in the first row.
Statistics
MEAN
Stores the arithmetic mean, or average. The mean is a commonly used measure of the center of a batch of numbers.
Note Missing values are omitted from the calculation of the function Mean.
SEMEAN
Stores the standard error of the mean. It is calculated as StDev / SQRT (N).
STDEV
Stores the sample standard deviation, which provides a measure of how spread out the data are. To calculate the
variance, simply square the standard deviation value.
If the column contains x1, x2, ..., xn, with mean x, then the standard deviation is calculated as follows:
Note Missing values are omitted from the calculation of the function Standard deviation.
VARIANCE
Stores the sample variance, which is a measure of how far the data are spread about the mean. Sample variance
equals the standard deviation squared. It can also be computed with this formula:
CVARIATION
Stores the coefficient of variation, a measure of relative variability. It is calculated as: 100 (s / x).
144
Minitab Statistical Software Basic Statistics
MEDIAN
Stores the median of a column. The median is in the middle of the data: half the observations are less than or
equal to it. Suppose the column contains n values. If n is odd, the median is the value in the middle. If n is even,
the median is the average of the two middle values.
Note Missing values are omitted from the calculation of the function Median.
TRMEAN
Stores a 5% trimmed mean. Minitab removes the smallest 5% and the largest 5% of the values (rounded to the
nearest integer).
SUMS
Stores the sum.
Note Missing values are omitted from the calculation of the function Sum.
MIN
Stores the smallest number in a column.
Note Missing values are omitted from the calculation of the function MIN.
MAX
Stores the largest number in a column.
Note Missing values are omitted from the calculation of the function MAX.
RANGE
Stores the difference between the largest and smallest data value.
SSQ
Stores the sum of squares. Squares each value in the column, and computes the sum of those squared values.
That is, if the column contains x
1
, x
2
, ..., x
n
, then sum of squares calculates (x
1
2
+ x
2
2
+ ... + x
n
2
).
Note Missing values are omitted from the calculation of the function the function Sum of Squares (corrected).
SKEWNESS
Stores the skewness value. Skewness is a measure of asymmetry. A value more than or less than zero indicates
skewness in the data. But a zero value does not necessarily indicate symmetry.
KURTOSIS
Stores the kurtosis value. Kurtosis is one measure of how different a distribution is from the normal distribution.
A positive value characterizes a distribution with a heavier tails than the normal distribution. A negative value
characterizes a distribution with lighter tails than the normal distribution.
MSSD
Stores half the Mean of the Squared Successive Differences of a batch of numbers. For example, suppose a column
contains 1, 2, 4, and 10. The successive differences are 2 1 = 1, 4 2 = 2, and 10 4 = 6. Then:
MSSD = mean(1-squared, 2-squared, and 6-squared) / 2 = 6.83333
N
Stores the number of nonmissing observations in a column.
145
Minitab Statistical Software Basic Statistics
NMISS
Stores the number of missing observations in a column.
COUNT
Stores the total number of observations in a column.
When used as an option with TALLY on page 903 (Stat > Tables > Tally > Tally Individual Variables) or the
STATS command, COUNT computes the number of observations in each group. For example, if you tally a column
containing 1s, 2s and 3s, COUNT tells you how many of each there are. Using COUNTS with STATS, you can store
these counts, which is useful if you want to generate a frequency plot.
CUMN
Stores a cumulative frequency count of the number of non-missing observations in each group listed in the BY
columns. If there are no BY columns listed, CUMN simply counts the non-missing observations in the columns
listed with DESCRIBE or STATS. CUMN counts observations for non-missing groups only, unless you include the
MISSING subcommand.
PERCENT
If you want statistics for different groups listed in one or more BY columns, PERCENT computes what percentage
of the whole is accounted for by each group.
For example, suppose you list one BY column containing five 1s, one 2, and four 3s. PERCENT computes 50% for
the first group, 10% for the second, and 40% for the third.
If you omit the BY subcommand, then PERCENT and CUMPERCENT calculate the value 100 (for 100%).
If you include columns on the main DESCRIBE or STAT command line, then PERCENT and CUMPERCENT calculate
percentages for only the non-missing values in those columns.
CUMPERCENT
If you want statistics for different groups listed in one or more BY columns, CUMPERCENT computes the cumulative
percentage represented by each group.
For example, suppose you list one BY column containing five 1s, one 2, and four 3s.
If you omit the BY subcommand, then PERCENT and CUMPERCENT calculate the value 100 (for 100%).
If you include columns on the main DESCRIBE or STAT command line, then PERCENT and CUMPERCENT calculate
percentages for only the non-missing values in those columns.
GSUMMARY: Session command for displaying a
graphical summary of each variable
GSUMMARY
Displays a graphical summary of each variable.
BY
Lists the columns that contain the group variables (such as a column named Temp containing the values
Low, Medium, and High). Columns listed with BY may contain numeric, text, or date/time data.
146
Minitab Statistical Software Basic Statistics
When you include the BY subcommand, GSUMMARY creates a summary for each group listed in the BY
column or columns. When you omit the BY subcommand, GSUMMARY creates a summary for whole columns
rather than for subgroups.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
SMCONF C C
Stores the confidence interval for the median in C and C.
SSCONF C C
Stores the confidence interval for the standard deviation in C and C.
ONEZ: Session command for performing a 1-sample
Z-test
ONEZ C...C
ONEZ K K
Performs a 1-sample Z-test for the raw or summarized data. You need to provide a value for population standard
deviation the SIGMA subcommand. When you do not know the population standard deviation, you can use ONET
on page 148.
ONEZ C...C performs a Z-test for each of the columns in C...C.
ONEZ K K performs a Z-test using summarized data with sample size and sample mean in K and K, respectively.
SIGMA K (required)
Specifies the value of the population standard deviation.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
TEST K
Tests the null hypothesis using the hypothesized mean specified in K.
SPVALUE C
SPVALUE stores the p-value of the test in a column.
147
Minitab Statistical Software Basic Statistics
SCONF C C
SCONF stores the confidence interval for the mean in two columns.
Graphs
Displays a graph for each column listed with ONEZ. Each graph displays the sample mean and a K% confidence interval
for the mean. No graph is displayed for the summarized data.
GHISTOGRAM
Displays a histogram.
GINDPLOT
Displays an individual value plot.
GBOXPLOT
Displays a boxplot.
ONET: Session command for performing a 1-sample
t-test
ONET C...C
ONET K K K
Performs a t-test using raw or summarized data. The population standard deviation for the test is estimated form
the columns listed with ONET. A test value is specified with the TEST subcommand. ONET performs a two-sided
test unless you use the ALTERNATIVE subcommand to specify a one-sided test. If you know the population
standard deviation or deviations, use ONEZ on page 147 instead.
ONET C...C performs a t-test for each of the columns in C...C.
ONET K K K performs a t-test for the summarized data using sample size, sample mean, and population standard
deviation specified in K, K, and K, respectively.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
TEST K
Tests the null hypothesis using the hypothesized mean specified in K.
148
Minitab Statistical Software Basic Statistics
SPVALUE C
SPVALUE stores the p-value of the test in a column.
SCONF C C
SCONF stores the confidence interval for the mean in two columns.
Graphs
Displays a graph for each column listed with ONET. Each graph displays the sample mean and a K% confidence interval
for the mean. No graph is displayed for the summarized data.
GHISTOGRAM
Displays a histogram.
GINDPLOT
Displays an individual value plot.
GBOXPLOT
Displays a boxplot.
TWOT: Session command for performing a 2-sample
t-test when samples are in one column
TWOT C C
TWOT K K K K K K
TWOT performs a two-sample t-test and confidence interval when the samples and subscripts are in separate
columns or when you have summarized data. Use TWOSAMPLE on page 150 when the samples are in different
columns.
You can specify a confidence level to change the default level for the confidence interval produced by TWOT. The
default level is 95%. K can be any number between 1 and 100. For example, if you enter the command TWOT 90
C1 C2, Minitab calculates a 90% confidence interval.
TWOT C C performs a 2-sample t-test when the samples are in one column and subscripts are in another column.
TWOT K K K K K K performs a 2-sample t-test using summarized data with sample size, mean, and standard
deviation listed for each sample.
ALTERNATIVE K
Specifies a one-sided test. K = –1 gives H1: μ < K, and K = +1 gives H1: μ > K1.
TEST K
Specifies the null hypothesis value K.
POOLED
Uses a pooled procedure to estimate σ. This procedure assumes the two populations have equal variances.
The POOLED procedure is slightly more powerful than the method that does not assume equal variances,
but can be seriously in error if the variances are not equal. Thus, the POOLED subcommand should not be
used in most cases.
149
Minitab Statistical Software Basic Statistics
GINDPLOT
The graph for GINDPLOT contains two individual value plots, one for each sample. The individual value plots
displays the sample mean and a K% confidence interval for each sample.
GBOXPLOT
The graph for GBOXPLOT contains two boxplots, one for each sample. The boxplots display the sample mean
and a K% confidence interval for each sample.
SPVALUE C
SPVALUE stores the p-value of the test in a column.
SCONF C C
SCONF stores the confidence interval for the mean in two columns.
TWOSAMPLE: Session command for performing a
2-sample t-test when the samples are in different
columns
TWOSAMPLE
TWOSAMPLE performs a 2-sample t-test and confidence interval when the samples are in different columns. Use
TWOT on page 149 when samples and subscripts are in separate columns or when you have summarized data.
You can specify a confidence level to change the default level for the confidence interval produced by TWOSAMPLE.
The default level is 95%. K can be any number between 1 and 100. For example, if you enter the command
TWOSAMPLE 90 C1 C2, then a 90% confidence interval is calculated.
ALTERNATIVE K
Specifies a one-sided test. K = –1 gives H1: μ < K, and K = +1 gives H1: μ > K1.
TEST K
Specifies the null hypothesis value K.
POOLED
Uses a pooled procedure to estimate σ. This procedure assumes the two populations have equal variances.
The POOLED procedure is slightly more powerful than the method that does not assume equal variances,
but can be seriously in error if the variances are not equal. Thus, the POOLED subcommand should not be
used in most cases.
GINDPLOT
The graph for GINDPLOT contains two individual value plots, one for each sample. The individual value plots
displays the sample mean and a K% confidence interval for each sample.
GBOXPLOT
The graph for GBOXPLOT contains two boxplots, one for each sample. The boxplots display the sample mean
and a K% confidence interval for each sample.
150
Minitab Statistical Software Basic Statistics
SPVALUE C
SPVALUE stores the p-value of the test in a column.
SCONF C C
SCONF stores the confidence interval for the mean in two columns.
PAIR: Session command for performing a paired
t-test
PAIR C C
PAIR K K K
Performs a paired t-test. This test is appropriate for testing the mean difference between paired observations
when the paired differences follow a normal distribution.
Use to calculate a confidence interval and perform a hypothesis test of the mean difference between paired
observations in the population. A paired t-procedure matches responses that are dependent or related in a pairwise
manner. This matching allows you to account for variability between the pairs usually resulting in a smaller error
term, thus increasing the sensitivity of the hypothesis test or confidence interval.
Typical examples of paired data include measurements on twins or before-and-after measurements. For a paired
t-test, the hypotheses are as follows:
H
0
: μ
d
= μ
0
versus H
1
: μ
d
μ
0
where μ
d
is the population mean of the differences and μ
0
is the hypothesized mean of the differences.
When the samples are drawn independently from two populations, use TWOSAMPLE on page 150 or TWOT on
page 149.
PAIR C C performs a paired t-test when the data are in columns.
PAIR K K K performs a paired t-test using summarized data when K = sample size, K = mean difference, and K =
standard deviation difference.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ALTERNATIVE K
Specifies a one-sided test. K = –1 gives H
1
: μ
d
< μ
0
, and K = +1 gives H
1
: μ
d
> μ
0
.
TEST K
Conducts a test of the null hypothesis μ = K.
SPVALUE C
SPVALUE stores the p-value of the test in a column.
SCONF C C
SCONF stores the confidence interval for the mean in two columns.
151
Minitab Statistical Software Basic Statistics
Graphs
Each of the following graphs displays the sample mean, a K% confidence interval for the mean, and the value under
H
0
.
GHISTOGRAM
Displays a histogram of the paired differences.
GINDPLOT
Displays an individual value plot of the paired differences.
GBOXPLOT
Displays a boxplot of the paired differences.
PONE: Session command for performing a
hypothesis test of the proportion
PONE C...C
PONE K K...K
Performs a test of one binomial proportion.
Use PONE to compute a confidence interval and perform a hypothesis test of the proportion. For example, an
automotive parts manufacturer claims that his spark plugs are less than 2% defective. You could take a random
sample of spark plugs and determine whether or not the actual proportion defective is consistent with the claim.
For a two-tailed test of a proportion:
H
0
: p = p
0
versus H
1
: p p
0
where p is the population proportion and p
0
is the hypothesized value.
To compare two proportions, use PTWO on page 154.
PONE C...C performs an analysis of one proportion on samples in columns.
PONE K K...K performs an analysis of one proportion on summarized data where K = the number of trials and
subsequent Ks = the number of events.
EVENT K
Specifies the event of interest in a column of data. Use a value from the column for K. Enclose text values in
quotation marks. For example, to assess the proportion of "Failure" in a column, enter EVENT "Failure".
TEST K
Specifies the null hypothesis value K.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
152
Minitab Statistical Software Basic Statistics
ALTERNATIVE K
Specifies the alternative hypothesis and the type of confidence interval. K = –1 gives H1: p < p
0
and an upper
bound for p. K = +1 gives H1: p > p
0
and a lower bound for p. The default of K = 0 gives H1: p p
0
and a two-sided
interval for p.
ABLAKER
When the argument for ALTERNATIVE is 0, specifies to use the adjusted Blaker's exact method for calculating the
two-sided hypothesis test and a two-sided confidence interval.
When the argument for the ALTERNATIVE subcommand is -1 or 1, specifies to use the Clopper-Pearson method
to calculate one-sided hypothesis tests and confidence intervals.
CTOLERANCE K
Specifies the convergence criterion for the calculation of the p-value and confidence interval for the adjusted
Blaker's exact method. K is a positive, real number. The default value is 10
-10
.
ITERATION K
Specifies the maximum number of iterations for the calculation of the p-value and confidence interval for
the adjusted Blaker's exact method. K is a non-negative integer. The default value is 100.
WILSON
Specifies to use the classical Wilson-score approximate procedure for calculating the hypothesis test and confidence
interval. The method is also known as the score method. To use the method with a continuity correction, issue
the CCORRRECTION sub-subcommand.
CCORRRECTION
Specifies to use the Wilson-score approximate method with a continuity correction. Without a continuity
correction, the method is liberal for small to moderate sample sizes. The continuity correction makes the
actual confidence level and the actual alpha value at least the levels that the analysis specifies.
ACOULL
Specifies to use the Agresti-Coull approximate procedure for calculating the hypothesis test and confidence
interval.
CPEARSON
Specifies to use the Clopper-Pearson exact method for calculating the hypothesis test and confidence interval.
USEZ
Specifies to use the normal approximation to the binomial distribution for calculating the hypothesis test and
confidence interval.
Storage
SPVALUE C
SPVALUE stores the p-value of the test in a column.
SCONF C (C)
For the default analysis or when the argument for ALTERNATIVE is 0, stores the lower side of the confidence
interval in the first column and the upper side of the confidence interval in the second column.
When the argument for ALTERNATIVE is -1 or 1, stores the confidence limit in one column.
153
Minitab Statistical Software Basic Statistics
PTWO: Session command for performing a
hypothesis test of the difference between two
proportions
PTWO C C
PTWO K K K K
Performs a test of two binomial proportions.
Use PTWO to compute a confidence interval and perform a hypothesis test of the difference between two
proportions. For example, suppose you wanted to know whether the proportion of consumers who return a survey
could be increased by providing an incentive such as a product sample. You might include the product sample
with half of your mailings and see if you have more responses from the group that received the sample than from
those who did not. For a two-tailed test of two proportions:
H
0
: p
1
= p
2
versus H
1
: p
1
p
2
where p
1
and p
2
are the proportions of success in populations 1 and 2, respectively.
To test one proportion, use PONE on page 152.
You can input either raw or summarized data.
Raw data can be entered in two ways: stacked and unstacked.
Enter both samples in a single column (stacked) with a group column to identify the population. Columns may
be numeric, text, or date/time. Successes and failures are determined by numeric or alphabetical order. Minitab
defines the lowest value as the failure; the highest value as the success. For example:
For the numeric column entries of "5" and "10", observations of 5 are considered failures; observations of
10 are considered successes.
For the text column entries of "agree" and "disagree," observations of agree are considered failures;
observations of disagree are considered successes. If the data entries are "yes" and "no", observations of
no are considered failures; observations of yes are considered successes.
Enter each sample (unstacked) in separate numeric or text columns. Both columns must be the same
type-numeric or text. Successes and failures are defined as above for stacked data.
You can reverse the definition of success and failure in a text column by applying a value order. For more
information, go to VORDER on page 137.
The sample sizes do not need to be equal. Minitab automatically omits missing data from the calculations.
For raw data, enter the number of trials and the number of successes for each sample on the main command line.
Enter four integers: the number of trials and the number of successes in the first sample followed by the number
of trials and the number of successes in the second sample.
PTWO C C performs a test of two proportions on samples in columns.
PTWO K K K K performs a test of two proportions on summarized data where K = the number of trials and K =
the number of events for the first proportion, and K = the number of trials and K = the number of events for the
second proportion.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
154
Minitab Statistical Software Basic Statistics
ALTERNATIVE K
Specify a one-sided test. K = –1 gives H1: p < K, and K = +1 gives H1: p > K1.
TEST K
Specifies the null hypothesis value K.
STACKED
Specifies that the data have been entered in a stacked format: the raw data is in one column and the subscripts
or group column to identify the population are in a second column.
POOLED
Specifies to use a pooled estimate of p to calculate the test statistic.
SPVALUE C
Stores the p-value of the test in a column.
SFISHER C
Stores the p-value for the Fisher's exact test in a column.
SCONFC C
Stores the confidence interval for the mean in two columns.
ONERATE: Session command for performing a
1-sample Poisson rate test
ONERATE C...C
ONERATE K K...K
Performs a hypothesis test and calculates a confidence interval for the population Poisson rate for each sample
you input. You can enter data in raw, summarized, or frequency format. Specify a hypothesized test value with
the TEST subcommand. Minitab performs a two-sided test unless you use the ALTE subcommand to specify a
one-sided test. Specify the length of the observation space with the LENGTH subcommand to analyze the mean
number of occurrences in addition to the occurrence rate.
ONERATE C...C calculates a confidence interval for the population Poisson rate for each column of raw sample
data.
ONERATE K K...K calculates a confidence interval for the population Poisson rate for summarized data. The first
K equals the sample size; subsequent values of K correspond to the number of events in each summarized sample.
You cannot use this command to analyze samples with different sample sizes.
FREQ C...C
If your data exists in frequency format, use this subcommand to specify the frequency columns. Enter them
in the same order in which you enter the columns of unique observations.
LENGTH K [K]...[K]
Specify the length of the observation space for each sample to obtain confidence intervals of mean number
occurrences in addition to the rate of occurrences. By default, length equals 1, and the occurrence rate equals
the mean number of occurrences.
155
Minitab Statistical Software Basic Statistics
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
TEST K
Performs a hypothesis test of population Poisson rate. Enter the hypothesized value of the population Poisson
rate for K.
USEZ
Specifies the normal approximation method for calculating the hypothesis test and confidence interval. By
default, Minitab uses the exact method instead of the normal approximation method. This subcommand
accepts no arguments.
TWORATE: Session command for performing a
2-sample Poisson rate test
TWORATE C C
TWORATE K K K K
Use TWORATE C C to perform a hypothesis test and calculates a confidence interval for the difference between
the Poisson rates of two populations. For unstacked data, the arguments correspond to the two columns of data.
For stacked data, the first C corresponds to the column of stacked sample data, and the second C corresponds
to the column of subscripts.
Use TWORATE K K K K with summarized data to perform a hypothesis test and calculate a confidence interval for
the difference between the Poisson rates of two populations. The first K equals the size of the first sample; the
second K equals the number of occurrences in the first sample; the third K equals the size of the second sample;
the fourth K equals the number of occurrences in the second sample.
LENGTH K [K]
Specify the length of observation for each sample to analyze both the mean number of occurrences and the
occurrence rate. If you enter one K, this value becomes the length for both samples. If you enter two values
for K, the first becomes the length for the first sample, and the second K becomes the length of the second
sample.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
156
Minitab Statistical Software Basic Statistics
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
TEST K
Specifies the hypothesized value for the difference between the two population Poisson rates. The default
value is 0.
STACKED
Indicates that the data for both samples are stacked in a single column. This subcommand accepts no
arguments.
FREQ C [C]
Use this subcommand if your data exists in frequency format. For stacked data, enter only one column of
frequencies. For unstacked data, enter two columns of frequency data in the same order in which you enter
the columns of unique observations.
POOLED
Uses a pooled estimate of the occurrence rate for both populations. The argument for the TEST subcommand
must equal zero to use this option. By default, Minitab estimates the rate of each population separately by
using the observed sample rates. This subcommand accepts no arguments.
ONEV: Session command for performing a 1 variance
test
ONEV C...C
ONEV K K
For each sample you input, this command performs a one variance hypothesis test and produces a confidence
interval for the population variance. A test value is specified with the STEST or VTEST subcommands. Minitab
performs a two-sided test unless you use the ALTERNATIVE subcommand to specify a one-sided test. If you prefer
to work in terms of standard deviation instead of variance, use the STDEV subcommand.
ONEV C...C calculates a confidence interval for the population variance for each column of raw data. Output
includes results of the chi-square method (for normal distributions) and the Bonett method (for any continuous
distribution).
ONEV K K calculates a confidence interval for the population variance with summarized data. The first K equals
the sample size; the second K equals the sample variance. Output only includes results of the chi-square method
(for normal distributions).
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
157
Minitab Statistical Software Basic Statistics
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
STEST K
STEST performs a hypothesis test of the population standard deviation.
STEST and VTEST are mutually exclusive.
VTEST K
VTEST performs a hypothesis test of the population variance. K specifies the hypothesized value of the
population and must be a positive number.
STEST and VTEST are mutually exclusive.
STDEV
This subcommand indicates that input values refer to standard deviation instead of variance, where applicable.
Furthermore, this subcommand causes Minitab to produce output in terms of standard deviation instead of
variance. By default, Minitab interprets input and produces output in terms of variance. This subcommand
accepts no arguments.
TWOVARIANCES: Session command for determining
whether the variances or standard deviations of two
groups differ
TWOVARIANCES performs hypothesis tests and computes confidence intervals for the ratios between two populations'
variances and standard deviations. You can use this command when samples and subscripts are in separate columns,
when each sample is in a single column, or when you have summarized data.
TWOVARIANCES C C
Performs two variances test when sample data are in different columns.
TWOVARIANCES C C
Performs two variances test when all sample data are in one column C and subscripts are in a second column C.
Use STACKED with this option.
STACKED
Specifies that data are stacked.
158
Minitab Statistical Software Basic Statistics
TWOVARIANCES K K K K
Performs two variances test using summarized data. Specify the sample size and variance for Sample 1 and the
sample size and variance for Sample 2. If you specify standard deviations instead of variances, use the STDEV
subcommand.
Options
STDEV
Indicates that the input summary values refer to standard deviations instead of variances.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
STEST K
STEST specifies the hypothesized value K for the ratio of two standard deviations. K must be a positive number.
The default is 1, which tests for equal standard deviations. STEST and VTEST are mutually exclusive.
VTEST K
VTEST specifies the hypothesized value K for the ratio of two variances. K must be a positive number. The default
is 1, which tests for equal variances. STEST and VTEST are mutually exclusive.
SNAMES K K
Specifies names for the samples when you enter summarized data. The default sample names are "Sample 1" and
"Sample 2".
USEF
Specifies to use the F-test method instead of Bonett's method and Levene's method. The F-test is accurate only
for normally distributed data. Any departure from normality can cause the F-test to yield inaccurate results.
However, if the data conform to the normal distribution, then the F-test is typically more powerful than either
Bonett's test or Levene's test.
Graphs
GINTERVAL
GINTERVAL displays a graphical summary of the results including the following:
Confidence intervals for the ratio of the standard deviations or variances
P-values for the hypothesis tests
Boxplots of each sample
159
Minitab Statistical Software Basic Statistics
GHISTOGRAM
GHISTOGRAM displays a graph containing a histogram for each sample.
GINDPLOT
GINDPLOT displays a graph containing an individual value plot for each sample.
Results
NODEFAULT
Specifies that none of the following results are displayed.
TMETHOD
TMETHOD displays the method table which includes the null hypothesis, the alternative hypothesis, and the
significance level (denoted by α or alpha).
TSTATISTICS
TSTATISTICS displays the statistic table which includes the standard deviation of each sample, the variance of
each sample, and the confidence interval for the standard deviation or the variance of each sample. The ratio of
the standard deviations and the ratio of the variances are also displayed.
TCONFIDENCE
TCONFIDENCE displays the confidence interval table which includes confidence intervals for the ratio of the
standard deviations and the ratio of the variances.
TTEST
TTEST displays the test table which includes the degrees of freedom, the test statistics, and the p-values. When
the sample sizes are unequal, the test statistic for Bonett's method is undefined. However, the p-value can be
calculated by inverting the confidence interval procedure.
CORRELATION: Session command for measuring
the strength and direction of the association
between two variables
CORRELATION C...C
Calculates the Pearson product moment correlation or the Spearman rank-order correlation for every pair of
samples in C...C.
Options
Minitab calculates the Pearson product moment correlation or the Spearman rank-order correlation and the associated
confidence intervals and p-values.
PEARSON
Calculates the Pearson (product-moment) correlation. Use the Pearson correlation coefficient to examine the
strength and direction of the linear relationship between two continuous variables.
160
Minitab Statistical Software Basic Statistics
For each pair of samples, Minitab calculates the p-value for the hypothesis test of zero-correlation and the
confidence interval for the Pearson correlation. The confidence intervals are based on the Fisher's Z transformation.
SPEARMAN
Calculates the Spearman rank-order correlation (also called Spearman's rho). The Spearman correlation evaluates
the monotonic relationship between two continuous or ordinal variables. In a monotonic relationship, the variables
tend to change together, but not necessarily at a constant rate. The Spearman correlation coefficient is based on
the ranked values for each variable rather than the raw data.
Spearman correlation is often used to evaluate relationships involving ordinal variables. For example, you might
use a Spearman correlation to evaluate whether the order in which employees complete a test exercise is related
to the number of months they have been employed.
For each pair of samples, Minitab calculates the p-value for the hypothesis test of zero-correlation and the
confidence interval for the Spearman correlation. The confidence intervals are based on the Fisher's Z transformation
of the Spearman correlation and Bonett and Wright adjustments.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table which includes the correlation method. When the matrix plot includes p-values or the
output includes the table of pairwise correlations, the Method table also includes the hypotheses and the
significance level.
TCORRELATION
Displays the correlation matrix.
TPCORRELATION M
Displays the table of pairwise correlations. The table includes pairwise sample sizes, the correlation estimates, the
confidence intervals, and the p-values.
Graphs
GMPLOT
Displays a matrix of scatterplots for all pairs. By default, the matrix plot includes correlation values and the matrix
plot is the lower left triangle of the matrix so that each pair of variables is on one plot. There are two groups of
optional subcommands used to control the statistics and the display of the plot.
Use one of the following optional subcommands to change the display statistics:
R
Displays the correlation values on the plots.
RPVALUES
Displays the correlation values and the p-values for the test of zero-correlation on the plots.
161
Minitab Statistical Software Basic Statistics
RCIS
Displays the correlation values and the confidence intervals on the plots.
NOSTATS
Suppresses the display of statistics on the plots.
Use one of the following optional subcommands to specify how to display the matrix plot:
LL
Displays the lower left triangle portion of the matrix plot.
UR
Displays the upper right triangle portion of the matrix plot.
FULL
Displays the entire matrix plot (both the lower left triangle and the upper right triangle) of the matrix plot.
Storage
SCORRELATION M
Stores the correlation matrix.
SPVALUES M
Stores a matrix that contains the p-values for the hypothesis test of zero-correlation.
SCIS M M
Stores two matrices that contain the lower bounds and the upper bounds of the confidence intervals for the
pairwise correlations. The first matrix stores the lower bounds and the second matrix stores the upper bound.
COVARIANCE: Session command for calculating the
covariance between pairs of columns
COVARIANCE C...C [M]
Calculates the covariance between each pair of columns. You can display the result or you can store the covariance
matrix.
When you list two columns on the command line, Minitab calculates the covariance for the pair. When you list
more than two columns, Minitab calculates the covariance for every pair of columns, and displays the lower triangle
of the resulting covariance matrix (in blocks if there is insufficient room to fit across a page). Minitab does not
display the covariance matrix when the matrix is stored in M.
162
Minitab Statistical Software Basic Statistics
NORMTEST: Session command for performing a
normality test
NORMTEST C
Generates a normal probability plot.
Normal plots use the values in the input column as x-values. The grid on the graph resembles the grids found on
normal probability paper. The horizontal axis is a linear scale. The line forms an estimate of the cumulative
distribution function for the population from which data are drawn.
By default, an Anderson-Darling test for normality is performed and the numerical results are displayed with the
graph. You can also use a Ryan-Joiner test (similar to a Shapiro-Wilk test) or a Kolmogorov-Smirnov test.
PTILES C
PTILES K...K
Specifies a set of reference percents. The values must be between 0 and 100 when percents are used as the
y-scale type or 0 to 1 when probability is the y-scale type. Minitab marks each percent in the column with a
horizontal reference line on the plot, and marks each line with the percent value. Minitab draws a vertical
reference line where the horizontal reference line intersects the line fit to the data, and marks this line with
the estimated data value.
DVALUE
Use DVALUE to show the percents at the reference x-scale positions specified in PTILES.
PERCENT
Specifies a percent y-scale.
PROBABILITY
Specifies a probability y-scale.
SCORES
Specifies a percentile y-scale.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
SPVALUE C
SPVALUE stores the p-value of the test in a column.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
163
Minitab Statistical Software Basic Statistics
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Goodness-of-fit tests
There are 3 types of goodness-of-fit test: a chi-square based test, an ECDF based test, and a correlation based test.
By default, Minitab uses the Anderson-Darling test, which is an ECDF based test.
When your α-value is greater than the p-value displayed with the graph, you reject the hypothesis of normality. The
α-value (also called significance level), is the probability that you will reject the hypothesis of normality when the
hypothesis is true.
For example, if you are using an α-value of 0.10 and the p-value is 0.07, then you reject the hypothesis of normality
at the 0.10 level.
RJTEST
Use RJTEST to perform a Ryan-Joiner test, which is a correlation based test.
KSTEST
Use KSTEST to perform a Kolmogorov-Smirnov test, which is a chi-square based test.
164
Minitab Statistical Software Basic Statistics
OUTLIER: Session command for performing an
outlier test
OUTLIER C...C
Use to identify a single outlier in a sample. The hypotheses are as follows:
H
0
(the null hypothesis): All values in the sample are from the same, normally distributed population.
H
1
(the alternative hypothesis): One of the values in the sample is not from the same, normally distributed
population.
You should not use Minitab's outlier tests more than once on the same sample. If you remove an outlier from
your sample and then retest, you risk removing values that are not actually outliers.
BY C...C
Lists the columns that contain the grouping variables (such as a column named Temp that contains the values
Low, Medium, and High). Columns listed with BY may contain numeric, text, or date time data. When you
include the BY subcommand, OUTLIER conducts a separate analysis for each group listed in the BY column
or columns.
Options
GRUBBS
GRUBBS specifies to use Grubbs' test, which is the default test.
The arguments K K specify the specific ratio to test. For example, to perform the standard Dixon's Q test, which
corresponds to a Dixon ratio of r10, the arguments are 1 and 0. The first argument can either be 1 or 2 and the
second argument can be 0, 1, or 2.
DIXON K K
DIXON specifies to use one of the six versions of Dixon's outlier test instead of Grubbs' test.
The arguments K K specify the specific ratio to test. For example, to perform the standard Dixon's Q test, which
corresponds to a Dixon ratio of r10, the arguments are 1 and 0. The first argument can either be 1 or 2 and the
second argument can be 0, 1, or 2.
ALPHA K
Specifies the significance level (denoted by α or alpha) for the test as K. The default is 0.05.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
165
Minitab Statistical Software Basic Statistics
Graphs
GOUTLIERPLOT
Displays the outlier plot with a summary of the results, including an individual value plot of the data which
highlights the outlier if one is identified. The outlier plot also includes summary statistics, the test statistic, and
the p-value for the test statistic.
Results
Minitab displays all output tables by default; you do not have to enter the subcommands.
NODEFAULT
If you enter NODEFAULT, then each table is only displayed if you enter TMETHOD, TTEST, or TOUTLIER.
TMETHOD
TMETHOD displays the method table which includes the null hypothesis, the alternative hypothesis, and the
significance level significance level (denoted by α or alpha).
TTEST
TTEST displays the test table which includes the specific test performed, summary statistics for the sample, and
the p-value for the hypothesis test.
TOUTLIER
TOUTLIER displays the value of the outlier if one is identified, and the row in the worksheet that contains the
outlier.
Storage
SINDICATOR C...C
Stores an indicator column for each variable. A one (1) is stored in the row that contains the outlier. A zero (0) is
stored in each of the remaining rows.
PGOODNESS: Session command for performing a
chi-square goodness-of-fit test for Poisson
distribution
PGOODNESS C...C
Performs a chi-square goodness-of-fit test for Poisson distribution for each data set. Each C corresponds to one
data set containing nonnegative integers. If the column contains missing data, that row is excluded from all
computations.
FREQUENCY C...C
Specifies the frequency column, one for each data set. The length of each column must match the length of
the corresponding data set.
166
Minitab Statistical Software Basic Statistics
MEAN C
MEAN K...K
Specifies the mean of the Poisson distribution for each data set as K...K or in C. If you specify only one value
for the mean, then this value applies to all data set.
Graphs
GBAR
Displays a bar chart of the observed and expected values.
GCHISQ
Displays a bar chart of each category's contribution to the chi-square value.
PARETO
Use PARETO with GCHISQ to display a bar chart that orders each category's contribution to the chi-square
value from largest to smallest.
Results
RTABLE
Displays a table of the observed values and the expected values and the test results.
167
Minitab Statistical Software Basic Statistics
Regression
INDICATOR: Session command for creating indicator
variables
INDICATOR C C...C
Creates indicator variables (also called dummy variables) that you can use in a regression analysis. If you use
REGRESS on page 169, you do not need to create indicator variables.
The smallest number in C2 is 2 and the largest is 6. INDICATOR creates one indicator variable for each unique
value.
C11 is the indicator variable for the value 2. C11 contains a 1 in every row where C2 contains a 2, and 0
otherwise.
C12 is the indicator variable for the value 3. C12 contains a 1 in every row where C2 contains a 3, and 0
otherwise.
C13 is the indicator variable for 5. C13 contains a 1 in every row where C2 contains 5, and 0 otherwise.
C14 is the indicator variable for 6. C13 contains a 1 in every row where C2 contains 6, and 0 otherwise.
If C2 contains an * (missing data code), then all indicator variables are also set to *.
The number of storage columns must be equal to the number of distinct values (not including *) in the input
column. Up to 100 storage columns are allowed on INDICATOR.
The following command language is an example of using INDICATOR.
INDICATOR C2, C11-C14
Before using INDICATOR
C1
2
2
5
3
6
5
*
After using INDICATOR
C14C13C12C11...C1
0001...2
0001...2
0100...5
168
Minitab Statistical Software Regression
C14C13C12C11...C1
0010...3
1000...6
0100...5
****...*
REGRESS: Session command for performing a
regression analysis
REGRESS
Performs simple, polynomial, and multiple regression using the least squares method.
REGRESS uses least squares to fit a model to one or more continuous or categorical predictors. Optionally, you
can:
Perform stepwise regression
Fit the model without an intercept
Perform weighted regression
Use a test data set or cross-validation to validate the model
Store the residuals, fitted values, and many other diagnostics for additional analysis
Generate point estimates, and prediction and confidence intervals for predicted values
Transform non-normal data using the Box-Cox transformation
Generate several plots for residual analysis. For more information, go to Residual analysis and regression
diagnostics on page 1178.
Options
Specifies information about the variables and terms to include in the model.
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
CONTINUOUS C...C
Specifies the continuous predictors if you have any. The column(s) must be numeric or date/time and must match
the length of the response column.
CATEGORICAL C...C
Specifies the categorical predictors if you have any. The column(s) can be numeric, text, or date/time and must
match the length of the response column.
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. Only continuous predictors may be repeated. Nested
terms are not allowed. The model can be nonhierarchical.
169
Minitab Statistical Software Regression
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
−1
(X' W Y)
This is equivalent to minimizing the weighted SS Error,
Σ w
i
(Y )
2
where w i is the weight in row i.
CONSTANT
When you use CONSTANT, Minitab includes the β
0
term (the intercept) in the equation. Thus, Minitab fits the
model:
Y = β
0
+ β
1
X
1
+ β
2
X
2
+...+ β
k
X
k
+ e
NOCONSTANT
When you use NOCONSTANT, Minitab omits the β
0
term (the intercept) from the equation. Thus, Minitab fits the
model:
Y = β
1
X
1
+ β
2
X
2
+...+ β
k
X
k
+ e
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
TOLER K
Specifies the tolerance level for collinearity and constant check. By default, K = 4 * 2.22e–012.
SSQUARES
Specifies sequential sum of squares for tests in the ANOVA table. The default is the adjusted sums of squares.
EFFECT
Specifies the effect coding (−1, 0, +1) scheme for categorical predictors.
If you do not specify either EFFECT or BINARY, Minitab uses the preference set in File > Options > Linear Models
> Coding of Predictors.
BINARY
Specifies the binary coding (1, 0) scheme for categorical predictors.
If you do not specify either EFFECT or BINARY, Minitab uses the preference set in File > Options > Linear Models
> Coding of Predictors.
170
Minitab Statistical Software Regression
REFERENCE C K ... C K
Changes the default coding for the categorical predictor columns. To change the default reference factor level,
specify the factor column followed by the reference level. (You must enclose text and date/time levels in double
quotation marks.) You can assign a reference level only when you use the binary coding (1, 0) scheme.
Standardizing the continuous predictor
Use this set of subcommands to standardize the continuous predictors in your model. You can use SCALE and LOCATION
in conjunction with each other. LEVELS is mutually exclusive with the LOCATION and SCALE subcommands.
If you do not specify LOCATION, SCALE, LEVELS, or UNSTANDARDIZED, Minitab uses the preferences set in File >
Options > Linear Models > Coding of Predictors.
LOCATION [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by subtracting a constant from
each predictor. If you do not specify any arguments, the mean of each predictor column is subtracted. K specifies
to subtract a constant. If you specify arguments, the number of arguments must match the number of continuous
predictors.
SCALE [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by dividing each predictor by a
constant. If you do not specify any arguments, each predictor column is divided by the standard deviation. K
specifies to divide by a constant. If you specify arguments, the number of arguments must match the number of
continuous predictors.
LEVELS [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by DOE-type coding for the specified
low and high levels K K&K K. The number of arguments must be twice the number of continuous predictors.
UNSTANDARDIZED
Specifies the analysis is to be performed on the original predictors.
Box-Cox
BOXCOX [K]
Performs a Box-Cox transformation with a specified lambda. K is the value of lambda and must be between −5
and +5. If you do not specify K, then Minitab will find the optimal lambda. By default, Minitab rounds the optimal
value.
Minitab cannot calculate the optimal lambda for stepwise regression. Consequently, you must specify a lambda
value for BOXCOX if you use STEPWISE, FORWARD, or BACKWARD.
Stepwise
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
171
Minitab Statistical Software Regression
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find an improvement of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
FVALIDATION
Specifies the use of forward selection with the validation R
2
as the criterion for the selection of the final model.
When you use FVALIDATION, you must also use TEST or CVTEST. When you use TEST, the procedure is similar
to forward selection for other methods. At the end of each step, Minitab Statistical Software calculates the test
R
2
statistic. At the end of the forward selection procedure, the model with the greatest test R
2
value is the final
model.
When you use CVTEST, the procedure repeats forward selection on each fold. The procedure evaluates all the
folds at each step and identifies the step with the best overall k-fold R
2
value. The last part of the procedure is to
perform forward selection on the full dataset, stopping at the best step from the selections on the folds.
FVALIDATION stops under the same conditions as FINFORMATION. The ATEND sub-subcommand that adds
terms to the model to make it hierarchical at the end is not compatible with FVALIDATION.
GRSQUARE
When you use GRSQUARE after FVALIDATION, displays a graph of the R
2
statistic and the validation R
2
statistic
for each step in the model selection procedure.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
172
Minitab Statistical Software Regression
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
173
Minitab Statistical Software Regression
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Validation
TEST C K
TEST K [K]
Specifies to perform validation with a test data set. When you specify a column you select the rows to include in
the test data set. The column has two distinct values. Use the constant to specify which value is for the test data
set.
When you specify a constant first, Minitab Statistical Software randomly selects the data for the test data set. The
constant is the fraction of the data in the test data set. The optional constant is a seed for the random number
generator. If you specify the seed, you can get the same test data set again by specifying the same seed.
CVTEST C
CVTEST K [K]
Specifies to perform k-fold cross validation. When you specify a column, you select the rows for each fold. Rows
with the same value in the column are in the same fold.
When you specify a constant, Minitab Statistical Software randomly selects the data for the folds. The constant
is the number of folds. The optional constant is a seed for the random number generator. If you specify the seed,
you can get the same folds again by specifying the same seed.
Graphs
When you use TEST, the residual plots include separate displays for the training data set and the test data set.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of errors. This plot lets you look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1– the confidence level that follows CONFIDENCE, unless you use stepwise selection. For forward
selection, the alpha level is the level that follows AENTER. For backward and stepwise selection, the alpha level is
the level that follows AREMOVE.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram or individual value plot of the residuals, depending on the sample size.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
174
Minitab Statistical Software Regression
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis ( for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Results
NODEFAULT
Specifies that no default tables or graphs will be displayed
TBASIC
Displays the tables for the Minitab 16 version of REGRESS.
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
Use FULL to display the coefficients, p-values, Mallows' Cp, and model summary statistics for each step of the
procedure. Use NOFULL to hide these statistics. If you do not specify FULL or NOFULL, Minitab uses the preferences
set in File > Options > Linear Models > Stepwise.
TEQUATION
Displays the regression equation table. Minitab will display up to 50 equations. If you want to see a single equation,
rather than a separate equation for each factor level combination, use SINGLE. To see the separate equations, use
SEPARATE. If you do not specify SINGLE or SEPARATE, Minitab uses the preferences set in File > Options > Linear
Models > Display of Results.
TCOEFFICIENTS
Displays the table of coefficients. Use FULL to display the full set of coefficients for categorical predictors. Use
NOFULL to show only the linearly independent coefficients. If you do not specify FULL or NOFULL, Minitab uses
the preferences set in File > Options > Linear Models > Display of Results.
TSUMMARY
Displays the summary of model table.
TANOVA
Displays the ANOVA table.
TDIAGNOSTICS
Displays a table of diagnostics. K = 0 displays diagnostics for only unusual observations. K = 1 displays diagnostics
for all observations. If you do not specify K, Minitab uses the preference set in File > Options > Linear Models
> Display of Results.
TDW
Displays Durbin-Watson statistics.
175
Minitab Statistical Software Regression
TSIMPLE
Displays the simple versions of the ANOVA table, table of coefficients, model summary table, and table of unusual
observations.
TEXPAND
Displays the expanded version of the ANOVA table, table of coefficients, model summary table, and table of
unusual observations.
Storage for Box-Cox transformation
BCRESP C
Stores the Box-Cox transformation of the response in C.
BFITS
Stores the fits for the original response.
Storage for fits and residuals
Use to store the fits and residuals in the specified column. When you use TEST , the following statistics are missing
for the test data set: studentized residuals, Cook's distance, and DFITS. The Durbin-Watson statistic is for the training
data set.
FITS C
Stores the fitted values.
RESIDUALS C
Stores the residuals (fitted values observed values).
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals.
HI C
Stores the leverages.
COOK C
Stores Cook's distance.
DFITS C
Stores the DFITS.
SDW C
Stores the Durbin-Watson statistic.
Storage for characteristics of the estimated equation
Use to store characteristics of the estimated equation in the specified column.
COEFFICIENTS C
Stores the estimated coefficients.
176
Minitab Statistical Software Regression
FITS C
Stores the fitted values, often called the Y-hats ( ).
MSE K
Stores the mean square error. When you use TEST, the statistic is for the training data set.
SPVALUE C
Stores the p-values for each predictor.
SVIF C
Stores the VIFs for each predictor.
SS C
Stores the standard deviation of the error term. When you use TEST, the first row is for the training data set and
the second row is for the test data set.
SRSQ C
Stores the R-squared for the model. When you use TEST, the first row is for the training data set and the second
row is for the test data set.
SRSADJ C
Stores the adjusted r-squared for the model. When you use TEST, the statistic is for the training data set.
SPRESS C
Stores the PRESS statistic for the model. When you use TEST, the statistic is for the training data set.
XMATRIX M
Stores the design matrix for regression model.
XPXINV M
Stores a p x p matrix, inverse of X'X. This matrix, when multiplied by MSE is the variance-covariance matrix of the
coefficients. If the WEIGHTS subcommand is used, then XPXINV stores the inverse of the X'WX. When you use
TEST, the matrix is for the training data set.
RMATRIX M
Stores the R matrix of the QR decomposition, also known as the Cholesky decomposition. When you use TEST,
the matrix is for the training data set.
Storage for validation
Use the following commands to store statistics for validation with a test data set or validation with k-fold cross validation.
SSAMPLE C
When CVTEST is used:
The storage column, Sample_Id, stores the fold identification in C.
C contains values 1, 2, ..., K.
When TEST is used:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the two values.
177
Minitab Statistical Software Regression
CVFIT C
Stores the fitted values from each fold's turn as the test data set.
CVRESID C
Stores the residuals from each fold's turn as the test data set.
BREG: Session command for performing best subsets
regression
BREG C C...C
Performs best subsets regression, using the maximum R-squared criterion.
Suppose you specify m predictors. BREG first looks at all one-predictor regression models, selects the model with
the largest R-squared, and displays information on this model and the next best one-predictor model. Then BREG
looks at all two-predictor models, selects the model with the largest R-squared, and displays information on this
and the next best one. The process continues until all m predictors are used.
BREG is an efficient way to select a group of "best subsets" for further analysis by selecting the smallest subset
that fulfills certain statistical criteria. The subset model may actually estimate the regression coefficients and
predict future responses with smaller variance than the full model using all predictors.
INCLUDE C...C
Includes the predictors specified in C...C in all models. Only columns that were specified with the BREG
command can be specified in INCLUDE.
NVARS K [K]
By default, displays the best one-predictor models, the best two-predictor models, on up to the best
m-predictor models. If you specify, for example, NVARS 5 12, then only the best 5-, 6-, ..., 12-predictor
models are displayed.
Note NVARS does not count the predictors given in INCLUDE. Thus, INCLUDE C1–C3 with NVARS 2 6, displays models
with 3 + 2 = 5 to 3 + 6 = 9 predictors.
BEST K
Displays information from the "best" K models of each size, if there are that many. K can be from 1 to 5. The
default is 2.
NOCONSTANT
When you use NOCONSTANT, Minitab omits the b 0 term (the intercept) from the equation. Thus, Minitab
fits the model:
Y = β
1
X
1
2
X
2
+...+ β
k
X
k
+ e
When NOCONSTANT is specified, Minitab does not display R-squared and adjusted R-squared, since their
interpretation is difficult.
You can also use NOCONSTANT as a main command. In that case, it applies to all BREG, REGRESS, and
STEPWISE commands that follow.
178
Minitab Statistical Software Regression
CONSTANT
When you use CONSTANT, Minitab includes the b 0 term (the intercept) in the equation. Thus, Minitab fits
the model:
Y = β
0
+ β
1
X
1
2
X
2
+...+ β
k
X
k
+ e
You can also use CONSTANT as a main command. In that case, it applies to all BREG, REGRESS, and STEPWISE
commands that follow.
NOWARN
When you specify more than 14 free variables with BREG, Minitab displays a prompt that asks whether you
want to continue with BREG computations even though it will take a long time. Use NOWARN if you want
to suppress this warning prompt.
TEXPAND
Displays the expanded table that includes PRESS, AICc, BIC, and condition number. You can also set this
option in File > Options.
FITLINE: Session command for creating a fitted line
plot
FITLINE C C
Plots the regression line through the actual data or the log 10 of the data. The fitted line plot shows you how
closely the actual data lie to the fitted regression line. You can include only one predictor in the model.
Polynomial regression is one method for modeling curvature in the relationship between a response variable (Y)
and a predictor variable (X). Polynomial modeling techniques try to account for the curvature by extending the
simple linear regression model to include higher powers of X - such as X-squared - as predictors.
Use the POLY subcommand to specify the order of the polynomial you want to fit. If you have not transformed
the X or Y variables, you can fit the following models with FITLINE:
Statistical modelPOLY KOrderModel type
Y = β
0
+ β
1
X + e1FirstLinear
Y = β
0
+ β
1
X + β
2
X
2
+ e2SecondQuadratic
Y = β
0
+ β
1
X + β
2
X
2
+ β
3
X
3
+ e3ThirdCubit
You can generate additional models by using the log
10
of X and/or Y for linear, quadratic, and cubic models. These
models provide another way of modeling curvature. In addition, taking the log
10
of Y can reduce right-skewness
and some forms of heteroskedasticity, such as unequal variances.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
179
Minitab Statistical Software Regression
Type of residualsValue of K
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis
(for example, 1 2 3 4 ... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Options
POLY K
Specifies the order of the polynomial model you want to fit and plot. K is an integer from 1 to 3. The default is 1.
LOGY
Uses log
10
Y as the response variable.
LOGX
Uses log
10
X as the predictor variable. If LOGX is used with polynomials of order greater than one, then the
polynomial regression will be based on powers of the log
10
X.
YSCALE
Plots the transformed response and predictor variables on a log scale. FITLINE ignores YSCALE if you do not use
LOGY.
XSCALE
Plots the transformed response and predictor variables on a log scale. FITLINE ignores XSCALE if you do not use
LOGX.
CI
Displays confidence bands about the fitted regression line.
PI
Displays prediction bands about the fitted regression line.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
180
Minitab Statistical Software Regression
Storage
RESIDUALS C
Stores the residuals in C. If you specified LOGY, Minitab stores the log-transformed residuals. The residual for the
i th log-transformed response is:
e
i
= (log
10
Y
i
log
10 i
)
FITS C
Stores the fitted values, often called the Y-hats ( ), in C. If you specified LOGY, Minitab stores the log-transformed
fits (log
10
).
COEFFICIENTS C
Stores the estimated coefficients in C.
BRESIDUALS C
Stores in C the residuals of the transformed response in the original scale of the data. This subcommand is only
available if you used LOGY.
BFITS C
Stores in C the fitted values of the transformed response in the original scale of the data. This subcommand is
only available if you used LOGY.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
181
Minitab Statistical Software Regression
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
SSWORKSHEET: Session command for creating a
stability study worksheet
Important SSWORKSHEET writes data to the active worksheet. To prevent possible confusion and lost data, it is best to use NEW immediately
prior to SSWORKSHEET. (Do not use NEW however, if you use the TIME subcommand.) NEW creates a new, blank worksheet and makes the
new worksheet the active worksheet.
SSWORKSHEET K K K
Creates a stability study worksheet with the following parameters (in the following order):
The number of times as K
The number of batches as K
The number of replicates per batch at each time as K
TIME C
TIME K...K
Optional subcommand TIME specifies the test times as values from column C or as constants K...K.
SSWORKSHEET K K
Creates a stability study worksheet with the following parameters (in the following order):
The number of batches as K
The number of replicates per batch at each time as K
TIME C...C (required)
Required subcommand TIME specifies a column of test times for each batch
182
Minitab Statistical Software Regression
Options
BNAME C
BNAME K...K
Specifies a name for each batch. The default batch names are the text values "1", "2", "3", ... .
TSUMMARY
Displays a summary of the design that includes the number of sampling times, the number of batches, the number
of samples per batch at each time, and the total number of runs.
SORDER C
Stores the standard order of the runs in column C.
RORDER C
Stores the run order in column C.
XMATRIX C C
Stores the sampling times for each run in the first column C and the batch names in the second column C.
Randomization
Use the following commands to control how the runs are randomized in the worksheet. If you do not use any of these
subcommands, then the runs are not randomized, so the run order is the same as the standard order.
To generate the same random order, you can optionally set the base as K, where K is an integer that is greater than
0.
RANDOMIZE [K] (default)
RANDOMIZE specifies to randomize the order of the batches at each test time, and the repeats at each test time.
BRANDOMIZE [K]
BRANDOMIZE specifies to randomize the order of the batches at each test time, but to keep all repeats from one
batch together before switching to the next batch.
NRANDOMIZE
NRANDOMIZE specifies to sample each batch in sequential order and to take all repeats from one batch before
switching to the next batch.
SHELFLIFE: Session command for performing a
stability study
SHELFLIFE
Analyzes the stability of a product over time to determine the product's shelf life. Minitab fits a linear model to
represent the relationship between the response variable, the time variable, and an optional batch factor. The
batch factor can be fixed or random. Based on the model, Minitab calculates the shelf life, which is the length of
time that the response is expected to remain within the specifications.
183
Minitab Statistical Software Regression
Options
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
TIME C (required)
Specifies the time variable. The column must be numeric or date/time and must match the length of the response
column.
BATCH C
Specifies the categorical batch factor, if you have one. The column can be numeric, text, or date/time and must
match the length of the response column.
RANDOM
Specifies that BATCH is a random factor. If BATCH is not issued, RANDOM is ignored. For random batches, Minitab
uses an iterative algorithm to estimate the variance components and to select the model. There can be cases
where the variance components cannot be estimated and no further analysis is possible.
MAXITER K
Specifies the maximum number of iterations. K must be a nonnegative integer.
STARTING K K K
Specifies the starting estimates for the variance components. If you do not use STARTING, Minitab uses the
minimum norm quadratic unbiased estimation (MINQUE) estimates. The MINQUE estimates are typically
good estimates.
CTOLERANCE K
Specifies the convergence tolerance value for object function. K must be greater than 0. If this subsubcommand
is not issued, Minitab uses the value 1E-7.
ETOLERANCE K
Specifies the convergence tolerance value for estimates. K must be greater than 0. If this subsubcommand
is not issued, Minitab uses the value 1E-7.
LSPEC K
Specifies the lower specification limit. You must use LSPEC, USPEC, or both. If both LSPEC and USPEC are issued,
USPEC must be greater than LSPEC. K must be numeric.
USPEC K
Specifies the upper specification limit. You must use LSPEC, USPEC, or both. If both LSPEC and USPEC are issued,
USPEC must be greater than LSPEC. K must be numeric.
BPERCENT K
Specifies using K percent of the response above the lower spec or below the upper spec to estimate shelflife. K
must be between 0 and 100. Minitab uses 50 percent if BPERCENT is not issued.
PVALUE K
Specifies the significance level that is used for model selection. K must be between 0 and 1. Minitab uses 0.25 if
PVALUE is not issued.
ONESPEC
Specifies to use a one-sided significance level when you specify both specification limits. Use this subcommand
when the response variable has two specification limits, but only one limit is relevant for the shelf life. For example,
if the confidence level is 95% and you select this option, then the confidence level for the single bound that is
relevant to the shelf life is also 95%. If you do not select this option, then the confidence level for both bounds
is 97.5%. The single 95% bound gives a longer shelf life.
184
Minitab Statistical Software Regression
For example, a medication has an upper specification limit of 12.5 micrograms and a lower specification limit of
12 micrograms. In storage, the medication degrades, but never increases in strength. Only the lower specification
limit is relevant to the shelf life.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
Box-Cox
BOXCOX [K]
Performs a Box-Cox transformation with a selected lambda. K is the value of lambda and must be between −5
and +5. If K is not given and you have a fixed batch, Minitab will find the optimal lambda. By default, Minitab
rounds the optimal value.
Minitab cannot calculate the optimal lambda when batch is a random factor. Consequently, you must specify a
lambda value for BOXCOX if you use RANDOM.
Graphs
GSHELFLIFE
Displays the shelf life plot. Use the subsubcommands to control how the batches are displayed.
INDIVIDUAL
Displays a graph for each individual batch.
ALL [K]
Displays all batches on one graph. If you specify K, each graph displays up to K batches.
RTYPE K
Specifies the type of residual to plot with the graph subcommands in K. If MARGINAL is issued, K must be 1 or 2.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
MARGINAL
Displays marginal residuals on the residual plots. If MARGINAL is not issued, the residual plots display
conditional residuals for random batches.
GHISTOGRAM
Displays a histogram or individual value plot of the residuals, depending on the sample size.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
185
Minitab Statistical Software Regression
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
GFOURPACK
Displays a layout that includes a histogram of the residuals, a normal probability plot of the residuals, residuals
vs fitted values, and residuals vs the order of the data.
Results
Displays a variety of tables in the output. The availability of some tables depends on whether BATCH is a fixed factor
or a random factor.
NODEFAULT
Specifies that no default tables and graphs will be displayed.
TMETHOD
Displays the method table.
TFACTOR
Displays the name, number of levels, and the values for the batch factor in your model.
TITERATION
Displays the estimation iteration history table when batch is a random factor.
TVARIANCE
Displays the variance component table when batch is a random factor.
TCOVARIANCE
Displays the asymptotic variance covariance matrix of variance estimates when batch is a random factor.
TMSELECTION
Displays the model selection results, including the terms that are removed from the final model.
TANOVA
Displays the ANOVA table for a fixed batch.
TSUMMARY
Displays the summary of model table.
TCOEFFICIENTS
Displays the table of coefficients. Use FULL to display the full set of coefficients for the batch factor. Use NOFULL
to show only the linearly independent coefficients. If you do not specify FULL or NOFULL, Minitab uses the
preferences set in File > Options > Linear Models > Display of Results.
FULL
Specifies to display the full set of coefficients for the batch factor
NOFULL
Specifies to not display the full set of coefficients for the batch factor
186
Minitab Statistical Software Regression
TRANDOM
Displays the random effect prediction table when batch is a random factor.
TEQUATION
Displays the regression equation table, or the marginal fitted equation table if batch is a random factor.
TDIAGNOSTICS [K]
Displays a table of fits and diagnostics. K = 0 displays diagnostics for only unusual observations. K = 1 displays
diagnostics for all observations. If you do not specify K, Minitab uses the preference set in File > Options > Linear
Models > Display of Results.
TCONDITIONAL [K]
Displays the conditional fits and residuals when batch is a random factor. K = 0 displays diagnostics for only
unusual observations. K = 1 displays diagnostics for all observations. If you do not specify K, Minitab uses K = 0.
TSHELFLIFE
Displays the shelf life table.
TSIMPLE
Displays the simple versions of the ANOVA table, table of coefficients, model summary table, and table of unusual
observations.
TEXPAND
Displays the expanded version of the ANOVA table, table of coefficients, model summary table, and table of
unusual observations.
Storage
Use to store analysis results in the specified column or matrix. The availability and function of the storage commands
depends on whether BATCH is a fixed factor or a random factor.
RESIDUALS C
Stores the residuals (fitted values observed values) if batch is a fixed factor. Marginal residuals (marginal fitted
values observed values) if batch is a random factor.
SRESIDUALS C
Stores the standardized residuals if batch is a fixed factor. Standardized marginal residuals if batch is a random
factor.
TRESIDUALS C
Stores the deleted Studentized residuals of the fit if batch is a fixed factor. If batch is a random factor, stores the
studentized marginal residuals.
CRESIDUALS C
Stores the conditional residuals when batch is a random factor.
CSRESIDUALS C
Stores the conditional standardized residuals when batch is a random factor.
FITS C
Stores the fitted values if batch is a fixed factor. Marginal fitted values if batch is a random factor.
CFITS C
Stores the conditional fitted values when batch is a random factor.
187
Minitab Statistical Software Regression
HI C
Stores the leverages.
COOK C
Stores Cook's distance.
DFITS C
Stores the DFITS.
COEFFICIENTS C
Stores the estimated coefficients.
BLUP C
Stores the best linear unbiased predictor when batch is a random factor.
XMATRIX M
Stores the design matrix for fixed effects terms.
ZMATRIX M
Stores the design matrix for random effects terms.
COVARIANCE M
Stores the variance-covariance matrix of the variance component estimates if batch is a random factor.
FCOVARIANCE M
Stores the covariance matrix of fixed effect estimates.
NLINEAR: Session command for performing
nonlinear regression
NLINEAR
Fits regression models in which the expected value of the response is a nonlinear function.
Use nonlinear regression to mathematically describe the nonlinear relationship between a response variable and
one or more predictor variables. Specifically, use nonlinear regression instead of ordinary least squares regression
when you cannot adequately model the relationship with linear parameters. Parameters are linear when each
term in the model is additive and contains only one parameter that multiplies the term. Use this procedure for
fitting models that are nonlinear in the parameters, storing regression statistics, examining residual diagnostics,
generating point estimates, and generating prediction and confidence intervals.
Required subcommands
RESPONSE C
Specifies the response column. The column cannot be a text column.
CONTINUOUS C...C
Specifies one or more predictor columns. The columns cannot be text columns, and they must have the same
number of rows as the response column.
188
Minitab Statistical Software Regression
PARAMETER "name" K...K
Use PARAMETER for each parameter in the model. The parameter name can match the name of a variable, but it
cannot match the name of the response column or any predictor columns.
The parameter name must be followed by one or more starting values for the parameter. Minitab does not allow
missing values.
If you give a parameter more than one starting value, Minitab evaluates the residual sum of squares (SSE) at all
combinations, and uses the combination with the smallest value of the SSE.
EXPECTATION expression
Specifies the expectation function. The expression must use all of the parameters and predictors. All columns you
use in the expression must be predictor columns.
If a parameter name looks like a variable name, Minitab interprets it as a variable name. To have Minitab interpret
it as a name, you must put quotes around it. For example, a parameter you named k1 must be referred to as 'k1'.
Options
LOCK parameters
Locks one or more parameters at their starting values. If you give a locked parameter more than one starting
value, the first value is used. You must leave at least one parameter unlocked. For example, LOCK "b1", locks the
parameter b1.
WEIGHT C
Specifies weights for weighted regression in C. Weights must be nonnegative. Rows with zero or missing weight
are omitted. Note that there is no provision for these weights to change from one iteration to the next.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
CONSTRAINT constraint
Specifies a constraint on a parameter. Repeat CONSTRAINT to specify multiple constraints. Each parameter can
appear one time on one CONSTRAINT subcommand. For example, CONSTRAINT 1200 < 'b1' < 1400
constrains the fitted value of parameter b1 to between 1200 and 1400.
MARQUARDT
Specifies the Levenberg-Marquardt algorithm rather than the default Gauss-Newton algorithm. Use this
subcommand if the Gauss-Newton algorithm fails to converge.
TOLERANCE K [K]
K is the tolerance level for convergence, and it must be a positive number. The default value is 10
−5
.
189
Minitab Statistical Software Regression
The convergence criterion is the relative offset orthogonality convergence criterion described in Bates and Watts
(1981).
ITERATIONS K
Specifies the maximum number of iterations used in the optimization algorithm. K must be a positive integer. If
you do not specify ITERATIONS, the default value is 200.
Predict
PCONTINUOUS E..E
PCONTINUOUS also computes the standard errors of the fitted values, 95% confidence intervals, and 95% prediction
intervals. The number of arguments must equal the number of predictors in the model. If you include columns,
they must have the same number of rows. Minitab assigns predictors in the same order as they appear on the
CONTINUOUS subcommand.
If you omit PCONTINUOUS and include any of PFITS, PSEFITS, CLIMITS, or PLIMITS, then those subcommands are
ignored.
The prediction interval computed by PREDICT assumes a weight of 1. If you used the WEIGHT subcommand with
values other than 1, you should adjust the prediction interval values manually.
PFITS C
Stores the predicted values in C.
PSEFITS C
Stores the standard errors of the predicted values in C.
CLIMITS C C
Stores the upper and lower limits of the confidence intervals in C C. If you specify -1 or 1 with ITYPE then only
one argument is allowed.
PLIMITS C C
Stores the upper and lower limits of the prediction intervals in C C. If you specify −1 or 1 with ITYPE then only
one argument is allowed.
Tables
TMETHOD
Displays a table of information about the method and options. Includes the type of algorithm used, the maximum
number of iterations, and the tolerance level for convergence.
TSTARTING
Displays the parameters' starting values.
TCONSTRAINTS
Displays a table of constraints for the parameters.
TITERATIONS
Displays the parameter estimates, and the residual sum of squares (SSE) at each iteration.
TEQUATION
Displays the regression equation.
190
Minitab Statistical Software Regression
TPARAMETERS
Displays the parameter estimates and their approximate standard errors.
CI
Adds a confidence interval for each parameter in the parameter estimates table.
TCORRELATION
Displays the correlation matrix for the parameter estimates.
TSUMMARY
Displays a test for lack of fit, and a summary of the fits that includes the number of iterations, SSE, the degrees
of freedom for error, MSE, and S.
TPREDICTIONS
Displays a table of fitted values, confidence intervals, and prediction intervals for the new observations specified
by PCONTINUOUS.
NODEFAULT
Suppresses the display of tables and graphs other than those specifically requested.
Graphs
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis ( for
example, 1 2 3 4... n).
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
GFCURVE
Displays a fitted curve plot. Minitab ignores the subcommand if there is more than one predictor.
GFCI
Overlays the confidence interval bands.
GFPI
Overlays the prediction interval bands.
191
Minitab Statistical Software Regression
Storage
RESIDUALS C
Stores the residuals (fitted values observed values).
FITS C
Stores the fitted values, often called the Y-hats ( ).
SPARAMETERS C
Stores the estimated parameters.
SSEPARAMETERS C
Stores the standard error of each parameter.
SGRID C...C
Stores each starting value combination and the corresponding initial sum of the squared residuals (SSE). Minitab
performs the nonlinear regression analysis using the starting value combination that produces the smallest initial
SSE.
OREG: Session command for performing orthogonal
regression
OREG
Performs orthogonal regression in which both the response and predictor contain measurement error.
OREG uses orthogonal regression to fit a model to one predictor. Optionally, you can do the following:
Store the residuals, fitted values, and variance estimates
Generate predicted values for new observations
Control display of results
Generate several plots for residual analysis. For more information, go to Residual analysis and regression
diagnostics on page 1178.
VARRATIO C
Specifies the error variance ratio (Y/X). K must be greater than 0.
Graphs
RTYPE K
Specifies the type of residual to plot with the graph subcommands in K.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
192
Minitab Statistical Software Regression
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis ( for
example, 1 2 3 4... n).
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
GFLINE
Displays a fitted line plot of the original data.
LSFIT
Displays the least squares fitted line on the fitted line plot. When you use LSFIT, both the orthogonal and the least
squares regression equations are displayed on the graph.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
PREDICT K
PREDICT C
Specifies the value of the predictor X. You can enter a constant or a column of values.
SPREDICT C
Stores the predicted values in the specified column.
SSTDEV C
Stores the standard deviations of the predicted values in the specified column.
Results
REVARRATIO
Displays the error variance ratio.
REQUATION
Displays the orthogonal regression equation.
193
Minitab Statistical Software Regression
RCOEFFICIENT
Displays the coefficient table.
RVARCOMP
Displays the error variance estimates.
RFITRESID
Displays the fitted values for the true predictor and true response as well as the residuals.
Storage
SRESIDUALS C
Stores the residuals in the specified column.
SSRESIDUALS C
Stores the standardized residuals in the specified column.
SCOEFFICIENT C
Stores the intercept and slope in the specified column.
SVARIANCE C
Stores the error variances for the predictor and response in the specified column.
SXFIT C
Stores the fitted values of the predictor.
SYFIT C
Stores the fitted values of the response.
PLS: Session command for performing partial least
squares regression
PLS C...C = termlist
Use partial least squares regression (PLS) to relate a set of predictors to one or more response variables. Use PLS
with ill-conditioned data, when predictors are highly collinear or predictors outnumber observations. Predictors
can be either continuous or categorical. Use NCOMPONENTS to specify the number of components to use in the
model. Use XVALIDATION to select the number of components that maximize the model's predictive ability. Use
PCONTINUOUS and PCATEGORICAL to calculate fitted values for new observations using the PLS model.
CONTINUOUS C...C
Specifies which columns of variables are continuous. Columns must contain numerical or date/time data.
CATEGORICAL C...C
Specifies which, if any, columns of variables are categorical. Columns may be numerical, text, or date/time.
NCOMP K
Sets the maximum number of components to extract or cross-validate, which cannot exceed the number of
predictors in your model or the number of observations minus one. Minitab extracts 10 or cross-validates
194
Minitab Statistical Software Regression
10 components by default, unless the number of predictors or the number of observations minus 1 is less
than 10.
Options
XVALIDATION K
XVALIDATION C
XVALIDATION estimates your model's predictive ability by recalculating your model, leaving 1 or more observations
out each time.
Use K to specify the number of observations to leave out each time the model is recalculated. Specifying 1 means
that the model is recalculated as many times as there are observations.
Use C as a group identifier to indicate which observations are deleted together each time the model is recalculated.
Observations with identical numbers in C are removed at the same time. The column must contain positive integers
and equal the length of the predictor and response columns.
CODING K
CODING specifies the type of coding to use for categorical predictors.
K = −1 for (−1, 0, +1) coding
K = 1 for (1, 0) coding
REFERENCE C K...C K
REFERENCE changes the default coding for the categorical predictor columns. To change the default reference
level, specify the categorical predictor column followed by the reference level. (You must enclose text and
date/time levels in double quotes.) You can assign a reference level only when you use 1, 0 coding.
Prediction
Computes the fitted Ys, or for new observations using your PLS model.
PCONTINUOUS E...E
Use PCONTINUOUS for new continuous predictors.
PCONTINUOUS displays a table that contains the fitted Y's, standard errors of the fitted Y's, a 95% confidence
interval, and a 95% prediction interval. E...E may be a list of constants or a list of columns, or a mixture of constants
and columns. The number of predictors must equal the number of predictors in your PLS model.
PCATEGORICAL E...E
Use PCATEGORICAL for new categorical predictors.
PCATEGORICAL displays a table that contains the fitted Y's, standard errors of the fitted Y's, a 95% confidence
interval, and a 95% prediction interval. E...E may be a list of constants or a list of columns, or a mixture of constants
and columns. The number of predictors must equal the number of predictors in your PLS model.
RESPONSE C...C
Specifies response values for your new observations. Minitab calculates a test R
2
that indicates how well the model
fits new observations.
195
Minitab Statistical Software Regression
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
PFITS C...C
Stores the fits from PCONTINUOUS and PCATEGORICAL.
PSEFITS C...C
Stores the estimated standard errors of the fits from PCONTINUOUS and PCATEGORICAL.
CLIMITS C, C...C, C
Stores the lower and upper confidence limits from PCONTINUOUS and PCATEGORICAL.
PLIMITS C, C...C, C
Stores the lower and upper prediction limits from PCONTINUOUS and PCATEGORICAL.
Storage of fits and residuals
FITS C...C
Stores the fitted values, often called the Y-hats ( ).
CVFITS C...C
Stores the cross-validated fitted values.
RESIDUALS C...C
Stores the residuals (fitted values observed values).
PRESIDUALS C...C
Stores the cross-validated residuals.
SRESIDUALS C...C
Stores the standardized residuals.
Storage of model information
COEFFICIENTS C...C
Stores the estimated coefficients, one stored column for each response.
SCOEFFICIENTS C...C
Stores the standardized coefficients, one stored column for each response.
HI C
Stores the severage values.
XDISTANCE C
Stores the distances from the x-model.
YDISTANCE C
Stores the distances from the y-model.
196
Minitab Statistical Software Regression
Storage of component information
XSCORES M
Stores the X-scores.
YSCORES M
Stores the Y-scores.
XLOADINGS M
Stores the X-loadings.
YLOADINGS M
Stores the Y-loadings.
XWEIGHTS M
Stores the X-weights.
XRESIDUALS M
Stores the X-residuals.
YRESIDUALS C...C
Stores the Y-residuals, one stored column for each response.
XCALCULATED M
Stores the X-calculated values.
YCALCULATED C...C
Stores the Y-calculated values, one stored column for each response.
Graphs for model evaluation
GSELECTIONPLOT
Displays a scatterplot of R
2
and predicted R
2
values vs the number of components
GFIT
Displays a scatterplot of fitted and cross-validated responses vs observed responses
GFCOEFFICIENT
Displays a projected scatterplot of the coefficients
GCCOEFFICIENT
Displays a projected scatterplot of the standardized coefficients
GDISTANCE
Displays a scatterplot of each observation's distance from the x-model and the y-model
Graphs for residual analysis
GHISTOGRAM
Displays a histogram of the standardized residuals
GNORMAL
Displays a normal probability plot of the standardized residuals
197
Minitab Statistical Software Regression
GRESIDUALS
Displays a scatterplot of residuals vs fitted values
GLEVERAGE
Displays a scatterplot of standardized residuals vs leverages
GFOURPACK
Displays a layout of a histogram of the standardized residuals, a normal probability plot of the standardized
residuals, standardized residuals vs fitted values, and standardized residuals vs order of the data.
Graphs for model evaluation
GSCORE
Displays a plot of the x-scores of the first component versus the x-scores of the second component
GTHREEDPLOT
Displays a three-dimensional plot of the x-scores of the first component, second and third components
GLOADING
Displays a plot of the x-loadings of the first component vs the x-loadings of the second component
GXRESIDUALS
Displays a line plot of the x-residual matrix
GXCALCULATED
Displays a line plot of the x-calculated matrix.
Results
TMETHOD
Displays the number of components and analysis of variance table.
TANOVA
Displays the analysis of variance table.
TSELECTION
Displays the model selection and validation table.
TCOEFFICIENTS
Displays the unstandardized and standardized coefficients.
TFITS
Displays the table of fitted values and residuals.
TLEVERAGES
Displays the leverages and distances from the x- and y-model.
TPREDICTION
Displays the prediction table.
TXSCORES
Displays the x-score matrix.
198
Minitab Statistical Software Regression
TYSCORES
Displays the y-score matrix.
TXLOADINGS
Displays the x-loading matrix.
TYLOADINGS
Displays the y-loading matrix.
TXRESIDUALS
Displays the x-residual matrix.
TYRESIDUALS
Displays the y-residual matrix.
TXCALCULATED
Displays the x-calculated matrix.
TYCALCULATED
Displays the y-calculated matrix.
GZLM: Session command for fitting a binary logistic
model or a Poisson model
GZLM
Creates a generalized linear model with the distribution model that you specify: logistic or Poisson. GZLM fits a
model with one or more predictors using an iterative-reweighted least squares algorithm to obtain maximum
likelihood estimates of the parameters. Use the logistic model for a binary response variable. Use the Poisson
model for a Poisson response variable.
The predictors can be either factors (categorical predictors) or covariates (continuous predictors). Factors can be
crossed. Covariates can be crossed with each other or with factors. For more information, go to How to specify
the model for ATCLASS, GZLM, OLOGISTIC and NLOGISTIC on page 1165. You can use stepwise methods to explore
different terms in the model. You can use a test data set or k-fold cross-validation to validate the results.
Factor columns can be numeric or text. For a numeric factor, Minitab designates the lowest numeric value as the
reference level. For a text factor, Minitab determines the reference level alphabetically. For an example, go to
Entering data for factor variables on page 1142.
When the response variable column is binary, the highest value is the reference event. When the response variable
column is text, reverse alphabetical order determines the event. For example, if you enter the response variable
as success and failure, success is the event. For examples and information on entering the response data, go to
Entering data for response variables on page 1142.
This analysis provides diagnostic plots, goodness-of-fit tests, and other diagnostic measures so you can assess
the validity of your model. For more information, go to Generalized linear model diagnostics and residual analysis
on page 1177.
Minitab excludes all observations with missing values on either the response variable or any of the predictors
from all calculations.
199
Minitab Statistical Software Regression
BINOMIAL
Analyzes the relationship between a binary response variable that you specify in RESPONSE and the predictors
that you with CONTINUOUS and CATEGORICAL. You specify the model with TERMLIST.
LOGIT
Use the logit link function.
NORMIT
Use the normit link function.
GOMPIT
Use the gompit link function. The gompit link function is also called the complementary log-log link
function.
POISSON
Analyzes the relationship between a Poisson response variable that you specify in RESPONSE and the predictors
that you with CONTINUOUS and CATEGORICAL. You specify the model with TERMLIST.
LOG
Use the natural log link function.
SQRT
Use the square root link function.
IDENTITY
Use the identity link function. The identity link function does not transform the response.
RESPONSE C [C]
Enters the response data as counts. With BINOMIAL, you can enter a column that contains the number of
events first and then a column that contains the number of trials. For examples, go to Entering data for
response variables on page 1142.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric or date/time and
must match the length of the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric, text, or date/time and
must match the length of the response column.
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. Only continuous predictors may be repeated.
Nested terms are not allowed. The model can be nonhierarchical. For examples, go to How to specify the
model for ATCLASS, GZLM, OLOGISTIC and NLOGISTIC on page 1165.
Options
FREQUENCY C
Indicates how often the data in a row occur. For examples, go to Entering data for response variables on page
1142.
CONSTANT
Fits the model with the intercept.
200
Minitab Statistical Software Regression
When you use CONSTANT, Minitab includes the intercept term in the model. For example, for a binomial logistic
regression, Minitab fits the model
g(p) = β
0
+ x'β
If you do not specify CONSTANT or NOCONSTANT, then Minitab includes the intercept.
NOCONSTANT
Fits the model without the intercept.
When you use NOCONSTANT, Minitab omits the intercept term.
g(p) = x'β
If you do not specify CONSTANT or NOCONSTANT, then Minitab includes the intercept.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
WALD
Use the Wald test for the ANOVA table.
LRT
Use the Likelihood ratio test for the ANOVA table.
ADJDEVIANCE
Use adjusted deviances for the tests of significance in the ANOVA table when the Likelihood ratio test is used.
SEQDEVIANCE
Use sequential deviances for the tests of significance in the ANOVA table when the Likelihood ratio test is used.
The order of the terms in TERMLIST affects the statistical significance. The default is to use adjusted deviances.
PEARSON
Specifies the use of Pearson residuals. The default is to use deviance residuals.
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
−1
(X' W Y)
EFFECT
Specifies an effect coding scheme for categorical predictors (+1, 0, −1). With effect coding, the coefficients compare
the levels of the categorical variable to the mean. The default is binary coding (1, 0). With binary coding, the
coefficients compare the levels of the categorical variable to a reference level.
201
Minitab Statistical Software Regression
HGROUP K
Specifies the number of groups for the Hosmer-Lemeshow goodness-of-fit test with K. The default is 10.
REFERENCE C K...C K
Specifies the reference level for categorical predictor C with K. The coefficients compare the other levels of
categorical variables to the reference level when you use binary coding.
LOCATION [K...K]
Standardize continuous predictors by subtracting the means. Optionally, you can subtract different constants that
you specify with K...K. The order of the constants matches the order of the columns after CONTINUOUS.
SCALE [K...K]
Standardize continuous predictors by dividing by the standard deviations. Optionally, you can divide by different
constants that you specify with K...K. The order of the constants matches the order of the columns after
CONTINUOUS.
LEVELS K K...K K
Standardize continuous predictors by coding the low and high levels K K of each predictor to −1 1. The order of
the constants matches the order of the columns after CONTINUOUS.
UNSTANDARDIZED
Use the original units for the continuous predictors. If you do not specify LOCATION, SCALE, LEVELS, or
UNSTANDARDIZED, then Minitab uses the preferences that are set in File > Options > Linear Models > Coding
of Predictors.
REVENT K
Specifies which is the response event with K. The value of K matches one of the values in the response column.
Enclose text values in quotation marks. For example, to model the probability of a "Fail" in the response column,
enter REVENT "Fail".
EVNAME K
When the RESPONSE command has two columns, you can specify the name of the event with K. Enclose text
values in quotation marks.
ITERATION K
Specifies the maximum number of iterations for the optimization algorithm that estimates the coefficients. The
default is 50.
TOLERANCE K
Specifies the tolerance level to keep a predictor in the model that is either highly correlated with another predictor
or nearly constant. By default, K = 4 * 2.22E–012. K must be a positive number. Lowering tolerance by giving a
very small argument can prevent Minitab from eliminating problematic predictor columns from the model.
Correlated predictors
1 R-squared, where R-squared is the value resulting from regressing one predictor on the remaining
predictors. If (1 R-squared) is < K, Minitab removes the predictor from the equation.
Constant predictors
The parameter for forcing in a variable that is nearly constant. If the coefficient of variation of a predictor
(the standard deviation / the mean) is < square root K, Minitab considers the predictor to be essentially
constant and removes it from the equation.
CTOLERANCE K
Specifies the convergence criterion for the algorithm that estimates the coefficients. By default, K = 1E-8.
202
Minitab Statistical Software Regression
START C
Specifies a column that contains starting values for the coefficients in the optimization algorithm. The column
begins with the estimate of the constant, then follows the order of the model after TERMS.
Stepwise selection
STEPWISE, FORWARD, BACKWARD, FINFORMATION and FVALIDATION perform a stepwise regression procedure to
fit the model. No arguments are needed for these subcommands.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
203
Minitab Statistical Software Regression
FVALIDATION
Specifies the use of forward selection with the test deviance R
2
as the criterion for the selection of the final model.
When you use FVALIDATION, you must also use TEST. FVALIDATION is not compatible with FREQUENCY or
ATEND.
When you use TEST, the procedure is similar to forward selection for other methods. At the end of each step,
Minitab Statistical Software calculates the test R
2
statistic. At the end of the forward selection procedure, the
model with the greatest test R
2
value is the final model. FVALIDATION stops under the same conditions as
FINFORMATION.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
204
Minitab Statistical Software Regression
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
GRSQUARE
After FVALIDATION, displays a graph of the R
2
statistic and the test deviance R
2
statistic for each step
in the model selection procedure.
Validation
TEST C K
Specifies to perform validation with a test data set that you specify. The column must have two distinct values
that indicate which rows are in the test data set and which rows are in the training data set. K is the value for rows
that are in the test data set.
TESTK [K]
Specifies to perform validation with a randomly-selected test data set. The first K is the fraction of the data in the
test data set, a value between 0 and 1. The second K is optional. The second K is a base for the random number
generator. If you specify the base, you can get the same test data set again by specifying the same base.
CVTEST C
Specifies to perform k-fold cross validation with a test data set that you specify. Rows with the same value in the
column are in the same fold.
CVTEST K [K]
Specifies to perform k-fold cross validation with randomly-selected folds. The constant is the number of folds.
The optional constant is a base for the random number generator. If you specify the base, you can get the same
folds again by specifying the same base.
Tables for all models
TMETHOD
Displays a table of information about the method and options.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the preferences that are set in File > Options > Linear
Models > Stepwise.
FULL
Specifies to display the coefficients, p-values, and model summary statistics for each step of the procedure.
If you use the TEST subcommand, the model summary statistics include test R
2
.
NOFULL
Hides these statistics.
205
Minitab Statistical Software Regression
TEQUATION
Displays the model equation.
SINGLE
SINGLE specifies to show one equation instead of a separate equation for each combination of the levels of
the categorical predictors. The equation has a coefficient for each level of the categorical variables.
SEPARATE
Specifies to show separate equations for each combination of the levels of the categorical predictors. Each
equation has a different constant term.
TDEVIANCE
Displays the ANOVA table for the Wald test or the likelihood ratio tests.
TSUMMARY
Displays the statistics that evaluate model fit, including deviance R
2
.
TCOEFFICIENTS
Displays the coefficients and the p-values for the Wald normal approximation tests.
If you do not specify FULL or NOFULL, Minitab uses the preferences set in File > Options > Linear Models >
Display of Results.
FULL
Specifies to show the coefficients for the reference level when you use (0, 1) coding for categorical predictors.
NOFULL
Hides these statistics.
TGOODNESS
Displays the Pearson and Deviance goodness-of-fit tests. For the binomial distribution models, also shows the
Hosmer-Lemeshow goodness-of-fit test.
TDIAGNOSTICS [K]
Displays a table of diagnostics. K = 0 displays diagnostics for only observations with high leverage values or
standardized residuals greater than 2. K = 1 displays diagnostics for all observations.
TSTEP
Displays the deviance at each iteration of the coefficients.
TEXPAND
Displays the expanded versions of the tables that have them. The expanded Analysis of Variance table adds the
sequential deviances and percent contributions for each term. The Coefficients table adds confidence intervals
for the coefficients. The Fits and Diagnostics table adds the standard error of the fit, the 95% confidence interval
for the fit, the deleted residual, the HI, the Cook's D, and the DFITS.
TSIMPLE
Displays the simple versions of the Analysis of Variance table, the Coefficients table, and the Fits and Diagnostics
table.
NODEFAULT
Hides default tables and graphs that you do not include the subcommand to display.
206
Minitab Statistical Software Regression
Tables for binomial distribution models
TRINFO
Displays the number of events, non-events, and the total. The table also indicates which response value is the
reference event.
TODDS
Displays odds ratios for each continuous predictor and each level of the categorical predictors. The output does
not show odds ratios for predictors with interactions in the model or for categorical predictors with (−1, 0,+1)
coding.
INCREMENT K...K
Specifies the increment for the odds ratio for the predictor with K. For example, if the predictor is mass in
grams, enter 1000 to see the change in the odds ratio for a kilogram. Enter the values in the same order that
the predictors follow CONTINUOUS. Enter 1 for a predictor to use the units of the data.
THOSMER
Displays the table of observed and expected values for the Hosmer-Lemeshow test.
TASSOCIATION
Displays the number of concordant and discordant pairs, the Somers' D, the Goodman-Kruskal Gamma, and
Kendall's Tau-a.
Graphs for all models
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Displays residuals versus fitted values. For binary logistic regression, this plot is not available when the data are
in response/frequency format because the pattern that appears is not a violation of the assumptions.
GORDER
Displays residuals versus the order of the worksheet. The row number for each data point is shown on the x-axis
(for example, 1 2 3 4...n).
GFOURPACK
Choose to display a layout of the residual plots. For Poisson models, the layout includes a histogram of residuals,
a normal plot of residuals, a plot of residuals versus fits, and a plot of residuals versus order.
207
Minitab Statistical Software Regression
For the binary logistic model, the layout depends on the format of the data. If the data are in response/frequency
format, the layout has a histogram of residuals, a normal plot of residuals, and a plot of residuals versus order. If
the data are in event/trial format, the layout also has a plot of residuals versus fits.
GVARIABLE C...C
Displays the residuals versus the variables in C. Typically, you enter the columns for the predictors.
Graphs for binomial distribution models
GROC
Displays the receiver operating characteristic (ROC) curve for a binomial logistic regression. A footnote on the
plot gives the area under the ROC curve. You can use the area under the ROC curve to compare models. The ROC
curve plots the true positive rate (TPR) against the false positive rate (FPR).
Storage for all models
When you use the TEST subcommand, Minitab Statistical Software stores the following statistics for the training data
set and not the test data set:
StatisticSubcommand
Deleted residualsTRESIDUALS
Cook's distancesCOOK
DFITSDFITS
Adjusted response valuesSADJUSTEDRESP
X'WX inverse matrix of the estimated coefficientsXPWXINVERSE
FITS C
Stores the event probabilities.
RESIDUALS C
Stores the Deviance residuals by default. Stores the Pearson residuals if you use the subcommand PEARSON.
SRESIDUALS C
Stores the standardized Deviance by default. Stores the standardized Pearson residuals if you use the subcommand
PEARSON.
TRESIDUALS C
Stores the deleted Deviance residuals by default. Stores the deleted Pearson residuals if you use the subcommand
PEARSON.
COOK C
Stores the Cook's distances. If you use a test data set, the storage is for the training data set only.
DFITS C
Stores the DFITS.
HI C
Stores the leverages.
208
Minitab Statistical Software Regression
SADJUSTEDRESP C
Stores the final adjusted response values.
SIWEIGHTS C
Stores the internal weights used to estimate the model parameters.
SECOEFFICIENTS C
Stores the standard errors of the estimated coefficients.
COEFFICIENTS C
Stores the estimated coefficients.
XMATRIX M
Stores the design matrix.
XPWXINVERSE M
Stores the X'WX inverse matrix of the estimated coefficients.
When you use the TEST subcommand or the CVTEST subcommand, Minitab Statistical Software stores the following
statistics for the training data set but not for the validation data set.
DBETA C
Stores the change in the estimated regression coefficients (delta b) when you delete all observations with a
particular factor/covariate pattern. Use the delta b values to detect observations with a strong influence on the
coefficients. If you use a test data set, the storage is for the training data set only.
DSBETA C
Stores the change in the estimated regression coefficients when you delete all observations with a particular
factor/covariate pattern based on the standardized Pearson residual. If you use a test data set, the storage is for
the training data set only.
DCHISQUARE C
Stores the change in the chi-square statistic when you delete all observations with a particular factor/covariate
pattern. Observations that are poorly fit by the model have high delta chi-square values. If you use a test data
set, the storage is for the training data set only.
DDEVIANCE C
Stores the change in the deviance when you delete all observations with a particular factor/covariate pattern. If
you use a test data set, the storage is for the training data set only.
Storage for validation
Use the following commands to store statistics for validation with a test data set. These commands are sub-sub
commands to the TEST subcommand. As such, these commands must come after TEST.
Use the following commands to store statistics for validation with a test data set or validation with k-fold cross validation.
SSAMPLE C
When CVTEST is used:
The storage column, Sample_Id, stores the fold identification in C.
C contains values 1, 2, ..., K.
When TEST is used:
The storage column, Sample_Id, stores the training and test sample assignments in C.
209
Minitab Statistical Software Regression
C is a binary text column that contains Training and Test as the two values.
CVFIT C
Stores the fitted values from each fold's turn as the test data set.
CVRESID C
Stores the residuals from each fold's turn as the test data set.
BFIT: Session command for creating a binary fitted
line plot
BFIT
Performs logistic regression on a binary response variable. A binary variable has only two possible values, such
as presence or absence. BFIT fits a model with one continuous predictor using an iterative-reweighted least squares
algorithm to obtain maximum likelihood estimates of the parameters.
For examples and information on entering the response data, go to Entering data for response variables on page
1142.
BFIT provides diagnostic plots, goodness-of-fit tests, and other diagnostic measures so you can assess the validity
of your model. For more information, go to Generalized linear model diagnostics and residual analysis on page
1177.
Note Minitab excludes all observations with missing values on either the response variable or any of the predictors from all calculations.
RESPONSE C [C]
Enters the response data as counts. For examples and information on entering the response data, go to
Entering data for response variables on page 1142.
CONTINUOUS C
Indicates the continuous predictor is in C.
LOGIT
Use the logit link function.
NORMIT
Use the normit link function.
GOMPIT
Use the gompit link function. The gompit link function is also called the complementary log-log link function.
Options
FREQUENCY C
Indicates how often the data in a row occur.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
210
Minitab Statistical Software Regression
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
REVENT K
Specifies which is the response event with K. The value of K matches one of the values in the response column.
Enclose text values in quotation marks. For example, to model the probability of a "Fail" in the response column,
enter REVENT "Fail".
EVNAME K
When the RESPONSE command has two columns, you can specify the name of the event with K. Enclose text
values in quotation marks.
Tables
TMETHOD
Displays the link function.
TRINFO
Displays the number of events, non-events, and the total.
TDEVIANCE
Displays the ANOVA table.
TSUMMARY
Displays the statistics that evaluate model fit, including deviance R
2
.
TCOEFFICIENTS
Displays the coefficients and the p-values for the Wald normal approximation tests.
TODDS
Displays odds ratios for each continuous predictor and each level of the categorical predictors. The output does
not show odds ratios for predictors with interactions in the model or for categorical predictors with (−1, 0, +1)
coding.
INCREMENT K
Specifies the increment for the odds ratio for the predictor with K. For example, if the predictor is mass in
grams, enter 1000 to see the change in the odds ratio for a kilogram.
TEQUATION
Displays the model equation.
TGOODNESS
Displays the deviance, Pearson, and Hosmer-Lemeshow tests. These tests assess the overall fit of the model.
TDIAGNOSTICS K
Displays a table of diagnostics. K = 0 displays diagnostics for only observations with high leverage values or
standardized residuals greater than 2. K = 1 displays diagnostics for all observations.
211
Minitab Statistical Software Regression
NODEFAULT
Hides default tables and graphs that you do not include the subcommand to display.
Graphs
GFLINE
Displays the fitted line plot. The plot also shows the equation for the probabilities.
PROPORTIONS
Shows the data on the plot.
DCONFIDENCE
Shows the confidence interval for the fitted line on the plot.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Displays residuals versus fitted values. This plot is not available when the data are in response/frequency format
because the pattern that appears is not a violation of the assumptions.
GORDER
Displays residuals versus the order of the worksheet. The row number for each data point is shown on the x-axis
(for example, 1 2 3 4... n).
GFOURPACK
Displays a layout of the residual plots. If the data are in response/frequency format, the layout has a histogram
of residuals, a normal plot of residuals, and a plot of residuals versus order. If the data are in event/trial format,
the layout also has a plot of residuals versus fits.
GVARIABLE C...C
Displays the residuals versus the variables. Typically, you enter the columns for the predictors.
Storage
FITS C
Stores the event probabilities.
212
Minitab Statistical Software Regression
RESIDUALS C
Stores the Deviance residuals.
SRESIDUALS C
Stores the standardized Deviance residuals.
TRESIDUALS C
Stores the deleted Deviance residuals.
COEFFICIENTS C
Stores the estimated coefficients.
OLOGISTIC: Session command for performing
ordinal logistic regression
OLOGISTIC C = C...C
Performs logistic regression on an ordinal response variable. Ordinal variables are categorical variables that have
3 or more possible levels with a natural ordering, such as strongly disagree, disagree, neutral, agree, and strongly
agree.
OLOGISTIC fits a model with one or more predictors using an iterative-reweighted least squares algorithm to
obtain maximum likelihood estimates of the parameters. OLOGISTIC assumes parallel lines; therefore, one set of
coefficients is associated with the predictors. When this assumption is not valid, use NLOGISTIC on page 216, which
generates separate logit functions.
The predictors can be either factors (nominal variables) or covariates (continuous variables). Factors can be crossed
or nested. Covariates can be crossed with each other or with factors, or nested within factors. The model can
include up to 9 factors and 50 covariates. Unless you specify a predictor in the model as a factor, Minitab assumes
the predictor is a covariate. Model continuous predictors as covariates and categorical predictors as factors. For
more information, go to How to specify the model for ATCLASS, GZLM, OLOGISTIC and NLOGISTIC on page 1165.
Factor columns can be numeric or text. For a numeric factor, Minitab designates the lowest numeric value as the
reference level. For a text factor, Minitab determines the reference level alphabetically. For an example, go to
Entering data for factor variables on page 1142. To change the default coding, use the REFERENCE subcommand.
When the response variable column is numeric, OLOGISTIC orders the levels from smallest to largest. When the
response variable column is text, OLOGISTIC orders the levels alphabetically. For examples and information on
entering the response data, go to Entering data for response variables on page 1142. Use the ORDER subcommand
to specify the ordering of the response variable.
FREQUENCY C
Enters the response data as counts. For examples, go to Entering data for response variables on page 1142.
Options
LOGIT
Specifies the logit link function (default).
NORMIT
Specifies the normit link function.
213
Minitab Statistical Software Regression
GOMPIT
Specifies the gompit link function (also called the complementary log-log function).
FACTORS C...C
Specifies which of the predictors are factors. Minitab assumes all variables in the model are covariates unless
specified to be factors. Model continuous predictors as covariates and categorical predictors as factors.
REFERENCE C K, ..., C K
Changes the default coding for factors. To change the default reference factor level, specify the factor column
followed by the reference level. (Text and date/time levels must be enclosed in quotes.) For a discussion and
examples of the default coding scheme, go to Entering data for factor variables on page 1142.
Use the ORDER subcommand to specify the ordering of the response variable.
ORDER C
ORDER K...K
Specifies the order of the response values from lowest to highest. Values can be stored in C or K.
ITERATION K
Changes the maximum number of iterations that Minitab performs to reach convergence. The default value is 20.
Minitab's logistic regression commands obtain maximum likelihood estimates through an iterative process. If the
maximum number of iterations is reached before convergence, the command terminates.
START C
Specifies the initial values for model parameters. The column containing the initial values must have one row for
each estimated coefficient in the model. For OLOGISTIC, the starting values for all the constants appear first,
followed by starting values for the predictors in the model.
Note Each degree of freedom must be in one row.
CTOLERANCE K [K]
Changes the convergence criteria. Both Ks must be positive numbers.
How convergence is attainedK
Convergence is attained relative to this criterion if from one iteration to the next the change
in the log-likelihood is less than K. The default is .0001.
First K
Convergence is attained relative to this criterion if from one iteration to the next the
maximum change in the coefficients is less than K. The default is .0001.
Second K
TOLERANCE K
Specifies the tolerance level to keep a predictor in the model that is either highly correlated with another predictor
or nearly constant. By default, K = 4 * 2.22E–012. K must be a positive number. Lowering tolerance by giving a
very small argument can prevent Minitab from eliminating problematic predictor columns from the model.
Correlated predictors
1 R-squared, where R-squared is the value resulting from regressing one predictor on the remaining
predictors. If (1 R-squared) is < K, Minitab removes the predictor from the equation.
Constant predictors
The parameter for forcing in a variable that is nearly constant. If the coefficient of variation of a predictor
(the standard deviation / the mean) is < square root K, Minitab considers the predictor to be essentially
constant and removes it from the equation.
214
Minitab Statistical Software Regression
Results
BRIEF K
Controls the amount of output with a value in K.
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage and displays the following
error messages, warnings, prompts, and notes; graphs; WRITE to the screen.
0
Minitab displays the response information, logistic regression table, log-likelihood, and test
that all slopes = 0.
1
In addition to the BRIEF 1 output, displays the Pearson and deviance tests.2 (default)
In addition to the BRIEF 2 output, displays factor level values and tests for terms with more
than 1 degree of freedom.
3
STEP
Displays the log-likelihood at each iteration of the parameter estimation process.
Storage of the characteristics of the estimated equation
COEFFICIENTS C
Estimated coefficients in a column.
SECOEFFICIENTS C
Standard errors of the coefficients in a column.
XPWXINVERSE M
Variance-covariance matrix of the estimated coefficients, expressed as (X' W X)
−1
.
LOGLIKELIHOOD K
Last log-likelihood value.
Storage of the event probabilities and aggregated data
EPROBABILITY C...C
Predicted event probabilities. Specify one column for each distinct value of the response.
CUMPROBABILITY C...C
Cumulative event probabilities. Specify one column for each distinct value of the response minus one.
NTRIALS C
Number of trials for each factor/covariate pattern.
NOCCUR C...C
Number of occurrences for the j
th
factor/covariate pattern. Specify one column for each distinct value of the
response.
215
Minitab Statistical Software Regression
NLOGISTIC: Session command for performing
nominal logistic regression
NLOGISTIC C = C…C
Performs logistic regression on a nominal response variable using an iterative-reweighted least squares algorithm
to obtain maximum likelihood estimates of the parameters. Nominal variables are categorical variables that have
3 or more possible levels but with no natural ordering. For example, the levels in a food-tasting study may include
crunchy, mushy, and crispy.
OLOGISTIC on page 213 assumes parallel lines. Therefore, one set of coefficients is associated with the predictors.
When this assumption is not valid, use NLOGISTIC, which generates separate logit functions.
The predictors can be either factors (nominal variables) or covariates (continuous variables). Factors can be crossed
or nested. Covariates can be crossed with each other or with factors, or nested within factors. The model can
include up to 9 factors and 50 covariates. Unless you specify a predictor in the model as a factor using the FACTORS
subcommand, Minitab assumes the predictor is a covariate. Model continuous predictors as covariates and
categorical predictors as factors. For more information, go to How to specify the model for ATCLASS, GZLM,
OLOGISTIC and NLOGISTIC on page 1165.
Factor columns can be numeric or text. For a numeric factor, Minitab designates the lowest numeric value as the
reference level. For a text factor, Minitab determines the reference level alphabetically. For an example, go to
Entering data for factor variables on page 1142.
When the response variable column is numeric, NLOGISTIC defines the highest value as the reference event. When
the response variable column is text, NLOGISTIC defines the event by reverse alphabetical order. For example, if
you enter the response variable as crunchy, mushy, and crispy, NLOGISTIC defines mushy as the event. For examples
and information on entering the response data, go to Entering data for response variables on page 1142.
Use the REFERENCE subcommand to change the default coding for both factor and response variables.
NLOGISTIC provides goodness-of-fit tests and other diagnostic measures so you can assess the validity of your
model.
FREQUENCY C
Enters the response data as counts. For examples and information on entering the response data, go to
Entering data for response variables on page 1142.
Options
FACTORS C...C
Specifies which of the predictors are factors. Minitab assumes all variables in the model are covariates unless
specified to be factors. Continuous predictors must be modeled as covariates; categorical predictors must be
modeled as factors.
REFERENCE C K, ..., C K
Changes the default coding for factor and response columns. To change the default reference factor level, specify
the factor column followed by the reference level. (Text and date/time levels must be enclosed in quotes.) For a
discussion and examples of the default coding scheme, go to Entering data for factor variables on page 1142.
To change the default event, specify the response column followed by the event value.
216
Minitab Statistical Software Regression
START C
Specifies the initial values for model parameters. The column containing the initial values must have one row for
each estimated coefficient in the model. For NLOGISTIC, the starting values for logit 1 appear before logit 2, and
so on. For each logit, the starting value for the constant appears before the starting values for the predictors in
the model.
Note Each degree of freedom must be in one row.
ITERATION K
Changes the maximum number of iterations that Minitab performs to reach convergence. The default value is 20.
Minitab's logistic regression commands obtain maximum likelihood estimates through an iterative process. If the
maximum number of iterations is reached before convergence, the command terminates.
CTOLERANCE K K
Changes the convergence criteria. Both Ks must be positive numbers.
How convergence is attainedK
Convergence is attained relative to this criterion if from one iteration to the next the change
in the log-likelihood is less than K. The default is .0001.
First K
Convergence is attained relative to this criterion if from one iteration to the next the
maximum change in the coefficients is less than K. The default is .0001.
Second K
TOLERANCE K
Specifies the tolerance level to keep a predictor in the model that is either highly correlated with another predictor
or nearly constant. By default, K = 4 * 2.22E–012. K must be a positive number. Lowering tolerance by giving a
very small argument can prevent Minitab from eliminating problematic predictor columns from the model.
Correlated predictors
1 R-squared, where R-squared is the value resulting from regressing one predictor on the remaining
predictors. If (1 R-squared) is < K, Minitab removes the predictor from the equation.
Constant predictors
The parameter for forcing in a variable that is nearly constant. If the coefficient of variation of a predictor
(the standard deviation / the mean) is < square root K, Minitab considers the predictor to be essentially
constant and removes it from the equation.
Results
BRIEF K
Controls the amount of output with a value in K.
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage and displays the following
error messages, warnings, prompts, and notes; graphs; WRITE to the screen.
0
Minitab displays the response information, logistic regression table, log-likelihood, and test
that all slopes = 0.
1
In addition to the BRIEF 1 output, displays the Pearson and deviance tests.2 (default)
In addition to the BRIEF 2 output, displays factor level values and tests for terms with more
than 1 degree of freedom.
3
217
Minitab Statistical Software Regression
STEP
Displays the log-likelihood at each iteration of the parameter estimation process.
Storage of the characteristics of the estimated equation
COEFFICIENTS C
Estimated coefficients in a column.
SECOEFFICIENTS C
Standard errors of the coefficients in a column.
XPWXINVERSE M
Variance-covariance matrix of the estimated coefficients, expressed as (X' W X)
−1
.
LOGLIKELIHOOD K
Last log-likelihood value.
Storage of the event probabilities and aggregated data
EPROBABILITY C...C
Predicted event probabilities. Specify one column for each distinct value of the response.
NTRIALS C
Number of trials for each factor/covariate pattern.
NOCCUR C...C
Number of occurrences for the j
th
factor/covariate pattern. Specify one column for each distinct value of the
response.
218
Minitab Statistical Software Regression
ANOVA
ONEWAY: Session command for performing a
one-way ANOVA
ONEWAY
Performs a one-way analysis of variance. Your data can be arranged in one of two ways:
Response data are in one column for all factor levels
Response data are in a separate column for each factor level
Minitab performs the traditional one-way ANOVA procedure if you assume that the variance is constant across
all groups. However, if your data exhibit unequal variances between groups, Minitab can perform Welch's ANOVA.
To perform Welch's ANOVA, use the WELCH subcommand.
Use the comparison method subcommands to determine which group means differ and by how much.
The factor column may be numeric or text, and may contain any value. The levels do not need to be in any special
order. SET is especially useful for entering data that follow a pattern, such as subscripts (factor level values). For
examples, go to Entering patterned data for the SET session command on page 1143. (TSET and DSET can be used
to enter text and date/time data, respectively, that follow a pattern.)
Variables and terms to include in the model
Specifies information about the variables and terms to include in the model. How you use these commands depends
on how your data are arranged in the worksheet. Your response data can either be in one column for all factor levels
or the response data can be in a separate column for each factor level.
RESPONSE C
RESPONSE C...C
Specifies the column or columns that contains the response data. The column or columns must be numeric or
date/time. If your response data are in one column, specify the column with C. If your response data are in a
separate column for each factor level, specify all of the response columns with C...C.
CATEGORICAL C
Required when your response data are in one column for all factor levels. For this data arrangement, you must
use CATEGORICAL to specify the single column that contains the categorical factor. If you specify more than one
column for RESPONSE, CATEGORICAL is not allowed.
Options
CONFIDENCE K
Specifies a confidence level for the interval plot and means table, but not the multiple comparisons, in K. For
example, for a 90% confidence level, enter CONFIDENCE 90. The default value of K is 95.
ITYPE K
Specifies the type of confidence interval for the interval plot and means table.
219
Minitab Statistical Software ANOVA
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
WELCH
Specifies the Welch method. Use WELCH when you do not assume that all groups have equal variances. One-way
ANOVA with equal variances is slightly more powerful than Welch's ANOVA, but serious error can result if the
variances are not equal.
Comparisons
TUKEY [K]
Calculates all pairwise differences between level means using Tukey's method (also called Tukey's HSD or
Tukey-Kramer method) with the family error rate specified as K. If K is not specified, Minitab uses the default
family error rate of .05.
To obtain output for this comparison method, you must issue at least one of the following subcommands:
TGROUPING, TMTEST, GMCI.
FISHER [K]
Calculates all pairwise differences between level means using Fisher's LSD procedure with the individual error rate
specified as K. If K is not specified, Minitab uses the default individual error rate of .05.
To obtain output for this comparison method, you must issue at least one of the following subcommands:
TGROUPING, TMTEST, GMCI.
DUNNETT [K] K
DUNNETT C
Calculates the difference between each treatment mean and a control mean. The family error rate is specified by
the first K. How you specify the control group depends on how your data are arranged.
Specify the control group as follows:
If your response data are in one column, specify the control group with the second K.
If your response data are in a separate column for each factor level, specify the control group column with C.
If the error rate is not specified, Minitab uses the default family error rate of .05.
When the column of levels contains text data, the control level will also be text so remember to enclose the value
you enter for K in double quotes.
To obtain output for this comparison method, you must issue at least one of the following subcommands:
TGROUPING, TMTEST, GMCI.
MCB [K] K
Calculates the difference between each level mean and the best of the other level means. The family error rate is
specified by the first K and the type of best is specified by the second K. If the error rate is not specified, Minitab
uses the default family error rate of .05.
There are two choices for "best." If the smallest mean is considered the best, set K = -1; if the largest is considered
the best, set K = 1.
220
Minitab Statistical Software ANOVA
To obtain output for this comparison method, you must issue at least one of the following subcommands:
TGROUPING, TMTEST, GMCI.
GAMES [K]
Calculates all pairwise differences between level means using Games-Howell method with the family error rate
specified as K. If K is not specified, Minitab uses the default family error rate of .05. GAMES is only available when
WELCH is issued.
To obtain output for this comparison method, you must issue at least one of the following subcommands:
TGROUPING, TMTEST, GMCI.
Results
NODEFAULT
Specifies that no default tables and graphs will be displayed.
TEXPAND
Displays the expanded versions of the ANOVA table, Model summary, and Multiple comparisons tables.
TSIMPLE
Displays the simple version of all tables.
TMETHOD
Displays the method table.
TFACTOR
Displays the name, number of levels, and the values for the categorical factor.
TANOVA
Displays the ANOVA table.
TSUMMARY
Displays the summary of model table.
TMEANS
Displays the table of group means.
TGROUPING
Displays the grouping information table for each comparison method subcommand that you issue. This table
highlights the significant and non-significant comparisons for each comparison method.
TMTEST
Displays the multiple comparison test table for each comparison method subcommand that you issue. This table
displays the hypothesis test form of the comparison output, which includes the differences of the means, the
numeric values for the confidences intervals, and the adjusted p-values.
Graphs that display information by group
GINTPLOT
Displays an interval plot of the group means.
221
Minitab Statistical Software ANOVA
GINDPLOT
Displays an individual value plot for each group.
GBOXPLOT
Displays a boxplot for each sample.
Graphs for the residuals
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis ( for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals versus fitted
values, and residuals versus order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Other graphs
GMCI
Displays an interval plot of the differences between group means for each comparison method subcommand that
you issue.
Storage
FITS C
FITS C...C
Stores fitted values. The fitted values are the level means. Specify one storage column C for each column that
contains response data.
RESIDUALS C
RESIDUALS C...C
Stores residuals. Residual = (response fit). Specify one storage column C for each column that contains response
data.
222
Minitab Statistical Software ANOVA
ANOM: Session command for creating an analysis
of means chart
ANOM C
Displays an analysis of means (ANOM) chart. You must choose one distribution that the response data follows:
normal (one-way or two-way), binomial, or Poisson.
For ANOM with a normal distribution and one factor, a single plot displaying the means for each level of the
factor, a center line which is the grand mean, and upper and lower decision limits is produced. If you use ANOM
with a normal distribution and two factors, three plots are given: one showing the interaction effects, one showing
the main effects for the first factor, and one showing the main effects for the second factor. If you choose an
ANOM for a binomial distribution or a Poisson distribution, a single plot displaying the means for each level of
the factor, a center line which is the grand mean, and upper and lower decision points is produced.
The subcommands NORMAL, BINOMIAL, and POISSON replace the commands %ANOM, %BANOM, and %PANOM.
respectively.
NORMAL C [C]
For normal data, each row of the response column represents an observation for measurement data. Response
data are typically measurement data, such as weight or moisture content.
BINOMIAL K
For binomial data, the values in the response column are the numbers of defectives found in each sample.
These values must be positive integers (0 or greater). You can include up to 500 samples.
POISSON
For Poisson data, the values in the response column are the numbers of defects that are found in each sample.
These values must be positive integers (0 or greater). You can include up to 500 samples.
ALPHA K
The decision lines on an ANOM chart are based on an experiment-wide error rate, similar to what you might
use when making pairwise comparisons or contrasts in an ANOVA. By default, a rate of 0.05 is used. Use
ALPHA to enter a number between 0 and 1. Values greater than or equal to 1.0 are interpreted as percentages.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
When you use TITLE with %graphs or the DENDROGRAM subcommand, you can use it only one time, and
you cannot use any of the TITLE subcommands available with the graph commands.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
223
Minitab Statistical Software ANOVA
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
ANOVA: Session command for performing a
balanced ANOVA
ANOVA C...C
Performs univariate and multivariate analysis of variance.
For one-way analysis of variance, you can have unbalanced designs. For multi-way analysis of variance, you must
have balanced designs (all cells must have the same number of observations). The command GLM on page 227
analyzes balanced and unbalanced designs. However, if your design is balanced, ANOVA is faster and requires
less space.
Factors can be crossed or nested, fixed or random. ANOVA calculates all exact F-tests, displays expected mean
squares, and estimates variance components. You can specify your own tests, store residuals and fitted values,
and display cell and marginal means. You can analyze up to 50 response variables and up to 9 factors on one
ANOVA command.
224
Minitab Statistical Software ANOVA
Minitab verifies that your model is valid and displays a message if it is not. Minitab also verifies that your data set
is balanced.
Note Balanced data are not required for one-factor models.
If you do not use the subcommand RANDOM, ANOVA fits a fixed effect model. In this case, the F-statistic for a
term is always (MS term) / (MSE). However, when some of your factors are random, the denominator of an F-test,
in general, is not MSE. For more information, see the subcommands RANDOM and EMS.
You can use the subcommands MANOVA, SSCP, EIGEN, PARTIAL, and NOUNIVARIATE to do multivariate analysis
of variance. Hotelling's T-squared test can be performed as a special case of ANOVA with MANOVA.
ANOVA can analyze very complex designs, but, if you have a simple model, ANOVA is very easy to use.
Fore more information, go to How to specify the model in ANOVA on page 1169 and How to enter data for ANOVA
and GLM on page 1158.
Model
RANDOM C...C
Specifies which factors are random. Do not include interaction terms or nested factors. If at least one factor in an
interaction term is random, then Minitab considers the term to be random. Any term that is nested within a
random factor is considered random.
RESTRICT
There are two mixed model analysis of variance models: one requires the crossed, mixed terms to sum to 0 over
subscripts that correspond to fixed effects (Minitab refers to this as the restricted model.), and the other does
not. Most textbooks and BMDP's program 8V use the restricted model. SAS uses the unrestricted model.
By default, ANOVA fits the unrestricted model. This subcommand instructs the program to fit the restricted model,
which assumes that the mixed interaction terms are restricted to sum to 0 over the fixed effects. For more
information, go to Restricted and unrestricted mixed models on page 1144.
Results
EMS
Displays a table that contains expected mean squares, estimated variance components, and the error term (the
denominator) used in each exact F-test. If no exact F-test for a term exists, then use the expected mean squares
to determine how to construct an approximate F-test using the subcommand TEST.
The estimates of the variance components are the usual unbiased analysis of variance estimates. They are obtained
by setting each calculated MS equal to its EMS. This gives a system of linear equations in the unknown variance
components. This system is then solved. Unfortunately, this method can result in negative estimates, which should
be set to 0. However, Minitab displays the negative estimates because they sometimes indicate that the model
that is being fit is inappropriate for the data.
Terms that are fixed do not have variance components estimated.
MEANS termlist
Displays a table of means corresponding to each term listed. For example, the following command language
displays four tables, one table for each main effect, A, B, D, and one for the three-way interaction, A*B*D.
ANOVA Y = A|B|C(A B) |D;
MEANS A B D A*B*D
225
Minitab Statistical Software ANOVA
Terms listed on the MEANS statement must also be terms listed in the model. If you specify more than one MEANS
subcommand, then Minitab uses the last one. For more information, go to How to specify the model in ANOVA
on page 1169.
TEST termlist / errorterm
Calculates univariate F-tests. Termlist is a list of terms in the model. Each term is used as the numerator in a test.
Errorterm is a term in the model to be used as the denominator in all the test. Alternatively, errorterm can be a
linear combination of terms in the model and MSE (denoted by the reserved word ERROR). Minitab calculates the
F-ratios and p-values for you. Here are two examples.
TEST A/A*B + A*C + B*C - 2*A*B*C - 2*ERROR
TEST A B/A*B
Minitab constructs the synthetic denominator MS for the F-test. This denominator is the linear combination of
the MSs that are specified on TEST, and should have the same expectation as the numerator MS under the
hypothesis being tested. Suppose the denominator is the linear combination:
Then it has approximate degrees of freedom calculated by
where DF
i
is the degrees of freedom for the term MS
i
. For more information, go to Restricted and unrestricted
mixed models on page 1144.
Storage
FITS C...C
Stores fitted values, using one column for each response. If you specify a full model (you include all interaction
terms), then the fitted values are just the cell means. If you fit a reduced model, the fitted values are not the cell
means, but are the sum of the least squares estimates of the effects in the model.
RESIDUALS C...C
Stores residuals, using one column for each response variable. Residual = (response fit).
Graphs
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis ( for
example, 1 2 3 4...n).
226
Minitab Statistical Software ANOVA
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Balanced MANOVA
MANOVA [termlist [ / errorterm]]
Performs four multivariate tests—Wilks' test, Lawley-Hotelling test, Pillai's test, and Roy's largest root test—for
each term in the model. If you include a termlist, MANOVA performs the four multivariate tests for each term
listed. Hotelling's T-squared test can be performed as a special case of ANOVA with MANOVA.
If you specify an errorterm, then it must be a single term that is in the model. MANOVA then uses this errorterm
in all tests. If you do not specify an errorterm, then Minitab determines an appropriate errorterm, as in the univariate
case.
All four tests are based on two SSCP (sums of squares and cross products) matrices: H = the hypothesis matrix
and E = the error matrix. There is one H associated with each term in termlist. E is the matrix associated with the
error for the test.
SSCP
Displays the hypothesis matrix, H, that corresponds to each term that is specified by MANOVA, and the error
matrix, E.
EIGEN
Displays a table that contains the eigenvalues and eigenvectors for the (nonsymmetric) matrix, E-1 H. These are
the eigenvalues that are used to calculate the four MANOVA tests. A separate table is displayed for each term
that is specified on MANOVA.
Note If an eigenvalue is repeated, then the corresponding eigenvectors are not unique. In this case, the eigenvectors that Minitab
displays and those in books or other software might not agree. However, the MANOVA tests are always unique.
PARTIAL
Displays a matrix of partial correlations. These are the correlations among the residuals or, equivalently, the
correlations among the responses conditioned on the model. The formula for the matrix is W**-.5 E W**-.5, where
E is the error matrix and W has the diagonal of E as its diagonal and 0s elsewhere.
NOUNIVARIATE
Suppresses the univariate output. Only the multivariate output is displayed.
GLM: Session command for fitting the general linear
model
GLM
Fits the general linear model (GLM). Using GLM, you can perform analysis of variance with balanced and unbalanced
designs, analysis of covariance, and regression.
227
Minitab Statistical Software ANOVA
Factors can be crossed or nested, fixed or random. Covariates can be crossed with each other or with factors, or
nested within factors. You can store residuals, fitted values, and many other diagnostics, and display cell and
marginal means.
GLM does tests for fixed effects models automatically. The TEST subcommand allows you to calculate the
appropriate univariate F-tests for mixed models.
Output contains both the sequential sums of squares and the adjusted sums of squares (that is, each term is fit
after all other terms in the model). Automatic tests are done using the adjusted SS, assuming all factors are fixed.
Observations that are considered unusual are displayed. You can also display coefficients, along with their standard
deviations and t-values, and cell and marginal means.
Calculations are performed using a regression approach. First a "full rank" design matrix is formed from the factors
and covariates. The columns of the design matrix are used as predictors. Then each response variable is regressed
on these columns.
You can store the residuals, fitted values, prediction and confidence intervals, and many other diagnostics for
further analysis.
For more information, go to How to specify the model for GLM on page 1167 and How to enter data for ANOVA
and GLM on page 1158.
Options
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
CONTINUOUS C...C
Specifies the continuous predictors if you have any. The column or columns must be numeric or date/time and
must match the length of the response column.
CATEGORICAL C...C
Specifies the categorical predictors if you have any. The column or columns can be numeric, text, or date/time
and must match the length of the response column.
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. Only continuous predictors may be repeated. Nested
terms are not entered in the term list. The model can be nonhierarchical when there are no random factors.
RANDOM C...C
Specifies random factors. Random factors must also be specified in CATEGORICAL.
NESTED C (C...), ..., C (C...C)
Specifies the nesting relationships. Parentheses are used for nesting. For example, when B is nested within A, use
B (A), and when C is nested within both A and B, use C (A, B). Terms in parentheses are always factors in the model
and are listed with commas between them. Thus, D (A, B, E) is correct but D (A*B E) and D (A*B*E) are not. Also,
parentheses are not used inside parentheses. Thus, C (A, B) is correct but C (A, B (A)) is not.
WEIGHT
Performs a weighted regression. Weights cannot be used with optimal Box-Cox transformation. Column must be
numeric with nonnegative values. Length must match response column length.
An n x n matrix W is formed with the column of weights as its diagonal and zeros elsewhere. The regression
coefficients are estimated by:
( X' W X)
−1
(X' W Y)
228
Minitab Statistical Software ANOVA
This is equivalent to minimizing the weighted SS Error:
Σ w
i
(Y )
2
where w
i
is the weight in row i
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
TOLER K
Specifies the tolerance level for collinearity and constant check. Use to force Minitab to keep a predictor in the
model which is either highly correlated with another predictor or nearly constant. The default k = 4*2.22E-16.
SSQUARES
Specifies sequential sum of squares for tests in the ANOVA table. The default is the adjusted sums of squares.
MEANS termlist
Calculates least squares means for specified terms. Terms must be in the model.
TEST termlist / error term
Use TEST to specify your own tests. Termlist is a list of terms in the model. List them exactly as on the TERMS
subcommand. Error term is the term to be used as the denominator for the F-test. This can be a term in the model,
a linear combination of terms in the model, or MSE (denoted by the word ERROR). Only available via command
line.
EFFECT
Specifies the effect coding (−1, 0, +1) scheme for categorical predictors. If you do not specify either EFFECT or
BINARY, then Minitab uses the preferences set in File > Options > Linear Models > Coding of Predictors.
BINARY
Specifies the binary coding (1, 0) scheme for categorical predictors. If you do not specify either EFFECT or BINARY,
then Minitab uses the preferences set in File > Options > Linear Models > Coding of Predictors.
REFERENCE C K...C K
Changes the default coding for the categorical predictor columns. To change the default reference factor level,
specify the factor column followed by the reference level. (You must enclose text and date/time levels in double
quotes.) You can assign a reference level only when you use the binary coding (1, 0) scheme.
Options for standardizing the continuous predictor
Use this set of subcommands to standardize the continuous predictors in your model. You can use SCALE and LOCATION
in conjunction with each other. LEVELS is mutually exclusive with the LOCATION and SCALE subcommands. If you do
not specify LOCATION, SCALE, LEVELS, or UNSTANDARDIZED, then Minitab uses the preferences set in File > Options
> Linear Models > Coding of Predictors.
229
Minitab Statistical Software ANOVA
LOCATION [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by subtracting a constant from
each predictor. If you do not specify any arguments, the mean of each predictor column is subtracted. K specifies
to subtract a constant. If you specify arguments, the number of arguments must match the number of continuous
predictors.
SCALE [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by dividing each predictor by a
constant. If you do not specify any arguments, each predictor column is divided by the standard deviation. K
specifies to divide by a constant. If you specify arguments, the number of arguments must match the number of
continuous predictors.
LEVELS [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by DOE-type coding for the specified
low and high levels K K…K K. The number of arguments must be twice the number of continuous predictors.
UNSTANDARDIZED
Specifies the analysis is to be performed on the original predictors.
Box-Cox
BOX-COX [K]
Performs a Box-Cox transformation with a specified lambda. K is the value of lambda and must be between −5
and +5. If K is not given, Minitab will find the optimal lambda. By default, Minitab rounds the optimal value.
Minitab cannot calculate the optimal lambda for stepwise regression or when the model contains random factors.
Consequently, you must specify a lambda value for BOXCOX if you use RANDOM, STEPWISE, FORWARD, or
BACKWARD.
Stepwise
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
230
Minitab Statistical Software ANOVA
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
231
Minitab Statistical Software ANOVA
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram or individual value plot of the residuals, depending on the sample size.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4...n).
232
Minitab Statistical Software ANOVA
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Results
NODEFAULT
Specifies that no default tables and graphs will be displayed.
TMETHOD
Displays the method table.
TFACTOR
Displays the name, number of levels, and the values for all categorical factors in your model.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the preferences set in File > Options > Linear Models
> Stepwise.
FULL
Displays the coefficients, p-values, Mallows' Cp, and model summary statistics for each step of the procedure.
NOFULL
Hides these statistics.
TEQUATION
Displays the regression equation table. Minitab will display up to 50 equations. If you do not specify SINGLE or
SEPARATE, Minitab uses the preferences set in File > Options > Linear Models > Display of Results.
SINGLE
If you want to view a single equation, rather than a separate equation for each factor level combination, use
SINGLE.
SEPARATE
To view the separate equations, use SEPARATE.
TCOEFFICIENTS
Displays the table of coefficients. If you do not specify FULL or NOFULL, Minitab uses the preferences set in File
> Options > Linear Models > Display of Results.
FULL
Displays the complete set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
Displays the summary of model table.
TANOVA
Displays the ANOVA table.
233
Minitab Statistical Software ANOVA
TDIAGNOSTICS K
Displays a table of diagnostics. K = 0 displays diagnostics for only unusual observations. K = 1 displays diagnostics
for all observations.
TDW
Displays Durbin-Watson statistics.
TEXPAND
Displays the expanded version of the ANOVA table, table of coefficients, model summary table, and table of
unusual observations.
TSIMPLE
Displays the simple version of the ANOVA table, table of coefficients, model summary table, and table of unusual
observations.
TEMS
Displays the table of expected mean squares, estimated variance components, and error term in each F-test.
TMEANS
Displays the table of least squares means.
TVARIANCE
Displays the table of variance components.
TTEST
Displays the table of your own tests.
Storage for Box-Cox
BCRESP
Stores the Box-Cox transformation of the response in C.
BFITS
Stores the fits for the original response.
BSMEANS
Stores the means for the original response.
Storage of fits and residuals
RESIDUALS
Stores the residuals (fitted values observed values).
SRESIDUALS
Stores the standardized residuals.
TRESIDUALS
Stores the deleted Studentized residuals.
HI
Stores the leverages.
234
Minitab Statistical Software ANOVA
COOK
Stores Cook's distance.
DFITS
Stores DFITS.
Storage of characteristics of the estimated equation
COEFFICIENTS
Stores the estimated coefficients.
FITS
Stores the fitted values, often called the Y-hats ( ).
SMEANS
Stores the least square means for the terms specified by MEANS.
XMATRIX
Stores the design matrix for regression model.
REML: Session command for fitting a mixed effects
model
REML
By default, fits a model with random factors with the Restricted Maximum Likelihood method (REML). Using REML,
you can perform analysis of variance on random factors with balanced or unbalanced designs. With the
subcommand MLE, you can use maximum likelihood estimation.
For REML, at least 1 factor must be random. Other factors can be fixed or random. Covariates can be crossed with
each other, with factors, or nested within factors. You can store residuals, fitted values, and other diagnostic
statistics.
REML tests for fixed effects with either the Kenward-Roger approximation or the Satterthwaite approximation.
To use the Satterthwaite approximation, use the subcommand SATTERTHWAITE. To show the tests, use the
subcommand TFIXEDEFFECT.
Tests use the adjusted sums of squares. Observations with standardized residuals that have absolute values greater
than 2 are in a table of unusual observations. to show the table, use the subcommand TDIAGNOSTICS.
REML has 4 required subcommands:
RESPONSE
RANDOM
CATEGORICAL
TERMS
For more information, go to the descriptions of the individual subcommands.
235
Minitab Statistical Software ANOVA
Options
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
CATEGORICAL C...C
Specifies the categorical predictors if you have any. The column or columns can be numeric, text, or date/time
and must match the length of the response column.
CONTINUOUS C...C
Specifies the continuous predictors if you have any. The column or columns must be numeric or date/time and
must match the length of the response column.
RANDOM C...C
Specifies random factors. Random factors must also be specified in CATEGORICAL. At least one factor must be
random.
NESTED C (C...), ..., C (C...C)
Specifies the nesting relationships. Parentheses are used for nesting. For example, when B is nested within A, use
B (A), and when C is nested within both A and B, use C (A, B). Terms in parentheses are always factors in the model
and are listed with commas between them. Thus, D (A, B, E) is correct but D (A*B E) and D (A*B*E) are not. Also,
parentheses are not used inside parentheses. Thus, C (A, B) is correct but C (A, B (A)) is not.
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. Only continuous predictors may be repeated. Nested
terms are not entered in the term list. The model can be nonhierarchical.
WEIGHT C
Performs a weighted regression. Weights cannot be used with optimal Box-Cox transformation. Column must be
numeric with nonnegative values. Length must match response column length.
An n x n matrix W is formed with the column of weights as its diagonal and zeros elsewhere. The regression
coefficients are estimated by:
( X' W X)
−1
(X' W Y)
This is equivalent to minimizing the weighted SS Error:
Σ w
I
(Y )
2
where w
I
is the weight in row I
REML
Specifies to use the restricted maximum likelihood estimation method to estimate the variance components.
MLE
Specifies to use the maximum likelihood method to estimate the variance components. Usually, you use the REML
method
MAXITER K
Specifies the maximum number of iterations for the Newton-Raphson algorithm to estimate the variance
components.
STARTING C...C or K...K
Specifies the starting estimates for the variance components for each response in C. The order of the values in
each column must be the same order of the random terms in TERMS. The last value in C is for the error term. If
you have only one response or you want to use the same starting estimates for all responses, you can enter
numbers K...K.
236
Minitab Statistical Software ANOVA
CTOLERANCE K
Specifies the convergence tolerance value in K for the objective function. The objective function is -2 log likelihood.
ETOLERANCE K
Specifies the convergence tolerance value in K for the estimates of the variance components.
KENWARDROGER
Use Kenward-Roger approximation to estimate the denominator degrees of freedom for the fixed effect tests.
SATTERTHWAITE
Use Satterthwaite approximation to estimate the denominator degrees of freedom for the fixed effects.
DROWSTAT
Computes statistics that require row deletion:
PRESS
R-Sq(Pred)
Cook's D
DFITS
Marginal deleted residuals
Marginal conditional residuals
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound−1
Two-sided0
Upper bound1
TOLERANCE K [K]
Specifies the tolerance level for the collinearity between variables and whether a variable is constant. The first K
specifies the tolerance for collinearity. The default value is 1E−18. The second K is for the tolerance for whether
a variable is constant. The default value is 1E−21. Lower the tolerance to keep variables in the model that Minitab
would exclude with the default values.
MEANS termlist
Calculates least squares means for specified terms. Terms must be in the model.
Options for standardizing the continuous predictor
Use this set of subcommands to standardize the continuous predictors in your model. You can use SCALE and LOCATION
in conjunction with each other. LEVELS is mutually exclusive with the LOCATION and SCALE subcommands. If you do
not specify LOCATION, SCALE, LEVELS, or UNSTANDARDIZED, then Minitab uses the preferences set in File > Options
> Linear Models > Coding of Predictors.
237
Minitab Statistical Software ANOVA
LOCATION [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by subtracting a constant from
each predictor. If you do not specify any arguments, the mean of each predictor column is subtracted. K specifies
to subtract a constant. If you specify arguments, the number of arguments must match the number of continuous
predictors.
SCALE [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by dividing each predictor by a
constant. If you do not specify any arguments, each predictor column is divided by the standard deviation. K
specifies to divide by a constant. If you specify arguments, the number of arguments must match the number of
continuous predictors.
LEVELS [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by DOE-type coding for the specified
low and high levels K K…K K. The number of arguments must be twice the number of continuous predictors.
UNSTANDARDIZED
Specifies the analysis is to be performed on the original predictors.
Graphs
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
CONDITIONAL
Specifies to plot residuals for conditional fits.
MARGINAL
Specifies to plot residuals for marginal fits.
GHISTOGRAM
Displays a histogram or individual value plot of the residuals, depending on the sample size.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4...n).
238
Minitab Statistical Software ANOVA
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Tables
NODEFAULT
Specifies that no default tables and graphs will be displayed.
TEXPAND
Displays the expanded version of the variance components table, the table of coefficients, the random effect
predictions table, the table of fits and diagnostics, and the table of conditional means.
TSIMPLE
Displays the simple version of the variance components table, the table of coefficients, the random effect predictions
table, the table of fits and diagnostics, and the table of conditional means.
TMETHOD
Displays the method table.
TFACTOR
Displays the name, number of levels, and the values for all categorical factors in your model.
TITERATION
Displays the iteration history table that shows the value of −2 log likelihood for each iteration of the variance
components.
TVARIANCE
Displays the variance component estimates and the tests of whether the components are 0.
TCOVARIANCE
Display the asymptotic variance-covariance matrix of the variance component estimates.
TFIXEDEFFECT
Display tests of the fixed factors in the model.
TSUMMARY
Display S, R
2
, and R
2
(adj). The expanded version of the table adds AICc and BIC.
TCOEFFICIENTS
Displays the table of coefficients for fixed factors and covariates. If you do not specify FULL or NOFULL, Minitab
uses the preferences set in File > Options > Linear Models > Display of Results.
FULL
Displays the complete set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TRANDOM
Displays the Best Unbiased Linear Predictions (BLUP) and tests of whether the BLUP are 0.
TEQUATION
Displays the marginal fitted equation. Minitab will display up to 50 equations. If you do not specify SINGLE or
SEPARATE, Minitab uses the preferences set in File > Options > Linear Models > Display of Results.
239
Minitab Statistical Software ANOVA
SINGLE
If you want to view a single equation, rather than a separate equation for each factor level combination, use
SINGLE.
SEPARATE
To view the separate equations, use SEPARATE.
TCEQUATION
Displays the conditional fitted equation. Minitab will display up to 50 equations. If you do not specify SINGLE or
SEPARATE, Minitab uses the preferences set in File > Options > Linear Models > Display of Results.
SINGLE
If you want to view a single equation, rather than a separate equation for each factor level combination, use
SINGLE.
SEPARATE
To view the separate equations, use SEPARATE.
TDIAGNOSTICS K
Displays a table of diagnostics for the marginal fits and residuals. K = 0 displays diagnostics for only unusual
observations. K = 1 displays diagnostics for all observations.
TCONDITIONAL K
Displays a table of diagnostics for the conditional fits and residuals. K = 0 displays diagnostics for only unusual
observations. K = 1 displays diagnostics for all observations.
TMEANS
Displays the table of least squares means.
Storage
RESIDUALS C
Stores the residuals for the marginal fits.
SRESIDUALS C
Stores the standardized residuals for the marginal fits.
TRESIDUALS C
Stores the deleted t residuals for the marginal fits.
FITS C
Stores the marginal fitted values.
CRESIDUALS C
Stores the conditional residuals.
CSRESIDUALS C
Stores the standardized residuals for the conditional fits.
CTRESIDUALS C
Stores the deleted t residuals for the conditional fits.
CFITS C
Stores the conditional fitted values.
240
Minitab Statistical Software ANOVA
HI C
Stores the leverages.
COOK C
Stores Cook's distance.
DFITS C
Stores DFITS.
COEFFICIENTS C
Stores the estimated coefficients.
BLUP C
Stores the best linear unbiased predictors.
XMATRIX M
Stores the design matrix for fixed effects terms.
ZMATRIX M
Stores the design matrix for random effects terms.
COVARIANCE M
Stores the variance-covariance matrix of the variance component estimates.
SMEANS C
Stores the least square means for the terms specified by MEANS.
VARCOMP C
Stores the estimates of the variance components in the same order as the terms appear after TERMS.
LOGLIKE C
Stores the −2 log likelihood values for all iterations.
FIXCOV M
Stores the variance-covariance matrix of the fixed parameters.
COMPARE: Session command for performing
multiple comparisons of means
COMPARE C
Generates comparisons based on a model from a general linear model or from a mixed effects model for response
C.
If you have a general linear model or a mixed effects model stored in the worksheet, you can use COMPARE to
obtain multiple comparisons of means. Multiple comparisons of means allow you to examine which means are
different and to estimate by how much they are different.
You have the following choices when using multiple comparisons:
All pairwise comparisons or comparisons with a control
Which means to compare
241
Minitab Statistical Software ANOVA
The method of comparison
How to display the results
Pairwise comparisons or comparison with a control
Use PAIRWISE when you do not have a control level but you would like to examine which pairs of means are different.
Use MCONTROL when you are comparing treatments to a control. When this method is suitable, it is inefficient to use
the all-pairwise approach, because the all-pairwise confidence intervals will be wider and the hypothesis tests less
powerful for a given family error rate.
Which means to compare
To specify which means to compare, enter terms from the model in the termslist for PAIRWISE or MCONTROL. If you
have 2 factors named A and B, entering A B will result in multiple comparisons within each factor. Entering A * B will
result in multiple comparisons for all level combinations of factors A and B.
The multiple comparisons method
You can choose from among four methods for both pairwise comparisons and comparisons with a control. Each
method provides simultaneous or joint confidence intervals, meaning that the confidence level applies to the set of
intervals computed by each method and not to each one individual interval. By protecting against false positives with
multiple comparisons, the intervals are wider than if there were no protection.
Some characteristics of the multiple comparison methods are summarized below. "Conservative" in this context indicates
that the true family error rate is less than the stated one.
PropertiesComparison method
Comparison to a control only, not proven to be conservativeDunnett
All pairwise differences only, not proven to be conservativeTukey
Most conservativeBonferroni
Conservative, but slightly less so than BonferroniSidak
Does not control the family error rateFisher's LSD
Display results
Minitab can present multiple comparison results in the following forms:
TGROUPING displays the grouping information table that highlights the significant and non-significant comparisons.
TMTEST displays the hypothesis test form which includes the adjusted p-values.
GINTPLOT displays the interval plots of the confidence the intervals for the mean difference between two groups.
Conditions that restrict comparisons for general linear models
For general linear models, comparisons cannot be done in the following situations:
242
Minitab Statistical Software ANOVA
Comparisons are not available for terms that contain or interact with random factors. Nesting is a form of interaction.
For a model with random factors, you can do comparisons if you use a mixed effects model with the Restricted
Maximum Likelihood estimation method (REML). Suppose the model contains A B C A*B, where both A and C are
random, and B is fixed. Because A*B is a term in the model, no multiple comparison results for B are available even
though B is a fixed factor. However, if the model does not include A*B, multiple comparison results are available
for B.
There is a special case for a balanced design that has two factors. Suppose the model contains A B A*B, where A
is random, and B is fixed. Even though A*B is in the model, you can perform multiple comparisons for B.
Comparisons is disabled if you choose (1, 0) coding and the model is non-hierarchical. To enable Comparisons
for this case, choose (−1, 0, +1) coding or specify a hierarchical model.
Commands
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
PAIRWISE [termlist}
Specifies pairwise comparisons using the terms in the termlist. The terms in the termlist must be in the model.
You must use at least one of the following sub-subcommands with PAIRWISE:
TUKEY
BONFERRONI
SIDAK
FISHER
MCONTROL [termlist]
Specifies comparisons with a control using the terms in the termlist. The terms in the termlist must be in the
model.
You must use at least one of the following sub-subcommands with PAIRWISE:
DUNNETT
BONFERRONI
SIDAK
FISHER
LEVELS C K...C K
You must use LEVELS with MCONTROL. Use LEVELS to provide a factor (C) with a control level (K). You must
specify a control level for each factor that you list in MCONTROL. If these levels are text or date/time, enclose
each with double quotation marks.
ALTERNATIVE K
ALTERNATIVE specifies the alternative hypothesis for comparisons to the control level.
Alternative hypothesisValue of K
Determines whether the treatment means are less than the control mean−1
Determines whether the treatment means are equal to the control mean0
243
Minitab Statistical Software ANOVA
Alternative hypothesisValue of K
Determines whether the treatment means are greater than the control mean1
GINTPLOT
Displays interval plots that represent the confidence interval for the mean difference between two groups. A
separate graph is created for each comparison.
TGROUPING
Displays the grouping information table for each comparison. This table highlights the significant and non-significant
comparisons for each selected comparison method.
TMTEST
Displays the multiple comparison test table. This table displays the hypothesis test form of the comparison output,
which includes the differences of the means, the numeric values for the confidences intervals, and the adjusted
p-values.
MANOVA: Session command for performing a
general MANOVA
MANOVA C...C = C...C
Performs a general MANOVA. The columns specified before the equal sign are the responses, and the columns
after the equal sign are the factors.
Use general MANOVA to perform multivariate analysis of variance (MANOVA) with balanced and unbalanced
designs, or if you have covariates. This procedure takes advantage of the data covariance structure to simultaneously
test the equality of means from different responses.
Calculations are done using a regression approach. A full rank design matrix is formed from the factors and
covariates and each response variable is regressed on the columns of the design matrix.
Factors can be crossed or nested, but they cannot be declared as random. You can work around this restriction
by specifying the error term to test model terms. Covariates can be crossed with each other or with factors, or
nested within factors. You can analyze up to 50 response variables with up to 31 factors and 50 covariates at one
time.
With the MANOVA subcommand, you can specify model terms for a custom multivariate test and designate the
error term in Error. Minitab performs four multivariate tests (see the MANOVA subcommand) for those terms.
This option is most useful when you have factors that you consider as random factors. Model terms that are
random or that are interactions with random terms may need a different error term than general MANOVA
supplies. You can determine the appropriate error term by entering one response variable with General Linear
Model, choose to display the expected mean square, and determine which error term was used for each model
terms.
If you specify an error term, it must be a single term that is in the model. This error term is used for all requested
tests. If you have different error terms for certain model terms, enter each separately and exercise the general
MANOVA dialog for each one. If you do not specify an error term, Minitab uses MSE.
For more information, go to How to specify the model for GLM on page 1167 and How to enter data for ANOVA
and GLM on page 1158.
244
Minitab Statistical Software ANOVA
Model
MANOVA [termlist [ / errorterm]]
Performs four multivariate tests—Wilks' test, Lawley-Hotelling test, Pillai's test, and Roy's largest root test—for
each term in the model. If you include a termlist, MANOVA does the four multivariate tests for each term listed.
If you specify an errorterm, it must be a single term that is in the model. MANOVA then uses this errorterm in all
tests. If you do not specify an errorterm, Minitab uses the error associated with MSE, as in the univariate case.
All four tests are based on two SSCP (sums of squares and cross products) matrices: H = the hypothesis matrix
and E = the error matrix.
If an error term is not specified on MANOVA, then the adjusted SSCP matrix is used for H and the SSCP matrix
associated with MSE is used for E. If an error term is specified on MANOVA, the sequential SSCP matrices associated
with H and E are used. Using sequential SSCP matrices guarantees that H and E are statistically independent.
COVARIATES C...C
The columns listed are used as covariates. If COVARIATES is used, it must be the first subcommand. This restriction
is needed to allow proper error checking. You may have up to 50 covariates.
Options
WEIGHTS C
Performs a weighted least squares fit. The weights must be greater than or equal to zero. An n x n matrix W is
formed with the column of weights as its diagonal and zeros elsewhere. The regression coefficients are calculated
by (X' WX)
−1
(X' WY).
This is equivalent to minimizing the weighted SS Error:
PREDICT
Computes the fitted Y's, or for given values of the predictors. PREDICT displays a table that contains the fitted
Y's, standard errors of the fitted Y's, a 95% confidence interval, and a 95% prediction interval. E...E may be a list
of values, one for each predictor, a list of columns, one for each predictor, or a mix of values and columns.
The prediction interval computed by PREDICT assumes a weight of 1. If you used the WEIGHT subcommand with
values other than 1, you should adjust the prediction interval values manually.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
PFITS C
Stores the fits.
PSDFITS C
Stores the estimated standard errors of the fits.
CLIMITS C C, ..., C C
Stores the lower and upper confidence limits.
PLIMITS C C, ..., C C
Stores the lower and upper prediction limits.
245
Minitab Statistical Software ANOVA
TEST termlist / errorterm
Use TEST to specify your own tests. Termlist is a list of terms in the model. List them exactly as on the MANOVA
subcommand. Error term is the term to be used as the denominator for the F-test. This can be a term in the model,
a linear combination of terms in the model, or MSE (denoted by the word ERROR). Only available via command
line.
TOLERANCE K [K]
Use TOLERANCE to force Minitab to keep a predictor in the model which is either highly correlated with another
predictor or which is nearly constant. Lowering tolerance by giving very small argument values can prevent Minitab
from eliminating problematic predictor columns from the model.
DescriptionK
1 R-squared, where R-squared is the value resulting from regressing one predictor on the
remaining predictors. The default is 1E 18. If (1 R-squared) is < (1E 18), the predictor is
removed from the equation.
First K
The parameter for forcing in a variable which is nearly constant. The default is 2E 21. If the
coefficient of variation of a predictor (the standard deviation / the mean) is < square root (2E
21), then the predictor is considered essentially constant and is removed from the equation.
Second K
Both Ks must be positive numbers.
Graphs
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4...n). Optionally, specify a column C that defines the order.
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
246
Minitab Statistical Software ANOVA
Results
MEANS termlist
Displays a table of adjusted means (sometimes called least squares means) corresponding to each term listed.
Terms listed on MEANS must also be listed on MANOVA. If more than one MEANS subcommand is specified,
only the last one is used.
EMS
Displays a table that contains expected mean squares, estimated variance components, and the error term (the
denominator) used in each exact F-test. If there is no exact F-test for a term, the expected mean squares allow
you to determine how to construct an approximate F-test using the subcommand TEST.
The estimates of the variance components are the usual unbiased analysis of variance estimates. They are obtained
by setting each calculated MS equal to its EMS. This gives a system of linear equations in the unknown variance
components. This system is then solved. Unfortunately, this method can result in negative estimates, which should
be set to zero. Minitab, however, prints the negative estimates because they sometimes indicate that the model
being fit is inappropriate for the data.
Terms that are fixed do not have variance components estimated.
BRIEF K
Controls the amount of output with a value in K. You can also use BRIEF as a main command. When you use BRIEF
as a main command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage and displays the following
error messages, warnings, prompts, and notes; graphs; WRITE to the screen.
0
Minitab displays the ANOVA table.1
K = 1, and Minitab displays the table of factor levels, coefficients for terms involving
covariates, and unusual observations.
2 (default)
K = 2 output, and Minitab displays all the coefficients.3
SSCP
Displays the hypothesis matrix, H, corresponding to each term specified by MANOVA, and the error matrix, E.
EIGEN
Displays a table containing the eigenvalues and eigenvectors for the (nonsymmetric) matrix, E**-1 H. These are
the eigenvalues that are used to calculate the four MANOVA tests. A separate table is printed for each term
specified on MANOVA.
Note If an eigenvalue is repeated, then the corresponding eigenvectors are not unique. In this case, the eigenvectors Minitab displays
and those in books or other software might not agree. However, the MANOVA tests are always unique.
PARTIAL
Displays a matrix of partial correlations. These are the correlations among the residuals or, equivalently, the
correlations among the responses conditioned on the model. The formula for the matrix is W**-.5 E W**-.5, where
E is the error matrix and W has the diagonal of E as its diagonal and 0's elsewhere.
NOUNIVARIATE
Suppresses the univariate output. Only the multivariate output is displayed.
247
Minitab Statistical Software ANOVA
INTERACT terms
Used with SMEANS to store means for two-way interactions. List the model terms for which you calculate means
for level pairs. The means will be calculated by the order of terms and levels.
SMEANS C...C
Stores means for two-way interactions, main effects, and the overall mean. Use with INTERACT to store means
for two-way interactions. Specify a storage column for each response variable.
Storage
FITS C...C
Stores fitted values, using one column for each response.
RESIDUALS C...C
Stores residuals, using one column for each response variable. Residual = (response fit).
SRESIDUALS C...C
Stores the standardized residuals, using one column for each response variable.
TRESIDUALS C...C
Stores the deleted Studentized residuals, using one column for each response variable.
HI C
Stores leverages.
COOKD C...C
Stores Cook's distance.
DFITS C...C
Stores the DFITS (also called DFFITS), using one column for each response.
XMATRIX M
Stores the design matrix corresponding to your model in M.
COEFFICIENTS C...C
Stores the coefficients for a model, using one column for each response. These are the same coefficients that are
printed under BRIEF 3. They correspond to the design matrix stored by XMATRIX. Thus, if M1 contains the design
matrix and C1 the coefficients, then M1 times C1 gives the fitted values.
NESTED: Session command for performing a
fully-nested ANOVA
NESTED C...C = C...C
Analyzes fully nested (hierarchical) designs. All factors are assumed to be random. Designs can be unbalanced.
In this case, F and p-values are not displayed. You can calculate these yourself using the expected mean squares
that are displayed.
You can analyze up to 50 response variables and up to 9 factors on one NESTED command. The columns specified
before the equal sign are the responses, and the columns after the equal sign are the factors. You can also have
replicates. One row then corresponds to one observation, giving the value of each response and the level of each
248
Minitab Statistical Software ANOVA
factor for that observation. Factor levels can be any real numbers. They do not need to be consecutive or in any
special order.
VARTEST: Session command for performing an equal
variances test
VARTEST C...C
If you do not specify UNSTACKED, VARTEST performs tests for equal variances with all response data in one C
and factor level information in additional columns.
If you do specify UNSTACKED, VARTEST performs tests for equal variances with data from each factor level in a
different column C...C.
UNSTACKED
Indicates that data for each factor level are in different columns.
Options
CONFIDENCE K
Specifies the confidence level for the Bonferroni simultaneous confidence intervals and also the significance level
(denoted by α or alpha) for the multiple comparison intervals, and the tests. The default is 95, which corresponds
to a confidence level of 95% and an α = 1 (95 / 100) = 0.05.
USEBARTLETT
Specifies to use the test based on the normal distribution instead of the multiple comparisons method and Levene's
method. If you have only 2 factor levels, then Minitab performs the F-test. If you have 3 or more factor levels,
then Minitab performs Bartlett's test.
The F-test and Bartlett's test are accurate only for normally distributed data. Any departure from normality can
cause these tests to yield inaccurate results. However, if the data conform to the normal distribution, then the
F-test and Bartlett's test are typically more powerful than either the multiple comparisons method or Levene's
method.
Graphs
GINTERVAL
Displays a graphical summary that includes the multiple comparison intervals for standard deviations and test
results by default. The multiple comparison intervals are not confidence intervals of the individual standard
deviations. The multiple comparison intervals are only useful for comparing the population standard deviations.
If USEBARTLETT is used, then GINTERVAL displays Bonferroni confidence intervals of the standard deviations.
GINDPLOT
Displays individual value plot.
GBOXPLOT
Displays a boxplot.
249
Minitab Statistical Software ANOVA
Results
NODEFAULT
Minitab displays all output tables by default. You do not have to enter the subcommands. If you enter NODEFAULT,
then each table is only displayed if you enter the specific subcommand.
TMETHOD
Displays the method table which includes the null hypothesis, the alternative hypothesis, and the significance
level (denoted by α or alpha).
TBONFERRONI
Displays the table of Bonferroni simultaneous confidence intervals for the standard deviations of each factor level.
TTEST
Displays the test table which includes the p-values for the hypothesis tests.
Storage
STDEVS C
Stores the standard deviation of each factor level in column C.
VARIANCES C
Stores the variance of each factor level in column C.
SBONFERRONI C C
Stores Bonferroni confidence limits for the standard deviation of each factor level. The lower limits are stored in
the first column C and the upper limits is stored in the second column C.
SMCI C C
Stores the limits of the multiple comparisons intervals for each factor level. The lower limits are stored in the first
column C and the upper limits is stored in the second column C.
SFPVALUE C
Stores the p-value for Bartlett's test (or the F-test if there are only 2 factor levels).
SLPVALUE C
Stores the p-value for Levene's test.
SMPVALUE C
Stores the p-value for the multiple comparison test.
INTPLOT: Session command for creating an interval
plot
INTPLOT C...C
INTPLOT (C...C) * C
Use to plot means and confidence intervals for one or more variables. An interval plot illustrates both a measure
of central tendency and the variability of the data.
250
Minitab Statistical Software ANOVA
By default, Minitab displays confidence intervals, but you can change the display type to standard error bars using
the INTBAR subcommand.
The data must be numeric or date/time. The categorical grouping data can be numeric, date/time, or text.
INTPLOT C...C displays a separate interval plot for each graph variable.
INTPLOT (C...C) * C displays a separate graph for each C on the left, with an interval for each category of the C on
the right.
The following table shows a few of the possible ways to generate interval plots.
What the command language displaysCommand language
Two graphs: interval plots of Sales and of Advertis
INTPLOT 'Sales' 'Advertis'.
A graph with intervals representing yearly sales
INTPLOT 'Sales'*'Year'.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
GAPWIDTH and COFFSET: Session subcommands for the space between clusters and items in a cluster on page 1028
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
ILABEL: Session subcommand for labeling individual values on a boxplot or interval plot on page 1033
INTLAB: Session subcommand for labeling interval bar endpoints on an interval plot on page 1039
MEALAB: Session subcommand for labeling means on a boxplot or an interval plot on page 1051
MEDLAB: Session subcommand for labeling medians on a boxplot on page 1055
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
BAR: Session subcommand for representing data values with bars on page 1003
251
Minitab Statistical Software ANOVA
CMEAN: Session subcommand for connecting means with lines on a boxplot on page 1010
CMEDIAN: Session subcommand for connecting means with lines on a boxplot on page 1011
INDIVIDUAL: Session subcommand for displaying a symbol for each individual data value on a boxplot or an
individual value plot on page 1036
INTBAR: Session subcommand for displaying a vertical line with horizontal lines at the endpoints of the confidence
interval for the mean on page 1037
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
MEAN: Session subcommand for displaying symbol for each mean on a boxplot, interval plot, or individual value
plot on page 1053
MEDIAN: Session subcommand for displaying a symbol for each median on a boxplot, interval plot, or individual
value plot on page 1054
SOFFSET: Session subcommand for offsetting points from the center on page 1082
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
252
Minitab Statistical Software ANOVA
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
MAIN: Session command for creating a main effects
plot
MAIN C...C
Draws a main effects plot where the points in the plot are the raw data means at the various levels of each factor.
A reference line is drawn through the plot representing the grand mean of the response data. You can use factors
from designs generated by commands such as GLM on page 227 and ANOVA on page 224.
MAIN generates a plot that uses data means. After you have fit a model, use FACPLOT on page 276 to generate
plots that use fitted means.
Data means are the raw response variable means for each factor level combination whereas fitted means use least
squares to predict the mean response values of a balanced design. Therefore, the two types of means are identical
for balanced designs but can be different for unbalanced designs. While you can use raw data with unbalanced
designs to obtain a general idea of which main effects may be evident, it is generally good practice to use the
fitted means to obtain more precise results.
Enter the factors on the main command line. The factor columns may be numeric or text, and may contain any
values. The levels do not need to be in any special order. When the factor column is text, the first entry (row 1) is
level 1, the next entry that is different is level 2, and so on.
RESPONSE C
Use RESPONSE to enter raw response data. Then, the main effects are calculated based on the means of the
data.
YMIN K
Specifies the y-axis minimum value. Making the minimum and maximum values the same is very useful when
you are comparing several main effects plots of related data.
YMAX K
Specifies the y-axis maximum value. Making the minimum and maximum values the same is very useful when
you are comparing several main effects plots of related data.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
253
Minitab Statistical Software ANOVA
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
INTERACT: Session command for creating an
interactions plot
INTERACT C...C
Draws a single interaction plot if 2 factors are entered on the command line, or a matrix of interaction plots if
more than 2 factors are entered. You can use factors from designs generated by commands such as GLM on page
227 and ANOVA on page 224.
INTERACT generates a plot that uses data means. After you have fit a model, use FACPLOT on page 276 to generate
plots that use fitted means.
254
Minitab Statistical Software ANOVA
Data means are the raw response variable means for each factor level combination whereas fitted means use least
squares to predict the mean response values of a balanced design. Therefore, the two types of means are identical
for balanced designs but can be different for unbalanced designs. While you can use raw data with unbalanced
designs to obtain a general idea of which main effects may be evident, it is generally good practice to use the
fitted means to obtain more precise results.
Enter the columns containing the factors as the arguments to the main command. The factor columns may be
numeric or text, and may contain any values. The levels do not need to be in any special order. When the factor
column is text, the first entry (row 1) is level 1, the next entry that is different is level 2, and so on.
You must use the RESPONSE subcommand with a column argument. When you specify RESPONSE and a response
column, Minitab goes through each two factor pair in sequential order and calculates the means of all the responses
for each unique combination of values in the two factors.
RESPONSE C
Specifies the column containing the response data.
The RESPONSE version of the interaction plot does not require any model to be fit. It is useful for preliminary
exploratory analysis in order to get a preliminary look at which two factor interactions appear to be significant.
It can also be used after a model has been fit, provided the design is balanced.
FULL
Specifies to use the full interaction matrix when more than two factors are specified instead of the default
display of the upper right portion of the matrix. In the full matrix, the transpose of each plot in the upper
right displays in the lower left portion of the matrix. The full matrix takes longer to display than the half
matrix.
YMIN K
Specifies the y-axis minimum value. Making the minimum and maximum values the same is very useful when
you are comparing several main effects plots of related data.
YMAX K
Specifies the y-axis maximum value. Making the minimum and maximum values the same is very useful when
you are comparing several main effects plots of related data.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
255
Minitab Statistical Software ANOVA
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
256
Minitab Statistical Software ANOVA
DOE
Screening Designs
DSDESIGN: Session command for creating a definitive screening
design
DSDESIGN K
Creates a definitive screening design with K factors. You can then use REPLICATES to replicate points and BLOCKS
to add block.
The design summary and design table can be displayed. The design table is displayed under BRIEF 3. Factors are
denoted by the letters A, B, C, D, E, F, G, H, J, K, ... , vv, ww, xx.
Note The letter I is not used.
Quotation marks around column names are required. If you use a subcommand more than one time, DSDESIGN
uses the last instance of the subcommand.
REPLICATES K
Replicates each point K times.
The following example generates a definitive screening design with 4 factors and 2 replicates. Thus, there
are a total of 26 runs in this experiment.
DSDESIGN 4;
REPLICATES 2.
BLOCKS K
Specifies the number of blocks in K. If your design includes blocks, and the number of blocks equals the
number of replicates, each replicate is a separate block. You can include multiple replicates in a block. Each
block has the same number of replicates.
LEVELS K K, ..., K K
With LEVELS K K, ..., K K, you list one pair of arguments for each factor. The first K should be the low level,
and the second K should be the high level. Minitab calculates the center points as the value that is half way
between the low and high levels.
The following example stores 0 for the low level of A, 10 for the high level, and 5 for the center point; 100
for the low level of B, 102 for the high level, and 101 for the center point; .2 for the low level of C, .3 for the
high level, and 2.5 for the center point.
DSDESIGN 3;
LEVELS 0 10 100 102 .2 .3.
With LEVELS K K, ..., K K, you can set levels to be text data. The arguments that define text data must be
enclosed in double quotation marks. For example, if factor B is whether a catalyst is present or absent, you
can use the following:
DSDESIGN 3;
LEVELS 0 10 "absent" "present" .2 .3.
257
Minitab Statistical Software DOE
RANDOMIZE [K]
Randomizes the runs in the design matrix. If you specify blocks, randomization is done separately within each
block, and then the blocks are randomized.
K is the base for the random number generator and can take any positive integer as an argument. To always
get the same ordering of the rows, create the same design and randomize the runs with the same base. For
more information, go to BASE on page 86.
FNAME K...K
Specifies the names of the factors. You must enter as many arguments as number of factors. The arguments
must be enclosed in double quotation marks.
BRIEF K
Controls the amount of output.
You can also use BRIEF as a main command. When you use BRIEF as a main command, it affects all other
commands that use BRIEF to control the amount of output.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays a summary of the design.1 or 2
In addition to the K = 1 or K = 2 output, Minitab displays the design table.3
PBDESIGN: Session command for creating a Plackett-Burman
design
PBDESIGN K [K]
Creates Plackett-Burman designs. Plackett-Burman designs are a class of resolution III, 2-level fractional factorial
designs that are often used to study main effects. In a resolution III design, main effects are aliased with 2-way
interactions.
The two constants on PBDESIGN specify a design. The first K is the number of factors. The second K is the number
of runs. Factor columns can be text or numeric.
To see the designs that Minitab generates, go to Plackett-Burman designs on page 1176. A design is based on the
number of runs, from 8 to 48 and always a multiple of 4. Therefore, the second K on PBDESIGN must be a multiple
of 4. The number of factors must be less than the number of runs. If you don't include the second K, Minitab sets
the number of runs to the smallest possible value for the specified number of factors.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTPYE, and XMATRIX.)
CENTER K
Adds up to 50 center points to the design. If the design is blocked, the center points are divided equally
between the blocks. If K is not a multiple of the number of blocks, then each of the last few blocks has one
less point than the other blocks.
REPS K
Specifies up to 50 replicates of each point. REPS does not replicate center points.
258
Minitab Statistical Software DOE
The following example generates a Plackett-Burman design that has 2 factors and 8 base runs. Thus, there
are a total of 16 runs in this experiment.
PBDESIGN 2 8;
REPS 2.
RBLOCK
Specifies blocks on replicates. Each set of replicate points are placed in a separate block. No arguments are
taken.
LEVELS
Use LEVELS to specify values for the levels of each factor. The level values can be text or numeric. The default
values are -1 for the low level, +1 for the high level, and 0 for a center point.
The two ways to use LEVELS are as follows.
LEVELS K K, ..., K K
With LEVELS K K, ..., K K, you list one pair of arguments for each factor. The first K should be the low
level and the second K should be the high level. When you add center points with CPBLOCK, Minitab
calculates the center points as the value that is half way between the low and high levels. The following
example stores 0 for the low level of A, 10 for the high level, and 5 for the center point. 100 for the low
level of B, 102 for the high level, and 101 for the center point; .2 for the low level of C, .3 for the high
level, and 2.5 for the center point.
PBDESIGN 2 8;
CENTER 2;
LEVELS 0 10 100 102;
DESIGN.
With LEVELS K K, ..., K K, you can set levels to be text data. The arguments that define text data must be
enclosed in double quotation marks. In the following example, factor B is whether a catalyst is present
or absent. Because you use CENTER 2 to add center points with a text factor, Minitab creates pseudo
center points.
PBDESIGN 2 8;
CENTER 2;
RBLOCK;
LEVELS 0 10 "absent" "present";
DESIGN.
LEVELS C
With LEVELS C, the level values must be numeric. Put the level values in a column, in the same order as
if they were listed on the subcommand. Then, specify the level column on the LEVELS subcommand.
RANDOMIZE [K]
Randomizes the runs in the design matrix. If you specify blocks, randomization is done separately within each
block and then the blocks are randomized. When you use RANDOMIZE, the standard order and the run order
are different and Minitab stores the design in run order.
K is the base for the random number generator and can take any integer as an argument. To get the same
ordering of the rows, create the same design and randomize the runs with the same base. For more
information, go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
259
Minitab Statistical Software DOE
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output for the command, but performs all specified storage
and displays the following output: error messages, warnings, prompts, and notes.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
SCREEN: Session command for analyzing a screening design
SCREEN
Analyzes a screening design with a continuous response. Fits definitive screening and Plackett Burman models,
which are produced by DSDESIGN on page 257 and PBDESIGN on page 258. Each factor must have two levels. Also,
you can have covariates and a blocking factor. You can specify a single response. Specify interactions in the
following way: C5*C6. For more information on specifying the model, go to How to specify the model for factorial
designs on page 1166.
The factor columns can be numeric or text, and can contain any values. The levels do not need to be in any special
order. When the factor column is text, Minitab uses the first entry (row 1) for the low level of the factor and the
other entry for the high level. To change this default order, use the LEVEL subcommand. When you include center
points in the model, Minitab tests for curvature.
You can display effects plots and residual plots. You can store the residuals, fitted values, and many other diagnostics
for further analysis. You can use extra text on the command and subcommand lines only after a #. Quotation
marks around column names that are one word long are optional.
For information about how Minitab handles missing data, go to Missing values in factorial, response surface, and
mixture designs on page 1171.
RESPONSE C
Specifies the column that contains the response variable in C. The column must be numeric or date/time.
BLOCK C (optional)
Specifies the column that contains the blocking information in C. Include the blocking column together with
TERMS to make a model that considers blocks.
FACTOR C...C (required)
Specifies the factors in columns C...C. The columns must have the same number of rows that the response
column has.
COVARIATES C...C
Specifies columns that include covariates in C...C. Include the covariate columns with terms to make a model
that considers the covariates. Covariates are fit first, the blocks second, and then all other terms. You can
have up to 50 covariates.
260
Minitab Statistical Software DOE
LEVELS K K,..., K K
LEVELS C
Specifies the uncoded factor levels for each factor, with K for the low level and K for the high level, or in C.
For each factor, the list or column must contain two values. Use LEVELS to change the default order of levels
that Minitab uses. You can use a column only when all of the levels are continuous or all of the levels are
categorical.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
TERMS termlist
Specifies the terms to include in the model. Only continuous predictors can repeat in a single term. Nested
terms are not allowed. The model can be nonhierarchical.
Options
WEIGHTS C
Specifies a numeric column (C) that contains weights to use in weighted regression analysis. The same weights
are used for all responses. If different responses require different weights, then SCREEN will need to be run as
many times as there are different weights.
Usually, the weights are the reciprocal of the variances of the responses. The leverages stored by HI are affected
by weights.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
BOXCOX [K]
Transforms each variable or group to follow a normal distribution using the lambda value in K. K must be between
–5 and +5. If you do not specify K, then Minitab finds the optimal lambda. By default, Minitab rounds the optimal
value.
To use the exact lambda, change the setting in File > Options > Linear Models > Display of Results.
Minitab cannot calculate the optimal lambda for stepwise regression. So you must specify a lambda value for
BOXCOX if you use STEPWISE, FORWARD, or BACKWARD.
261
Minitab Statistical Software DOE
NOROUNDING
Specifies no rounding of calculated lambda parameter.
MEANS termlist
Calculates the least squares means for the terms that you specify in the termlist. You can use the following
commands to display and store the least squares means.
TMEANS
Displays the least squares means for the specified terms.
SMEANS
Stores the least squares means for the specified terms.
BSMEANS
If you transformed the data, stores the least squares means for the specified terms.
TOLERANCE K
Specifies the value in K above which Minitab removes highly correlated predictors and nearly constant predictors.
Requires that Minitab retain a factor in the model that is either highly correlated with a different factor or that is
almost constant. Lowering tolerance by giving very small argument values can prevent Minitab from eliminating
problematic predictor columns from the model.
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
Stepwise regression
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
262
Minitab Statistical Software DOE
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
263
Minitab Statistical Software DOE
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection. For forward selection, the alpha level is the level that follows AENTER. For
backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection. For forward selection, the alpha level is the level that follows AENTER. For
backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1 the confidence level that follows CONFIDENCE, unless you use stepwise selection. For forward
selection, the alpha level is the level that follows AENTER. For backward and stepwise selection, the alpha level is
the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. K can
only be 1 or 2. When K = 2, Minitab includes square terms as well as 2-factor interactions. If you specify a stepwise
method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
264
Minitab Statistical Software DOE
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
Results
The following subcommands specify what is displayed in the results.
NODEFAULT
Specifies that no default tables or graphs are displayed.
TEXPAND
Displays the expanded versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TSIMPLE
Displays the simple versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the settings in File > Options > Linear Models >
Stepwise.
265
Minitab Statistical Software DOE
FULL
Displays the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step of the
procedure.
NOFULL
Does not display the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step
of the procedure.
TEQUATION
Displays the regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model
is nonhierarchical, the equation is in coded units.
TCOEFFICIENT
Displays the table of coefficients. If you do not specify FULL or NOFULL, then Minitab uses the settings in File >
Options > Linear Models > Display of Results.
FULL
Displays the full set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
Displays the summary of model table, which includes the R
2
statistics and S. The expanded version of the table
includes the prediction sum of squares (PRESS), the corrected Akaike's Information Criterion (AICc) and the Bayesian
Information Criterion (BIC).
TANOVA
Displays the ANOVA table. The expanded version of the table includes the sequential sums of squares and the
percent contribution to the total sum of squares.
TDIAGNOSTICS [K]
Displays the table of diagnostics. The expanded version of the table includes the standard error of the fit, the
confidence interval for the fit, the deleted residual, the leverage, Cook's D, and DFITS.
Diagnostics that are displayedValue of K
Only for unusual observations0
For all observations1
TALIAS [K]
Displays the alias table up to order K. One line is displayed for each term in the model, with a list of all terms, up
to order K, that are aliased with the model term. If K is omitted, then Minitab uses the default rule of FFDESIGN:
all interactions for 2 to 6 factors, up to three-way interaction for 7 to 10 factors, and two-way interactions for
more than 10.
TMEANS
Displays the table of least squares means for all combinations of the factor levels that you specify in MEANS.
Storage
The following subcommands specify what is stored in the worksheet.
266
Minitab Statistical Software DOE
FITS C
Stores the fitted values.
RESIDUALS C
Stores the residuals (response fit) in C.
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals in C.
HI C
Stores the leverage values.
COOK C
Stores Cook's distance values, using one column for each response.
DFITS C
Stores DFITS (also called DFFITS), using one column for each response.
COEFFICIENTS C
Stores the coefficients that are included in the coefficients table in C.
The coefficients are based on coded levels (–1, 0, +1), not on the actual levels in the data set. A coefficient is
always half the value of the corresponding effect.
XMATRIX M
Stores the design matrix. The first column is a column of ones for the constant term. Next, there is one column
for each covariate. Next, if the design was blocked into k blocks, there are (k 1) columns. Next, there is one
column for each factor, using –1 for the low level, 0 for a center point, and +1 for the high level. Next, there is
one column for each interaction in the model. The column for an interaction is the product of all the columns that
correspond to the factors that are contained in that interaction.
If FFACTORIAL or VFACTORIAL removed some of the interactions that you specified in your model, the interactions
are not included in the stored design matrix. The columns in XMATRIX match the coefficients that are displayed
and stored.
BCRESP C
Stores the Box-Cox transformation of the response.
BFITS C
Stores the back-transformed fits after the Box-Cox transformation in C.
BSMEANS C
If you use a Box-Cox transformation, BSMEANS stores the means for the back-transformed response in C.
SMEANS C
Stores the least squares means from MEANS in C.
If you use a Box-Cox transformation, SMEANS stores the means for the transformed response in C.
267
Minitab Statistical Software DOE
BSCREEN: Session command for analyzing a screening design with
a binary response
Required commands
To perform the analysis, use the main command and at least these accompanying subcommands.
BSCREEN
Analyzes a screening design with a binary response.
Fits definitive screening and Plackett Burman models, which are produced by DSDESIGN on page 257 and PBDESIGN
on page 258. Each factor must have two levels. Also, you can have covariates and a blocking factor.
Specify interactions in the following way: C5*C6. For more information on specifying the model, go to How to
specify the model for factorial designs on page 1166.
This analysis provides diagnostic plots, goodness-of-fit tests, and other diagnostic measures so you can assess
the validity of your model. For more information, go to Generalized linear model diagnostics and residual analysis
on page 1177.
Minitab excludes all observations with missing values on either the response variable or any of the predictors
from all calculations.
RESPONSE C C
Enters the response data as a column that contains the number of events first and then a column that contains
the number of trials. The columns must have the same number of rows. For examples, go to Entering data
for response variables on page 1142.
FACTOR C...C
Specifies the factors in columns C...C. The columns must have the same number of rows as the response
columns.
TERMS termlist
Specifies the terms to include in the model. Only continuous predictors can repeat in a single term. Nested
terms are not allowed. The model can be nonhierarchical.
LEVELS K K,..., K K or LEVELS C
Specifies the uncoded factor levels for each factor. In a pair of levels, the first K is the low level and the second
K is the high level. In a pair of column rows, the first row is the low level and the second row is the high level.
For each factor, the list or column must contain two values. Use LEVELS to change the default order of levels
that Minitab uses. You can use a column only when all of the levels are continuous or all of the levels are
categorical.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
268
Minitab Statistical Software DOE
Optional subcommands
Use these subcommands and the subcommands in the following sections to change the default analysis.
EVNAME K
Specify the name of the event with K. Enclose text values in double quotation marks.
LOGIT
Use the logit link function.
NORMIT
Use the normit link function.
GOMPIT
Use the gompit link function. The gompit link function is also called the complementary log-log link function.
BLOCKS C
Specifies the column that contains the blocking information in C. Include the blocking column together with
TERMS to make a model that considers blocks.
COVARIATES C...C
Specifies columns that include covariates in C...C. Include the covariate columns with TERMS to make a model
that considers the covariates. Covariates are fit first, the blocks second, and then all other terms. You can have up
to 50 covariates.
Options subcommands
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
SEQDEVIANCE
Use sequential deviances for the tests of significance in the ANOVA table. The order of the terms in TERMS affects
the statistical significance. The default is to use adjusted deviances.
PEARSON
Specifies the use of Pearson residuals. The default is to use deviance residuals.
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
−1
(X' W Y)
269
Minitab Statistical Software DOE
HGROUP K
Specifies the number of groups for the Hosmer-Lemeshow goodness-of-fit test with K. The default is 10.
MEANS termlist
Calculates the fitted mean probability for the terms that you specify in the termlist. You can use the following
commands to display and store the probabilities.
TMEANS
Displays the fitted mean probability for the specified terms.
SMEANS C
Stores the fitted mean probability for the specified terms.
ITERATION K
Specifies the maximum number of iterations for the optimization algorithm that estimates the coefficients. The
default is 50.
TOLERANCE K
Specifies the value in K above which Minitab removes highly correlated predictors and nearly constant predictors.
By default, K = 1E-12.
The tolerance value determines when Minitab retains a factor in the model that is either highly correlated with a
different factor or that is almost constant. Lowering tolerance by giving very small argument values can prevent
Minitab from eliminating problematic predictor columns from the model.
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
CTOLERANCE K
Specifies the convergence criterion for the algorithm that estimates the coefficients. By default, K = 1E-8.
START C
Specifies a column that contains starting values for the coefficients in the optimization algorithm. The column
begins with the estimate of the constant, then follows the order of the model after TERMS.
Stepwise regression subcommands
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
270
Minitab Statistical Software DOE
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
271
Minitab Statistical Software DOE
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs subcommands
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
272
Minitab Statistical Software DOE
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is (1 the confidence level) that follows CONFIDENCE, unless you use stepwise selection that depends
on an alpha level. For forward selection, the alpha level is the level that follows AENTER. For backward and stepwise
selection, the alpha level is the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Displays residuals versus fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Displays the residuals versus the variables in C. Typically, you enter the columns for the predictors.
Results subcommands
NODEFAULT
Hides default tables and graphs that you do not include the subcommand to display.
TEXPAND
Displays the expanded versions of the tables that have them. The expanded Analysis of Variance table adds the
sequential deviances and percent contributions for each term. The Coefficients table adds confidence intervals
for the coefficients. The Fits and Diagnostics table adds the standard error of the fit, the 95% confidence interval
for the fit, the deleted residual, the HI, the Cook's D, and the DFITS.
TSIMPLE
Displays the simple versions of the Analysis of Variance table, the Coefficients table, and the Fits and Diagnostics
table.
TMETHOD
Displays a table of information about the method and options.
273
Minitab Statistical Software DOE
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the preferences that you set in File > Options > Linear
Models > Stepwise.
FULL
Specifies to display the coefficients, p-values, and model summary statistics for each step of the procedure.
NOFULL
Hides these statistics.
TRINFO
Displays the number of events, non-events, and the total. The table also indicates which response value is the
reference event.
TSTEP
Displays the deviance at each iteration of the coefficients.
TCOEFFICIENTS
Displays the coefficients and the p-values for the Wald normal approximation tests.
If you do not specify FULL or NOFULL, Minitab uses the preferences that you set in File > Options > Linear
Models > Display of Results.
FULL
Specifies to show the coefficients for the reference level when you use (0, 1) coding for categorical predictors.
NOFULL
Hides these statistics.
TODDS
Displays odds ratios for each continuous predictor and each level of the categorical predictors. The output does
not show odds ratios for predictors with interactions in the model.
INCREMENT K...K
Specifies the increment for the odds ratio for the predictor with K. For example, if the predictor is mass in
grams, enter 1000 to see the change in the odds ratio for a kilogram. Enter a value for each numeric factor
in the same order that the factors follow the FACTOR subcommand. Then, enter a value for each covariate
in the order that the covariates follow the COVARIATE subcommand. Enter 1 for a factor or covariate to use
the same units as the data.
TSUMMARY
Displays the statistics that evaluate model fit, including deviance R
2
.
TGOODNESS
Displays the Pearson and deviance goodness-of-fit tests. For the binomial distribution models, also shows the
Hosmer-Lemeshow goodness-of-fit test.
TDEVIANCE
Displays the ANOVA table.
TEQUATION
Displays the regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model
is nonhierarchical, the equation is in coded units.
274
Minitab Statistical Software DOE
TMEANS
Displays the table of fitted mean probabilities for all combinations of the factor levels that you specify in MEANS.
THOSMER
Displays the table of observed and expected values for the Hosmer-Lemeshow test.
TASSOCIATION
Displays the number of concordant and discordant pairs, the Somers' D, the Goodman-Kruskal Gamma, and
Kendall's Tau-a.
TDIAGNOSTICS [K]
Displays a table of diagnostics. K = 0 displays diagnostics for only observations with high leverage values or
standardized residuals greater than 2. K = 1 displays diagnostics for all observations.
TALIAS [K]
Displays the alias table up to order K. One line is displayed for each term in the model, with a list of all terms, up
to order K, that are aliased with the model term. If K is omitted, then Minitab uses the default rule of FFDESIGN:
all interactions for 2 to 6 factors, up to three-way interaction for 7 to 10 factors, and two-way interactions for
more than 10.
Storage subcommands
FITS C
Stores the event probabilities in C.
RESIDUALS C
Stores the deviance residuals by default in C. Stores the Pearson residuals if you use the subcommand PEARSON.
SRESIDUALS C
Stores the standardized deviance residuals by default in C. Stores the standardized Pearson residuals if you use
the subcommand PEARSON.
TRESIDUALS C
Stores the deleted deviance residuals by default in C. Stores the deleted Pearson residuals if you use the
subcommand PEARSON.
COOK C
Stores the Cook's distances in C.
DFITS C
Stores the DFITS in C.
HI C
Stores the leverages in C.
SADJUSTEDRESP C
Stores the final adjusted response values in C.
SIWEIGHTS C
Stores the internal weights used to estimate the model parameters in C.
SECOEFFICIENTS C
Stores the standard errors of the estimated coefficients in C.
275
Minitab Statistical Software DOE
COEFFICIENTS C
Stores the estimated coefficients in C.
EFFECTS C
Stores the effects that are included in the output in C.
Note Effects are not displayed or stored for the constant, covariates, or blocks.
SMEANS C
Stores the fitted mean probability for the specified terms in C.
DBETA C
Stores the change in the estimated regression coefficients (delta b) when you delete all observations with a
particular factor/covariate pattern in C. Use the delta b values to detect observations with a strong influence on
the coefficients.
DSBETA C
Stores the change in the estimated regression coefficients when you delete all observations with a particular
factor/covariate pattern based on the standardized Pearson residual in C.
DCHISQUARE C
Stores the change in the chi-square statistic when you delete all observations with a particular factor/covariate
pattern in C. Observations that are poorly fit by the model have high delta chi-square values.
DDEVIANCE C
Stores the change in the deviance when you delete all observations with a particular factor/covariate pattern in
C.
XMATRIX M
Stores the design matrix in M.
XPWXINVERSE M
Stores the X'WX inverse matrix of the estimated coefficients in M.
Plot Factorial Design
FACPLOT: Session command for creating a factorial plot
FACPLOT C
Displays factorial plots for the model associated with the response variable in the specified column To create this
graph, you need to specify a model. To produce an interaction plot, you must have two or more variables.
These plots can illustrate how a response variable relates to one or more variables. You can produce two types
of factorial plots.
Use a main effects plot to compare fitted means or data means across levels of one or more variables.
Use an interactions plot to assess the effects of one variable at levels of another variable. An interactions plot
displays the fitted means for a level of a variable with the level of a second variable held constant.
Although you can use these plots to display the effects, be sure to evaluate significance by looking at the effects
in the analysis of variance table.
276
Minitab Statistical Software DOE
FACTORS C...C
Specifies the variables to display in both the main effect and interaction plots. You must specify 2 or more
variables to generate an interaction plot.
GMAIN
GMAIN displays the main effect plot.
GINT
GINT displays the interactions plot.
FULL
Use FULL to display both interaction plots for each pair of categorical variables, such as Predictor 1 by
Predictor 2 and Predictor 2 by Predictor 1. Sometimes you can identify interactions more easily when
you examine both plots.
LOWER
Use LOWER to display one version of each interaction plot.
GMODEL (default)
GMODEL display plots for only terms that are in the model and listed in FACTORS. For purposes of a main
effect plot, a variable is in the model if the model includes any terms that involve only that variable, e.g. A,
A*A, or A*A*A. For purposes of an interaction plot, the interaction of two variables is in the model if the
model includes any terms that involve both variables, e.g. A*B, A*B*B.
GALL
GALL displays plots for all terms involving variables on the FACTORS subcommand.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
Factorial Designs
FDESIGN: Session command for creating a general full factorial
design
FDESIGN K...K
FDESIGN creates a general full factorial design. The values of K specify the number of levels of each factor. The
values of K must be integers that are greater than or equal to 2. The model generated is always full. To store your
design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces the obsolete
subcommands SORDER, PTTYPE, and XMATRIX.)
FDESIGN is similar to FFDESIGN, but FDESIGN has arbitrary levels and no fractional designs.
REPS K
Replicates each point K times. Specifies up to 50 replicates of each point. REPS does not replicate center
points.
277
Minitab Statistical Software DOE
The following example generates a full factorial that has 3 factors and 2 observations per cell. Thus, there
are a total of 48 runs in this experiment.
FDESIGN 4 3 2;
REPS 2.
BLOCK C
Specifies a blocking variable column (C). You can specify up to 64 blocks. The blocking variable column can
contain numeric data or text data, and can contain any value. The levels do not need to be in any special
order. When the blocking column is text, the first entry (row 1) is block 1, the next entry that is different is
block 2, and so on. When the blocking column is numeric, the smallest value is block 1, the second smallest
value is block 2, and so on. If you use BLOCK without REPS, Minitab stores a column of 1s.
RBLOCK
Specifies blocks on replicates. Each set of replicate points are placed in a separate block. No arguments are
taken.
LEVELS K K,..., K K
LEVELS C
Specifies factor levels for each factor.
Use LEVELS to specify values for the levels of each factor. The level values can be text or numeric. If you do
not use the subcommand, the levels are the integers 1, 2, 3, and so on.
With LEVELS K K, ..., K K, you can set levels to be text or numeric data. The arguments that define text data
must be enclosed in double quotation marks. List a pair of arguments for each factor. The first K is the low
level. The second K is the high level.
With LEVELS C, the level values must be numeric. Put the level values in a column, in the same order as if
they were listed on the subcommand. Then, specify the level column on the LEVELS subcommand.
RANDOMIZE [K]
Randomizes the runs in the design matrix. If you specify blocks, randomization is done separately within each
block and then the blocks are randomized. When you use RANDOMIZE, the standard order and the run order
are different and Minitab stores the design in run order.
The optional K is the base for the random number generator and can take any integer as an argument. To
get the same ordering of the rows, create the same design and randomize the runs with the same base. For
more information, go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
278
Minitab Statistical Software DOE
Output that is displayedValue of K
Minitab displays no output for the command, but performs all specified storage
and displays the following output: error messages, warnings, prompts, and notes.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
FFDESIGN: Session command for creating a full or fractional
factorial design
FFDESIGN K [K]
Creates a full or fractional factorial design with K factors and K number of runs. These designs are often referred
to as screening designs. If the second K is omitted and the first K is 7 or less, a full factorial design is generated.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, CTPT, and XMATRIX.)
Minitab has a catalog of designs. For a summary of the catalog, go to Designs generated by FFDESIGN on page
1141. The two constants (K) on FFDESIGN specify a design from that catalog. The first K is the number of factors,
and the second K is the number of runs. You can then use REPS to replicate points, FOLD the design, and add
center points (CPBLOCK). You may also ADD additional factors, provided the total number is at most 15.
The design generators, resolution, and alias structure are displayed. The design matrix is displayed under BRIEF
3. The defining relation is displayed under BRIEF 4. Factors are denoted by the letters A, B, C, D, E, F, G, H, J, K, L,
M, N, O, P on the output and in the subcommands BLOCKS, ADD, and FOLD.
Note The letter I is not used.
The alias structure that is displayed by default depends on the number of factors. You can use ALIAS to change
what is displayed.
What is displayedNumber of factors
All terms2–6
Up to three-way interactions7–10
Up to two-way interactions11–15
Quotation marks around column names are required. If you use a subcommand more than one time, FFDESIGN
uses the last instance of the subcommand.
REPS K
Replicates each point K times. Specifies up to 50 replicates of each point. REPS does not replicate center
points.
The following example generates a full factorial design that has 4 factors and 2 observations per cell. Thus,
there are a total of 32 runs in this experiment.
FFDESIGN 4 16;
REPS 2.
BLOCKS
Specifies the number of blocks in K, or specifies the terms to use as block generators in termlist.
279
Minitab Statistical Software DOE
If you use the subcommand ADD, you must also specify your own block generators. You cannot use an
integer with BLOCKS when you specify ADD. Minitab cannot determine good block generators in this case.
No extra text is allowed on the BLOCKS line, except after a #.
Blocking a design can reduce its resolution. Let r
1
= the resolution before blocking. Let r
2
= the length of the
shortest term that is confounded with blocks. Then the resolution after blocking is the smaller of r
1
and ( r
2
+ 1).
BLOCKS K
With BLOCKS K, you specify the number of blocks that you want, from 2 to 99. This number must evenly
divide the total number of runs, excluding center points (those given on FFDESIGN times those given
on REPS). Minitab then chooses an appropriate design.
If your design has replicates and you specify an integer on BLOCKS, then Minitab attempts to put
replicates in different blocks. The exact rule is a bit complicated.
BLOCKS termlist
With BLOCKS termlist, you specify terms to use as block generators.
The following example generates a 64 run design with 8 factors.
FFDESIGN 8 64;
BLOCKS ABC CDE.
The factors are labeled A, B, C, D, E, F, G, H. The block generators are ABC and CDE. This gives four blocks.
The blocks are numbered in standard order (also called Yates order). The blocks are as follows.
CDEABCBlock
1
+2
+3
++4
CPBLOCK K
Adds center points to the design.
Note CPBLOCK supersedes the CENTER subcommand.
CPBLOCK adds center points as follows:
When all factors are numeric, Minitab adds K center points as follows:
If the design is not blocked, then Minitab adds K center points to the design.
If the design is blocked, then Minitab adds K center points to each block.
When all factors are text, you cannot use CPBLOCK to add center points.
280
Minitab Statistical Software DOE
When factors are both numeric and text, the design does not have a true center. In this case, center points
are called pseudo-center points, and Minitab adds K center points as follows:
If the design is not blocked, then Minitab adds K center points for each combination of the levels of
the text factors.
If the design is blocked, then Minitab adds K center points for each combination of the levels of the
text factors to each block.
For example, consider an unblocked 2**3 design, factors A and C are numeric. Factor B is text that indicates
whether a catalyst is absent or present. The LEVELS subcommand assigns text data for the levels of factor
B.
FFDESIGN 3 8;
CPBLOCK 3;
BLOCKS 1;
LEVELS 0 10 "absent" "present" .2 .3
DESIGN.
Factor B has 2 levels: present or absent. With CPBLOCK 3, Minitab adds a total of 2 x 3 = 6 center points,
three points for the low level of factor B and 3 for the high level. The six points are as follows:
5 present .25
5 present .25
5 present .25
5 absent .25
5 absent .25
5 absent .25
Next, consider a blocked 2**5 design where 3 factors are text. There are 2 x 2 x 2 = 8 combinations of text
levels. If you use CPBLOCK 2 and BLOCKS 2, then Minitab adds 8 x 2 = 16 pseudo-center points to each
of the 2 blocks.
LEVELS
Use LEVELS to specify values for the levels of each factor. The level values can be text or numeric. The default
values are –1 for the low level, +1 for the high level, and 0 for a center point.
LEVELS K K, ..., K K
With LEVELS K K, ..., K K, you list one pair of arguments for each factor. The first K should be the low
level, and the second K should be the high level. When you add center points with CPBLOCK, Minitab
calculates the center points as the value that is half way between the low and high levels.
The following example stores 0 for the low level of A, 10 for the high level, and 5 for the center point;
100 for the low level of B, 102 for the high level, and 101 for the center point; .2 for the low level of C,
.3 for the high level, and 0.25 for the center point.
FFDESIGN 3 8;
CPBLOCK 2;
LEVELS 0 10 100 102 .2 .3;
BLOCKS 1;
DESIGN
281
Minitab Statistical Software DOE
With LEVELS K K, ..., K K, you can set levels to be text data. The arguments that define text data must be
enclosed in double quotation marks. For example, if factor B is whether a catalyst is present or absent,
you can use the following:
FFDESIGN 3 8;
CPBLOCK 2;
LEVELS 0 10 "absent" "present" .2 .3;
BLOCKS 1;
DESIGN.
Because you use CPBLOCK 2 to add center points with a text factor, Minitab creates pseudo-center
points. For more information, see the CPBLOCK subcommand.
LEVELS C
With LEVELS C, the level values must be numeric. Put the level values in a column, in the same order as
if they were listed on the subcommand. Then, specify the level column on the LEVELS subcommand.
FOLD [factor...factor]
Folds the design on the specified factors. If you don't include factors, Minitab folds the design on all factors.
The signs on the factors that you specify are switched. The signs on the remaining factors are not switched.
These rows for the non-specified factors are then appended to the end of the design matrix, which doubles
the number of runs.
Consider the following example.
FFDESIGN 3 4;
FOLD A.
First, Minitab generates a 3 factor design in 4 runs. The first 4 rows of the data matrix below are these runs.
Then, Minitab folds on factor A. This adds 4 additional runs.
CBA
+
+
+
+++
++
++
++
Folding is a way to reduce confounding. If you fold on one factor, say A, then A and all its two-factor
interactions are free from other main effects and two-factor interactions. If you fold on all factors, then all
main effects are free from all two-factor interactions.
When you fold, the defining relation is usually shortened. Specifically, any word in the defining relation that
has an odd number of the letters on which you folded the design is omitted. If you fold a design and the
defining relation is not shortened, then the folding adds replicates, but it does not reduce confounding. In
this case, Minitab displays an error message.
If you fold a design that is blocked, the same block generators are used for the folded design as for the
unfolded design.
282
Minitab Statistical Software DOE
FRACTION K
Specifies which fraction of a fractional design to use. The default fraction is called the principal fraction. This
is the fraction where all signs are positive. Consider the following example.
FFDESIGN 5 8;
FRACTION 3.
A full design with 5 factors requires 32 runs. With just 8 runs, a one-fourth fraction is used. You can use any
of the four possible fractions of the design. Minitab numbers them in standard order (also called Yates' order)
using the design generators, as follows.
E = –ACD = –AB1
E = –ACD = AB2
E = ACD = –AB3
E = ACD = AB4
The default fraction is called the principal fraction. This is the fraction where all signs are positive. FRACTION
3 specifies the third fraction. This is the one with design generators D = –AB, E = AC.
FRACTION applies to all the factors: the ones specified on the command line and any you added with ADD.
If you use both FRACTION and ADD, you cannot use minus signs in the design generators that are listed on
ADD. Actually, in this case, minus signs on ADD are not useful.
Sometimes a design contains points that are impractical to run. Choosing an appropriate fraction can avoid
these points. For example, suppose you could not run the design in the example with all five factors set at
their high level. The principal fraction contains this point, but the third fraction does not.
RANDOMIZE [K]
Randomizes the runs in the design matrix. If you specify blocks, randomization is done separately within each
block, and then the blocks are randomized. When you use RANDOMIZE, the standard order and the run
order are different and Minitab stores the design in run order.
K is the base for the random number generator and can take any positive integer as an argument. To always
get the same ordering of the rows, create the same design and randomize the runs with the same base. For
more information, go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, center point indicator, block assignment, and each factor
in separate columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in
a new worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output.
You can also use BRIEF as a main command. When you use BRIEF as a main command, it affects all other
commands that use BRIEF to control the amount of output.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays a summary of the design.1
283
Minitab Statistical Software DOE
Output that Minitab displaysValue of K
In addition to the K = 1 output, Minitab displays the alias table.2 (default)
In addition to the K = 2 output, Minitab displays the design table.3
In addition to the K = 3 output, Minitab displays the defining relation. If the design
is a full factorial, there is no defining relation, so K = 4 is equivalent to K = 3.
4
ALIAS K
Specifies the highest-order interaction to print in the alias table. For example, ALIAS 3 displays single factors,
and two- and three-way interactions.
Important A large K with a large number of factors might take a very long time to calculate.
ADD factor = term...factor = term
ADD is used primarily when you want to create custom designs rather than use a design in Minitab's catalog.
With ADD, you can add factors to a design by specifying the appropriate generators.
Consider the following example.
FFDESIGN 3 8;
ADD D=AB E=AC.
The example starts with three factors labeled A, B, and C. Then, factors D and E are added. D is confounded
with the AB interaction. E is confounded with the AC interaction. This gives a 2
(5–2)
design. You can also use
a minus interaction (for example, D = –AB). The added factors must be given in alphabetical order. The total
number of factors, those listed on FFDESIGN plus those listed on ADD, can be at most 15.
No extra text is allowed on the ADD line, except after a #.
If you use BLOCKS with ADD, you must specify your own block generators. You cannot use an integer with
BLOCKS when you specify ADD. Minitab cannot determine good block generators for a user-specified design.
SPDESIGN: Session command for creating a 2-level split-plot design
SPDESIGN K K
Creates 2-level split-plot designs, either full or fractional. In a split-plot experiment, levels of the hard-to-change
factor are held constant for several experimental runs. The experimental runs are collectively treated as a whole
plot. The easy-to-change factors are varied over these runs. Each combination of the factors is considered a
subplot. To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand
replaces the obsolete subcommands SORDER, PTTYPE, and XMATRIX.)
You can have 2-7 factors in a split-plot experiment. The number of hard-to-change factors that you can have
depends on the number of factors. For 2 factors, you can have only 1 hard-to-change factor. For 3 factors, you
can have 1 or 2 hard-to-change factors. For 4, 5, 6, or 7 factors, you can have 1, 2, or 3 hard-to-change factors.
You specify a full or fractional design with the PLOTS subcommand.
PLOTS K K
Specifies K whole plots with K subplots.
WREPLICATES K
Replicates the base design by multiplying the number of whole plots by K.
284
Minitab Statistical Software DOE
SREPLICATES K
Replicates the subplots within each whole plot K times.
RBLOCK
Specifies blocks on whole block replicates. Each replicate of the base design is placed in a separate block.
No arguments are taken.
LEVELS
Specifies the values for the levels of each factor. The level values can be text or numeric. The default values
are –1 for the low level and +1 for the high level.
The two ways to use LEVELS are as follows.
LEVELS K K, ..., K K
With LEVELS K K, ..., K K, you can set levels to be text or numeric data. The arguments that define text
data must be enclosed in double quotation marks. List a pair of arguments for each factor. The first K
should be the low level. The second K should be the high level.
In the following example, factor B is whether a catalyst is present or absent.
SPDESIGN 2 1;
PLOT 2 2;
WPREPLICATES 2;
RANDOMIZE;
ALIAS 2;
LEVELS 0 10 "absent" "present";
DESIGN.
LEVELS C
With LEVELS C, the level values must be all numeric or all text. First, put the level values in a column, in
the same order as if they were listed on the subcommand. Then, specify this column on the LEVELS
subcommand.
FRACTION K
Specifies which fraction of a fractional design to use with K. K must be a positive integer.
A full design that has 5 factors requires 32 runs. A full factorial design has no fractions, so no value of K is
legal. The legal values for a ½-fractional design are 1 and 2. The legal values for a ¼-fraction are 1, 2, 3, and
4. The following example is a design with 2 whole plots and 8 subplots, which makes a ½-fraction.
SPDESIGN 5 1;
PLOT 2 8;
FRACTION 2.
As in FFDESIGN, the fractions are numbered according to the signs that are used in the defining relation.
Defining relationFraction number
I ABCD - CDE + ABE1
I + ABCD CDE ABE2
I ABCD + CDE ABE3
I + ABCD + CDE + ABE4
The default fraction is called the principal fraction. This is the fraction for which all signs are positive in the
defining relation.
285
Minitab Statistical Software DOE
Sometimes a design contains points that are impractical to run. Choose an appropriate fraction to avoid
these points.
RANDOMIZE [K]
Randomizes the runs in the design matrix. If you specify blocks, randomization is done separately within each
block and then the blocks are randomized. When you use RANDOMIZE, the standard order and the run order
are different and Minitab stores the design in run order.
K is the base for the random number generator and can take any integer as an argument. To get the same
ordering of the rows, create the same design and randomize the runs with the same base. For more
information, go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that Minitab displaysValue of K
Minitab does not display output, but does complete all specified storage.0
Minitab displays a summary of the design.1
In addition to the K = 1 output, Minitab displays the alias table.2 (default)
In addition to the K = 2 output, Minitab displays the design table.3
In addition to the K = 3 output, Minitab displays the defining relation. If the design is
a full factorial, there is no defining relation, so K = 4 is equivalent to K = 3.
4
ALIAS K
Specifies the highest order interaction to display in the alias table. For example, ALIAS 3 displays single factors,
and 2- and 3-way interactions.
Important A large K along with a large number of factors might take a very long time to calculate.
PBDESIGN: Session command for creating a Plackett-Burman
design
PBDESIGN K [K]
Creates Plackett-Burman designs. Plackett-Burman designs are a class of resolution III, 2-level fractional factorial
designs that are often used to study main effects. In a resolution III design, main effects are aliased with 2-way
interactions.
The two constants on PBDESIGN specify a design. The first K is the number of factors. The second K is the number
of runs. Factor columns can be text or numeric.
286
Minitab Statistical Software DOE
To see the designs that Minitab generates, go to Plackett-Burman designs on page 1176. A design is based on the
number of runs, from 8 to 48 and always a multiple of 4. Therefore, the second K on PBDESIGN must be a multiple
of 4. The number of factors must be less than the number of runs. If you don't include the second K, Minitab sets
the number of runs to the smallest possible value for the specified number of factors.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTPYE, and XMATRIX.)
CENTER K
Adds up to 50 center points to the design. If the design is blocked, the center points are divided equally
between the blocks. If K is not a multiple of the number of blocks, then each of the last few blocks has one
less point than the other blocks.
REPS K
Specifies up to 50 replicates of each point. REPS does not replicate center points.
The following example generates a Plackett-Burman design that has 2 factors and 8 base runs. Thus, there
are a total of 16 runs in this experiment.
PBDESIGN 2 8;
REPS 2.
RBLOCK
Specifies blocks on replicates. Each set of replicate points are placed in a separate block. No arguments are
taken.
LEVELS
Use LEVELS to specify values for the levels of each factor. The level values can be text or numeric. The default
values are -1 for the low level, +1 for the high level, and 0 for a center point.
The two ways to use LEVELS are as follows.
LEVELS K K, ..., K K
With LEVELS K K, ..., K K, you list one pair of arguments for each factor. The first K should be the low
level and the second K should be the high level. When you add center points with CPBLOCK, Minitab
calculates the center points as the value that is half way between the low and high levels. The following
example stores 0 for the low level of A, 10 for the high level, and 5 for the center point. 100 for the low
level of B, 102 for the high level, and 101 for the center point; .2 for the low level of C, .3 for the high
level, and 2.5 for the center point.
PBDESIGN 2 8;
CENTER 2;
LEVELS 0 10 100 102;
DESIGN.
With LEVELS K K, ..., K K, you can set levels to be text data. The arguments that define text data must be
enclosed in double quotation marks. In the following example, factor B is whether a catalyst is present
or absent. Because you use CENTER 2 to add center points with a text factor, Minitab creates pseudo
center points.
PBDESIGN 2 8;
CENTER 2;
RBLOCK;
LEVELS 0 10 "absent" "present";
DESIGN.
287
Minitab Statistical Software DOE
LEVELS C
With LEVELS C, the level values must be numeric. Put the level values in a column, in the same order as
if they were listed on the subcommand. Then, specify the level column on the LEVELS subcommand.
RANDOMIZE [K]
Randomizes the runs in the design matrix. If you specify blocks, randomization is done separately within each
block and then the blocks are randomized. When you use RANDOMIZE, the standard order and the run order
are different and Minitab stores the design in run order.
K is the base for the random number generator and can take any integer as an argument. To get the same
ordering of the rows, create the same design and randomize the runs with the same base. For more
information, go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output for the command, but performs all specified storage
and displays the following output: error messages, warnings, prompts, and notes.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
FFACTORIAL: Session command for analyzing a full or fractional
factorial design
Analyzes a factorial design with a continuous response. Fits full and fractional factorial models, including those produced
by FFDESIGN on page 279 and PBDESIGN on page 258. Each factor must have two levels. Also, you can have covariates
and a blocking factor. The design does not have to be orthogonal. You can specify a single response. Specify interactions
in the following way: C5*C6. For more information on specifying the model, go to How to specify the model for factorial
designs on page 1166.
The factor columns can be numeric or text, and can contain any values. The levels do not need to be in any special
order. When you include center points in the model, Minitab tests for curvature.
You can display effects plots and residual plots. You can store the residuals, fitted values, and many other diagnostics
for further analysis. You can use extra text on the command and subcommand lines only after a #. Quotation marks
around column names that are one word long are optional.
For information about how Minitab calculates the model, go to Calculations for FFACTORIAL on page 1136.
288
Minitab Statistical Software DOE
For information about how Minitab handles missing data, go to Missing values in factorial, response surface, and
mixture designs on page 1171.
RESPONSE C
Specifies the column that contains the response variable in C. The column must be numeric or date/time.
FACTOR C...C (required)
Specifies the factors in columns C...C. The columns must have the same number of rows that the response column
has.
COVARIATES C...C
Specifies columns that include covariates in C...C. Include the covariate columns with terms to make a model that
considers the covariates. Covariates are fit first, the blocks second, and then all other terms. You can have up to
50 covariates.
BLOCKS C (optional)
Specifies the column that contains the blocking information in C. Include the blocking column together with
TERMS to make a model that considers blocks.
CTPT C
Specifies the column that identifies which design points are center points in C. Include the center point column
together with TERMS to make a model that tests for curvature.
TERMS termlist
Specifies the terms to include in the model. Only continuous predictors can repeat in a single term. Nested terms
are not allowed. The model can be nonhierarchical.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
LEVELS K K,..., K K
LEVELS C
Specifies the uncoded factor levels for each factor. In a pair of levels, the first K is the low level and the second K
is the high level. In a pair of column rows, the first row is the low level and the second row is the high level. For
each factor, the list or column must contain two values. Use LEVELS to change the default order of levels that
Minitab uses. You can use a column only when all of the levels are continuous or all of the levels are categorical.
Options
WEIGHTS C
Specifies a numeric column (C) that contains weights to use in weighted regression analysis. The same weights
are used for all responses. If different responses require different weights, then FFACTORIAL will need to be run
as many times as there are different weights.
Typically, the weights are the reciprocal of the variances of the responses. In this case, weights are based on the
fitted variances calculated and stored by VFACTORIAL. You can use other weight variables.
The leverages stored by HI are affected by weights.
289
Minitab Statistical Software DOE
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
BOXCOX [K]
Transforms each variable or group to follow a normal distribution using the lambda value in K. K must be between
–5 and +5. If you do not specify K, then Minitab finds the optimal lambda. By default, Minitab rounds the optimal
value.
To use the exact lambda, change the setting in File > Options > Linear Models > Display of Results.
Minitab cannot calculate the optimal lambda for stepwise regression. So you must specify a lambda value for
BOXCOX if you use STEPWISE, FORWARD, or BACKWARD.
MEANS termlist
Calculates the least squares means for the terms that you specify in the termlist. You can use the following
commands to display and store the least squares means.
TMEANS
Displays the least squares means for the specified terms.
SMEANS
Stores the least squares means for the specified terms.
BSMEANS
If you transformed the data, stores the least squares means for the specified terms.
TOLERANCE K
Specifies the value in K above which Minitab removes highly correlated predictors and nearly constant predictors.
By default, K = 1E-12.
The tolerance value determines when Minitab retains a factor in the model that is either highly correlated with a
different factor or that is almost constant. Lowering tolerance by giving very small argument values can prevent
Minitab from eliminating problematic predictor columns from the model.
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
290
Minitab Statistical Software DOE
Stepwise regression
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
291
Minitab Statistical Software DOE
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
292
Minitab Statistical Software DOE
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1 the confidence level that follows CONFIDENCE, unless you use stepwise selection that depends
on an alpha level. For forward selection, the alpha level is the level that follows AENTER. For backward and stepwise
selection, the alpha level is the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
293
Minitab Statistical Software DOE
Results
The following subcommands specify what is displayed in the results.
NODEFAULT
Specifies that no default tables or graphs are displayed.
TEXPAND
Displays the expanded versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TSIMPLE
Displays the simple versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the settings in File > Options > Linear Models >
Stepwise.
FULL
Displays the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step of the
procedure.
NOFULL
Does not display the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step
of the procedure.
TEQUATION
Displays the regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model
is nonhierarchical, the equation is in coded units.
TCOEFFICIENT
Displays the table of coefficients. If you do not specify FULL or NOFULL, then Minitab uses the settings in File >
Options > Linear Models > Display of Results.
FULL
Displays the full set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
Displays the summary of model table, which includes the R
2
statistics and S. The expanded version of the table
includes the prediction sum of squares (PRESS), the corrected Akaike's Information Criterion (AICc) and the Bayesian
Information Criterion (BIC).
TANOVA
Displays the ANOVA table. The expanded version of the table includes the sequential sums of squares and the
percent contribution to the total sum of squares.
TDIAGNOSTICS [K]
Displays the table of diagnostics. The expanded version of the table includes the standard error of the fit, the
confidence interval for the fit, the deleted residual, the leverage, Cook's D, and DFITS.
294
Minitab Statistical Software DOE
Diagnostics that are displayedValue of K
Only for unusual observations0
For all observations1
TALIAS [K]
Displays the alias table up to order K. One line is displayed for each term in the model, with a list of all terms, up
to order K, that are aliased with the model term. If K is omitted, then Minitab uses the default rule of FFDESIGN:
all interactions for 2 to 6 factors, up to three-way interaction for 7 to 10 factors, and two-way interactions for
more than 10.
TMEANS
Displays the table of least squares means for all combinations of the factor levels that you specify in MEANS.
Storage
The following subcommands specify what is stored in the worksheet.
FITS C
Stores the fitted values.
RESIDUALS C
Stores the residuals (response fit) in C.
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals in C.
HI C
Stores the leverage values.
COOK C
Stores Cook's distance values, using one column for each response.
DFITS C
Stores DFITS (also called DFFITS), using one column for each response.
EFFECTS C
Stores the effects that are included in the output in C.
Note Effects are not displayed or stored for the constant, covariates, or blocks.
COEFFICIENTS C
Stores the coefficients that are included in the coefficients table in C.
The coefficients are based on coded levels (–1, 0, +1), not on the actual levels in the data set. A coefficient is
always half the value of the corresponding effect.
XMATRIX M
Stores the design matrix. The first column is a column of ones for the constant term. Next, there is one column
for each covariate. Next, if the design was blocked into k blocks, there are (k 1) columns. Next, there is one
column for each factor, using –1 for the low level, 0 for a center point, and +1 for the high level. Next, there is
295
Minitab Statistical Software DOE
one column for each interaction in the model. The column for an interaction is the product of all the columns that
correspond to the factors that are contained in that interaction.
If FFACTORIAL or VFACTORIAL removed some of the interactions that you specified in your model, the interactions
are not included in the stored design matrix. The columns in XMATRIX match the coefficients that are displayed
and stored.
BCRESP C
Stores the Box-Cox transformation of the response.
BFITS C
Stores the back-transformed fits after the Box-Cox transformation in C.
BSMEANS C
If you use a Box-Cox transformation, BSMEANS stores the means for the back-transformed response in C.
SMEANS C
Stores the least squares means from MEANS in C.
If you use a Box-Cox transformation, SMEANS stores the means for the transformed response in C.
BFFACTORIAL: Session command for analyzing a full or fractional
factorial design with a binary response
Required commands
To perform the analysis, use the main command and at least these accompanying subcommands.
BFFACTORIAL
Analyzes a factorial design with a binary response. Fits full and fractional factorial models, including those produced
by FFDESIGN on page 279 and PBDESIGN on page 258. Each factor must have two levels. Also, you can have
covariates and a blocking factor. The design does not have to be orthogonal. You can specify a single response.
Specify interactions in the following way: C5*C6. When you include center points in the model, Minitab tests for
curvature. For more information on specifying the model, go to How to specify the model for factorial designs
on page 1166.
This analysis provides diagnostic plots, goodness-of-fit tests, and other diagnostic measures so you can assess
the validity of your model. For more information, go to Generalized linear model diagnostics and residual analysis
on page 1177.
Minitab excludes all observations with missing values on either the response variable or any of the predictors
from all calculations.
RESPONSE C C
Enters the response data as a column that contains the number of events first and then a column that contains
the number of trials. The columns must have the same number of rows.For examples, go to Entering data
for response variables on page 1142.
FACTOR C...C
Specifies the factors in columns C...C. The columns must have the same number of rows as the response
columns.
296
Minitab Statistical Software DOE
TERMS termlist
Specifies the terms to include in the model. Only continuous predictors can repeat in a single term. Nested
terms are not allowed. The model can be nonhierarchical.
LEVELS K K,..., K K or LEVELS C
Specifies the uncoded factor levels for each factor. In a pair of levels, the first K is the low level and the second
K is the high level. In a pair of column rows, the first row is the low level and the second row is the high level.
For each factor, the list or column must contain two values. Use LEVELS to change the default order of levels
that Minitab uses. You can use a column only when all of the levels are continuous or all of the levels are
categorical.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
Optional subcommands
Use these subcommands and the subcommands in the following sections to change the default analysis.
EVNAME K
Specify the name of the event with K. Enclose text values in double quotation marks.
LOGIT
Use the logit link function.
NORMIT
Use the normit link function.
GOMPIT
Use the gompit link function. The gompit link function is also called the complementary log-log link function.
BLOCKS C
Specifies the column that contains the blocking information in C. Include the blocking column together with
TERMS to make a model that considers blocks.
COVARIATES C...C
Specifies columns that include covariates in C...C. Include the covariate columns with TERMS to make a model
that considers the covariates. Covariates are fit first, the blocks second, and then all other terms. You can have up
to 50 covariates.
CTPT C
Specifies the column that identifies which design points are center points in C. Include the center point column
together with TERMS to make a model that tests for curvature.
297
Minitab Statistical Software DOE
Options subcommands
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
SEQDEVIANCE
Use sequential deviances for the tests of significance in the ANOVA table. The order of the terms in TERMS affects
the statistical significance. The default is to use adjusted deviances.
PEARSON
Specifies the use of Pearson residuals. The default is to use deviance residuals.
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
−1
(X' W Y)
HGROUP K
Specifies the number of groups for the Hosmer-Lemeshow goodness-of-fit test with K. The default is 10.
MEANS termlist
Calculates the fitted mean probability for the terms that you specify in the termlist. You can use the following
commands to display and store the probabilities.
TMEANS
Displays the fitted mean probability for the specified terms.
SMEANS C
Stores the fitted mean probability for the specified terms.
ITERATION K
Specifies the maximum number of iterations for the optimization algorithm that estimates the coefficients. The
default is 50.
TOLERANCE K
Specifies the value in K above which Minitab removes highly correlated predictors and nearly constant predictors.
By default, K = 1E-12.
The tolerance value determines when Minitab retains a factor in the model that is either highly correlated with a
different factor or that is almost constant. Lowering tolerance by giving very small argument values can prevent
Minitab from eliminating problematic predictor columns from the model.
298
Minitab Statistical Software DOE
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
CTOLERANCE K
Specifies the convergence criterion for the algorithm that estimates the coefficients. By default, K = 1E-8.
START C
Specifies a column that contains starting values for the coefficients in the optimization algorithm. The column
begins with the estimate of the constant, then follows the order of the model after TERMS.
Stepwise regression subcommands
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
299
Minitab Statistical Software DOE
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
300
Minitab Statistical Software DOE
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs subcommands
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is (1 the confidence level) that follows CONFIDENCE, unless you use stepwise selection that depends
on an alpha level. For forward selection, the alpha level is the level that follows AENTER. For backward and stepwise
selection, the alpha level is the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
301
Minitab Statistical Software DOE
GFITS
Displays residuals versus fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Displays the residuals versus the variables in C. Typically, you enter the columns for the predictors.
Results subcommands
NODEFAULT
Hides default tables and graphs that you do not include the subcommand to display.
TEXPAND
Displays the expanded versions of the tables that have them. The expanded Analysis of Variance table adds the
sequential deviances and percent contributions for each term. The Coefficients table adds confidence intervals
for the coefficients. The Fits and Diagnostics table adds the standard error of the fit, the 95% confidence interval
for the fit, the deleted residual, the HI, the Cook's D, and the DFITS.
TSIMPLE
Displays the simple versions of the Analysis of Variance table, the Coefficients table, and the Fits and Diagnostics
table.
TMETHOD
Displays a table of information about the method and options.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the preferences that you set in File > Options > Linear
Models > Stepwise.
FULL
Specifies to display the coefficients, p-values, and model summary statistics for each step of the procedure.
NOFULL
Hides these statistics.
TRINFO
Displays the number of events, non-events, and the total. The table also indicates which response value is the
reference event.
TSTEP
Displays the deviance at each iteration of the coefficients.
TCOEFFICIENTS
Displays the coefficients and the p-values for the Wald normal approximation tests.
302
Minitab Statistical Software DOE
If you do not specify FULL or NOFULL, Minitab uses the preferences that you set in File > Options > Linear
Models > Display of Results.
FULL
Specifies to show the coefficients for the reference level when you use (0, 1) coding for categorical predictors.
NOFULL
Hides these statistics.
TODDS
Displays odds ratios for each continuous predictor and each level of the categorical predictors. The output does
not show odds ratios for predictors with interactions in the model.
INCREMENT K...K
Specifies the increment for the odds ratio for the predictor with K. For example, if the predictor is mass in
grams, enter 1000 to see the change in the odds ratio for a kilogram. Enter a value for each numeric factor
in the same order that the factors follow the FACTOR subcommand. Then, enter a value for each covariate
in the order that the covariates follow the COVARIATE subcommand. Enter 1 for a factor or covariate to use
the same units as the data.
TSUMMARY
Displays the statistics that evaluate model fit, including deviance R
2
.
TGOODNESS
Displays the Pearson and deviance goodness-of-fit tests. For the binomial distribution models, also shows the
Hosmer-Lemeshow goodness-of-fit test.
TDEVIANCE
Displays the ANOVA table.
TEQUATION
Displays the regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model
is nonhierarchical, the equation is in coded units.
TMEANS
Displays the table of fitted mean probabilities for all combinations of the factor levels that you specify in MEANS.
THOSMER
Displays the table of observed and expected values for the Hosmer-Lemeshow test.
TASSOCIATION
Displays the number of concordant and discordant pairs, the Somers' D, the Goodman-Kruskal Gamma, and
Kendall's Tau-a.
TDIAGNOSTICS [K]
Displays a table of diagnostics. K = 0 displays diagnostics for only observations with high leverage values or
standardized residuals greater than 2. K = 1 displays diagnostics for all observations.
TALIAS [K]
Displays the alias table up to order K. One line is displayed for each term in the model, with a list of all terms, up
to order K, that are aliased with the model term. If K is omitted, then Minitab uses the default rule of FFDESIGN:
all interactions for 2 to 6 factors, up to three-way interaction for 7 to 10 factors, and two-way interactions for
more than 10.
303
Minitab Statistical Software DOE
Storage subcommands
FITS C
Stores the event probabilities in C.
RESIDUALS C
Stores the deviance residuals by default in C. Stores the Pearson residuals if you use the subcommand PEARSON.
SRESIDUALS C
Stores the standardized deviance residuals by default in C. Stores the standardized Pearson residuals if you use
the subcommand PEARSON.
TRESIDUALS C
Stores the deleted deviance residuals by default in C. Stores the deleted Pearson residuals if you use the
subcommand PEARSON.
COOK C
Stores the Cook's distances in C.
DFITS C
Stores the DFITS in C.
HI C
Stores the leverages in C.
SADJUSTEDRESP C
Stores the final adjusted response values in C.
SIWEIGHTS C
Stores the internal weights used to estimate the model parameters in C.
SECOEFFICIENTS C
Stores the standard errors of the estimated coefficients in C.
COEFFICIENTS C
Stores the estimated coefficients in C.
EFFECTS C
Stores the effects that are included in the output in C.
Note Effects are not displayed or stored for the constant, covariates, or blocks.
SMEANS C
Stores the fitted mean probability for the specified terms in C.
DBETA C
Stores the change in the estimated regression coefficients (delta b) when you delete all observations with a
particular factor/covariate pattern in C. Use the delta b values to detect observations with a strong influence on
the coefficients.
DSBETA C
Stores the change in the estimated regression coefficients when you delete all observations with a particular
factor/covariate pattern based on the standardized Pearson residual in C.
304
Minitab Statistical Software DOE
DCHISQUARE C
Stores the change in the chi-square statistic when you delete all observations with a particular factor/covariate
pattern in C. Observations that are poorly fit by the model have high delta chi-square values.
DDEVIANCE C
Stores the change in the deviance when you delete all observations with a particular factor/covariate pattern in
C.
XMATRIX M
Stores the design matrix in M.
XPWXINVERSE M
Stores the X'WX inverse matrix of the estimated coefficients in M.
GFACTORIAL: Session command for fitting a general full factorial
design
GFACTORIAL
Analyzes a general factorial design that can have categorical predictors and continuous covariates using least
squares regression.
Fits general full factorial models, including those produced by FDESIGN on page 277. In addition, you can have
covariates and a blocking factor.
For general full factorial designs, you specify the number of factors and the levels of each factor. You can have
arbitrary levels but no fractional designs.
The design does not have to be orthogonal. You can specify up to 25 responses and have 2 to 15 factors. Each
factor must have at least 2 levels and at most 100 levels. The number of levels can be different for each factor.
Specify interactions in the following way: C5*C6. For more information on specifying the model, go to How to
specify the model for factorial designs on page 1166.
Optionally, you can store the residuals, fitted values, and many other diagnostics for further analysis.
You can use extra text on the command and subcommand lines only after a #. Quotation marks around column
names are optional.
For information about how Minitab calculates the model, go to Calculations for FFACTORIAL on page 1136.
For information on how Minitab handles missing data, go to Missing values in factorial, response surface, and
mixture designs on page 1171.
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
BLOCKS C (optional)
Specifies the column that contains the blocking information. Include the blocking column together with
TERMS to make a model that considers blocks.
FACTOR C...C
Specifies the categorical factors, if you have any. The columns can be numeric, text, or date/time. The columns
must have the same number of rows as the response column.
305
Minitab Statistical Software DOE
NLEVELS K...K
Use both NLEVELS and LEVELS when the factor levels in the worksheet are coded and you want to display
uncoded levels in the results.
NLEVELS specifies the number of levels for each factor. Each K must be an integer from 2 to 100. You must
specify the same number of K arguments as the number of columns that you specify in FACTOR.
LEVELS E...E
Use both NLEVELS and LEVELS when the factor levels in the worksheet are coded and you want to display
uncoded levels in the results.
LEVELS specifies the uncoded values for all the factor levels. You must specify the same number of values
for LEVELS as the number of arguments that you specify for NLEVELS. The group of values for each factor
must be of the same type.
COVARIATES C...C
Specifies which columns of variables are continuous. Include the covariate columns with terms to make a
model that considers the covariates. Covariates are fit first, then the blocks, then all other terms. You can
have up to 50 covariates.
TERMS termlist
Specifies the terms to include in the model. Terms can contain a maximum of two factors. Only continuous
predictors can be repeated. Nested terms are not allowed. If terms are to be fitted, they must contain the
blocks. The model can be nonhierarchical.
Options
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by the following:
(X' W X)
–1
(X' W Y)
This is equivalent to minimizing the weighted SS Error as follows:
Σ w
i
(Y )
2
where w
i
is the weight in row i
The prediction interval that is calculated by PREDICT assumes a weight of 1. If you use the WEIGHT subcommand
with values other than 1, you should adjust the prediction interval values manually.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
306
Minitab Statistical Software DOE
TOLER K
Specifies the tolerance level for collinearity and constant check. By default, K = 1E–12.
Box-Cox
BOXCOX [K]
Transforms each variable or group to follow a normal distribution using the lambda value in K. K must be between
–5 and +5. If you do not specify K, then Minitab finds the optimal lambda. By default, Minitab rounds the optimal
value.
To use the exact lambda, change the setting in File > Options > Linear Models > Display of Results.
Minitab cannot calculate the optimal lambda for stepwise regression. So you must specify a lambda value for
BOXCOX if you use STEPWISE, FORWARD, or BACKWARD.
Means
MEANS termlist
Calculates least squares means for the specified terms. You can use the following commands to display and store
the least squares means.
TMEANS
Displays the calculated least squares means for the specified terms.
SMEANS
Stores the calculated least squares means for the specified terms.
BSMEANS
If you transformed the data, stores the calculated least squares means for the specified terms.
Stepwise
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
307
Minitab Statistical Software DOE
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
308
Minitab Statistical Software DOE
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1 the confidence level that follows CONFIDENCE, unless you use stepwise selection that depends
on an alpha level. For forward selection, the alpha level is the level that follows AENTER. For backward and stepwise
selection, the alpha level is the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
309
Minitab Statistical Software DOE
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
Results
The following subcommands specify what is displayed in the results.
NODEFAULT
Specifies that no default tables or graphs are displayed.
TEXPAND
Displays the expanded versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TSIMPLE
Displays the simple versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the settings in File > Options > Linear Models >
Stepwise.
FULL
Displays the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step of the
procedure.
NOFULL
Does not display the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step
of the procedure.
TFACTOR
Displays information about the factors.
TEQUATION
Displays the regression equation table.
310
Minitab Statistical Software DOE
TCOEFFICIENT
Displays the table of coefficients. If you do not specify FULL or NOFULL, then Minitab uses the settings in File >
Options > Linear Models > Display of Results.
FULL
Displays the full set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
Displays the summary of model table, which includes the R
2
statistics and S. The expanded version of the table
includes the prediction sum of squares (PRESS), the corrected Akaike's Information Criterion (AICc) and the Bayesian
Information Criterion (BIC).
TANOVA
Displays the ANOVA table. The expanded version of the table includes the sequential sums of squares and the
percent contribution to the total sum of squares.
TDIAGNOSTICS [K]
Displays a table of diagnostics. The expanded version of the table includes the standard error of the fit, the
confidence interval for the fit, the deleted residual, the leverage, the Cook's D, and the DFITS.
Diagnostics that are displayedValue of K
Diagnostics only for unusual observations0
Diagnostics for all observations1
TMEANS
Displays the least squares means for all combinations of the factor levels that you specify in MEANS.
Storage
The following subcommands specify what is stored in the worksheet.
BCRESP C
Stores the Box-Cox transformation of the response.
BFITS C
Stores the fits for the original response.
FITS C
Stores the fitted values.
SMEANS C
Stores the least squares means for all combinations of factor levels that you specified in MEANS, in C.
BSMEANS C
Stores the least squares means for the original response, if the data were transformed. Stores all combinations
of factor levels that you specified in MEANS, in C.
RESIDUALS C
Stores the residuals (fitted values observed values).
311
Minitab Statistical Software DOE
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals in C.
HI C
Stores the leverage values.
COOK C
Stores the Cook's distance values, using one column for each response, in C.
DFITS C
Stores the DFITS (also called DFFITS), using one column for each response, in C.
COEFFICIENTS C
Stores the estimated coefficients.
XMATRIX M
Stores the design matrix for the regression model in M.
BGFACTORIAL: Session command for analyzing a general full
factorial design with a binary response.
Required commands
To perform the analysis, use the main command and at least these accompanying subcommands.
BGFACTORIAL
Analyzes a general factorial design that can have categorical predictors and continuous covariates with a binary
response.
Fits general full factorial models, including those produced by FDESIGN on page 277. In addition, you can have
covariates and a blocking factor.
For general full factorial designs, you specify the number of factors and the levels of each factor. You can have
arbitrary levels but no fractional designs.
The design does not have to be orthogonal. You can specify up to 25 responses and have 2 to 15 factors. Each
factor must have at least 2 levels and at most 100 levels. The number of levels can be different for each factor.
Specify interactions in the following way: C5*C6. For more information on specifying the model, go to How to
specify the model for factorial designs on page 1166.
This analysis provides diagnostic plots, goodness-of-fit tests, and other diagnostic measures so you can assess
the validity of your model. For more information, go to Generalized linear model diagnostics and residual analysis
on page 1177.
Minitab excludes all observations with missing values on either the response variable or any of the predictors
from all calculations.
312
Minitab Statistical Software DOE
RESPONSE C C
Enters the response data as a column that contains the number of events first and then a column that contains
the number of trials. The columns must have the same number of rows.For examples, go to Entering data
for response variables on page 1142.
FACTOR C...C
Specifies the factors in columns C...C. The columns must have the same number of rows as the response
columns.
TERMS termlist
Specifies the terms to include in the model. Only continuous predictors can repeat in a single term. Nested
terms are not allowed. The model can be nonhierarchical.
Optional subcommands
Use these subcommands and the subcommands in the following sections to change the default analysis.
EVNAME K
Specify the name of the event with K. Enclose text values in double quotation marks.
LOGIT
Use the logit link function.
NORMIT
Use the normit link function.
GOMPIT
Use the gompit link function. The gompit link function is also called the complementary log-log link function.
BLOCKS C
Specifies the column that contains the blocking information in C. Include the blocking column together with
TERMS to make a model that considers blocks.
COVARIATES C...C
Specifies columns that include covariates in C...C. Include the covariate columns with TERMS to make a model
that considers the covariates. Covariates are fit first, the blocks second, and then all other terms. You can have up
to 50 covariates.
NLEVELS K...K
Use both NLEVELS and LEVELS when the factor levels in the worksheet are coded and you want to display uncoded
levels in the results.
NLEVELS specifies the number of levels for each factor. Each K must be an integer from 2 to 100. You must specify
the same number of K arguments as the number of columns that you specify in FACTOR.
LEVELS E...E
Use both NLEVELS and LEVELS when the factor levels in the worksheet are coded and you want to display uncoded
levels in the results.
LEVELS specifies the uncoded values for all the factor levels. You must specify the same number of values for
LEVELS as the number of arguments that you specify for NLEVELS. The group of values for each factor must be
of the same type.
313
Minitab Statistical Software DOE
Options subcommands
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
SEQDEVIANCE
Use sequential deviances for the tests of significance in the ANOVA table. The order of the terms in TERMS affects
the statistical significance. The default is to use adjusted deviances.
PEARSON
Specifies the use of Pearson residuals. The default is to use deviance residuals.
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
−1
(X' W Y)
HGROUP K
Specifies the number of groups for the Hosmer-Lemeshow goodness-of-fit test with K. The default is 10.
MEANS termlist
Calculates the fitted mean probability for the terms that you specify in the termlist. You can use the following
commands to display and store the probabilities.
TMEANS
Displays the fitted mean probability for the specified terms.
SMEANS C
Stores the fitted mean probability for the specified terms.
ITERATION K
Specifies the maximum number of iterations for the optimization algorithm that estimates the coefficients. The
default is 50.
TOLERANCE K
Specifies the value in K above which Minitab removes highly correlated predictors and nearly constant predictors.
By default, K = 1E-12.
The tolerance value determines when Minitab retains a factor in the model that is either highly correlated with a
different factor or that is almost constant. Lowering tolerance by giving very small argument values can prevent
Minitab from eliminating problematic predictor columns from the model.
314
Minitab Statistical Software DOE
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
CTOLERANCE K
Specifies the convergence criterion for the algorithm that estimates the coefficients. By default, K = 1E-8.
START C
Specifies a column that contains starting values for the coefficients in the optimization algorithm. The column
begins with the estimate of the constant, then follows the order of the model after TERMS.
Stepwise regression subcommands
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
315
Minitab Statistical Software DOE
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
316
Minitab Statistical Software DOE
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs subcommands
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is (1 the confidence level) that follows CONFIDENCE, unless you use stepwise selection that depends
on an alpha level. For forward selection, the alpha level is the level that follows AENTER. For backward and stepwise
selection, the alpha level is the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
317
Minitab Statistical Software DOE
GFITS
Displays residuals versus fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Displays the residuals versus the variables in C. Typically, you enter the columns for the predictors.
Results subcommands
NODEFAULT
Hides default tables and graphs that you do not include the subcommand to display.
TEXPAND
Displays the expanded versions of the tables that have them. The expanded Analysis of Variance table adds the
sequential deviances and percent contributions for each term. The Coefficients table adds confidence intervals
for the coefficients. The Fits and Diagnostics table adds the standard error of the fit, the 95% confidence interval
for the fit, the deleted residual, the HI, the Cook's D, and the DFITS.
TSIMPLE
Displays the simple versions of the Analysis of Variance table, the Coefficients table, and the Fits and Diagnostics
table.
TMETHOD
Displays a table of information about the method and options.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the preferences that you set in File > Options > Linear
Models > Stepwise.
FULL
Specifies to display the coefficients, p-values, and model summary statistics for each step of the procedure.
NOFULL
Hides these statistics.
TFACTOR
Displays information about the factors.
TRINFO
Displays the number of events, non-events, and the total. The table also indicates which response value is the
reference event.
TSTEP
Displays the deviance at each iteration of the coefficients.
318
Minitab Statistical Software DOE
TCOEFFICIENTS
Displays the coefficients and the p-values for the Wald normal approximation tests.
If you do not specify FULL or NOFULL, Minitab uses the preferences that you set in File > Options > Linear
Models > Display of Results.
FULL
Specifies to show the coefficients for the reference level when you use (0, 1) coding for categorical predictors.
NOFULL
Hides these statistics.
TODDS
Displays odds ratios for each continuous predictor and each level of the categorical predictors. The output does
not show odds ratios for predictors with interactions in the model.
INCREMENT K...K
Specifies the increment for the odds ratio for a covariate with K. For example, if the covariate is mass in grams,
enter 1000 to see the change in the odds ratio for a kilogram. Enter a value for each covariate in the order
that the covariates follow the COVARIATE subcommand. Enter 1 for a covariate to use the same units as the
data.
TSUMMARY
Displays the statistics that evaluate model fit, including deviance R
2
.
TGOODNESS
Displays the Pearson and deviance goodness-of-fit tests. For the binomial distribution models, also shows the
Hosmer-Lemeshow goodness-of-fit test.
TDEVIANCE
Displays the ANOVA table.
TEQUATION
Displays the regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model
is nonhierarchical, the equation is in coded units.
TMEANS
Displays the table of fitted mean probabilities for all combinations of the factor levels that you specify in MEANS.
THOSMER
Displays the table of observed and expected values for the Hosmer-Lemeshow test.
TASSOCIATION
Displays the number of concordant and discordant pairs, the Somers' D, the Goodman-Kruskal Gamma, and
Kendall's Tau-a.
TDIAGNOSTICS [K]
Displays a table of diagnostics. K = 0 displays diagnostics for only observations with high leverage values or
standardized residuals greater than 2. K = 1 displays diagnostics for all observations.
Storage subcommands
FITS C
Stores the event probabilities in C.
319
Minitab Statistical Software DOE
RESIDUALS C
Stores the deviance residuals in C by default. Stores the Pearson residuals if you use the subcommand PEARSON.
SRESIDUALS C
Stores the standardized deviance residuals in C by default. Stores the standardized Pearson residuals if you use
the subcommand PEARSON.
TRESIDUALS C
Stores the deleted deviance residuals in C by default. Stores the deleted Pearson residuals if you use the
subcommand PEARSON.
COOK C
Stores the Cook's distances in C.
DFITS C
Stores the DFITS in C.
HI C
Stores the leverages in C.
SADJUSTEDRESP C
Stores the final adjusted response values in C.
SIWEIGHTS C
Stores the internal weights used to estimate the model parameters in C.
SECOEFFICIENTS C
Stores the standard errors of the estimated coefficients in C.
COEFFICIENTS C
Stores the estimated coefficients in C.
SMEANS C
Stores the fitted mean probability for the specified terms in C.
DBETA C
Stores the change in the estimated regression coefficients (delta b) when you delete all observations with a
particular factor/covariate pattern in C. Use the delta b values to detect observations with a strong influence on
the coefficients.
DSBETA C
Stores the change in the estimated regression coefficients when you delete all observations with a particular
factor/covariate pattern based on the standardized Pearson residual in C.
DCHISQUARE C
Stores the change in the chi-square statistic when you delete all observations with a particular factor/covariate
pattern in C. Observations that are poorly fit by the model have high delta chi-square values.
DDEVIANCE C
Stores the change in the deviance when you delete all observations with a particular factor/covariate pattern in
C.
XMATRIX M
Stores the design matrix in M.
320
Minitab Statistical Software DOE
XPWXINVERSE M
Stores the X'WX inverse matrix of the estimated coefficients in M.
SPFACTORIAL: Session command for analyzing a 2-level split-plot
design
SPFACTORIAL
Analyzes a 2-level split-plot designs that is produced by SPDESIGN on page 284. In a split-plot experiment, levels
of the hard-to-change factor are held constant for several experimental runs, which are collectively treated as a
whole plot treatment. The easy-to-change factors are varied over these runs, each of which is considered a subplot
treatment.
Your split-plot design can include covariates and blocks. Specify interactions in the following way: C5*C6.
You can display effects plots (normal, half-normal, and Pareto) for either subplot effects only or subplot and whole
plot effects. You can also display residual plots. You can store the residuals, fitted values, and other diagnostics
for further analysis.
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
FACTOR C...C (required)
Specifies the column that contains the response variable. The column must be numeric or date/time.
HTCHANGE C...C
Specifies factors C...C as hard-to-change. These columns are a subset of the columns that follow FACTOR.
WPID C
Specifies the whole plot that each experimental run belongs in.
TERMS termlist
Specifies the model terms. Only continuous predictors can repeat in a single term. Nested terms are not
allowed. The model can be nonhierarchical.
BLOCKS C
Specifies the column that contains the blocking information (optional). Include the blocking column with
TERMS to make a model that considers blocks.
COVARIATES C...C
Specifies columns that include covariates. Include the covariate columns with terms to make a model that
considers the covariates. Covariates are fit first, the blocks second, and then all other terms. You can have
up to 50 covariates.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
321
Minitab Statistical Software DOE
LEVELS K K,..., K K
LEVELS C
Specifies the uncoded levels for the factors. For each factor, the list or column must contain two numerical
values. Use LEVELS to change the default order of levels that Minitab uses. You can use a column only when
all the levels are continuous or all of the levels are categorical.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
BOXCOX [K]
Performs a Box-Cox transformation with a specified lambda. K is the value of lambda and must be between –5
and +5. If K is not given, Minitab will find the optimal lambda. By default, Minitab rounds the optimal value. To
use the exact lambda, specify NOROUND.
Minitab cannot calculate the optimal lambda for stepwise regression. Consequently, you must specify a lambda
value for BOXCOX if you use STEPWISE, FORWARD, or BACKWARD.
NOROUND
Specifies to use the exact lambda.
MEANS termlist
Calculates least squares means for the specified terms. Use TMEANS to display these means. Use SMEANS to
store these means, or BSMEANS if you transformed the data.
TOLERANCE K
Requires that Minitab retain a factor in the model that is either highly correlated with a different factor or that is
almost constant. Lowering tolerance by giving very small argument values can prevent Minitab from eliminating
problematic predictor columns from the model.
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
K must be positive and less than 1. The default value is 8.88E-16.
322
Minitab Statistical Software DOE
Graphs
GEFFECTS
Displays a normal probability plot of the effects or standardized effects. Minitab labels the effects on the probability
plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE, unless
you use stepwise selection. For forward selection, the alpha level is the level that follows AENTER. For backward
and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection. For forward selection, the alpha level is the level that follows AENTER. For
backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1 the confidence level that follows CONFIDENCE, unless you use stepwise selection. For forward
selection, the alpha level is the level that follows AENTER. For backward and stepwise selection, the alpha level is
the level that follows AREMOVE.
GWHOLE
Specifies to show plots for whole plot effects that are in the model as well as subplot effects.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and displays the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram or an individual value plot of the residuals, depending on the sample size.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
323
Minitab Statistical Software DOE
GFOURPACK [C]
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals versus fitted
values, and residuals versus the order of the data, or versus the order specified in C.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column that.
Results
The following subcommands specify what is displayed in the results.
NODEFAULT
Specifies that no default tables or graphs are displayed.
TEXPAND
Displays the expanded versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TSIMPLE
Displays the simple versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TMETHOD
Displays the method table.
TEQUATION
The regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model is
nonhierarchical, the equation is in coded units.
TCOEFFICIENTS
Displays the table of coefficients.
FULL
Displays the full set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
The summary of model table, which includes the R
2
statistics and S. The expanded version of the table includes
the prediction sum of squares (PRESS).
TANOVA
The ANOVA table. The expanded version of the table includes the sequential sums of squares and the percent
contribution to the total sum of squares.
TDIAGNOSTICS [K]
A table of diagnostics. The expanded version of the table includes the standard error of the fit, the confidence
interval for the fit, the deleted residual, the leverage, the Cook's D, and the DFITS.
Diagnostics that are displayedValue of K
Diagnostics only for unusual observations0
Diagnostics for all observations1
324
Minitab Statistical Software DOE
TALIAS [K]
Displays alias information. One line is displayed for each term in the model, with a list of all terms, up to order K,
that are aliased with the model term. If K is omitted, Minitab uses the default rule of FFDESIGN: all interactions
for 2 to 6 factors, up to three-way interaction for 7 to 10 factors, and two-way interactions for more than 10.
Note A value of K that is larger than the default can take a long time to calculate.
TMEANS
The least squares means for all combinations of the factor levels that you specify in MEANS.
Storage
The following subcommands specify what is stored in the worksheet.
FITS C
Stores the fitted values.
BFITS
Stores the back-transformed fits after the Box-Cox transformation.
BCRESP C
Stores the Box-Cox transformation of the response.
RESIDUALS C
Stores the residuals (response fit)
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals.
WRESIDUALS C...C
Stores thole plot residuals.
EFFECTS C
Stores the effects that are included in the output.
Note Effects are not printed or stored for the constant, covariates, or blocks.
COEFFICIENTS C
Stores the coefficients that are included in the coefficients table.
The coefficients are based on coded levels (–1, 0, +1), not on the actual levels in the data set. A coefficient is
always half the value of the corresponding effect.
XMATRIX M
Stores the design matrix. The first column is a column of ones for the constant term. Next, there is one column
for each covariate. Next, if the design was blocked into k blocks, there are (k 1) columns. Next, there is one
column for each factor, using –1 for the low level, 0 for a center point, and +1 for the high level. Next, there is
one column for each interaction in the model. The column for an interaction is the product of all the columns that
correspond to the factors that are contained in that interaction.
325
Minitab Statistical Software DOE
If SPFACTORIAL removed some of the interactions that you specified in your model, those interactions do not
appear in the stored design matrix. The columns in XMATRIX match the coefficients that are displayed and stored.
WXMATRIX M
WXMATRIX is like XMATRIX, but it includes the whole plot error terms.
WCOEFFICIENTS C...C
Stores coefficients in C...C (including whole plot error terms).
HI C
Stores the leverage values that you use to identify influential observations.
SMEANS C
Stores the least squares means from MEANS in the specified column.
If you use a Box-Cox transformation, SMEANS stores the means for the transformed response.
BSMEANS C
If you use a Box-Cox transformation, BSMEANS stores the means for the back-transformed response.
VPREPROCESS: Session command to preprocess responses for
analyze variability
Note VPREPROCESS replaces the obsolete session command PREPROCESS.
VPREPROCESS
Use VPREPROCESS to calculate and store standard deviations and counts of repeat or replicate measurements
before you use VFACTORIAL on page 327 to analyze the variability of responses. Use one of the following
subcommands: REPEATS, REPLICATES, or DEFINE. Then use the sub-subcommands to specify how to preprocess
the data.
REPEATS
Specifies that repeats of the measurement are in the same row of different columns.
RESPONSE C...C
Specifies which columns contain the repeated measurements of the response variable.
STDEV C
Specifies where to store the standard deviations of the repeated measurements for analysis.
COUNT C
Specifies where to store the number of repeated measurements for analysis.
RMEAN C
Specifies where to store the mean of the repeated measurements for analysis.
REPLICATES
Specifies that replicated measurements of a response variable are in the same column.
RESPONSE C...C
Specifies which columns contain the replicated measurements of a response variable. Each column is a
separate response variable.
326
Minitab Statistical Software DOE
STDEV C...C
Specifies where to store the standard deviations of the replicate measurements for analysis. Enter a
column for each response variable.
COUNT C...C
Specifies where to store the number of replicated measurements for analysis. Enter a column for each
response variable.
COVARIATES C...C
Specifies covariates to adjust for in the calculation of the standard deviations.
DEFINE C...C
Specifies that standard deviations for analysis are already in the worksheet. Each column contains the standard
deviations for a different response variable.
COUNT E...E
Specifies the number of measurements for the standard deviation in each row. If the numbers of
measurements are all the same, enter the number or enter a column of constant values. If the numbers
of measurements vary, use a column to indicate the number for each row.
VFACTORIAL: Session command for analyzing variability in a 2-level
factorial design
VFACTORIAL
Analyzes variability in a 2-level factorial design, including those produced by FFDESIGN on page 279 and PBDESIGN
on page 258. You can specify covariates and a blocking factor. You can fit one response at a time. Before you use
VFACTORIAL, you must calculate and store standard deviations using PREPROCESS on page 326. Minitab uses
least squares estimation by default, but you can specify maximum likelihood estimation using MLE.
The factor columns can be numeric or text, and can contain any values. The levels do not need to be in any special
order. When the factor column is text, Minitab defines the low level as the level that is first using alphabetical
order. Change the order of the levels after the LEVELS subcommand to change this default ordering.
Optionally, you can display seven plots: a normal plot of the effects, a half normal plot of the effects, a Pareto
chart of the effects, and four different residual plots. In addition, you can store the residuals, fitted values, and
many other diagnostics for further analysis.
RESPONSE C
Specifies the column that contains the standard deviations.
COUNT E (required)
Specifies the constant or column that contains the number of repeat or replicate measurements. The columns
must have the same number of rows that the response column has.
FACTOR C (required)
Specifies the factors. The columns must have the same number of rows that the response column has.
BLOCKS C
Specifies the column that contains the blocking information (optional). A blocking variable column can be
numeric or text, and can contain any value. The levels do not need to be in any special order. When the
327
Minitab Statistical Software DOE
blocking column is numeric, the smallest value is block 1, the second smallest value is block 2, and so on.
Include the blocking column with TERMS to make a model that considers blocks.
CTPT C
Specifies the column that identifies which design points are center points. Include the center point column
with TERMS to make a model that tests for curvature.
TERMS C
Specifies the model terms. Only continuous predictors can repeat in a single term. Nested terms are not
allowed. The model can be nonhierarchical.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
LEVELS
Specifies the uncoded levels for the factors. For each factor, the list or column must contain two numerical
values. Use LEVELS to change the default order of levels that Minitab uses. You can use a column only when
all the levels are continuous or when all the levels are categorical.
MLE
Specifies maximum likelihood estimation. By default, Minitab uses least squares estimation to fit the model.
Covariates
COVARIATES C...C
Lists the covariates to include in the model. You can have up to 50 covariates.
Options
MLE
Specifies using maximum likelihood estimation to analyze the model. The default method is least squares estimation.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
328
Minitab Statistical Software DOE
MEANS termlist
Calculates least squares means for the specified terms. You can use the following commands to display and store
the least squares means. If the design is orthogonal and there are no covariates, each mean is the average of all
the observations in the corresponding cell. Use the same syntax and abbreviations on MEANS as you use in
specifying a model.
TMEANS
Displays the calculated least squares means for the specified terms.
SMEANS
Stores the calculated least squares means for the specified terms.
BSMEANS
If you transformed the data, stores the calculated least squares means for the specified terms.
TOLERANCE K
Requires that Minitab retain a factor in the model that is either highly correlated with a different factor or that is
almost constant. Lowering tolerance by giving very small argument values can prevent Minitab from eliminating
problematic predictor columns from the model.
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
K must be positive and less than 1. The default value is 8.88E-16.
Stepwise
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
Once Minitab fits the full model or a model that leaves 1 degree of freedom for error, the procedure stops. Minitab
displays the results of the analysis for the model with the minimum value of the selected information criterion,
either the corrected Akaike's Information Criterion (AICc) or the Bayesian Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
329
Minitab Statistical Software DOE
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
330
Minitab Statistical Software DOE
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs
GEFFECTS
Displays a normal probability plot of the effects or standardized effects. Minitab labels the effects on the probability
plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE, unless
you use stepwise selection. For forward selection, the alpha level is the level that follows AENTER. For backward
and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection. For forward selection, the alpha level is the level that follows AENTER. For
backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1 the confidence level that follows CONFIDENCE, unless you use stepwise selection. For forward
selection, the alpha level is the level that follows AENTER. For backward and stepwise selection, the alpha level is
the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
331
Minitab Statistical Software DOE
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
Results
The following subcommands specify what is displayed in the results.
NODEFAULT
Specifies that no default tables or graphs are displayed.
TEXPAND
Displays the expanded versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TSIMPLE
Displays the simple versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the settings in File > Options > Linear Models >
Stepwise.
FULL
Displays the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step of the
procedure.
NOFULL
Does not display the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step
of the procedure.
TEQUATION
The regression equation table. If the model is hierarchical, the equation is in uncoded units. If the model is
nonhierarchical, the equation is in coded units.
332
Minitab Statistical Software DOE
TCOEFFICIENT
Displays the table of coefficients. If you do not specify FULL or NOFULL, then Minitab uses the settings in File >
Options > Linear Models > Display of Results.
FULL
Displays the full set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
The summary of model table, which includes the R
2
statistics and S. The expanded version of the table includes
the prediction sum of squares (PRESS), the corrected Akaike's Information Criterion (AICc) and the Bayesian
Information Criterion (BIC).
TANOVA
The ANOVA table. The expanded version of the table includes the sequential sums of squares and the percent
contribution to the total sum of squares.
TDIAGNOSTICS [K]
Displays a table of diagnostics.
Diagnostics that are displayedValue of K
Diagnostics only for unusual observations0
Diagnostics for all observations1
If you do not specify K, then Minitab uses the settings in File > Options > Linear Models > Display of Results.
TALIAS [K]
Alias information. One line is printed for each term in the model, with a list of all terms, up to order K, that are
aliased with the model term. If K is omitted, Minitab uses the default rule of FFDESIGN: all interactions for 2 to 6
factors, up to 3-way interaction for 7 to 10 factors, and 2-way interactions for more than 10.
TMEANS
The least squares means for all combinations of the factor levels that you specify in MEANS.
Storage
The following subcommands specify what is stored in the worksheet.
LFITS C
Stores the fitted values for the natural log of the standard deviation.
RRESIDUALS C
Stores the ratio residual, which is the ratio of the response standard deviation to the fitted standard deviation.
LRESIDUALS C
Stores the log residual, which is the difference between the natural log of the response standard deviation and
the natural log of the fitted standard deviation.
SLRESIDUALS C
Stores the standardized log residual, which is the log residual divided by its (asymptotic) standard error.
333
Minitab Statistical Software DOE
EFFECTS C
Stores the effects that are included in the output.
Note Effects are not printed or stored for the constant, the covariates, or the blocks.
REFFECTS C
Stores the ratio effects.
COEFFICIENTS C
Stores the coefficients that are included in the coefficients table.
The coefficients are based on coded levels (–1, 0, +1), not on the actual levels in the data set. A coefficient is
always half the value of the corresponding effect.
XMATRIX M
Stores the design matrix.
HI C
Stores the leverage values.
COOK C
Stores Cook's distance.
DFITS C
Stores the DFITS (also called DFFITS) values.
LNRESP C
Stores the log of the standard deviations. This column is the response for the model.
BFITS
Stores the back-transformed fitted values for the standard deviations.
SMEANS C
Stores the means for terms that are specified in the MEANS subcommand in the specified columns.
BSMEANS C
If you use a Box-Cox transformation, BSMEANS stores the back-transformed means.
SWEIGHTS C
Stores the unadjusted weights based on the fitted variances to use when you analyze location effects with
FFACTORIAL.
SADJUSTED C
If your data contain repeats with some replicated points, SADJUSTED stores the adjusted weights.
RMEANS C
Specifies the row means that are associated with the row standard deviations used as the response.
ACOVARIATES C...C
Accounts for covariates in C...C in calculating adjusted weights.
334
Minitab Statistical Software DOE
Plot Factorial Design
FACPLOT: Session command for creating a factorial plot
FACPLOT C
Displays factorial plots for the model associated with the response variable in the specified column To create this
graph, you need to specify a model. To produce an interaction plot, you must have two or more variables.
These plots can illustrate how a response variable relates to one or more variables. You can produce two types
of factorial plots.
Use a main effects plot to compare fitted means or data means across levels of one or more variables.
Use an interactions plot to assess the effects of one variable at levels of another variable. An interactions plot
displays the fitted means for a level of a variable with the level of a second variable held constant.
Although you can use these plots to display the effects, be sure to evaluate significance by looking at the effects
in the analysis of variance table.
FACTORS C...C
Specifies the variables to display in both the main effect and interaction plots. You must specify 2 or more
variables to generate an interaction plot.
GMAIN
GMAIN displays the main effect plot.
GINT
GINT displays the interactions plot.
FULL
Use FULL to display both interaction plots for each pair of categorical variables, such as Predictor 1 by
Predictor 2 and Predictor 2 by Predictor 1. Sometimes you can identify interactions more easily when
you examine both plots.
LOWER
Use LOWER to display one version of each interaction plot.
GMODEL (default)
GMODEL display plots for only terms that are in the model and listed in FACTORS. For purposes of a main
effect plot, a variable is in the model if the model includes any terms that involve only that variable, e.g. A,
A*A, or A*A*A. For purposes of an interaction plot, the interaction of two variables is in the model if the
model includes any terms that involve both variables, e.g. A*B, A*B*B.
GALL
GALL displays plots for all terms involving variables on the FACTORS subcommand.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
MFFCUBE: Session command for creating a cube plot for fitted means
MFFCUBE C
Creates a cube plot of the fitted means for the response in C.
335
Minitab Statistical Software DOE
You can draw a cube plot for a model from a 2-level factorial design. The factor columns can be numeric or text,
and can contain any values. When the factor column is text, the first entry (row 1) is level 1, the next entry that is
different is level 2. All factors must have 2 levels, and can have center points.
To draw a cube plot of the data means or a cube plot of the process variables in a mixtures design, use FFCUBE
on page 340.
FACTORS C...C
Specifies the factors to include on the cube plot in C...C. You can specify 2–8 factors.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
FFINT: Superseded by FACPLOT except for mixture designs
Note FFINT is superseded by FACPLOT on page 276, except for mixture designs.
FFINT C...C
Creates interaction plots for factors in C...C.
Creates an interaction plot for 2-level factorial designs. If you enter 2 factors on the command line, then Minitab
displays a single interaction plot. If you enter more than 2 factors, then Minitab displays a matrix of interaction
plots. You can use factors from designs that are generated by FFDESIGN and PBDESIGN.
You can specify up to 15 columns that contain the factors. The factor columns can be numeric or text, and can
contain any values. The levels do not need to be in any special order. When the factor column is text, the first
entry (row 1) is level 1, the next entry that is different is level 2, and so on. All factors must have 2 levels, and can
have center points.
RESPONSE C (required)
Plots the response data in C. If you specify RESPONSE without FMEANS, then Minitab plots the raw response
data. The interaction effects are calculated based on the means of the data. If you plot process variables from
a mixture design, then Minitab fits only the raw response data, not the fitted means.
You can specify up to 15 factors.
FMEANS C...C
Plots the least squares or fitted means in C...C. If you specify RESPONSE with FMEANS, then Minitab plots
the predicted values from the model. The interaction effects are calculated based on the fitted means. If you
plot process variables from a mixture design, Minitab fits only the raw response data, not the fitted means.
FULL
Displays the full interaction matrix when you enter more than 2 factors. By default, Minitab displays the half
matrix. The half matrix displays the plots in the upper right portion of the matrix. In the full matrix, the
transpose of each plot in the upper right is displayed in the lower left portion of the matrix. The full matrix
takes longer to display than the half matrix.
YMIN K
Specifies the minimum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
336
Minitab Statistical Software DOE
YMAX K
Specifies the maximum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
CTPT C
Specifies the center point column in C. Minitab considers a value of 0 as a center point.
LEVELS K K, ..., K K
Specifies the levels for the uncoded units for each factor in K K, ..., K K. Use LEVELS to change the default
order of levels that Minitab uses.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
337
Minitab Statistical Software DOE
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
MIXTURE
Specifies a mixture design, which indicates that the factors are process variables.
FFMAIN: Superseded by FACPLOT except for mixture designs
Note FFMAIN is superseded by FACPLOT on page 276, except for mixture designs.
FFMAIN C...C
Creates a main effects plot for 2-level factorial designs, for factors in C...C.
FFMAIN plots the means at the two levels of each factor and connects them with a line. FFMAIN plots any center
points you have, using a different symbol than that used for the factorial points. A reference line is drawn through
the plot to represent the overall mean (also called grand mean) of the response data.
Specify up to 50 factors. The factor columns can be numeric or text, and can contain any values. The levels do not
need to be in any special order. When the factor column is text, the first entry (row 1) is level 1. The next entry
that is different is level 2. All factors must have 2 levels, and can have center points.
RESPONSE C (required)
Plots the response data in C. If you specify RESPONSE without FMEANS, then Minitab plots the raw response
data. The main effects are calculated based on the means of the data. If you plot process variables from a
mixture design, Minitab fits only the raw response data, not the fitted means.
With RESPONSE, you can specify up to 50 factors.
FMEANS C...C
Plots the least squares or fitted means in C...C. If you specify RESPONSE with FMEANS, then Minitab plots
the predicted values from the model. The main effects are calculated based on the fitted means. If you plot
process variables from a mixture design, Minitab fits only the raw response data, not the fitted means.
With FMEANS, you can specify up to 10 factors.
YMIN K
Specifies the minimum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
YMAX K
Specifies the maximum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
338
Minitab Statistical Software DOE
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
CTPT K
Specifies the center point column in K. Minitab considers a value of 0 as a center point.
LEVELS K K, ..., K K
Specifies the levels for the uncoded units for each factor in K K, ..., K K. Use LEVELS to change the default
order of levels that Minitab uses.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
339
Minitab Statistical Software DOE
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
MIXTURE
Specifies a mixture design, which indicates that the factors are process variables.
FFCUBE: Session command for creating a cube plot
FFCUBE C...C
Use FFCUBE to draw a cube plot that does not show mean response values. With a mixture design, you can use
FFCUBE to draw a cube plot that shows mean response values. For all other models, such as the models from
FFAC or REGR, use MFFCUBE on page 335 to draw a cube plot that shows mean response values.
Displays a cube plot for factors in C...C. You can draw a cube plot with 2–8 factors for each response entered with
the RESPONSE subcommand with data means or 2–7 factors with fitted means. The factor columns can be numeric
or text, and can contain any values. The levels do not need to be in any special order. When the factor column is
text, the first entry (row 1) is level 1, the next entry that is different is level 2, and so on. All factors must have 2
levels, and can have center points.
When you use the RESPONSE subcommand, FFCUBE displays the means for the response at each point in the
cube where observations are measured. When you do not use the RESPONSE subcommand, FFCUBE draws points
on the cube for the effects that are in your model, which helps you visualize the design.
RESPONSE C...C
Plots the raw response data that is in columns C...C. The means for the cube points are calculated from the
data. You can specify 2–8 factors.
If you use FMEANS, RESPONSE is required.
FMEANS C...C
Plots the least squares or the fitted means that are in columns C...C. You can specify 2-7 factors. The column
must contain the fitted means in standard order for the cube points. The last row must be the overall mean
of the data.
If you use FMEANS, RESPONSE is required.
INUNIT K (required)
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded form0
Uncoded form1
CTPT C
Specifies a center point column in C. Minitab considers a value of 0 to be a center point. A valid column
contains only values of 0 and 1.
340
Minitab Statistical Software DOE
If you don't use MIXTURE, CTPT is required. You cannot use both MIXTURE and CTPT.
LEVELS K K, ..., K K (required)
Specifies the levels for the uncoded units for each factor in K K, ..., K K. The order of the parameters must be
identical to the order of the factors that follow FFCUBE.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
MIXTURE
Specifies a mixture design, indicating that the factors are process variables.
341
Minitab Statistical Software DOE
Response Surface Designs
BBDESIGN: Session command for creating a Box-Behnken design
BBDESIGN K [K]
Generates Box-Behnken designs for 3, 4, 5, 6, 7, 9, or 10 continuous factors and optional categorical factors.
Enter the number of factors on BBDESIGN. For a summary of the designs generated by BBDESIGN, go to
Box-Behnken designs on page 1135. All the blocked designs have orthogonal blocks.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTYPE, and XMATRIX.)
CENTER K
Adds the number of center points to the design that you specify in K, up to 50. If you do not use this
subcommand, then Minitab uses a default number of center points, based on the design you specified.
If the design is blocked, the center points are divided equally (as much as possible) among the blocks.
REPS K
Replicates each point the number of times that you specify in K, up to 50 replicates of each point.
BLOCKS K
Specifies the number of blocks in K. The choices for K are limited. The "Optional number of blocks" column
in Box-Behnken designs on page 1135 shows which values of K you can use for different designs.
RBLOCK
Use to specify blocks on replicates. Each set of replicate points is placed in a separate block. No arguments
are taken.
LEVELS K K, ..., K K
LEVELS C
LEVELS allows you to override the default values normally assigned to the levels of each factor. The default
values use -1 for the low level of the corner point, +1 for the high level, and 0 for the center point.
With LEVELS K K, ..., K K, you list a pair of arguments for each factor. The first K should be the low level and
the second K should be the high level. Levels must be numeric.
With LEVELS C, put the level values in a column, in the same order as if they were listed on the subcommand.
Then specify the level column on the LEVELS subcommand.
CNUM K...K
Specifies the number of levels in categorical factors. The number of arguments must match the second
argument for the main command. Each K must be an integer from 2 to 100. The default number of levels in
categorical factors is 2.
CLEVEL K...K
CLEVEL C
Specifies the uncoded values of the categorical factor levels in K...K or stored in C. The number of arguments
K must equal the sum of arguments in CNUM. The group of arguments for each factor must be of the same
type. If stored in column C, the column can be numerical or text and must equal the sum of arguments in
CNUM. The default categorical factor levels are "1", "2", "3", and so on.
342
Minitab Statistical Software DOE
RANDOMIZE [K]
Randomizes the run order and optionally uses base K. If you specify blocks, randomization is done separately
within each block and then the blocks are randomized. When you use RANDOMIZE, the standard order and
the run order are different and Minitab stores the design in run order.
K is the base for the random number generator and can take any integer as an argument. To get the same
ordering of the rows, create the same design and randomize the runs with the same base. For more
information, go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output for the command, but performs all specified storage
and displays the following output: error messages, warnings, prompts, and notes.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
CCDESIGN: Session command for creating a central composite
design
CCDESIGN K
Creates a central composite design with K number of continuous factors and optional K categorical factors.
Generates central composite designs for 2 to 10 continuous factors and optional categorical factors.
Specify the number of factors on CCDESIGN. Designs for 1 to 7 factors can use either a full or fractional factorial
design. Designs with 5 to 8 factors can use a one-half fraction of the full factorial portion of the central composite
design. Use HALF to specify the one-half fraction. Designs with 8 or 9 factors can use a one-quarter fraction of
the full factorial portion of the central composite design. Use QUARTER to specify one-quarter fraction. Designs
with 10 factors can use a one-eighth quarter fraction of the full factorial portion of the central composite design.
Use EIGHTH to specify one-eighth fraction.
Central composite designs on page 1136 summarizes the designs generated by CCDESIGN. The default values of
alpha provide orthogonal blocking and, whenever possible, rotatability. To generate a face-centered design, use
ALPHA = 1. The cube portions of these designs are identical to those generated by FFDESIGN on page 279 with
the same number of center points and blocks. Thus, a design generated by FFDESIGN with the same number of
runs, center points, and blocks as shown below can be built up into an orthogonally blocked central composite
343
Minitab Statistical Software DOE
design. Any FFDESIGN with the right number of runs and blocks can be built up into a blocked CCDESIGN. However,
to make the blocks orthogonal the FFDESIGN must use the number of center points shown in the table.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTYPE, and XMATRIX.).
HALF
Specifies the one-half fraction of a full factorial design. All the default designs generated by CCDESIGN use
a full factorial in the cube portion of the design. With five or six factors, you can optionally use a one-half
fraction of the full factorial. Use HALF to do so.
QUARTER
Specifies the one-quarter fraction of a full factorial design. Use QUARTER if you have eight or nine factors
and want to use a one-quarter fraction of the full factorial.
EIGHTH
Specifies the one-eighth fraction of a full factorial design. Use EIGHTH if you have ten factors and want to
use a one-eighth fraction of the full factorial.
CENTER K [K]
Adds K center points to cube and optionally, K center points to the axial block. If you do not give this
subcommand, Minitab uses a default number of center points, based on the design you specify.
If the design is blocked, you must give both Ks. The first gives the number of center points in the cube and
the second gives the number of center points in the axial block. If the cube is blocked, the number of center
points in the cube is split equally (as much as possible) among the blocks.
Central composite designs on page 1136 shows the defaults for blocked and unblocked designs. The defaults
for unblocked designs are in the "Total center points" column. For blocked designs, the defaults are in the
"Cube center points" and "Axial center points" columns.
ALPHA K
Specifies an alpha value in K. CCDESIGN has a default value for alpha, shown in Central composite designs
on page 1136, for each design. This subcommand allows you to change the default. The value must be positive.
A value of 1 results in a face-centered design. A value that is less than 1 places the axial points inside the
cube. A value that is greater than 1 places the axial points outside the cube.
REPS K
Replicates each point the number of times that you specify in K, up to 50 replicates of each point.
BLOCKS K
Specifies number of blocks in K. The choices for K are limited. The "Total blocks" column in Central composite
designs on page 1136 shows which values of K you can use for different designs.
RBLOCK
Blocks on replicates. Each set of replicate points is placed in a separate block. No arguments are taken.
LEVELS K K, ..., K K
LEVELS C
LEVELS allows you to override the default values normally assigned to the levels of each factor. The default
values use -1 for the low level of the corner point, +1 for the high level, 0 for the center point, and plus and
minus alpha for the axial points.
With LEVELS K K, ..., K K, you list one pair of arguments—giving first the low level and then the high level for
each factor. The center point and star points are scaled accordingly. Levels must be numeric.
344
Minitab Statistical Software DOE
With LEVELS C, put the level values in a column, in the same order as if they were listed on the subcommand.
Then specify this level column on the LEVELS subcommand.
One important thing to note is that the values you enter in LEVELS are usually not the minimum and maximum
values in the design. They are the low and high settings for the cube portion of the design. The axial points
are usually outside the cube (unless you specify an alpha that is less than or equal to 1). If you are not careful,
this could lead to axial points that are not in the region of interest, or that may be impossible to run.
If you wish, you can use LEVELS to guarantee that all of the design points will fall within a predetermined
minimum and maximum value for the factors. What you need to determine are the appropriate low and high
settings for the cube, so you can enter these into LEVELS. All you need to do so are the desired minimum
and maximum and the value of alpha for the design. Default alpha values are shown in Central composite
designs on page 1136.
CNUM K...K
Specifies the number of levels in categorical factors. The number of arguments must match the second
argument for the main command. Each K must be an integer from 2 to 100. The default number of levels in
categorical factors is 2.
CLEVELS K...K
CLEVELS C
Specifies the uncoded values of the categorical factor levels in K...K or stored in C. The number of arguments
K must equal the sum of arguments in CNUM. The group of arguments for each factor must be of the same
type. If stored in column C, the column can be numerical or text and must equal the sum of arguments in
CNUM. The default categorical factor levels are "1", "2", "3", and so on.
INSCRIBE
Defines the low and high pairs in LEVELS as the axial points instead of the cube points.
RANDOMIZE [K]
Randomizes the run order and optionally uses base K. If you specify blocks, randomization is done separately
within each block and then the blocks are randomized. When you use RANDOMIZE, the standard order and
the run order are different and Minitab stores the design in run order.
K is the base for the random number generator and can take any integer as an argument. To get the same
ordering of the rows, create the same design and randomize the runs with the same base. For a discussion,
go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output from the command, but performs all specified storage
and displays the following output: error messages, warnings, prompts, and notes.
0
345
Minitab Statistical Software DOE
Output that is displayedValue of K
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
RSREG: Session command for analyzing a response surface design
with least squares regression
RSREG
Analyzes a response surface design that can have continuous or categorical predictors using least squares
regression.
Fits a response surface model. Designs generated with BBDESIGN on page 342 and CCDESIGN on page 343 can be
analyzed using this command. Specify interactions in the following way: C5*C6. You can only use extra text on
the command and subcommand lines after a #. For more information on specifying the model, go to How to
specify the model for response surface designs on page 1168.
You can have up to 9 factors. To block the design, specify a blocking variable with the BLOCKS subcommand.
Optionally, you can display any of the five residual plots, and store the residuals, fitted values, and diagnostics
for further analysis.
XMATRIX is useful for storing the design matrix for use in other Minitab commands. It takes the factors, creates
the squares and cross-products, and stores all of these in a matrix. Copy the matrix into columns for use in other
commands.
You can store the residuals, fitted values, and many other diagnostics for further analysis.
For information on how Minitab handles missing data, go to Missing values in factorial, response surface, and
mixture designs on page 1171.
RESPONSE C
Specifies the column that contains the response variable. The column must be numeric or date/time.
BLOCK C
Specifies the column that contains the blocking information (optional). If you use BLOCK, you must also
include the blocking column in TERMS.
FACTOR C...C
Is mandatory and specifies the continuous factors. The columns must be numeric or date/time and must
match the length of the response column.
CFACTOR C...C
Specifies the categorical factors if you have any. The columns can be numeric, text, or date/time and must
match the length of the response column.
CNUM K...K
Use both CNUM and CLEVELS when the categorical factor levels in the worksheet are coded and you want
to display uncoded levels in the results.
CNUM specifies the number of levels for each categorical factor. Each K must be an integer from 2 to 100.
You must specify the number of K arguments as the number of columns that you specify in CFACTOR.
346
Minitab Statistical Software DOE
CLEVELS E...E
Use both CNUM and CLEVELS when the categorical factor levels in the worksheet are coded and you want
to display uncoded levels in the results.
CLEVELS specifies the uncoded values for all the categorical factor levels. You must specify the same number
of arguments as the number of K arguments that you specify in CNUM. The group of arguments for each
factor must be of the same type.
LEVELS C
LEVELS K K, ..., K K
Specifies uncoded levels for all continuous factors in C or K...K. For each continuous factor, the list or column
must contain two numerical values. Use LEVELS to change the default order of levels that Minitab uses.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
TERMS termlist
Specifies the terms to include in the model. Terms can contain a maximum of two factors. Only continuous
predictors may be repeated. Nested terms are not allowed. Terms must contain the blocks if they are to be
fitted. The model can be nonhierarchical.
Options
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
–1
(X' W Y)
This is equivalent to minimizing the weighted sum of squares for error:
i = 1
n
w
i
(
y
i
y
^
i
)
2
The prediction interval computed by PREDICT assumes a weight of 1. If you used the WEIGHT subcommand with
values other than 1, you should adjust the prediction interval values manually.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
347
Minitab Statistical Software DOE
Type of confidence intervalValue of K
Upper bound1
TOLER K
Specifies tolerance level for collinearity and constant check. By default, K = 2.2204460492503131e–016.
Box-Cox transformation
BOXCOX [K]
Performs a Box-Cox transformation with a specified lambda. K is the value of lambda and must be between –5
and + 5. If K is not given, Minitab will find the optimal lambda. By default, Minitab rounds the optimal value.
Minitab cannot calculate the optimal lambda for stepwise regression. Consequently, you must specify a lambda
value for BOXCOX if you use STEPWISE, FORWARD, or BACKWARD.
Stepwise regression
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
348
Minitab Statistical Software DOE
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
349
Minitab Statistical Software DOE
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Graphs
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is 1 the confidence level that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of errors. This plot lets you look at both the magnitude and the importance of an effect at the same time. The
alpha level is 1– the confidence level that follows CONFIDENCE, unless you use stepwise selection. For forward
selection, the alpha level is the level that follows AENTER. For backward and stepwise selection, the alpha level is
the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. K can
be 1 or 2. If you specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
350
Minitab Statistical Software DOE
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals versus fitted
values, and residuals versus order of the data.
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
Results
NODEFAULT
Specifies that no default tables or graphs are displayed.
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the settings in File > Options > Linear Models >
Stepwise.
FULL
Displays the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step of the
procedure.
NOFULL
Does not display the coefficients, the p-values, Mallows' Cp, and the model summary statistics for each step
of the procedure.
TEQUATION
Displays the regression equation table. Minitab displays up to 50 equations. If you do not specify SINGLE or
SEPARATE, then Minitab uses the settings in File > Options > Linear Models > Display of Results.
SINGLE
Displays a single equation, rather than a separate equation for each factor level combination.
SEPARATE
Displays separate equations.
TCOEFFICIENT
Displays the table of coefficients. If you do not specify FULL or NOFULL, then Minitab uses the settings in File >
Options > Linear Models > Display of Results.
351
Minitab Statistical Software DOE
FULL
Displays the full set of coefficients for categorical predictors.
NOFULL
Displays only the linearly independent coefficients.
TSUMMARY
Displays the model summary table.
TANOVA
Displays the ANOVA table.
TDIAGNOSTICS [K]
Displays a table of diagnostics.
Diagnostics that are displayedValue of K
Diagnostics only for unusual observations0
Diagnostics for all observations1
If you do not specify K, then Minitab uses the settings in File > Options > Linear Models > Display of Results.
TEXPAND
Displays the expanded versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
TSIMPLE
Displays the simple versions of the ANOVA table, the table of coefficients, the model summary table, and the
table of unusual observations.
Storage
BCRESP C
Stores the Box-Cox transformation of the response.
BFITS C
Stores the fits for the original response.
FITS C
Stores the fitted values.
RESIDUALS C
Stores the residuals (fitted values observed values).
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals in C.
HI C
Stores the leverage values.
352
Minitab Statistical Software DOE
COOK C
Stores Cook's distance.
DFITS C
Stores the DFITS (also called DFFITS) values.
COEFFICIENTS C
Stores the estimated coefficients.
XMATRIX M
Stores the design matrix for the regression model in M.
BRSREG: Session command for analyzing a response surface design
with a binary response
Required commands
To perform the analysis, use the main command and at least these accompanying subcommands.
BRSREG
Analyzes a response surface design that can have continuous or categorical predictors with a binary response.
Fits a response surface model. Designs generated with BBDESIGN on page 342 and CCDESIGN on page 343 can be
analyzed using this command. Specify interactions in the following way: C5*C6. For more information on specifying
the model, go to How to specify the model for response surface designs on page 1168.
You can have up to 9 factors. To block the design, specify a blocking variable with the BLOCKS subcommand.
Optionally, you can display any of the five residual plots, and store the residuals, fitted values, and diagnostics
for further analysis.
XMATRIX is useful for storing the design matrix for use in other Minitab commands. It takes the factors, creates
the squares and cross-products, and stores all of these in a matrix. Copy the matrix into columns for use in other
commands.
You can store the residuals, fitted values, and many other diagnostics for further analysis.
For information on how Minitab handles missing data, go to Missing values in factorial, response surface, and
mixture designs on page 1171.
RESPONSE C C
Enters the response data as a column that contains the number of events first and then a column that contains
the number of trials. The columns must have the same number of rows. For examples, go to Entering data
for response variables on page 1142.
FACTOR C...C
Specifies the continuous factors. The columns must be numeric or date/time and must have the same number
of rows as the response columns. Specify any categorical factors after CFACTOR instead of FACTOR.
TERMS termlist
Specifies the terms to include in the model. Terms can contain a maximum of two factors. Only continuous
predictors may be repeated. Nested terms are not allowed. Terms must contain the blocks if they are to be
fitted. The model can be nonhierarchical.
353
Minitab Statistical Software DOE
LEVELS C or LEVELS K K, ..., K K
Specifies uncoded levels for all continuous factors in C or K...K. For each continuous factor, the list or column
must contain two numerical values. Use LEVELS to change the default order of levels that Minitab uses. Specify
levels for categorical factors after CLEVELS instead of LEVELS. Also specify the number of levels for categorical
factors after CNUM.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
Optional subcommands
Use these subcommands and the subcommands in the following sections to change the default analysis.
CFACTOR C...C
Specifies the categorical factors if you have any. The columns can be numeric, text, or date/time and must match
the length of the response column.
CNUM K...K
Use both CNUM and CLEVELS when the categorical factor levels in the worksheet are coded and you want to
display uncoded levels in the results.
CNUM specifies the number of levels for each categorical factor. Each K must be an integer from 2 to 100. You
must specify the number of K arguments as the number of columns that you specify in CFACTOR.
CLEVELS E...E
Use both CNUM and CLEVELS when the categorical factor levels in the worksheet are coded and you want to
display uncoded levels in the results.
CLEVELS specifies the uncoded values for all the categorical factor levels. You must specify the same number of
arguments as the number of K arguments that you specify in CNUM. The group of arguments for each factor
must be of the same type.
BLOCKS C
Specifies the column that contains the blocking information in C. Include the blocking column together with
TERMS to make a model that considers blocks.
EVNAME K
Specify the name of the event with K. Enclose text values in double quotation marks.
LOGIT
Use the logit link function.
NORMIT
Use the normit link function.
GOMPIT
Use the gompit link function. The gompit link function is also called the complementary log-log link function.
354
Minitab Statistical Software DOE
Options subcommands
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
SEQDEVIANCE
Use sequential deviances for the tests of significance in the ANOVA table. The order of the terms in TERMS affects
the statistical significance. The default is to use adjusted deviances.
PEARSON
Specifies the use of Pearson residuals. The default is to use deviance residuals.
WEIGHT C
Performs a weighted regression. An n x n matrix W is formed with the column of weights as its diagonal and zeros
elsewhere. The regression coefficients are estimated by:
(X' W X)
−1
(X' W Y)
HGROUP K
Specifies the number of groups for the Hosmer-Lemeshow goodness-of-fit test with K. The default is 10.
ITERATION K
Specifies the maximum number of iterations for the optimization algorithm that estimates the coefficients. The
default is 50.
TOLERANCE K
Specifies the value in K above which Minitab removes highly correlated predictors and nearly constant predictors.
By default, K = 1E-12.
The tolerance value determines when Minitab retains a factor in the model that is either highly correlated with a
different factor or that is almost constant. Lowering tolerance by giving very small argument values can prevent
Minitab from eliminating problematic predictor columns from the model.
1 R
2
, where R
2
is the value that results from regressing one predictor on the remaining
predictors. If (1 R
2
) is < (K), then the predictor is removed from the equation.
Collinearity
If the coefficient of variation of a predictor (the standard deviation / the mean) is <
square root (K), then the predictor is considered essentially constant and is removed
from the equation.
Almost constant
CTOLERANCE K
Specifies the convergence criterion for the algorithm that estimates the coefficients. By default, K = 1E-8.
355
Minitab Statistical Software DOE
START C
Specifies a column that contains starting values for the coefficients in the optimization algorithm. The column
begins with the estimate of the constant, then follows the order of the model after TERMS.
Stepwise regression subcommands
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find a new minimum of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
356
Minitab Statistical Software DOE
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
357
Minitab Statistical Software DOE
Graphs subcommands
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GEFFECTS
Displays a normal probability plot of the effects or the standardized effects. Minitab labels the effects on the
probability plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GHALF
Displays a half normal probability plot of the effects or standardized effects. Minitab labels the effects on the half
normal plot that are considered significant. The alpha level is (1 the confidence level) that follows CONFIDENCE,
unless you use stepwise selection that depends on an alpha level. For forward selection, the alpha level is the level
that follows AENTER. For backward and stepwise selection, the alpha level is the level that follows AREMOVE.
GPARETO
Displays a Pareto chart of the absolute effects. GPARETO draws a vertical reference line on the plot at the margin
of error. This plot lets you to look at both the magnitude and the importance of an effect at the same time. The
alpha level is (1 the confidence level) that follows CONFIDENCE, unless you use stepwise selection that depends
on an alpha level. For forward selection, the alpha level is the level that follows AENTER. For backward and stepwise
selection, the alpha level is the level that follows AREMOVE.
GALLEFFECTS K
Specifies to include the model terms and the terms that are not in the model up to order K on the plots. If you
specify a stepwise method, Minitab ignores K and shows the terms in the candidate list.
GMODEL
Specifies that only the terms that are in the model are on the plots.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Displays residuals versus fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
358
Minitab Statistical Software DOE
GVARIABLE C...C
Displays the residuals versus the variables in C. Typically, you enter the columns for the predictors.
Results subcommands
NODEFAULT
Hides default tables and graphs that you do not include the subcommand to display.
TEXPAND
Displays the expanded versions of the tables that have them. The expanded Analysis of Variance table adds the
sequential deviances and percent contributions for each term. The Coefficients table adds confidence intervals
for the coefficients. The Fits and Diagnostics table adds the standard error of the fit, the 95% confidence interval
for the fit, the deleted residual, the HI, the Cook's D, and the DFITS.
TSIMPLE
Displays the simple versions of the Analysis of Variance table, the Coefficients table, and the Fits and Diagnostics
table.
TMETHOD
Displays a table of information about the method and options.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
If you do not specify FULL or NOFULL, then Minitab uses the preferences that you set in File > Options > Linear
Models > Stepwise.
FULL
Specifies to display the coefficients, p-values, and model summary statistics for each step of the procedure.
NOFULL
Hides these statistics.
TRINFO
Displays the number of events, non-events, and the total. The table also indicates which response value is the
reference event.
TSTEP
Displays the deviance at each iteration of the coefficients.
TCOEFFICIENTS
Displays the coefficients and the p-values for the Wald normal approximation tests.
If you do not specify FULL or NOFULL, Minitab uses the preferences that you set in File > Options > Linear
Models > Display of Results.
FULL
Specifies to show the coefficients for the reference level when you use (0, 1) coding for categorical predictors.
NOFULL
Hides these statistics.
359
Minitab Statistical Software DOE
TODDS
Displays odds ratios for each continuous predictor and each level of the categorical predictors. The output does
not show odds ratios for predictors with interactions in the model.
INCREMENT K...K
Specifies the increment for the odds ratio for the predictor with K. For example, if the predictor is mass in
grams, enter 1000 to see the change in the odds ratio for a kilogram. Enter a value for each numeric factor
in the same order that the factors follow the FACTOR subcommand. Enter 1 for a factor to use the same units
as the data.
TSUMMARY
Displays the statistics that evaluate model fit, including deviance R
2
.
TGOODNESS
Displays the Pearson and deviance goodness-of-fit tests. For the binomial distribution models, also shows the
Hosmer-Lemeshow goodness-of-fit test.
TDEVIANCE
Displays the ANOVA table.
TEQUATION
Displays the model equation.
SINGLE
Specifies to show one equation instead of a separate equation for each combination of the levels of the
categorical predictors. The equation has a coefficient for each level of the categorical variables.
SEPARATE
Specifies to show separate equations for each combination of the levels of the categorical predictors. Each
equation has a different constant term.
THOSMER
Displays the table of observed and expected values for the Hosmer-Lemeshow test.
TASSOCIATION
Displays the number of concordant and discordant pairs, the Somers' D, the Goodman-Kruskal Gamma, and
Kendall's Tau-a.
TDIAGNOSTICS [K]
Displays a table of diagnostics. K = 0 displays diagnostics for only observations with high leverage values or
standardized residuals greater than 2. K = 1 displays diagnostics for all observations.
Storage subcommands
FITS C
Stores the event probabilities in C.
RESIDUALS C
Stores the deviance residuals by default in C. Stores the Pearson residuals if you use the subcommand PEARSON.
SRESIDUALS C
Stores the standardized deviance residuals by default in C. Stores the standardized Pearson residuals if you use
the subcommand PEARSON.
360
Minitab Statistical Software DOE
TRESIDUALS C
Stores the deleted deviance residuals by default in C. Stores the deleted Pearson residuals if you use the
subcommand PEARSON.
COOK C
Stores the Cook's distances in C.
DFITS C
Stores the DFITS in C.
HI C
Stores the leverages in C.
SADJUSTEDRESP C
Stores the final adjusted response values in C.
SIWEIGHTS C
Stores the internal weights used to estimate the model parameters in C.
SECOEFFICIENTS C
Stores the standard errors of the estimated coefficients in C.
COEFFICIENTS C
Stores the estimated coefficients in C.
DBETA C
Stores the change in the estimated regression coefficients (delta b) when you delete all observations with a
particular factor/covariate pattern in C. Use the delta b values to detect observations with a strong influence on
the coefficients.
DSBETA C
Stores the change in the estimated regression coefficients when you delete all observations with a particular
factor/covariate pattern based on the standardized Pearson residual in C.
DCHISQUARE C
Stores the change in the chi-square statistic when you delete all observations with a particular factor/covariate
pattern in C. Observations that are poorly fit by the model have high delta chi-square values.
DDEVIANCE C
Stores the change in the deviance when you delete all observations with a particular factor/covariate pattern in
C.
XMATRIX M
Stores the design matrix in M.
XPWXINVERSE M
Stores the X'WX inverse matrix of the estimated coefficients in M.
OPTDES: Session command for selecting an optimal design
OPTDES K [C...C]
Select an optimal design by specifying the number of final design points in K and optionally, specifying candidate
design columns in C...C.
361
Minitab Statistical Software DOE
The purpose of an optimal design is to select design points according to some criteria. Minitab's optimal design
capabilities can be used with response surface designs and mixture designs. You can use Select Optimal Design
to do the following:
Select an optimal set of design points.
Augment (add points to) an existing design.
Improve the D-optimality of an existing design.
Evaluate and compare designs.
OPTDES has the following forms:
OPTDES K: Specifies the number of final design points to select based on D-optimality. For this command
form either a factorial model, mixture model, or response surface model must be specified by subcommands
FACMODEL, MIXMODEL, or RESMODEL. The constant K must be a positive integer or 0. If K = zero, you must
use either the AUGMENT or EVALUATE subcommand.
OPTDES K, C...C: Specifies the number of final design points and the design columns that contain the candidate
set. Constant K must be a positive integer. You must specify at least 2 design columns. All columns must have
the same length and must be numeric. With this form of the main command you cannot have the following
subcommands: FACMODEL, RESMODEL, MIXMODEL, EVALUATE, BLOCK, GENERATE, EXCHANGE, FEDOROV,
SEQUENTIAL.
Note The subcommands DESIGN and COPY replace the obsolete subcommands XMATRIX and CARRY.
FACMODEL terms
Species the terms of a factorial model used in selecting D-optimal design. The legal term list is the same as
in GLM.
FACMODEL, RESMODEL, and MIXMODEL are mutually exclusive and one of them must be the first
subcommand.
MIXMODEL terms
Specifies the terms of a mixture model used in selecting D-optimal design. The legal term list is the same as
in MIXREG.
FACMODEL, RESMODEL, and MIXMODEL are mutually exclusive and one of them must be the first
subcommand.
RESMODEL terms
Specifies the terms of a response surface model used in selecting D-optimal design. The legal term list is the
same as in RSREG. When you use RESMODEL, also use INUNIT and LEVELS.
FACMODEL, RESMODEL, and MIXMODEL are mutually exclusive and one of them must be the first
subcommand.
INUNIT
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
362
Minitab Statistical Software DOE
LEVELS K K, ..., K K
Specifies uncoded levels for all continuous factors K K, ..., K K. Enter the low level, then the high level,
for each continuous factor that follows RESMODEL. List the pairs of levels in the order of the factors that
follow RESMODEL.
AUGMENT C
Augments or improves an existing design indicated by row flags in C. Column C must be numeric and must
contain integers. The column length must match the length of the design columns.
Cannot be specified together with EVALUATE, GENERATE, or SEQUENTIAL.
EVALUATE C
Evaluates an existing design indicated by row flags in C. Column C must be numeric and must contain
non-negative integers. The column length must match the length of the design columns.
Cannot be specified with OPTDES K C...C, AUGMENT, EXCHANGE, FEDOROV, SEQUENTIAL, GENERATE,
INDICATOR.
BLOCK C
Specifies the blocking column. The column can be alpha or numeric with 2–64 distinct values. Column length
must match the length of the design columns. Must not be on the term list.
Cannot be specified with OPTDES K C...C.
PROCESS C...C
Specifies process variable columns. Columns must be either on the main line if OPTDES K C...C or on the term
list. Columns may be alpha or numeric with exactly 2 levels. With OPTDES K C...C, only numerical process
variable columns are allowed. The number of columns must be between 1 and 7. Column lengths must match
the length of design columns.
Cannot be specified with AMOUNT or with factorial or response surface models.
AMOUNT C
Specifies the mixture amount column. Column must be either on the main line if OPTDES K C...C or on the
term list. The column must be numeric with 2–5 distinct numerical values. The column length must match
the length of the design columns.
Cannot be specified with PROCESS or with factorial or response surface models.
PSEUDO
Specifies that calculations are performed using pseudo-components. PSEUDO is ignored in cases of factorial
or response surface designs.
GENERATE K [K [K]]
Generates K % of initial points randomly, and adds the rest of points by sequential method. The second K is
the number of random trials. The third K is the base for the random data generator. Legal values are as
follows: first and second K integer, third K any positive real. 0 < first K <=100, 1 <= second K <= 25.
Cannot be specified with OPTDES K C...C, AUGMENT, EVALUATE, SEQUENT.
SEQUENTIAL
Selects design points by the sequential algorithm for the initial design.
363
Minitab Statistical Software DOE
Cannot be specified with OPTDES K C...C, AUGMENT, EVALUATE, GENERATE.
EXCHANGE K
Improves the initial design matrix by adding and dropping K design points one at a time. Legal values are
as follows: K is an integer, 1 <= K <= 5.
Cannot be specified with OPTDES K C...C, EVALUATE, FEDOROV.
FEDOROV
Improves the initial design matrix using Fedorov's algorithm.
Cannot be specified with OPTDES K C...C, EVALUATE, EXCHANGE.
INDICATOR C
Stores selection indicators in the specified column.
Cannot be specified with EVALUATE.
DESIGN
Copies the standard order, run order, point type, blocks, and factors to a new worksheet for rows in the
optimal design.
COPY C...C
Copies rows in the optimal design to the new worksheet for columns that are not part of the design.
For example, you can use COPY to copy a column of covariate measurements.
BRIEF K
Controls the amount of output with a value in K.
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays a summary table for the final design only.1
Minitab displays summary tables for the intermediate design and the final design.2 (default)
Displays summary tables and the final design matrix.3
DETZERO [K]
Overrides the lower limit for the determinant, which is E-30. Use when you receive the "rank deficient data"
error message, but still want to perform the analysis. K is an integer that is greater than or equal to 30. The
default value is 30.
Plot Response Surface Designs
FACPLOT: Session command for creating a factorial plot
FACPLOT C
Displays factorial plots for the model associated with the response variable in the specified column To create this
graph, you need to specify a model. To produce an interaction plot, you must have two or more variables.
364
Minitab Statistical Software DOE
These plots can illustrate how a response variable relates to one or more variables. You can produce two types
of factorial plots.
Use a main effects plot to compare fitted means or data means across levels of one or more variables.
Use an interactions plot to assess the effects of one variable at levels of another variable. An interactions plot
displays the fitted means for a level of a variable with the level of a second variable held constant.
Although you can use these plots to display the effects, be sure to evaluate significance by looking at the effects
in the analysis of variance table.
FACTORS C...C
Specifies the variables to display in both the main effect and interaction plots. You must specify 2 or more
variables to generate an interaction plot.
GMAIN
GMAIN displays the main effect plot.
GINT
GINT displays the interactions plot.
FULL
Use FULL to display both interaction plots for each pair of categorical variables, such as Predictor 1 by
Predictor 2 and Predictor 2 by Predictor 1. Sometimes you can identify interactions more easily when
you examine both plots.
LOWER
Use LOWER to display one version of each interaction plot.
GMODEL (default)
GMODEL display plots for only terms that are in the model and listed in FACTORS. For purposes of a main
effect plot, a variable is in the model if the model includes any terms that involve only that variable, e.g. A,
A*A, or A*A*A. For purposes of an interaction plot, the interaction of two variables is in the model if the
model includes any terms that involve both variables, e.g. A*B, A*B*B.
GALL
GALL displays plots for all terms involving variables on the FACTORS subcommand.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
Mixture Designs
EVDESIGN: Session command for creating an extreme vertices
design
EVDESIGN K
Creates an extreme vertices design for K components. In EVDESIGN, Minitab uses an algorithm that generates
extreme vertices and their blends up to the specified degrees. You must use these designs when your chosen
design space is not an L-simplex design. The presence of both lower and upper bound constraints on the
365
Minitab Statistical Software DOE
components often create this condition. The goal of an extreme vertices design is to choose design points that
adequately cover the design space.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTYPE, and XMATRIX.).
Design
DEGREE K
Specifies the degree of the design in K. For lattice designs, 1 K 10. For extreme vertices designs, 1 K
number of components. The default K = 1.
AUGMENT
Augments (that is, adds points to) the design using axial points. Each axial point is added halfway between a
vertex and the center of the design.
By augmenting a design, you can better understand what occurs on the interior of the design, instead of relying
only on points on the edges.
AXIAL
Augments the design with axial points halfway between each vertex and centroid. The default is no axial points.
CENTER
Augments the design with center points if no center points exist in the design. The default is no center point.
ALLREP K
Replicates all points in the design K times. The default is K = 1.
REPS K, K...K, K
Specifies the number of replicates for design points of the selected type. In each constant pair (K, K), the first K
value indicates the point type (1, 2,...q, 0, –1), and the second K value indicates the number of replicates. The
default is no replicates.
Components
TOTAL K [K...K]
TOTAL C
Specifies the mixture design as actual measurements, not proportions, in K or C, with up to 5 different amounts.
For example, suppose you measure all the components of a mixture in liters. If the total mixture adds up to 5.2
liters, set TOTAL to 5.2. This generates the settings for components in the design in terms of liters. Or, suppose
you want to evaluate plant growth when one gram versus two grams of food are applied. You set TOTAL to 1 2.
K can be any positive number, with up to 5 values. The default value is 1. You can also enter the values in a column
(C) and use the column as the argument.
LOWER K...K
LOWER C
Specifies the lower bounds for the q components in K...K, one for each component. The first argument is for the
first component, the second for the second component, and so on. The default value is 0. If the sum of all the
lower bounds is less than the value of TOTAL, you can specify any non-negative values for LOWER. You can also
enter the values in a column (C) and use the column as the argument for LOWER.
366
Minitab Statistical Software DOE
When you change the default lower bounds of one component, the achievable upper values on the other
components are also adjusted downward. Specifically, the achievable upper bound (U
I
) for component I is as
follows:
U
I
= TOTAL [L
1
+ L
2
+ ... + L (
I–1
) + L (
I+1
) + ... + L
q
]
Minitab displays both the specified lower bounds and the achievable upper bounds in the output. For example,
suppose you have 3 components: TOTAL = 10, L
1
= 0, L
2
= 2, and L
3
= 1. In this case, the achievable upper bounds
are U
1
= 7, U
2
= 9, and U
3
= 8.
UPPER K...K
UPPER C
Specifies upper bounds for the components in K...K or C. Must be a positive value for each component. The default
is 1 for each value if the units are proportions or pseudo-components. The default is the whole amount if the
units are amounts.
PSEUDO and PROPORTIONS
Specifies the scale in which data are represented, including: amounts, proportions, or pseudo-components.
Amounts are what you actually measure. By default, Minitab uses amounts to display and store your data. PSEUDO
specifies that the data is represented by pseudo-components. PROPORTIONS specifies that the data is represented
by proportions.
To get proportions, divide the measurement amounts by the value of TOTAL. When you use PROPORTIONS,
Minitab uses proportions to print and store the design. When you do not specify TOTAL, the amount scale and
the proportion scale are the same.
You generally use pseudo-components when you specify lower bounds. Pseudo-components, in effect, rescale
the constrained data area so that the least allowable amount (the lower bound) of each component is 0, and the
greatest allowable amount of a component is 1. This makes the pseudo-component terms of a constrained design
(that is, a design with lower bounds) the same as the proportional terms of an unconstrained design.
Mathematically, this translates to the following: Let X
1
be the settings expressed as proportions. Let L
i
be the lower
bounds expressed as proportions. Let Low = L
1
+ L
2
+ ... + L
q
. Then pseudo-component p
i
= (X
i
L
i
) / (1 Low).
When you use PSEUDO, then Minitab uses pseudo-components to print and store the design. When the design
has no LOWER bounds, pseudo-components and proportions are the same. When you do not use TOTAL or
LOWER, the PSEUDO, PROPORTIONS, and amount scales are the same.
You cannot use both PSEUDO and PROPORTIONS in the same command.
In the following example, 2 components show amounts, proportions, and pseudo-components. Suppose the total
mixture is 50 ml. Let X1 and X2 be the amount scale. Thus X1 + X2 = 50. Suppose X1 has a LOWER bound of 20.
(This means that the UPPER bound of X2 is 50 20, or 30.)
SCDESIGN 2;
TOTAL 50;
LOWER 20 0.
The following table shows some points on the three scales.
Pseudo-componentsProportionsAmounts
X2X1X2X1X2X1
0.01.00.01.0050
1.00.00.60.43020
0.50.50.30.71535
367
Minitab Statistical Software DOE
LINEAR K...K
LINEAR C
Specifies linear constraints for the components in K...K or C. The number of values equals the number of components
+ 2. The first constant is the lower bound. The last constant is the upper bound. One of the bounds can be ' * '.
All values must be numeric. The default is no linear constraint.
Process variables
PROC K1 [K2 [K3]]
Specifies the number of process variables, the factorial design, and the fraction id. The default is no process
variables. The Ks can equal: 1 K1 7; K2 = 1, 2, 4, 8, 16; 1 K3 K2.
LEVELS K...K
Specifies level values for the process variables in K...K. The default is –1 and +1 for each variable. The number of
Ks equals twice the number of process variables. K can be numeric or text.
Options
RANDOMIZE [K]
Randomizes the runs in the design matrix. When you use RANDOMIZE, the standard order and the run order are
different and Minitab stores the design in run order.
K is the base for the random data generator and can take any integer as an argument. To always get the same
ordering of the rows, create the same design and randomize the runs with the same base. For more information,
go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate columns.
Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new worksheet.
NAMES K K, ..., K K
Specifies names for the mixture components. Enclose names in quotation marks. If you do not use NAMES,
then the names of the components are letters, skipping the letter I: A, B, C…
PNAMES K K, ..., K K
Specifies names for the process variables. Enclose names in quotation marks. If you do not use PNAMES,
then the names of the process variables are the letter X followed by sequential numbers: X1, X2, X3…
STOTAL C
Stores one or more totals in C. The default is no storage. STOTAL is incompatible with DESIGN.
SLOWER C
Stores the lower bounds of the components in C. The default is no storage. SLOWER is incompatible with DESIGN.
SUPPER C
Stores the upper bounds of the components in C. The default is no storage. SUPPER is incompatible with DESIGN.
SLINEAR C...C
Stores linear constraints in C...C, one per column. The default is no storage. SLINEAR is incompatible with DESIGN.
368
Minitab Statistical Software DOE
Results
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all requested storage.0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the data matrix.3
SCDESIGN: Session command for creating a simplex centroid
design
SCDESIGN K
Creates a simplex centroid design for K components.
Generates a series of settings for the components in an experiment with a simplex centroid design. A simplex
centroid design consists of the following for a mixture with q components:
All points (x1, x2, .., xq) where one component, xi = 1, and the other components are 0. These are called vertex
points.
All points where one component, xi = 1/2, another component, xj = 1/2, and the other components are 0.
All points where one component, xi = 1/3, another component, xj = 1/3, another component, xk = 1/3, and
the other components are 0.
And so on, up to the stage where all components are 1/q. This last point (where all components are equal) is
called the center or centroid of the design.
Simplex centroid designs contain a total of 2q 1 points.
The constant argument on the command line is an integer from 2 to 7 that specifies the number of components
or variables (which is generally called q).
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTYPE, and XMATRIX.).
Design
AUGMENT
Augments (or adds points to) the design using the axial points shown below. Each added point is half way between
a vertex and the center of the design.
By augmenting a design, you can get a better picture of what happens on the interior of the design, instead of
just relying on points on the edges.
AXIAL
Augments the design with axial points half way between each vertex and centroid. The default is no axial points.
369
Minitab Statistical Software DOE
ALLREP K
Replicates all points in the design K times. The default is K = 1.
REPS K K, ..., K K
Specifies the number of replicates for design points of selected type. In each constant pair K, K the first value
indicates the point type (1, 2, ..q, 0, –1), the second value specifies the number of replicates. The default is no
replicates.
Components
TOTAL K [K...K]
TOTAL C
Specifies the mixture design in terms of actual measurements, not proportions. For example, if you measure all
the components of your mixture in liters and the total mixture adds up to 5.2 liters, set TOTAL to 5.2 to generate
the settings for components in the design in terms of liters. Or, suppose you are testing plant food and would
like to evaluate plant growth when one gram versus two grams are applied. You would set TOTAL to 1 2.
The TOTAL argument can be any positive number, with up to five values for total. The default value is 1. You can
also enter the values in a column and use the column as the argument.
LOWER K...K
LOWER C
Specifies the lower bounds for the q components. The first argument is for the first component, the second for
the second component, and so on. The default is to set the lower bound for each component to 0. You may specify
any non-negative values for LOWER provided the sum of all the lower bounds is less than the value of TOTAL.
You can also enter the values in a column and use the column as the argument for LOWER.
When you change the default lower bounds of one component, the achievable upper values on the other
components are also adjusted downward. Specifically, the achievable upper bound (U i) for component i is
U
i
= TOTAL [L
1
+ L
2
+ ... + L
(i–1)
+ L
( i+1)
+ ... + L
q
]
Minitab displays both the specified lower bounds and achievable upper bounds in the output. As an example,
suppose you have 3 components, TOTAL = 10, L
1
= 0, L
2
= 2 and L
3
= 1. Then the achievable upper bounds are
U
1
= 7, U
2
= 9 and U
3
= 8.
UPPER K...K
UPPER C
Specifies upper bounds for the components in K...K or C. Must be a positive value for each component. The default
is 1 for each value if the units are proportions or pseudo-components. The default is the whole amount if the
units are amounts.
PSEUDO and PROPORTIONS
Specifies the scale in which data is represented, including: amounts, proportions, or pseudo-components. Amounts
are what you actually measure. By default, Minitab uses amounts to print and store your data.
To get proportions, divide the measurement amounts by the value of TOTAL. When you use PROPORTIONS,
Minitab uses proportions to print and store the design. When you do not specify TOTAL, the amount scale and
the proportion scale are the same.
You generally use pseudo-components when you specify lower bounds. Pseudo-components, in effect, rescale
the constrained data area so the least allowable amount (the lower bound) of each component is 0, and the
370
Minitab Statistical Software DOE
greatest allowable amount of a component is 1. This makes the pseudo-component terms of a constrained design
(that is, a design with lower bounds) the same as the proportional terms of an unconstrained design.
Mathematically, this translates to the following. Let x 1 be the settings expressed as proportions. Let Li be the
lower bounds expressed as proportions and let Low = L
1
+ L
2
+ & + L
q
. Then pseudo-component p
i
= ( x
i
L
i
) /
(1 Low).
When you use PSEUDO, then Minitab uses pseudo-components to print and store the design. When the design
has no LOWER bounds, pseudo-components and proportions are the same. When you do not use TOTAL or
LOWER, the PSEUDO, PROPORTIONS, and amount scales are the same.
You cannot use both PSEUDO and PROPORTIONS in the same command.
Here is an example with 2 components that shows amounts, proportions, and pseudo-components. Suppose the
total mixture is 50 ml. Let X1 and X2 be the amount scale. Thus X1 + X2 = 50. Suppose X1 has a LOWER bound
of 20 (this means that the UPPER bound of X2 is 50 minus 20, or 30). The session commands for this are as follows.
SCDESIGN 2;
TOTAL 50;
LOWER 20 0.
The following table shows some points on the three scales.
Pseudo-componentsProportionsAmounts
X2X1X2X1X2X1
0.01.00.01.0050
1.00.00.60.43020
0.50.50.30.71535
Process variables
PROC K1 [K2 [K3]]
Specifies the number of process variables, the factorial design and fraction id. The default is no proc vars 1 <=
K1 <= 7; K2 = 1, 2, 4, 8, 16; 1 <= K3 <= K2.
LEVELS K...K
Specifies level values for the process variables. The default is –1 and +1 for each variable. The number of Ks equals
twice the number of process variables. K may be numerical or text.
Options
RANDOMIZE [K]
Randomizes the runs in the design matrix. When you use RANDOMIZE, the standard order and the run order are
different and Minitab stores the design in run order.
K is the base for the random data generator and can take any integer as an argument. To always get the same
ordering of the rows, create the same design and randomize the runs with the same base. See BASE on page 86
for a discussion.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate columns.
Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new worksheet.
371
Minitab Statistical Software DOE
NAMES K K, ..., K K
Specifies names for the mixture components. Enclose names in quotation marks. If you do not use NAMES,
then the names of the components are letters, skipping the letter I: A, B, C…
PNAMES K K, ..., K K
Specifies names for the process variables. Enclose names in quotation marks. If you do not use PNAMES,
then the names of the process variables are the letter X followed by sequential numbers: X1, X2, X3…
STOTAL C
Stores one or more totals in C. The default is no storage. STOTAL is incompatible with DESIGN.
SLOWER C
Stores the lower bounds of the components in C. The default is no storage. SLOWER is incompatible with DESIGN.
SUPPER C
Stores the upper bounds of the components in C. The default is no storage. SUPPER is incompatible with DESIGN.
Results
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output from the command, but performs all specified storage and
displays the following output: error messages, warnings, prompts, and notes.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
SLDESIGN: Session command for creating a mixture design
SLDESIGN K [K]
Generates a series of settings for an experiment that uses a simplex lattice design with q components (variables),
of degree m. The degree m can be 1–10. For more information, go to Simplex lattice design descriptions on page
1180.
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands SORDER, PTTYPE, and XMATRIX.).
Design
DEGREE K
Specifies the degree of the design in K. For lattice designs, 1 K 10. For extreme vertices designs, 1 K
number of components. The default K = 1.
372
Minitab Statistical Software DOE
AUGMENT
Augments (that is, adds points to) the design using axial points. Each axial point is added halfway between a
vertex and the center of the design.
By augmenting a design, you can better understand what occurs on the interior of the design, instead of relying
only on points on the edges.
AXIAL
Augments the design with axial points halfway between each vertex and centroid. The default is no axial points.
CENTER
Augments the design with center points if no center points exist in the design. The default is no center point.
ALLREP K
Replicates all points in the design K times. The default is K = 1.
REPS K, K...K, K
Specifies the number of replicates for design points of the selected type. In each constant pair (K, K), the first K
value indicates the point type (1, 2,...q, 0, –1), and the second K value indicates the number of replicates. The
default is no replicates.
Components
TOTAL K [K...K]
TOTAL C
Specifies the total mixture amount in actual measurements in K or C. The TOTAL argument can be any positive
number, with up to five values for total. The default value is 1. You can also enter the values in a column and use
the column as the argument.
Specifies the mixture design in terms of actual measurements, not proportions. For example, if you measure all
the components of your mixture in liters and the total mixture adds up to 5.2 liters, set TOTAL to 5.2 to generate
the settings for components in the design in terms of liters. Or, suppose you are testing plant food and want to
evaluate plant growth when one gram versus two grams are applied. You would set TOTAL to 1 2.
LOWER K...K
LOWER C
Specifies the lower bounds for the q components in K...K, one for each component, or in C.
The first argument is for the first component, the second for the second component, and so on. The default is to
set the lower bound for each component to 0. You may specify any non-negative values for LOWER provided the
sum of all the lower bounds is less than the value of TOTAL. You can also enter the values in a column and use
the column as the argument for LOWER.
When you change the default lower bounds of one component, the achievable upper values on the other
components are also adjusted downward. Specifically, the achievable upper bound (U
i
) for component i is
U
i
= TOTAL [L
1
+ L
2
+ ... + L
(i-1)
+ L
(i+1)
+ ... + L
q
]
Minitab displays both the specified lower bounds and achievable upper bounds in the output. For example,
suppose you have 3 components, TOTAL = 10, L
1
= 0, L
2
= 2 and L
3
= 1. Then the achievable upper bounds are
U
1
= 7, U
2
= 9 and U
3
= 8.
373
Minitab Statistical Software DOE
UPPER K...K
UPPER C
Specifies upper bounds for the components in K...K or C. Must be a positive value for each component. The default
is 1 for each value if the units are proportions or pseudo-components. The default is the whole amount if the
units are amounts.
PSEUDO and PROPORTIONS
Specifies the scale in which data are represented, including: amounts, proportions, or pseudo-components.
Amounts are what you actually measure. By default, Minitab uses amounts to display and store your data. PSEUDO
specifies that the data is represented by pseudo-components. PROPORTIONS specifies that the data is represented
by proportions.
To get proportions, divide the measurement amounts by the value of TOTAL. When you use PROPORTIONS,
Minitab uses proportions to print and store the design. When you do not specify TOTAL, the amount scale and
the proportion scale are the same.
You generally use pseudo-components when you specify lower bounds. Pseudo-components, in effect, rescale
the constrained data area so that the least allowable amount (the lower bound) of each component is 0, and the
greatest allowable amount of a component is 1. This makes the pseudo-component terms of a constrained design
(that is, a design with lower bounds) the same as the proportional terms of an unconstrained design.
Mathematically, this translates to the following: Let X
1
be the settings expressed as proportions. Let L
i
be the lower
bounds expressed as proportions. Let Low = L
1
+ L
2
+ ... + L
q
. Then pseudo-component p
i
= (X
i
L
i
) / (1 Low).
When you use PSEUDO, then Minitab uses pseudo-components to print and store the design. When the design
has no LOWER bounds, pseudo-components and proportions are the same. When you do not use TOTAL or
LOWER, the PSEUDO, PROPORTIONS, and amount scales are the same.
You cannot use both PSEUDO and PROPORTIONS in the same command.
In the following example, 2 components show amounts, proportions, and pseudo-components. Suppose the total
mixture is 50 ml. Let X1 and X2 be the amount scale. Thus X1 + X2 = 50. Suppose X1 has a LOWER bound of 20.
(This means that the UPPER bound of X2 is 50 20, or 30.)
SLDESIGN 2;
TOTAL 50;
LOWER 20 0.
The following table shows some points on the three scales.
Pseudo-componentsProportionsAmounts
X2X1X2X1X2X1
0.01.00.01.0050
1.00.00.60.43020
0.50.50.30.71535
Process variables
PROC K1 [K2 [K3]]
Specifies the number of process variables, the factorial design, and the fraction id. The default is no process
variables. The Ks can equal: 1 K1 7; K2 = 1, 2, 4, 8, 16; 1 K3 K2.
LEVELS K...K
Specifies level values for the process variables in K...K. The default is –1 and +1 for each variable. The number of
Ks equals twice the number of process variables. K can be numeric or text.
374
Minitab Statistical Software DOE
Options
RANDOMIZE [K]
Randomizes the runs in the design matrix. When you use RANDOMIZE, the standard order and the run order are
different and Minitab stores the design in run order.
K is the base for the random data generator and can take any integer as an argument. To always get the same
ordering of the rows, create the same design and randomize the runs with the same base. For more information,
go to BASE on page 86.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate columns.
Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new worksheet.
NAMES K K, ..., K K
Specifies names for the mixture components. Enclose names in quotation marks. If you do not use NAMES,
then the names of the components are letters, skipping the letter I: A, B, C…
PNAMES K K, ..., K K
Specifies names for the process variables. Enclose names in quotation marks. If you do not use PNAMES,
then the names of the process variables are the letter X followed by sequential numbers: X1, X2, X3…
STOTAL C
Stores one or more totals in C. The default is no storage. STOTAL is incompatible with DESIGN.
SLOWER C
Stores the lower bounds of the components in C. The default is no storage. SLOWER is incompatible with DESIGN.
SUPPER C
Stores the upper bounds of the components in C. The default is no storage. SUPPER is incompatible with DESIGN.
Results
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output from the command, but performs all specified storage and
displays the following output: error messages, warnings, prompts, and notes.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
MIXREG: Session command for analyzing a mixture design
MIXREG C...C = C...C
Analyzes (or fit) Scheffe mixture models, including simplex centroid and simplex lattice designs. You have a choice
of four standard models: linear, quadratic (default), special cubic, special quadratic, full cubic, and full quadratic.
375
Minitab Statistical Software DOE
The main command contains a list of the response variables before the equal sign and a list of the components
after the equal sign. If the design is blocked, give the blocking variable with the BLOCKS subcommand.
You can have up to 25 responses before the equal sign. For information on how Minitab handles missing data,
go to Missing values in factorial, response surface, and mixture designs on page 1171.
To use commands on the Minitab menu that use model information, such as the response optimizer, use the
subcommand DESIGN.
PROC C...C
Specifies the columns that contain process variables. The number of columns must be from 1 to 7. The process
variables must be specified in term list.
AMOUNT C
Specifies the column that contains the mixture amounts. This column should not be specified in MIXREG on
the term list.
INUNIT K
Specifies the unit of the components.
Unit of the componentsValue of K
Pseudo-component units0
Proportion units1
Amount units2
PSEUDO
Specifies that the analysis is performed in pseudo-components.
Stepwise
Specifies a model selection procedure. STEPWISE, FORWARD, BACKWARD are the three subcommands that correspond
to stepwise, forward, and backward model selection procedures.
You can specify one model selection procedure at a time.
STEPWISE
If you specify STEPWISE, then the FORCE, ENTER, AENTER, AREMOVE, and BEST subcommands are valid.
FORWARD
If you specify FORWARD, then the FORCE, AENTER, and BEST subcommands are valid.
BACKWARD
If you specify BACKWARD, then the FORCE, AREMOVE, and BEST subcommands are valid.
FORCE terms
Specifies the terms to be forced in the model. Main component terms are always present. Terms selected must
be a subset of the model terms given on MIXREG.
ENTER terms
Specifies the terms that are contained in a starting model for stepwise selection procedure. The term entered
here must be one of the model terms specified on MIXREG
Only the STEPWISE subcommand uses ENTER.
376
Minitab Statistical Software DOE
AENTER K
Specifies the alpha level at which a term is entered to the model. K is a constant between 0 and 1 (including 0
and 1). The default value is 0.15 for STEPWISE, and 0.25 for FORWARD.
For stepwise selection, K for AREMOVE must be greater than or equal to K for AENTER. If only AREMOVE is specified
by a user, then AENTER = AREMOVE, vice versa.
AREMOVE K
Specifies the alpha level at which a term is removed from the model. K is a constant between 0 and 1 (including
0 and 1). The default value is 0.15 for STEPWISE, and 0.1 for BACKWARD. The FORWARD subcommand doesn't
use this input.
For stepwise selection, K for AREMOVE must be greater than or equal to K for AENTER. If only AREMOVE is specified
by a user, then AENTER = AREMOVE, vice versa.
BEST K
Specifies the best K alternative terms to show in the output. K is an integer from 1 to 10.
If BEST K is not entered, no alternative term will appear in the output. The default is no alternative term.
Terms
LOWER K...K
If you do not use LOWER, the lower bound of each component is the minimum value in the column of the
component. Specify as many bounds as you specify components. Specify 0 for components that do not have
lower bounds.
BLOCKS C
Specifies a blocking variable column when you specify your model explicitly on MIXREG. That is, you are not using
a model that you have stored with another command. The blocking variable column can be numeric or text, and
can contain any value. The levels do not need to be in any special order. When the blocking column is numeric,
the smallest value is block 1, the second smallest value is block 2, and so on.
Prediction
PREDICT E...E
Computes the fitted response values for given values of the components. PREDICT displays a table that contains
the fitted Ys, standard errors of the fitted Ys, a 95% confidence interval, and a 95% prediction interval. E...E can
be a list of constants or a list of columns, or a mixture of constants and columns. Component columns or constants
should be listed first, followed by process variables, if specified, and the amount variable, if specified.
PBLOCK E
Specifies the block of new design points if blocks are included in your design.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
PSFITS C
Stores the fits in C.
377
Minitab Statistical Software DOE
PSEFIT C
Stores the estimated standard errors of the fits in C.
CLIMITS C...C
Stores the lower and upper confidence limits in C...C.
PLIMITS C...C
Stores the lower and upper prediction limits in C...C.
Graphs
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data, or versus the order specified in C. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4...n).
GFOURPACK [C]
Displays four residual plots—a histogram of the residuals, a normal probability plot of the residuals, the residuals
versus fitted the values, and the residuals versus the order of the data, or versus the order specified in C—in one
graph.
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
Results
TOLERANCE K
Specifies the tolerance level for collinearity and constant check. By default, K = 4 * 2.22e-016
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
378
Minitab Statistical Software DOE
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the table of coefficients, s, R-sq, R-sq(adj), the analysis of variance table,
the unusual values in the table of fits and residuals.
1
Same as K = 1 output.2 (default)
Same as K = 2 output, but also displays the full table of fits and residuals.3
ORDER C
Specifies the row order of the table of fits and residuals that is displayed in the output. Specify the StdOrder
column in C.
Storage
FITS C...C
Stores the fitted values in C...C.
RESIDUALS C...C
Stores the residuals (response fit) in C...C.
SRESIDUALS C...C
Stores the standardized residuals in C...C.
TRESIDUALS C...C
Stores the deleted Studentized residuals in C...C.
COEFFICIENTS C...C
Stores the coefficients, using one column for each response. These are the same coefficients that are displayed
in the output. If MIXREG removes some terms because the data cannot support them, then the removed terms
do not appear on the output.
MODEL C...C
Requests storage of model term codes. The number of columns matches the number of responses in C...C.
XMATRIX M
Stores the design matrix. If the design was blocked into k blocks, then there are (k 1) columns for block dummy
variables. MIXREG uses the same method of coding blocks as GLM. The block dummy variables are followed by
one column for each component. When the model has 2-way interactions, the design matrix contains a column
for each interaction. The column for a 2-way interaction is the product of the corresponding two components.
When the model has 3-way interactions, the design matrix contains a column for each interaction. The column
for a 3-way interaction is the product of the corresponding three components. When the model has additional
terms for a full cubic, then the design matrix contains one column for each additional term. For example, the
column for a term such as X1 * X3 * (X1 X3), with X1 in C1 and X3 in C3, is calculated using the equation C1 *
C3 * (C1 C3).
Because MIXREG allows no constant in the model, the design matrix does not contain a column of 1s.
When MIXREG removes terms because the data cannot support them, the design matrix does not contain the
removed terms. The columns of the stored matrix match the coefficients that are displayed and/or stored.
HI C
Stores the leverage values.
379
Minitab Statistical Software DOE
COOKD C...C
Stores Cook's distance values, using one column for each response.
DFITS C...C
Stores the DFITS (also called DFFITS), using one column for each response.
DESIGN
Stores model information to enable items on the menu that use the model, such as the response optimizer. To
use session commands to run the analyses that use the model, store the model information in a column with
MODEL.
OPTDES: Session command for selecting an optimal design
OPTDES K [C...C]
Select an optimal design by specifying the number of final design points in K and optionally, specifying candidate
design columns in C...C.
The purpose of an optimal design is to select design points according to some criteria. Minitab's optimal design
capabilities can be used with response surface designs and mixture designs. You can use Select Optimal Design
to do the following:
Select an optimal set of design points.
Augment (add points to) an existing design.
Improve the D-optimality of an existing design.
Evaluate and compare designs.
OPTDES has the following forms:
OPTDES K: Specifies the number of final design points to select based on D-optimality. For this command
form either a factorial model, mixture model, or response surface model must be specified by subcommands
FACMODEL, MIXMODEL, or RESMODEL. The constant K must be a positive integer or 0. If K = zero, you must
use either the AUGMENT or EVALUATE subcommand.
OPTDES K, C...C: Specifies the number of final design points and the design columns that contain the candidate
set. Constant K must be a positive integer. You must specify at least 2 design columns. All columns must have
the same length and must be numeric. With this form of the main command you cannot have the following
subcommands: FACMODEL, RESMODEL, MIXMODEL, EVALUATE, BLOCK, GENERATE, EXCHANGE, FEDOROV,
SEQUENTIAL.
Note The subcommands DESIGN and COPY replace the obsolete subcommands XMATRIX and CARRY.
FACMODEL terms
Species the terms of a factorial model used in selecting D-optimal design. The legal term list is the same as
in GLM.
FACMODEL, RESMODEL, and MIXMODEL are mutually exclusive and one of them must be the first
subcommand.
MIXMODEL terms
Specifies the terms of a mixture model used in selecting D-optimal design. The legal term list is the same as
in MIXREG.
FACMODEL, RESMODEL, and MIXMODEL are mutually exclusive and one of them must be the first
subcommand.
380
Minitab Statistical Software DOE
RESMODEL terms
Specifies the terms of a response surface model used in selecting D-optimal design. The legal term list is the
same as in RSREG. When you use RESMODEL, also use INUNIT and LEVELS.
FACMODEL, RESMODEL, and MIXMODEL are mutually exclusive and one of them must be the first
subcommand.
INUNIT
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
LEVELS K K, ..., K K
Specifies uncoded levels for all continuous factors K K, ..., K K. Enter the low level, then the high level,
for each continuous factor that follows RESMODEL. List the pairs of levels in the order of the factors that
follow RESMODEL.
AUGMENT C
Augments or improves an existing design indicated by row flags in C. Column C must be numeric and must
contain integers. The column length must match the length of the design columns.
Cannot be specified together with EVALUATE, GENERATE, or SEQUENTIAL.
EVALUATE C
Evaluates an existing design indicated by row flags in C. Column C must be numeric and must contain
non-negative integers. The column length must match the length of the design columns.
Cannot be specified with OPTDES K C...C, AUGMENT, EXCHANGE, FEDOROV, SEQUENTIAL, GENERATE,
INDICATOR.
BLOCK C
Specifies the blocking column. The column can be alpha or numeric with 2–64 distinct values. Column length
must match the length of the design columns. Must not be on the term list.
Cannot be specified with OPTDES K C...C.
PROCESS C...C
Specifies process variable columns. Columns must be either on the main line if OPTDES K C...C or on the term
list. Columns may be alpha or numeric with exactly 2 levels. With OPTDES K C...C, only numerical process
variable columns are allowed. The number of columns must be between 1 and 7. Column lengths must match
the length of design columns.
Cannot be specified with AMOUNT or with factorial or response surface models.
AMOUNT C
Specifies the mixture amount column. Column must be either on the main line if OPTDES K C...C or on the
term list. The column must be numeric with 2–5 distinct numerical values. The column length must match
the length of the design columns.
Cannot be specified with PROCESS or with factorial or response surface models.
381
Minitab Statistical Software DOE
PSEUDO
Specifies that calculations are performed using pseudo-components. PSEUDO is ignored in cases of factorial
or response surface designs.
GENERATE K [K [K]]
Generates K % of initial points randomly, and adds the rest of points by sequential method. The second K is
the number of random trials. The third K is the base for the random data generator. Legal values are as
follows: first and second K integer, third K any positive real. 0 < first K <=100, 1 <= second K <= 25.
Cannot be specified with OPTDES K C...C, AUGMENT, EVALUATE, SEQUENT.
SEQUENTIAL
Selects design points by the sequential algorithm for the initial design.
Cannot be specified with OPTDES K C...C, AUGMENT, EVALUATE, GENERATE.
EXCHANGE K
Improves the initial design matrix by adding and dropping K design points one at a time. Legal values are
as follows: K is an integer, 1 <= K <= 5.
Cannot be specified with OPTDES K C...C, EVALUATE, FEDOROV.
FEDOROV
Improves the initial design matrix using Fedorov's algorithm.
Cannot be specified with OPTDES K C...C, EVALUATE, EXCHANGE.
INDICATOR C
Stores selection indicators in the specified column.
Cannot be specified with EVALUATE.
DESIGN
Copies the standard order, run order, point type, blocks, and factors to a new worksheet for rows in the
optimal design.
COPY C...C
Copies rows in the optimal design to the new worksheet for columns that are not part of the design.
For example, you can use COPY to copy a column of covariate measurements.
BRIEF K
Controls the amount of output with a value in K.
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays a summary table for the final design only.1
Minitab displays summary tables for the intermediate design and the final design.2 (default)
Displays summary tables and the final design matrix.3
382
Minitab Statistical Software DOE
DETZERO [K]
Overrides the lower limit for the determinant, which is E-30. Use when you receive the "rank deficient data"
error message, but still want to perform the analysis. K is an integer that is greater than or equal to 30. The
default value is 30.
Plot Mixture Designs
SIMPLEX: Session command for creating a simplex design plot
SIMPLEX C...C
Creates a simplex design plot to visualize the mixture design space (or a slice of the design space, if you have
more than three components). Minitab plots the design points on triangular axes. You can plot components,
components and process variables, or components and an amount variable.
For information about graphics options for SIMPLEX, go to Graphics options for SIMPLEX on page 1154.
SINGLE C C C
Specifies three components for a single plot in C C C. Specified columns must be on the main command list.
ALLTRIPLETS
Requests multiple plots to show all component triplets (for only 3–5 components).
PANEL
Displays plots in one graph.
SEPARATE
Displays each graph in a separate graph.
TOTAL K [K...K]
TOTAL C
Specifies single or multiple total values. A single K must equal the common row sum of components. Multiple
Ks are accepted only if the Amount column is specified. The total subcommand must be specified if the
Amount column's specified either with a single K = 1 or with multiple K values that match the values in the
Amount column.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
383
Minitab Statistical Software DOE
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
PROCESS C...C
Specifies process variable columns in C...C. The length of the columns must match component columns.
Columns may be numeric or alpha and must contain 2 levels. The maximum number of process variables is
7.
AMOUNT C
Specifies the mixture amount column in C. The length of the column must match the component columns.
The column must be numeric and must contain 2–5 distinct positive values. Must have a Total subcommand
with either K = 1, or multiple Ks must match the values in C.
LABEL [C]
Specifies the labels of the design points in C. If you omit C, then label points by number of replicates. The
length of the column must match component columns.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
Middle levelCMIDDLE
Upper boundCHIGH
CHOLD K...K
Holds components that are not on the plot to values that you specify in K...K. Each K must be between the
lower and upper bounds (inclusive) of the corresponding component. Only design points that match these
values are plotted. By default, all components that are not on the plot are held at their lower bound.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
384
Minitab Statistical Software DOE
FHOLD K...K
FHOLD C
Holds process variables to values that you specify. Sets the levels of process variables at a combination of
–1 and 1. K must equal the number of process variables in the model. Only design points that match these
values are plotted. By default, all process variables are held at –1.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
SGRID [K]
Displays grid lines at 0.1 intervals or at intervals specified in K.
SPSIMP: Session command for creating a simplex design plot
SPSIMP C...C
Creates three types of special simplex design plots:
Simplex plot with four components
Simplex plot with process variables
Simplex plot with amount variable
C...C must include all components in the design matrix.
Enables you to visualize the mixture design space (or a slice of the design space if you have more than three
components). Minitab plots the design points on triangular axes. You can plot components, components and
process variables, or components and an amount variable.
For information on graphics options for SPSIMP, go to Graphics options for SPSIMP on page 1157.
TYPE K
Determines which of the three simplex plots is created in K.
When to usePlot that is createdValue of K
The model contains at least four components.Four component matrix plot1
385
Minitab Statistical Software DOE
When to usePlot that is createdValue of K
The model contains process variables.Contour plot with process variables2
The amount variable is specified in the model.Contour plot with mixture amounts3
SINGLE C C C [C]
Specifies components in C C C [C] on the three or four axes of a single plot.
Three components must be specified if the plot type is 2 or 3. Four components must be specified if the plot
type is 1. Columns must be listed in the main command. If this command isn't specified, then Minitab uses
the first 3 or 4 components listed in SPSIMP according to the type of plot that you specify in TYPE.
ALLTRIPLETS
Displays multiple plots to show all component triplets (only for 3–5 components).
PANEL
Displays the plots in one graph.
SEPARATE
Displays the plots in separate graphs.
TOTAL K [K...K]
TOTAL C
Specifies 1 to 5 total values. Single K must equal the common row sum of components. Multiple Ks are
accepted only if Amount column specified. The total subcommand must be specified if the Amount columns
specified either with a single K = 1 or with multiple K values matching the values in column Amount.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
386
Minitab Statistical Software DOE
PROCESS C...C
Specifies that the process variables are in C...C. The length of the columns must match component columns.
Columns can be numeric or text and must contain 2 levels. The maximum number of process variables is 7.
AMOUNT C
Specifies the mixture amount in C. The length of the column must match the component columns. The column
must be numeric, and contain 2–5 distinct positive values. Must have Total subcommand with either K = 1,
or multiple Ks must match values in C.
LABEL [C]
Specifies labels for design points are in C. If you omit C, then you should label the points by the number of
replicates. The length of the column must match the component columns.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
Middle levelCMIDDLE
Upper boundCHIGH
CHOLD K...K
CHOLD C
Holds components that are not on the plot to values specified in K...K or C. The number of constants or the
length of the column must match the number of components. Each K must be between the lower and upper
bounds (inclusive) of the corresponding component. Only design points that match these values are plotted.
By default, all components that are not on the plot are held at their lower bound.
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
FHOLD K...K
FHOLD C
Holds process variables to values that you specify. Sets the levels of process variables at a combination of
–1 and 1. K must equal the number of process variables in the model. Only design points that match these
values are plotted. By default, all process variables are held at –1.
387
Minitab Statistical Software DOE
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
SGRID [K]
Displays grid lines at 0.2 intervals or at intervals specified in K. All K must be 0 < K < 1. The default is K = 0.2.
%SIMPROC: Session command for creating a simplex plot
%SIMPROC C...C
Creates a simplex plot of components in C...C. %SIMPROC is used for certain simplex plots when all level
combinations are plotted and there are process variables in the model. A simplex plot helps you visualize the
mixture design space. Minitab plots the design points on triangular axes.
SINGLE C C C
Specifies the three components on the three axes in C C C. Columns must be listed in main command.
TOTAL K
Specifies one total value in K. K must equal the common row sum of components.
LOWER K...K
Specifies the lower bound of components in K...K. The number of Ks must equal the number of components.
All Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL.
UPPER K...K
Specifies the upper bound of components in K...K. The number of K's equals the number of components. All
Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL.
LN1 K...K, LN2 K...K, ... LN10 K...K
Specifies the linear constraints in K...K. The first linear constraint is in LN1, the second linear constraint is in
LN2, and so on. You can have a maximum of 10 linear constraints.
Each subcommand specifies a linear constraint on components in mixture models. The first K represents the
lower bound of a linear combination of the components, and the last K the upper bound of the linear
combination. The Ks in between represent the coefficients of the components.
For example, let A, B, and C be three components in a mixture design. A linear constraint on A, B, and C is
represented by:
0.5 <= 3A+2B+C<=0.9
Then, the LN1 subcommand is specified as:
LN1 0.5 3 2 1 0.9.
388
Minitab Statistical Software DOE
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PROCESS C C C
Specifies process variable columns in C C C. The length of the columns must match component columns.
Columns may be numeric or text and must contain 2 levels. The number of process variables must equal 3.
CHOLD K...K
Specifies the hold values in K...K for components that are not on plot. Each K must be between the lower and
upper bounds (inclusive) of the corresponding component. Only design points that match these values are
plotted.
CMIN K...K
Specifies the minimum axis values of all components, including those not on the plot, in K...K. Values may
be in constants. The number of constants must match the number of components.
SGRID K
Specifies that grid lines are drawn on each axis at intervals specified in K.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
TRACE: Session command for creating a response trace plot
TRACE C C
Displays a response trace plot for the response in the first C and the model column in the second C, which is
stored using MIXREG and contains the model information.
A response trace plot (also called component effects plot) shows the effect of each component on the response.
Several response traces, which are a series of predictions from the fitted model, are plotted along a component
direction. The trace curves show the effect of changing the corresponding component along an imaginary line
(direction) connecting the reference blend to the vertex.
Each component in the mixture has a corresponding trace direction. The points along a trace direction of a
component are connected thereby producing as many curves as there are components in the mixture.
Specify a single response column, and the column where the model is stored. The model column contains the
number and ID of components, number and ID of process variables, ID of blocking column, ID of mixture amount
column, term codes and coefficients. The response column length must match the length of component columns.
TOTAL K [K...K]
TOTAL C
Specifies the total amount in K, or in C, from 1–5 values.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The column must be numeric.
The number of values equals the number of components specified in the model column.
389
Minitab Statistical Software DOE
All values must be 0 <= K < TOTAL and SUM(K) < TOTAL (TOTAL is row sum of components).
UPPER K...K
UPPER C
Specifies the upper bound of the components. The column must be numeric.
The number of values equals the number of components specified in the model column.
All values must be 0 < K <= TOTAL and SUM(K) > TOTAL (TOTAL is row sum of comps).
CLINEAR K...K
CLINEAR C
Specifies a linear constraint on the components. There can be up to 10 such subcommands. The column
must be numeric.
The number of values equals the number of components + 2. The first value, the lower bound, must be
smaller than last value, the upper bound. One of the bounds might be missing, i.e., set to ' * '.
Note You can also use LINEAR to specify a linear constraint on the components.
PIEPEL
Specifies the plot uses Piepel directions.
REFERENCE K
REFERENCE K...K
Specifies the row ID of the reference blend or the coordinates of the reference blend. If you do not specify
XREFERENCE, then the default is to use the centroid of vertices.
XREFERENCE K specifies row id of the reference blend; 0 < K <= number of design points (length of design
columns).
XREFERENCE K...K specifies coordinates of the reference blend. The number of Ks equals the number of
components. Each K must be between the corresponding lower and upper bounds.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
FHOLD K...K
Sets process variable levels to specified values.
The number of Ks must equal the number of process variables. Constants must be between -1 and 1.
AHOLD K
Sets mixture amount to a specified value. The specified value must be between min and max of IPAMNT
column.
390
Minitab Statistical Software DOE
MAXIMUM K K
Specifies the maximum value of an axis. The first K specifies the x- (use 1) or y- (use 2) axis and the second
K specifies the maximum value. You can also use MAX to specify the maximum value of an axis.
MINIMUM K K
Specifies the minimum value of an axis. The first K specifies the x- (use 1) or y- (use 2) axis and the second
K specifies the minimum value. You can also use MIN to specify the minimum value of an axis.
CURVE
Specifies different type and color for trace curves.
TYPE K...K
Use TYPE to specify the line type of trace curves. The default is solid lines.
COLOR K...K
Use COLOR to specify the line color of trace curves. The default is different colors.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
MIXCONTOUR: Session command for creating a contour plot
MIXCONTOUR C C
Displays a contour plot for the response in the first C and the model column in the second C, which is stored
using MIXREG and contains the model information.
The model column contains the number and the ID of the components, the number and the ID of the process
variables, the ID of the blocking column, the ID of the mixture amount column, the term codes, and the coefficients.
The response column and the component columns must have the same number of rows.
For more information about graphics options for MIXCONTOUR, go to Graphics options for MIXCONTOUR on
page 1148.
SINGLE C C [C]
Specifies three components in C C C or two numerical process variables in C C for a single plot. You must
specify the components or process variables that are on the list in the model column.
ALLTRIPLETS
Specifies that multiple plots show all component triplets (only for 3–5 components).
PANEL
Displays all the plots in one graph.
SEPARATE
Displays each plot on a separate page.
ALLPAIRS
Specifies that multiple plots show all pairs of numerical process variables.
PANEL
Displays all the plots in one graph.
SEPARATE
Displays each plot on a separate page.
391
Minitab Statistical Software DOE
NLEVELS K
Specifies the number of contour levels in K. K must be 2–15.
LEVELS K...K
Specifies the values of contour levels in K. K must be 2–15.
NMESH K K
Specifies number of mesh points. The first constant specifies the direction for the number of mesh points:
1 = Horizontal
2 = Vertical
To specify both directions, issue NMESH twice.
The second constant specifies the number of mesh points. The second K must be 2–101.
TOTAL K [K...K]
TOTAL C
Specifies single or multiple total values. A single K must equal the common row sum of components. Multiple
Ks are accepted only if the Amount column is specified. The total subcommand must be specified if the
Amount column's specified either with a single K = 1 or with multiple K values that match the values in the
Amount column.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
392
Minitab Statistical Software DOE
Bound or levelCommand
Middle levelCMIDDLE
Upper boundCHIGH
CHOLD K...K
Holds components that are not on the plot to values that you specify in K...K. Each K must be between the
lower and upper bounds (inclusive) of the corresponding component. Only design points that match these
values are plotted. By default, all components that are not on the plot are held at their lower bound.
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
FHOLD K...K
FHOLD C
Holds process variables to values that you specify. Sets the levels of process variables at a combination of
–1 and 1. K must equal the number of process variables in the model. Only design points that match these
values are plotted. By default, all process variables are held at –1.
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
SGRID [K]
Displays grid lines on each axis at intervals specified in K. All K must be 0 < K < 1. The default is K = 0.1.
393
Minitab Statistical Software DOE
SPCONT: Session command for creating a contour design plot
SPCONT C C
Creates three types of special contour design plots:
Contour plot with four components
Contour plot with process variables
Contour plot with an amount variable
The first C is the response, and the second C contains the model information.
Enables you to visualize the mixture design space (or a slice of the design space if you have more than three
components). Minitab plots the design points on triangular axes. You can plot components, components and
process variables, or components and an amount variable.
For information on graphics options that are available for SPCONT, go to Graphics options for SPCONT on page
1155.
TYPE K
Determines which of the three simplex plots is created in K.
When to use the plotPlot that is createdValue of K
The model contains at least four components.Four component matrix plot1
The model contains process variables.Contour plot with process variables2
The amount variable is specified in the model.Contour plot with mixture amounts3
SINGLE C C C [C]
Specifies components in C C C [C] on the three or four axes of a single plot.
Three components must be specified if plot type is 2 or 3. Four components must be specified if plot type
is 1. Columns must be listed in the model column. If this command isn't specified, Minitab uses the first 3 or
4 components listed in SPCONT according to the type of plot you specified in TYPE.
ALLTRIPLETS
Displays multiple plots to show all component triplets (only for 3–5 components).
PANEL
Displays the plots in one graph.
SEPARATE
Displays the plots in separate graphs.
NLEVELS K
Specifies the number of contour levels. K must be between 2 and 15.
LEVELS K...K
Specifies the values of contour levels in K...K. K must be between 2 and 15.
TOTAL K [K...K]
TOTAL C
Specifies single or multiple total values. A single K must equal the common row sum of components. Multiple
Ks are accepted only if the Amount column is specified. The total subcommand must be specified if the
394
Minitab Statistical Software DOE
Amount column's specified either with a single K = 1 or with multiple K values that match the values in the
Amount column.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
PROCESS C...C
Specifies that the process variables are in C...C. The length of the columns must match component columns.
Columns can be numeric or alpha and must contain 2 levels. The maximum number of process variables is
7.
AMOUNT C
Specifies the mixture amount in C. The length of the column must match the component columns. The column
must be numeric, and contain 2–5 distinct positive values. Must have Total subcommand with either K = 1,
or multiple Ks must match values in C.
LABEL [C]
Specifies labels for design points are in C. If you omit C, then you should label the points by the number of
replicates. The length of the column must match the component columns.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
Middle levelCMIDDLE
Upper boundCHIGH
395
Minitab Statistical Software DOE
CHOLD K...K
CHOLD C
Holds components that are not on the plot to values specified in K...K or C. The number of constants or the
length of the column must match the number of components. Each K must be between the lower and upper
bounds (inclusive) of the corresponding component. Only design points that match these values are plotted.
By default, all components that are not on the plot are held at their lower bound.
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
FHOLD K...K
FHOLD C
Holds process variables to values that you specify. Sets the levels of process variables at a combination of
–1 and 1. K must equal the number of process variables in the model. Only design points that match these
values are plotted. By default, all process variables are held at –1.
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
SGRID [K]
Displays grid lines at 0.2 intervals or at intervals specified in K. All K must be 0 < K < 1. The default is K = 0.2.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
396
Minitab Statistical Software DOE
MIXSURFACE: Session command for creating a surface plot
MIXSURFACE C C
Displays surface plot for response in C and the model column in C, which is stored using MIXREG and contains
the model information.
Specifies a single response column and the column where the model is stored. The model column contains the
number and ID of components, number and ID of process variables, ID of blocking column, ID of mixture amount
column, term codes, and coefficients. The length of the response column must match that of component columns.
For information graphics options for MIXSURFACE, go to Graphics options for MIXSURFACE on page 1150.
SINGLE C C [C]
Specifies three components in CCC or two numerical process variables in C C for a single plot. The components
or process variables must be specified on the list in the model column.
ALLTRIPLETS
Displays multiple plots to show all component triplets (only for 3–5 components).
PANEL
Displays plots in one graph.
SEPARATE
Displays each graph on a separate page.
ALLPAIRS
Displays multiple plots to show all numerical process variable pairs.
PANEL
Displays plots in one graph.
SEPARATE
Displays each graph on a separate page.
NMESH K K
Specifies number of mesh points. The first constant specifies the direction for the number of mesh points:
1 = Horizontal
2 = Vertical
To specify both directions, issue NMESH twice.
The second constant specifies the number of mesh points. The second K must be from 2 to 101.
TOTAL K [K...K]
TOTAL C
Specifies single or multiple total values. A single K must equal the common row sum of components. Multiple
Ks are accepted only if the Amount column is specified. The total subcommand must be specified if the
Amount column's specified either with a single K = 1 or with multiple K values that match the values in the
Amount column.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
397
Minitab Statistical Software DOE
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
Middle levelCMIDDLE
Upper boundCHIGH
CHOLD K...K
Holds components that are not on the plot to values that you specify in K...K. Each K must be between the
lower and upper bounds (inclusive) of the corresponding component. Only design points that match these
values are plotted. By default, all components that are not on the plot are held at their lower bound.
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
398
Minitab Statistical Software DOE
FHOLD K...K
FHOLD C
Holds process variables to values that you specify. Sets the levels of process variables at a combination of
–1 and 1. K must equal the number of process variables in the model. Only design points that match these
values are plotted. By default, all process variables are held at –1.
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
SGRID [K]
Displays grid lines on each axis at specified intervals. All K must be 0 < K < 1. The default is K = 0.1.
MIXOVER: Session command for creating an overlaid contour plot
MIXOVER
Draws an overlaid contour plot for multiple (up to 10) responses of mixture models.
Contour plots for mixture designs show how response variables are related to three continuous design variables,
while holding the other variables in a model at certain settings. In a contour plot, the fitted response model is
viewed as a 2-dimensional surface where all points that have the same fitted value are connected to produce
contour lines of constants. Contour plots are useful for establishing operating conditions that produce desirable
response values.
Applications that involve multiple responses present a different challenge than single-response experiments.
Because each response is important in determining the quality of the product, you need to consider the responses
simultaneously. Optimal settings for input variables for one response might be far from optimal for another
response. Overlaid contour plots allow you to visually identify an area of compromise among the various responses.
For more information about graphics options for MIXOVER, go to Graphics options for MIXOVER on page 1150.
RESPONSE C...C
Specifies a set of up to 10 response variables for the experiment in C...C.
MODEL C...C
Specifies a set of model columns (one for each response), which contain design and model information in
C...C. Each model column is stored by the MODEL subcommand of MIXREG.
SINGLE C C [C]
Specifies three components or two numerical process variables for a single plot. You must specify the
components or process variables on the list in the model column.
399
Minitab Statistical Software DOE
LEVELS K...K
Specifies the values of contour levels in K...K. K must be between 2 and 15.
TOTAL K [K...K]
TOTAL C
Specifies single or multiple total values. A single K must equal the common row sum of components. Multiple
Ks are accepted only if the Amount column is specified. The total subcommand must be specified if the
Amount column's specified either with a single K = 1 or with multiple K values that match the values in the
Amount column.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
Middle levelCMIDDLE
Upper boundCHIGH
CHOLD K...K
Holds components that are not on the plot to values that you specify in K...K. Each K must be between the
lower and upper bounds (inclusive) of the corresponding component. Only design points that match these
values are plotted. By default, all components that are not on the plot are held at their lower bound.
400
Minitab Statistical Software DOE
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
SGRID [K]
Displays grid lines on each axis at specified intervals. All Ks must be 0 < K < 1. By default, K is 0.2.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
FFMAIN: Superseded by FACPLOT except for mixture designs
Note FFMAIN is superseded by FACPLOT on page 276, except for mixture designs.
FFMAIN C...C
Creates a main effects plot for 2-level factorial designs, for factors in C...C.
FFMAIN plots the means at the two levels of each factor and connects them with a line. FFMAIN plots any center
points you have, using a different symbol than that used for the factorial points. A reference line is drawn through
the plot to represent the overall mean (also called grand mean) of the response data.
Specify up to 50 factors. The factor columns can be numeric or text, and can contain any values. The levels do not
need to be in any special order. When the factor column is text, the first entry (row 1) is level 1. The next entry
that is different is level 2. All factors must have 2 levels, and can have center points.
401
Minitab Statistical Software DOE
RESPONSE C (required)
Plots the response data in C. If you specify RESPONSE without FMEANS, then Minitab plots the raw response
data. The main effects are calculated based on the means of the data. If you plot process variables from a
mixture design, Minitab fits only the raw response data, not the fitted means.
With RESPONSE, you can specify up to 50 factors.
FMEANS C...C
Plots the least squares or fitted means in C...C. If you specify RESPONSE with FMEANS, then Minitab plots
the predicted values from the model. The main effects are calculated based on the fitted means. If you plot
process variables from a mixture design, Minitab fits only the raw response data, not the fitted means.
With FMEANS, you can specify up to 10 factors.
YMIN K
Specifies the minimum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
YMAX K
Specifies the maximum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
CTPT K
Specifies the center point column in K. Minitab considers a value of 0 as a center point.
LEVELS K K, ..., K K
Specifies the levels for the uncoded units for each factor in K K, ..., K K. Use LEVELS to change the default
order of levels that Minitab uses.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
402
Minitab Statistical Software DOE
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
MIXTURE
Specifies a mixture design, which indicates that the factors are process variables.
FFINT: Superseded by FACPLOT except for mixture designs
Note FFINT is superseded by FACPLOT on page 276, except for mixture designs.
FFINT C...C
Creates interaction plots for factors in C...C.
Creates an interaction plot for 2-level factorial designs. If you enter 2 factors on the command line, then Minitab
displays a single interaction plot. If you enter more than 2 factors, then Minitab displays a matrix of interaction
plots. You can use factors from designs that are generated by FFDESIGN and PBDESIGN.
You can specify up to 15 columns that contain the factors. The factor columns can be numeric or text, and can
contain any values. The levels do not need to be in any special order. When the factor column is text, the first
entry (row 1) is level 1, the next entry that is different is level 2, and so on. All factors must have 2 levels, and can
have center points.
RESPONSE C (required)
Plots the response data in C. If you specify RESPONSE without FMEANS, then Minitab plots the raw response
data. The interaction effects are calculated based on the means of the data. If you plot process variables from
a mixture design, then Minitab fits only the raw response data, not the fitted means.
403
Minitab Statistical Software DOE
You can specify up to 15 factors.
FMEANS C...C
Plots the least squares or fitted means in C...C. If you specify RESPONSE with FMEANS, then Minitab plots
the predicted values from the model. The interaction effects are calculated based on the fitted means. If you
plot process variables from a mixture design, Minitab fits only the raw response data, not the fitted means.
FULL
Displays the full interaction matrix when you enter more than 2 factors. By default, Minitab displays the half
matrix. The half matrix displays the plots in the upper right portion of the matrix. In the full matrix, the
transpose of each plot in the upper right is displayed in the lower left portion of the matrix. The full matrix
takes longer to display than the half matrix.
YMIN K
Specifies the minimum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
YMAX K
Specifies the maximum values on the y-axis of every plot that is displayed by the current command in K.
Making the minimum and maximum values the same is useful when you compare several plots of related
data.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
CTPT C
Specifies the center point column in C. Minitab considers a value of 0 as a center point.
LEVELS K K, ..., K K
Specifies the levels for the uncoded units for each factor in K K, ..., K K. Use LEVELS to change the default
order of levels that Minitab uses.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
404
Minitab Statistical Software DOE
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
MIXTURE
Specifies a mixture design, which indicates that the factors are process variables.
FFCUBE: Session command for creating a cube plot
FFCUBE C...C
Use FFCUBE to draw a cube plot that does not show mean response values. With a mixture design, you can use
FFCUBE to draw a cube plot that shows mean response values. For all other models, such as the models from
FFAC or REGR, use MFFCUBE on page 335 to draw a cube plot that shows mean response values.
Displays a cube plot for factors in C...C. You can draw a cube plot with 2–8 factors for each response entered with
the RESPONSE subcommand with data means or 2–7 factors with fitted means. The factor columns can be numeric
or text, and can contain any values. The levels do not need to be in any special order. When the factor column is
text, the first entry (row 1) is level 1, the next entry that is different is level 2, and so on. All factors must have 2
levels, and can have center points.
When you use the RESPONSE subcommand, FFCUBE displays the means for the response at each point in the
cube where observations are measured. When you do not use the RESPONSE subcommand, FFCUBE draws points
on the cube for the effects that are in your model, which helps you visualize the design.
RESPONSE C...C
Plots the raw response data that is in columns C...C. The means for the cube points are calculated from the
data. You can specify 2–8 factors.
405
Minitab Statistical Software DOE
If you use FMEANS, RESPONSE is required.
FMEANS C...C
Plots the least squares or the fitted means that are in columns C...C. You can specify 2-7 factors. The column
must contain the fitted means in standard order for the cube points. The last row must be the overall mean
of the data.
If you use FMEANS, RESPONSE is required.
INUNIT K (required)
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded form0
Uncoded form1
CTPT C
Specifies a center point column in C. Minitab considers a value of 0 to be a center point. A valid column
contains only values of 0 and 1.
If you don't use MIXTURE, CTPT is required. You cannot use both MIXTURE and CTPT.
LEVELS K K, ..., K K (required)
Specifies the levels for the uncoded units for each factor in K K, ..., K K. The order of the parameters must be
identical to the order of the factors that follow FFCUBE.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
406
Minitab Statistical Software DOE
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
MIXTURE
Specifies a mixture design, indicating that the factors are process variables.
Response Optimization for Mixtures
MIXOVER: Session command for creating an overlaid contour plot
MIXOVER
Draws an overlaid contour plot for multiple (up to 10) responses of mixture models.
Contour plots for mixture designs show how response variables are related to three continuous design variables,
while holding the other variables in a model at certain settings. In a contour plot, the fitted response model is
viewed as a 2-dimensional surface where all points that have the same fitted value are connected to produce
contour lines of constants. Contour plots are useful for establishing operating conditions that produce desirable
response values.
Applications that involve multiple responses present a different challenge than single-response experiments.
Because each response is important in determining the quality of the product, you need to consider the responses
simultaneously. Optimal settings for input variables for one response might be far from optimal for another
response. Overlaid contour plots allow you to visually identify an area of compromise among the various responses.
For more information about graphics options for MIXOVER, go to Graphics options for MIXOVER on page 1150.
RESPONSE C...C
Specifies a set of up to 10 response variables for the experiment in C...C.
MODEL C...C
Specifies a set of model columns (one for each response), which contain design and model information in
C...C. Each model column is stored by the MODEL subcommand of MIXREG.
407
Minitab Statistical Software DOE
SINGLE C C [C]
Specifies three components or two numerical process variables for a single plot. You must specify the
components or process variables on the list in the model column.
LEVELS K...K
Specifies the values of contour levels in K...K. K must be between 2 and 15.
TOTAL K [K...K]
TOTAL C
Specifies single or multiple total values. A single K must equal the common row sum of components. Multiple
Ks are accepted only if the Amount column is specified. The total subcommand must be specified if the
Amount column's specified either with a single K = 1 or with multiple K values that match the values in the
Amount column.
LOWER K...K
LOWER C
Specifies the lower bound of the components. The number of Ks must equal the number of components. All
Ks must be 0 <= K < TOTAL and SUM(K) < TOTAL. (TOTAL is the first value on Total.)
UPPER K...K
UPPER C
Specifies the upper bound of the components in K...K. The number of Ks must equal the number of
components. All Ks must be 0 < K <= TOTAL and SUM(K) > TOTAL. (TOTAL is the first value on Total.) Each
upper bound must be greater than the corresponding lower bound.
CLINEAR K...K
CLINEAR C
Specifies the linear constraints on the components. The number of Ks must equal the number of components
+ 2. The first K, the lower bound, must be less than the last K, the upper bound. If one of the bounds is
missing, set it to the missing value ' * '. You can use up to 10 CLINEAR subcommands.
PROPORTION
Specifies the proportion unit for the axes on the plot.
PSEUDO
Specifies the pseudo-component unit for the axes on the plot.
CLOW, CMIDDLE, and CHIGH
Sets the values of all the components that are not on the plot. Only design points that match these values
are plotted. By default, all components that are not on the plot are held at their lower bound. These commands
are not available for the process variable contour plot.
Bound or levelCommand
Lowest boundCLOW
Middle levelCMIDDLE
Upper boundCHIGH
408
Minitab Statistical Software DOE
CHOLD K...K
Holds components that are not on the plot to values that you specify in K...K. Each K must be between the
lower and upper bounds (inclusive) of the corresponding component. Only design points that match these
values are plotted. By default, all components that are not on the plot are held at their lower bound.
CMIN K...K
CMIN C
Specifies the minimum axis values for all components, including those that are not on the plot. The number
of constants and the length of the column must match the number of components.
FLOW, FMIDDLE, and FHIGH
Sets the level of all the process variables that are not on plot. By default, all process variables are held at –1.
LevelCommand
Low level (–1)FLOW
Middle level (0)FMIDDLE
High level (1)FHIGH
FMIN K...K
FMIN C
Specifies the minimum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
FMAX K...K
FMAX C
Specifies the maximum axis values for all process variables, including those that are not on the plot. The
number of constants or the length of the column must match the number of process variables.
AHOLD K
Sets the mixture amount at the specified value in K. Only design points that match these values are plotted.
By default, the amount value is held at the first value in the Amount column.
SGRID [K]
Displays grid lines on each axis at specified intervals. All Ks must be 0 < K < 1. By default, K is 0.2.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
MROPT: Session command for the Response Optimizer
MROPT C...C
Use the Response Optimizer to identify the combination of input variable settings that optimize a single response
or that jointly optimize a set of responses. Joint optimization must satisfy the requirements for all the responses
in the set. The overall desirability (D) is a measure of how well you satisfied the combined goals for all the responses.
Overall desirability has a range of 0 to 1. A value of 1 represents the ideal case. A value of 0 indicates that one or
more responses are outside their acceptable limits.
409
Minitab Statistical Software DOE
Minitab calculates an optimal solution and draws a plot. The optimal solution serves as the starting point for the
plot. With the optimization plot, you can interactively change the input variable settings to perform sensitivity
analyses and to possibly improve the initial solution.
Note Although numerical optimization, along with graphical analysis, can provide useful information, it is not a substitute for subject
matter expertise. Be sure to use relevant background information, theoretical principles, and knowledge from observation or previous
experimentation when you apply these methods.
Enter a set of response columns (up to 10) in the main command. You can use MIXTURE to match the responses
with their appropriate column. This column contains the model information that MROPT needs to find the optimum
solution and draw the trace plots.
For each response, you must do the following:
Select a goal.
Specify a minimum acceptable value, a maximum acceptable value, and a target value.
Specify a utility transfer function value.
Specify a weight or an importance level.
MODELS C...C
Specifies the model for the responses to be optimized. The arguments, one for each response, are the columns
stored by the MODEL subcommand of MIXREG. If you use session commands to optimize responses, you
must manually store the columns using MIXREG and MODEL.
LINEAR K...K
Specifies linear constraints for mixture components. You can use LINEAR up to 10 times.
For p mixture components, you must specify (p + 2) constant arguments. The first argument specifies
the lower bound for a linear inequality constraint. The next p arguments are the coefficients of the linear
function. The final argument is the upper bound on the linear function. Therefore, the subcommand
actually specifies two linear inequality constraints. If one of the bound arguments is ' * ' then there is
only one inequality, defined by the other bound. An inequality with an upper bound can be expressed
in terms of a lower bound by multiplying all coefficients and the bound by –1.
Used only as a subsubcommand with MIXTURE.
TOTAL K
Specifies the total mixture amount or amounts. K is 1–5.
INUNIT K
Specifies whether the design is in coded form or uncoded form.
Form of designValue of K
Coded0
Uncoded1
FLEVELS K K, ..., K K
Specifies values for the levels of each factor in K K,..., K K. The level values can be text or numeric.
GOAL K...K
GOAL C
Specifies a goal for each response. Enter the goal as a code from the following table in either a list of constants
(K...K) or a column (C).
410
Minitab Statistical Software DOE
DescriptionGoalCode
Set the response as small as possible.Smaller is better1
Set the response as close to the target as possible.Target is best2
Set the response as large as possible.Largest is best3
UTWEIGHTS K...K
UTWEIGHTS C
Specifies the weights for each response. The weight defines the shape of the desirability function for each
response. For each response, you can select a weight (from 0.1 to 10) to emphasize or de-emphasize the
target.
EmphasisWeight
Less emphasis the targetLess than 1 (minimum is 0.1)
Equal emphasis on the target and the boundsEqual to 1
More emphasis on the targetGreater than 1 (maximum is 10)
IMPORTANCE K...K
IMPORTANCE C
Specifies importance levels for each response. The levels are numbers between 0.1 and 10. If all responses
are equally desirable, use the default value of 1.0 for each response. Enter one argument (K) for each response,
or a column C) that contains the importance values.
The composite desirability is then the geometric mean of the individual desirabilities. However, if some
responses are more important than others, then you can include this information in the optimal solution by
setting unequal importance values.
Larger values correspond to more important responses. Smaller values correspond to less important responses.
You can also change the weights to perform sensitivity analyses on the optimal solution. For example, the
optimal solution when a response has a large weight might be very different from the optimal solution when
the same response has a small weight.
START K...K
Specifies a starting point for the search algorithm by giving a coordinate for each factor. Enter the coordinates
as constants. Each factor must have one value, and each value must be between the minimum and the
maximum for that factor.
DSTORE C
Stores the composite desirability values that are calculated at the points in the original design in a column.
You can use these values to produce wireframe plots or contour plots of the composite desirability surface
using CONTOURPLOT.
OPTIPLOT
Displays a table that shows the numerically optimal solution, the desirabilities for the responses, and the
interactive optimization plot.
Minimum, maximum, and target values
Specifies the minimum acceptable values, the maximum acceptable values, and the target values for the responses.
You must use all three subcommands. All three commands are needed to obtain the numerically optimum solution.
411
Minitab Statistical Software DOE
You must also enter a value for each response in each of these subcommands. In other words, for each response, you
need a minimum acceptable value, a maximum acceptable value, and a target value. You can enter the values by using
a list of constants, or a column.
If you have a smaller-is-better goal for a response, your goal is to minimize the response. Identify the point of diminishing
returns. That is, you want to minimize the response, but going beyond a certain value makes a small difference or no
difference. If such a point exists, use it as the target value. If it does not exist, use a very small number, one that is
probably not achievable, as the target value. For a smaller-is-better response, the target and the minimum acceptable
value are also equal.
The same is true when the goal is larger-is-better. However, in the larger-is-better case, you need a value on the upper
end of the range instead of on the lower end.
When the goal is target-is-best, you probably have upper and lower specification limits for the response. You can use
these limits as minimum and maximum acceptable values. If not, you might want to use upper and lower points of
diminishing returns, or some other method.
MINACCEPT K...K
MINACCEPT C
Specifies the minimum acceptable values.
MAXACCEPT K...K
MAXACCEPT C
Specifies the maximum acceptable values.
TARGET K...K
TARGET C
Specifies the target values.
Taguchi Designs
OADESIGN: Session command for creating a Taguchi orthogonal
array design
OADESIGN K K K [K K]
Creates a Taguchi orthogonal array design, where the first K specifies the number of runs in the design and the
remaining Ks specify number of levels and number of factors, respectively.
Use OADESIGN to specify a Taguchi orthogonal array design. OADESIGN can take either 3 or 5 integer arguments,
which correspond to the standard Taguchi notation. For example, a commonly used orthogonal array is denoted
by L18 (2**1 3**7). This means that the design has 18 runs, with one two-level factor, and seven three-level factors.
The Minitab command that will specify this design is as follows:
OADESIGN 18 2 1 3 7.
Or, as follows:
OADESIGN 18 3 7 2 1.
If you want to use this array with one two-level factor and six three-level factors, the command is as follows:
OADESIGN 18 2 1 3 6.
412
Minitab Statistical Software DOE
To store your design for additional analysis, use the DESIGN subcommand. (The DESIGN subcommand replaces
the obsolete subcommands XMATRIX and SIGNAL.)
LEVELS K K, ..., K K
Specifies the levels for each factor in K K, K K ... K K.
If you do not specify levels, Minitab uses the default levels given in the catalogue of arrays. For example, the
default levels of a 3-level column are 1, 2, and 3.
The following example shows how LEVELS is used:
OADESIGN 18 3 4 2 1;
DESIGN;
LEVELS 1 2 3 "red" "green" "blue" 2.7 2.9 3.4 3.9 4.2 6.8 -1 1.
This design will use five columns of the L18 (2**1 3**7) array. The first four factors, which will be stored in
columns C1-C4, will have 3 levels each. The fifth factor, which will be stored in column C5, will have 2 levels.
The levels of factor C1 will be 1, 2, and 3. The levels of C2 will be "red", "green", and "blue". The levels of
factor C3 are 2.7, 2.9, ad 3.4.
Note It is acceptable to repeat levels for the same factor, as long as there are at least two distinct levels. This allows the use of
"dummy treatments", an important technique for customizing Taguchi designs. For example, the 8-level column in the L16 (8**1
2**8) array can be used for a 7-level factor by specifying levels 1 1 2 3 4 5 6 7.
COLUMNS K...K
Specifies which columns of the full orthogonal array are used in the design in K...K.
Consider the following example:
OADESIGN 18 3 4 2 1;
DESIGN;
COLUMNS 2 3 5 7 1.
Worksheet column C1 will be the same as column 2 in the L18 (2**1 3**7) array. Column C2 will be the same
as column 3; C3 will be column 5; C4 will be column 7; and C5 will be column 1.
INTERACTIONS C C, ..., C C
Specifies which interactions among factors in C C you want to estimate. INTERACTIONS requests that Minitab
automatically assign factors to columns in such a way that the 2-way interactions listed are not confounded
with any of the main effects or with each other. If you want to remove an interaction from your model, you
should run the OADESIGN command to re-specify your model with the appropriate terms.
DESIGN
Names and stores the standard order, run order, point type, block assignment, and each factor in separate
columns. Unless you have only 1 empty worksheet in the project, Minitab stores the columns in a new
worksheet.
NAMES K K, ..., K K
Specifies names for the factors. Enclose names in quotation marks. If you do not use NAMES, then the
names of the factors are letters, skipping the letter I: A, B, C…
SNAME K
Use SNAME to add a signal factor to create a dynamic Tauchi design. Enter the name within double
quotation marks. When you specify SNAME, also specify SLEVEL.
SLEVEL K…K
Use SLEVEL specify the levels of the signal factor for a dynamic Taguchi design. Levels for a signal factor
must be numeric. Minitab replicates the orthogonal array part of the design at each level of the signal
factor.
413
Minitab Statistical Software DOE
Consider the following example:
OADesign 4 2 3;
Design;
SNAME "Signal";
SLEVEL 1:5/2.
The design stored in the worksheet would be as follows:
C4C3C2C1
SignalCBA
1111
3111
5111
1221
3221
5221
1212
3212
5212
1122
3122
5122
In general, the total number of runs will be the number of rows in the orthogonal array times the number
of levels in the signal variable.
ROBUST: Session command for analyzing a Taguchi design
ROBUST C = C...C
Analyzes a Taguchi design with responses in C and factors and interactions in C...C.
Calculates signal-to-noise ratios for an inner-outer array design and generates main effects and interactions plots
of the signal-to-noise ratios, means, slopes, or standard deviations versus the control factors in the inner array.
Use response tables and ANOVA results to determine what factors and interactions are important and which
factor settings minimize variability.
To use Predict Taguchi Results on the Minitab menu, use DESIGN and DOE to store the model information.
DESIGN C...C
Specifies all of the factors in your design in C...C if you have omitted some factors in the model specified in
ROBUST.
DOE
Stores model information to enable Predict Taguchi Results on the Taguchi menu. You can make
predictions with OAPREDICT whether or not you store the model information.
414
Minitab Statistical Software DOE
DYNAMIC C
Specifies that the signal factor is in C. DYNAMIC cannot be used with any subcommands that apply only to
static response analysis: NOMONE, NOMTWO, LOWER, HIGHER, GMEANS, MEANS, CV, TMEANS.
Graphs
GSN
Displays main effects for s/n ratios. GSN plots the S/N ratio as the response variable. Choose the appropriate S/N
ratio with the NOMONE, NOMTWO, LOWER, or HIGHER subcommands (the default is NOMTWO).
GMEANS
Displays main effects for means. GMEANS cannot be used with DYNAMIC. You can use as many GMEANS as you
want. See LOGSTD if you want to use the log-transformed standard deviations as the response variable.
GSTDS
Displays main effects for standard deviations. You can use as many GSTDS as you want. See LOGSTD if you want
to use the log-transformed standard deviations as the response variable.
GSLOPES
Displays main effects for slopes. GSLOPES can only be used with DYNAMIC. You can use as many GSLOPES as
you want. See LOGSTD if you want to use the log-transformed standard deviations as the response variable.
GSCATTER
Displays scatterplots of data with fitted lines. Use GSCATTER to request scatterplots of the responses versus the
signal. GSCATTER can be used only with DYNAMIC.
INTROWS C...C
Specifies factors to be used as the grouping variable in the interaction plot matrix. The plots in the same row
share the factor that is used as the grouping variable.
INTCOLS C...C
Specifies factors to use for the horizontal scale of the interaction plot matrix. The plots in the same column share
the factor used for the horizontal scale.
INTSEP
Generates separate interaction plots for interactions specified in the model.
RTYPE K
Specifies the type of residual to plot with the graph subcommands.
Type of residualsValue of K
Regular or raw residuals (RESIDUALS)1 (default)
Standardized residuals (SRESIDUALS)2
Deleted Studentized residuals (TRESIDUALS)3
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
415
Minitab Statistical Software DOE
GFITS
Plots the residuals versus the fitted values.
GORDER [C]
Plots the residuals versus the order of the data or vs the order specified in [C]. The row number for each data
point is shown on the x-axis (for example, 1 2 3 4... n).
GFOURPACK [C]
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data or vs order specified in [C].
GVARIABLE C...C
Plots the residuals versus variables. Displays a separate graph for the residuals versus each specified column.
Analysis
TMEANS
Generates a response table for means. TMEANS cannot be used with DYNAMIC.
TSN
Generates a response table for s/n ratios.
TSTDS
Generates a response table for standard deviations.
TSLOPES
Generates a response table for slopes. TSLOPES can only be used with DYNAMIC.
AMEANS
Generates ANOVA results for means. AMEANS cannot be used with DYNAMIC.
ASN
Generates ANOVA results for s/n ratios.
ASTDS
Generates ANOVA results for standard deviations.
ASLOPES
Generates ANOVA results for slopes ratios. ASLOPES can only be used with DYNAMIC
Options
NOMONE
Specifies the s/n ratio based on standard deviations only.
Use NOMONE when the goal is to target the response. The formula is S / N = –10 (log
10
(s
2
)).
NOMTWO
Specifies the s/n ratio based on means and standard deviations (default).
Use NOMTWO when the goal is to target the response. The formula is S / N = 10 (log
10
(Xbar
2
/ s
2
)).
416
Minitab Statistical Software DOE
LOWER
Specifies the s/n ratio when the goal is to minimize the response.
Use LOWER when the goal is to minimize the response. The formula is S / N = 10 (log
10
Y
2
/ n)).
HIGHER
Specifies the s/n ratio when the goal is to maximize the response.
Use HIGHER when the goal is to maximize the response. The formula is
S / N = –10 (log
10
(1 / Y
2
) / n))
LOGSTD
Specifies the loge transformation for standard deviations. If you want to produce main effects and interactions
plots using the standard deviation as the response variable, consider using a loge transformation on the standard
deviations to stabilize their variability.
YREF K
Specifies the response reference value for dynamic designs.
Specifies the reference point through which the regression line must pass in a dynamic response model. If the
subcommand is not used, the reference value is taken to be zero by default. If neither YREF nor SREF are used,
the regression line passes through the origin.
YREF can only be used with DYNAMIC.
SREF K
Specifies the signal reference value for dynamic designs.
Specifies the reference point through which the regression line must pass in a dynamic response model. If the
subcommand is not used, the reference value is taken to be zero by default. If neither YREF nor SREF are used,
the regression line passes through the origin.
SREF can only be used with DYNAMIC.
NOREF
Specifies no reference values for the regression. Minitab estimates a separate regression intercept for each run.
Storage
You must use storage commands with one or more of the commands AMEANS, ASLOPES, ASNS, or ASTDS.
SNRATIO C
Stores s/n ratios in C.
MEANS C
Stores means in C. MEANS cannot be used with DYNAMIC.
SLOPES
Stores slopes in C. SLOPES can only be used with DYNAMIC.
INTERCEPTS
Stores intercepts in C. INTERCEPTS can only be used with DYNAMIC.
417
Minitab Statistical Software DOE
STDEVS
Stores standard deviations in C.
LSTDEVS
Stores natural log of standard deviations in C.
CV
Stores coefficients of variation in C. CV cannot be used with DYNAMIC.
FITS C
Stores the fitted values.
RESIDUALS C
Stores the residuals (fitted values observed values).
SRESIDUALS C
Stores the standardized residuals.
TRESIDUALS C
Stores the deleted Studentized residuals in C.
COEFFICIENTS C
Stores the estimated coefficients.
XMATRIX M
Stores the design matrix for the regression model in M.
HI C
Stores the leverage values.
COOK C
Stores Cook's distance.
DFITS C
Stores the DFITS (also called DFFITS) values.
OAPREDICT: Session command for calculating predicted response
values
OAPREDICT C...C = C...C
Predicts response values for statistics stored in C...C for factors and interactions in C...C.
Calculate predicted response values after you have analyzed a Taguchi design and examined the response tables,
ANOVA results, and plots to determine which factor settings should achieve a robust product design. OAPREDICT
allows you to predict S/N ratios and response characteristics for selected factor settings.
To use OAPREDICT, first store response characteristics (S/N ratios, means, slopes, standard deviations) you want
to predict with ROBUST. Specify stored response characteristic columns on left-side of model. Specify factors and
interactions on the right-side of the model.
For example, you might choose the best settings for the factors that have the greatest effect on the S/N, and then
wish to predict the S/N and mean response for several combinations of other factors. OAPREDICT provides the
expected responses for those settings. You should choose the results that come closest to the desired mean
418
Minitab Statistical Software DOE
without significantly reducing the S/N ratio. You should then perform a follow-up experiment using the selected
levels, to determine how well the prediction matches the observed result.
If there are minimal interactions among the factors or if the interactions have been correctly accounted for by
the predictions, the observed results should be close to the prediction, and you will have succeeded in producing
a robust product. On the other hand, if there is substantial disagreement between the prediction and the observed
results, then there may be unaccounted for interactions or unforeseen noise effects, which may require further
investigation.
LABELS K...K
Specifies labels for the predicted values in the output. The arguments must be text constants.
LEVELS E...E
Specifies the factor levels for which you want to calculate predicted response values. The arguments may be
either constants or columns. The levels must agree with the levels in the factor columns.
PFITS C...C
Stores the predicted values in specified columns. The number of arguments should match the number of
response characteristics listed on the left-hand side of the model in the OAPREDICT command.
UNITS K K
Specifies the units of the inner array factors and the units for the new levels, 0 for coded and 1 for uncoded.
The first argument indicates the units of the inner array columns and the second argument indicates the
units of the levels given by the LEVELS subcommand.
NLEVELS K...K
Specifies the number of levels for each factor. Use when the two arguments of UNITS are different. It is used
in conjunction with FLEVELS to match coded levels with uncoded levels for each factor.
FLEVELS K...K
Specifies the uncoded levels of the factors listed in the model. Use FLEVELS if the two arguments of UNITS
are different. The number of arguments for FLEVELS should be the sum of the arguments of NLEVELS. NLEVELS
is used to determine which levels correspond to which factors.
Example:
OAPREDICT 'SNRA1' = C1 C3-C5;
LEVELS 2 1 1 1;
UNITS 1 0;
NLEVELS 2 3 3 3;
FLEVELS "low" "high" "low" "low" "high" 1 2 3 1 2 3.
In this example, OAPREDICT would predict a new value of the s/n ratio by fitting a main effects model based
on the four inner array factors C1, C3–C5. The UNITS subcommand indicates that the inner array is displayed
in uncoded units, and the new levels are specified in coded units. The NLEVELS subcommand indicates that
C1 has 2 levels and C3–C5 have 3 levels each. The FLEVELS subcommand indicates that for factor C1, the
uncoded units are "low" and "high"; for factor C3, the uncoded units are "low", "low" and "high", i.e. coded
levels 1 and 2 would both correspond to uncoded level "low", etc.
419
Minitab Statistical Software DOE
Modify and Display Designs
MDESIGN: Session command to modify the design properties or
display of a design in the worksheet
MDESIGN
The modifications that are available depend on the type of design in the worksheet. You can use NEWWS to put
the modified design in a new worksheet for all types of designs. Generally, you can make only 1 modification to
the design each time you use MDESIGN. For detailed explanations, including instances where you can make
multiple modifications, go to the section on the subcommands.
Modifications for screening designs
SubcommandModification
VARModify factor names or levels
REPLICATEReplicate the design
RANDOMIZERandomize the design
RENUMBERRenumber the design
SORTDisplay the points in run order or standard order
CODED and UNCODEDDisplay the levels in coded or uncoded units
FOLDFold the design (Plackett-Burman only)
AXIALAdd axial points (Plackett-Burman only)
Modifications for factorial designs
SubcommandModification
VARModify factor names or levels
REPLICATEReplicate the design
RANDOMIZERandomize the design
RENUMBERRenumber the design
SORTDisplay the points in run order or standard order
CODED and UNCODEDDisplay the levels in coded or uncoded units
FOLDFold the design (2-level fractional factorial designs and Plackett-Burman
designs)
AXIALAdd axial points (2-level fractional factorial designs and Plackett-Burman
designs)
Modifications for response surface designs
SubcommandModification
VARModify factor names or levels
420
Minitab Statistical Software DOE
SubcommandModification
REPLICATEReplicate the design
RANDOMIZERandomize the design
RENUMBERRenumber the design
SORTDisplay the points in run order or standard order
CODED and UNCODEDDisplay the levels in coded or uncoded units
Modifications for mixture designs
SubcommandModification
VARRename mixture components, rename process variables, or change the
levels of process variables
REPLICATEReplicate the design
RANDOMIZERandomize the design
RENUMBERRenumber the design
SORTDisplay the points in run order or standard order
CODED and UNCODEDDisplay the levels of the process variables in coded or uncoded units
AMOUNT, PROPORTION, and PSEUDODisplay the levels of the mixture components in amount, proportion, or
pseudocomponent units
Modifications for Taguchi designs
SubcommandModification
VARModify factor names or levels
CODED and UNCODEDDisplay the levels in coded or uncoded units
SIGNALAdd a signal factor to a static design, ignore an existing signal factor (treat the
design as static), or add new levels to an existing signal factor.
Subcommands
NEWWS
Use NEWWS to put the modified design in a new worksheet. Without NEWWS, the modification overwrites the
columns in the existing worksheet. You can use NEWWS in combination with any of the other commands.
VAR C
Use VAR to change the name or levels of a factor, process variable, or mixture component. Use C to specify which
column to modify. You can specify VAR multiple times for a single instance of MDESIGN. You can use NAME and
LEVELS at the same time. You cannot use LEVELS for mixture components.
NAME K
Use NAME to specify the new name for a factor, process variable, or mixture component. Enter the name
within double quotation marks.
421
Minitab Statistical Software DOE
LEVELS K … K
Specify the new uncoded levels for the factor or process variable that you specify with VAR. For a factor with
low and high levels, the first K is the low level and the second K is the high level. Enter text levels within
double quotation marks. For a text factor with more than 2 levels, as in a general full factorial design, specify
the new levels in the same order as in the command language for the creation of the design.
REPLICATE K
Use REPLICATE to reproduce the rows in the current worksheet K times. If the original design is all in 1 block, each
replicate is a new block. If the original design has multiple blocks, each replicate contains the same number of
blocks as the original design.
Because the order from the worksheet is the same for each replicate, modify the design a second time to randomize
it after you add the replicates. Use the RANDOMIZE subcommand with a new instance of MDESIGN. For more
information, go to the RANDOMIZE subcommand.
RANDOMIZE
Use RANDOMIZE to replace the run order column with a new, random order. You can use RANDOMIZE and SORT
at the same time to put the design in the new run order.
BASE K
Use BASE to get the same random order when you modify the design again. Enter a positive integer as the
seed for the random number generator.
WP K
Use WP with split-plot designs. The randomization affects only the rows where the value in the whole plot
column equals K.
BLOCKS K
Use BLOCKS with a blocked design. The randomization affects only the rows where the value in the block
column equals K. For example, if you add a replicate to a design after you collected some response data, you
can use BLOCKS to randomize only the rows in the block for the new replicate.
RENUMBER
Use RENUMBER to make the run order the order of the rows in the worksheet.
SORT C
Use SORT to sort the worksheet by the column that you specify. You can specify only the column that contains
the standard order for the design or the column that contains the run order for the design. By default, the standard
order is in column C1 and the run order is in column C2. Minitab adds missing value symbols to columns that are
shorter than the design columns so that the rows can be in the new order. SORT does not affect columns that are
longer than the design.
EXCLUDE C…C
Use EXCLUDE to preserve the order of columns that you do not want to sort.
CODED
When the worksheet shows uncoded units, specify CODED to change to coded units.
UNCODED
When the worksheet shows coded units, specify UNCODED to change to uncoded units.
FOLD [C]
Use FOLD with 2-level fractional factorial designs or Plackett-Burman designs. FOLD folds the design on the
specified factor. To fold on multiple factors, use FOLD once for each factor within the same instance of MDESIGN.
If you do not include a factor, Minitab folds the design on all factors.
422
Minitab Statistical Software DOE
The signs on the factors that you specify are switched. The signs on the remaining factors are not switched. These
rows for the non-specified factors are then appended to the end of the design matrix, which doubles the number
of runs.
Consider the following example.
FFDESIGN 3 4;
DESIGN.
MDESIGN;
FOLD A.
First, Minitab generates a 3 factor design in 4 runs. The first 4 rows of the data matrix below are these runs. Then,
Minitab folds on factor A. This adds 4 additional runs.
CBA
+
+
+
+++
++
++
++
Folding is a way to reduce confounding. If you fold on one factor, say A, then A and all its two-factor interactions
are free from other main effects and two-factor interactions. If you fold on all factors, then all main effects are
free from all two-factor interactions.
When you fold, the defining relation is usually shortened. Specifically, any word in the defining relation that has
an odd number of the letters on which you folded the design is omitted. If you fold a design and the defining
relation is not shortened, then the folding adds replicates, but it does not reduce confounding. In this case, Minitab
displays an error message.
If you fold a design that is blocked, the same block generators are used for the folded design as for the unfolded
design.
AXIAL
Use AXIAL with 2-level factorial designs and Plackett-Burman designs. To use AXIAL, the design must have only
continuous factors. Use AXIAL to change the design into a central composite response surface design by adding
a block of axial points.
ALPHA K
Use ALPHA to specify the alpha for the central composite design. Alpha is the distance from the center of
the design to the axial points in coded units. If you do not use ALPHA, Minitab chooses alpha so that the
design is as rotatable as possible with orthogonal blocks. Alpha must be positive. A value of 1 results in a
face-centered design. A value that is less than 1 places the axial points inside the cube. A value that is greater
than 1 places the axial points outside the cube.
Central composite designs on page 1136 shows the values of alpha that Minitab uses when Minitab creates a
central composite design.
FACE
Use FACE to specify an alpha value of 1. This alpha creates a face-centered central composite design. Alpha
is the distance from the center of the design to the axial points in coded units.
423
Minitab Statistical Software DOE
CENTER K
Use CENTER to specify the number of center points to add to the axial block.
Central composite designs on page 1136 shows the number of center points that Minitab includes in the axial
block when Minitab creates a central composite design.
AMOUNT
When the worksheet shows proportion or pseudocomponent units for a mixture design, use AMOUNT to change
to amount units.
PROPORTION
When the worksheet shows amount or pseudocomponent units for a mixture design, use PROPORTION to change
to proportion units.
PSEUDO
When the worksheet shows proportion or amount units for a mixture design, use PSEUDO to change to
pseudocomponent units.
SIGNAL
Use SIGNAL to add, add levels to, or ignore a signal factor in a Taguchi design. Use the sub-subcommands to
specify the use.
INCLUDE
Use INCLUDE to add a signal column to a Taguchi design. Also use SNAME and SLEVEL to specify the name
and levels of the signal factor. Omit INCLUDE when you add levels to a signal factor.
SNAME K
Use SNAME to name the signal factor that you add to a design. Enter the name within double quotation
marks.
SLEVEL K…K
Use SLEVEL with INCLUDE to specify the levels for a signal factor that you add to a design. Use SLEVEL without
INCLUDE to add levels to an existing signal factor. Levels for a signal factor must be numeric. Minitab replicates
the orthogonal array part of the design at each level of the signal factor.
IGNORE
Use IGNORE to change a dynamic Taguchi design into a static Taguchi design. The column for the signal
factor that is in the worksheet does not change.
424
Minitab Statistical Software DOE
Quality and Process Improvement
Quality Planning Tools
FISHBONE: Session command for creating a cause-and-effect
diagram
FISHBONE
Generates a cause-and-effect diagram (also called a fishbone diagram).
Branches
Specifies lists of causes for the corresponding branches and subbranches of the diagram. You can use these commands
repeatedly and specify up to 10 branches.
When data are in columns, each column contains the names of the causes for a branch of the diagram. Entries in the
columns can be up to 72 characters wide. The first 20 characters of each entry in the column display on the diagram.
Odd branches are on top (5, 3, then 1, left to right), and even branches on the bottom (6, 4, then 2).
BRANCH K C
Use BRANCH K C and SUBBRANCH K C when the causes are listed in columns.
SUBBRANCH K C
Use BRANCH K C and SUBBRANCH K C when the causes are listed in columns.
BRANCH K K
Use BRANCH K K and SUBBRANCH K K when you type the causes as text.
SUBBRANCH K K
Use BRANCH K K and SUBBRANCH K K when you type the causes as text.
Other subcommands
NAME K "text"
By default, the labels for branches 1 through 6 are (in order) Personnel, Machines, Materials, Methods, Measures,
and Environment. NAME K "text" changes the default labels for K branch. Odd branches are on top (5, 3, then 1,
left to right), and even branches on the bottom (6, 4, then 2).
NOEMPTY C
Suppresses branches that you have not specified data for with BRANCH 1, BRANCH 2, BRANCH 3, BRANCH 4,
BRANCH 5, and BRANCH 6. When you do not specify NOEMPTY, empty branches still display.
NOLABELS
Suppresses the default branch labels. Use NOLABELS to draw a blank diagram.
425
Minitab Statistical Software Quality and Process Improvement
EFFECT "text"
Displays the name of the effect, or problem, that is being solved. The text string can be up to 72 characters in
length. The first 20 (approximately) characters display on the diagram.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
426
Minitab Statistical Software Quality and Process Improvement
MVARCHART: Session command for creating a multi-vari chart
MVARCHART
Creates multi-vari charts for up to four factors. Multi-vari charts are a way of presenting analysis of variance data
in a graphical form to provide a visual alternative to analysis of variance. You can use a multi-vari chart in the
preliminary stages of data analysis to see the data. The chart displays the means at each factor level for every
factor.
RESPONSE C
Specifies the numeric response column C.
FACTORS C...C
Specifies one to four factor columns.
DATAON
Displays individual data points on the plot.
MUAON
Displays connect lines for the means for factor A.
MUBON
Displays connect lines for the means for factor B.
MUCON
Displays connect lines for the means for factor C.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
NMVARCHART: Session command for creating variability charts
NMVARCHART
Creates variability charts for up to 8 factors. Use these charts to visualize different sources of variation. You can
use variability charts in the preliminary stages of data analysis to see the data. For example, you can view analysis
of variance data or variation from a measurement system graphically.
The command can produce two charts. The first chart, the average response with variation chart, is shown by
default. This chart plots the original data points and the range of each cell formed by the combination of levels
from all factors. This chart also optionally displays the means for each factor level. Use to evaluate measurement
consistency within cells and to see how different cell means are from each other.
The second chart, the standard deviation chart, plots the standard deviations for each cell formed by the
combination of levels from all factors.
RESPONSE C
Specifies the numeric response column C.
FACTORS C...C
Specifies one to eight factor columns. The first C is the first factor, the second C is the second factor, and so
on.
The factor columns must be the same length as the response column.
DATAON
Displays individual data points of each cell, defined by the factors, on the average chart.
427
Minitab Statistical Software Quality and Process Improvement
RANGE
Displays every range bar that connects the min and max of the data points within each cell.
CELLON
Connects the cell means.
MUAON
Displays level means for factor A.
MUBON
Displays level means for factor B.
MUCON
Displays level means for factor C.
MUDON
Displays level means for factor D.
MUEON
Displays level means for factor E.
MUFON
Displays level means for factor F.
MUGON
Displays level means for factor G.
OMEAN
Displays the overall mean.
GSTD
Displays the standard deviation chart.
SMEAN
Displays the mean of the standard deviations.
PARETO: Session command for creating a Pareto chart
PARETO C
Generates a Pareto chart for one sample, or one for each group when you use a BY variable.
You can use PARETO in either of two ways. First, you enter a column of raw data, where each observation is an
occurrence of a type of defect. PARETO counts the number of occurrences for each unique defect, then uses the
counts to construct the chart. Second, you enter a list of defect names in a column as the PARETO argument and
a list of counts in a second column as the COUNTS argument. The defect name and count in the same row are
paired in the plot. In both cases, the defects can be either text or numeric data. Thus, you can use either the actual
defect names, or you can use numeric codes that represent the defects.
OTHERS K
By default, PARETO generates bars for defects until the cumulative percent surpasses 95. PARETO groups
remaining defects into a bar named "Others." Use OTHERS to specify a value other than 95 for the cumulative
percent. For example, OTHERS 90 plots all defects until the cumulative percent surpasses 90, then lumps the
rest into "Others."
428
Minitab Statistical Software Quality and Process Improvement
NOOTHERS
Use NOOTHERS if you do not want to combine defects into an "Others" category.
COUNTS C
Instead of entering raw data, you may already know how many of each defect there are. In that case, enter
the defect names in one column and the counts in another. Give the column of names in the main command
line and the column of counts with COUNTS. PARETO then matches up the name and count in the same row
when drawing the chart. The data in C must be integers.
BY C
Use BY to generate a separate Pareto chart for each unique value in the specified BY column. All graphs
display together and use the same y-axis scale. When you do not use SEPARATE or INDEPEND, bars in all
graphs display in the same x-axis order when you use BY. You can specify up to 25 by variable levels.
SEPARATE
When you use BY with SEPARATE, each graph displays in a separate graph, one after another, in the output
pane. All graphs use the same y-axis scale and x-axis order.
INDEPEND
When you use BY with INDEPEND, the graphs are independent. Although all graphs use the same y-axis
scale, each graph has an independent x-axis order. Thus, the bars in each graph display in Pareto order—from
largest to smallest. When you use BY with INDEPEND, each graph displays in a separate graph, one after
another, in the output pane.
YLABEL "text"
Specifies the y-axis default label of "Count".
XLABEL "text"
Specifies the x-axis default label of "Defect".
NOCUMULATIVE
Suppresses the cumulative symbols and line and percent scale.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
429
Minitab Statistical Software Quality and Process Improvement
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
RUNCHART: Session command for creating a run chart
RUNCHART C C
RUNCHART K
Draws a run chart with tests for randomness based on runs.
RUNCHART shows the spread of your process data, and performs two tests for non-random behavior.
The command is entered differently depending on how the data is structured in the worksheet. For details, go to
How to enter subgroup data on page 1163. RUNCHART can be used to plot subgroup means, subgroup medians,
or the individual observations.
Regardless of subgroup size, RUNCHART plots all the individual observations versus the subgroup number. When
you use a subgroup size greater than 1, RUNCHART also plots the subgroup data versus the subgroup number.
Minitab connects the subgroup data with a line. The subgroup mean is plotted by default. Use MEDIANS to plot
the subgroup medians instead of the subgroup means. A horizontal reference line shows the median of all
observations.
RSUB C...C [K]
Enters subgroup data in rows. Enter a series of columns. You can optionally specify the number of models
you would like. For example, if you have data across rows C1–C6 and you have two models (C1–C3 and
C4–C6), you can enter RSUB C1-C6 2 to produce two run charts. The number of models you specify must
430
Minitab Statistical Software Quality and Process Improvement
divide evenly into the number of columns on the RSUB subcommand. For details, go to How to enter subgroup
data on page 1163.
MEDIANS
Plots the subgroup medians rather than the subgroup means as points on the graph. If you do not use this
subcommand, Minitab uses the subgroup means as the points on the graph. The points you choose to plot
are used to count the number of runs for the tests for randomness.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks
("file_name"), or as a stored text constant (K). You can also use any of the following subcommands to save
the graph in a different graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002,
and so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
431
Minitab Statistical Software Quality and Process Improvement
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
SYMPLOT: Session command for creating a symmetry plot
SYMPLOT C...C
Symmetry plots can be used to assess whether sample data come from a symmetric distribution. Many statistical
procedures assume that data come from a normal distribution. However, many procedures are robust to violations
of normality, so having data from a symmetric distribution is often sufficient. Other procedures, such as
nonparametric methods, assume symmetric distributions rather than normal distributions. Therefore, a symmetry
plot is a useful tool in many circumstances.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
Control Charts
Box-Cox Transformation
BOXCOX: Session command for performing a Box-Cox transformation
BOXCOX [C...C E]
Performs a box-cox transformation when the data are in C...C and the subgroups = E.
The Box-Cox transformation can be useful for correcting both nonnormality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, you do not need to correct for nonnormality
unless the data are highly skewed. Some authors suggest that you should not transform data that are used in
control charts, because control charts work well in situations where data are not normally distributed. They give
an excellent demonstration of the performance of control charts when data are collected from a variety of
non-symmetric distributions.
You can enter data when data are in columns or when data are in subgroups across rows. For details, go to How
to enter subgroup data on page 1163.
You can use BOXCOX only with positive data.
BOXCOX can be used several ways:
To estimate the best lambda value for the transformation, use BOXCOX with no subcommand.
To estimate the best lambda value for the transformation, transform the data, and store the transformed data
in the column or columns that you specify, use BOXCOX with STORE.
To transform the data with a lambda value that you enter, and store the transformed data in a columns you
specify, use BOXCOX with LAMBDA and STORE.
RSUB C...C
Specifies when data are in subgroups across rows.
432
Minitab Statistical Software Quality and Process Improvement
LAMBDA K...K
LAMBDA C...C
Specifies your own value of lambda to use in the transformation. When you use LAMBDA, Minitab bypasses
the lambda estimation step and transforms the data using the lambda value you specify. You must use the
STORE subcommand with LAMBDA to see the transformed data in a column.
The within standard deviation is used in the estimation of lambda when you use optimal lambda.
STORE C...C
Stores the transformed data in column C...C.
Variables Charts for Subgroups
XRCHART: Session command for creating an Xbar-R chart
XRCHART [C...C E]
Creates an Xbar and R chart for subgroup means and ranges with subgroup size = E.
If the subgroups are in columns, enter a data column followed by a subgroup indicator. If the subgroups are in
rows, omit the arguments on the main command line and use the RSUB subcommand to enter the data. For
details, go to How to enter subgroup data on page 1163. The mean of the data in each subgroup is calculated and
plotted on the chart.
The process standard deviation is estimated by the average of subgroup ranges. You can optionally enter an
historical standard deviation with the SIGMA subcommand. Base your estimate on the pooled standard deviation
with the POOLED subcommand.
You can run the eight common tests for special causes. Use the TEST subcommand to specify which tests to use.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
433
Minitab Statistical Software Quality and Process Improvement
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
434
Minitab Statistical Software Quality and Process Improvement
Parameters
MU K...K
MU C
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA K...K
SIGMA C
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
435
Minitab Statistical Software Quality and Process Improvement
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
BIASED
Specifies to not use unbiasing constants when calculating the within-subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
the pooled standard deviation method of estimating σ.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOLOWER K
Sets lower control limit bound for Xbar chart.
LOUPPER K
Sets upper control limit bound for Xbar chart.
VALOWER K
Sets lower control limit bound for R chart.
VAUPPER K
Sets upper control limit bound for R chart.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
436
Minitab Statistical Software Quality and Process Improvement
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
Note RCHART supports only tests 1 through 4.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
437
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
438
Minitab Statistical Software Quality and Process Improvement
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
XSCHART: Session command for creating an Xbar-S chart
XSCHART [C...C E]
Creates an Xbar and S chart for subgroup means and subgroup standard deviations with subgroup size = E.
439
Minitab Statistical Software Quality and Process Improvement
If the subgroups are in columns, enter data with the CSUB subcommand. If the subgroups are in rows, enter data
with the RSUB subcommand. For details, go to How to enter subgroup data on page 1163. The X chart is drawn in
the upper half of the screen; the S chart in the lower half. Seeing both charts together allows you to examine both
process level and process variation at the same time.
The process standard deviation is estimated the average of the subgroup standard deviations. You can optionally
enter an historical value for the process standard deviation with the SIGMA subcommand, or base your estimate
on the pooled standard deviations with the POOLED subcommand.
You can run the eight common tests for special causes. Use the TEST subcommand to specify which tests to use.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
440
Minitab Statistical Software Quality and Process Improvement
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
If you use a column, the column can contain different values for each historical group. If you enter one constant,
all historical stages use that value. Otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA K...K
SIGMA C
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, the column can contain different values for each historical group. If you enter one constant,
all historical stages use that value. Otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
441
Minitab Statistical Software Quality and Process Improvement
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
the pooled standard deviation method of estimating σ.
442
Minitab Statistical Software Quality and Process Improvement
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOLOWER K
Sets lower control limit bound for Xbar chart.
LOUPPER K
Sets upper control limit bound for Xbar chart.
VALOWER K
Sets lower control limit bound for S chart.
VAUPPER K
Sets upper control limit bound for S chart.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
Note SCHART supports only tests 1 through 4.
443
Minitab Statistical Software Quality and Process Improvement
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
444
Minitab Statistical Software Quality and Process Improvement
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal l for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
445
Minitab Statistical Software Quality and Process Improvement
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
BWCHART: Session command for creating an I-MR-R/S chart
BWCHART [C...C E]
Creates a three-way control chart using both between-subgroup and within-subgroup variations, with subgroup
size = E. You can enter data arranged in a single column or across rows. For more information, go to How to enter
subgroup data on page 1163. When data are arranged across rows, you can optionally specify the number of models
you would like. For example, if you have data across rows C1–C6 and you have two models (C1–C3 and C4–C6),
you can enter RSUB C1–C6 2 to produce two control charts. The number of models you specify must divide
evenly into the number of columns on the RSUB subcommand.
In BWCHART, setup the data in several columns, with each row representing a subgroup. For example, if you took
five measurements of each part, but in different locations, each column would contain the measurements from
one of the locations, and each row would contain the measurements from a single part.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
446
Minitab Statistical Software Quality and Process Improvement
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
447
Minitab Statistical Software Quality and Process Improvement
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C
Use MU to estimate a value for the historical mean. The value that you enter can be either an actual known process
parameter or an estimate that was obtained from past data.
If you use a column, it can contain different values for each historical stage. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical stage.
If you do not specify a value, Minitab estimates it from the data.
BSIG K...K
BSIG C
Use BSIG to estimate a value for the historical between-subgroup standard deviation. The value that you enter
can be either an actual known process parameter or an estimate that was obtained from past data.
If you use a column, it can contain different values for each historical stage. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical stage.
If you do not specify a value, Minitab estimates it from the data.
WSIG K...K
WSIG C
Use WSIG to estimate values for the historical within-subgroup standard deviation. The value that you enter can
be either an actual known process parameter or an estimate that was obtained from past data.
If you use a column, it can contain different values for each historical stage. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical stage.
If you do not specify a value, Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
448
Minitab Statistical Software Quality and Process Improvement
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation 2
(using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set, you
must enter observation 2 as the observation to omit.
RBAR
RBAR, SSBAR, and SPOOLED are mutually exclusive subcommands that control the estimation of the
within-subgroup standard deviation when 1 < subgroup size <= 8.
RBAR uses the average of the subgroup ranges to estimate standard deviation. This method is the one that appears
in many books and manuals that describe control charts.
SSBAR
RBAR, SSBAR, and SPOOLED are mutually exclusive subcommands that control the estimation of the
within-subgroup standard deviation when 1 < subgroup size <= 8.
SSBAR uses the average of the subgroup standard deviations to estimate standard deviation.
SPOOLED
RBAR, SSBAR, and SPOOLED are mutually exclusive subcommands that control the estimation of the
within-subgroup standard deviation when 1 < subgroup size <= 8.
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
SBAR
SBAR and POOLED are mutually exclusive subcommands that control the estimation of the within-subgroup
standard deviation when subgroup size > 8.
SBAR specifies the average of the subgroup standard deviations to estimate standard deviation.
449
Minitab Statistical Software Quality and Process Improvement
POOLED
SBAR and POOLED are mutually exclusive subcommands that control the estimation of the within-subgroup
standard deviation when subgroup size > 8.
POOLED specifies the pooled standard deviation to estimate standard deviation. The pooled standard deviation
is the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups. Minitab displays an S chart in the output.
AMR
Specifies the average moving range to estimate the between subgroup standard deviation.
MMR
Specifies the median moving range to estimate the between subgroup standard deviation.
SRMSSD
Specifies the square root of half the mean of the squared successive differences to estimate the between subgroup
standard deviation.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations.
RSPAN K
Specifies the length of the moving range. By default, a span of 2 is used because consecutive values have the
greatest chance of being alike. The span must be < 100. RSPAN is ignored when the subgroup size > 1.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and below
the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first, second,
and third standard deviations.
LOLOWER K
Sets lower control limit bound for I chart.
LOUPPER K
Sets upper control limit bound for I chart.
RSLOWER K
Sets lower control limit bound for R or S chart.
RSUPPER K
Sets upper control limit bound for R or S chart.
VALOWER K
Sets lower control limit bound for MR chart.
450
Minitab Statistical Software Quality and Process Improvement
VAUPPER K
Sets upper control limit bound for MR chart.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
Note RCHART, SCHART, and MRCHART only support tests 1 through 4.
DEFTEST applies to any chart that supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
451
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal l for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, Minitab finds the optimal value of lambda.
452
Minitab Statistical Software Quality and Process Improvement
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
BVARIATION C
Stores between standard deviations, one row for each historical stage.
WVARIATION C
Stores within standard deviation, one row for each historical stage.
TVARIATION C
Stores total standard deviation, one row for each historical stage.
PPOINTS C C C
Stores plotted points, one row for each subgroup.
CENLINE C C C
Stores center line values, one row for each plotted point.
CONLIMITS C C C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
453
Minitab Statistical Software Quality and Process Improvement
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
XBARCHART: Session command for creating an Xbar chart
XBARCHART [C...C E]
Creates an Xbar chart for subgroup means with subgroup size = E.
If the subgroups are in columns, enter a data column followed by a subgroup indicator. If the subgroups are in
rows, omit the arguments on the main command line and use the RSUB subcommand to enter the data. For
details, go to How to enter subgroup data on page 1163. The mean of the data in each subgroup is calculated and
plotted on the chart.
The process standard deviation is estimated by a pooled standard deviation by default. You can optionally enter
an historical standard deviation with the SIGMA subcommand. Base your estimate on the average of the subgroup
ranges with the RBAR subcommand. Or base your estimate on the average of the subgroup standard deviations
with the SBAR subcommand.
You can run the eight common tests for special causes. Use the TEST subcommand to specify which tests to use.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
454
Minitab Statistical Software Quality and Process Improvement
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
455
Minitab Statistical Software Quality and Process Improvement
SIGMA K...K
SIGMA C
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
456
Minitab Statistical Software Quality and Process Improvement
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
AMR
Specifies the average moving range to estimate σ when subgroup size = 1.
MMR
Specifies the median moving range to estimate σ when subgroup size = 1.
SRMSSD
Specifies the square root of MSSD to estimate σ.
BIASED
Specifies to not use unbiasing constants when calculating the within-subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
the pooled standard deviation method of estimating σ.
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. Use RSPAN only when you want to change the length
of the moving range from the default of 2. K must be < 100. RSPAN is ignored when the subgroup size is less
than 1.
When OMIT or ESTIMATE are used with RSPAN, any moving ranges which include omitted data are excluded from
the calculations.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
457
Minitab Statistical Software Quality and Process Improvement
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
458
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX C
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
459
Minitab Statistical Software Quality and Process Improvement
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
460
Minitab Statistical Software Quality and Process Improvement
RCHART: Session command for creating an R chart
RCHART [C...C E]
Creates an R chart for subgroup ranges, for subgroup size = E.
If the subgroups are in columns, enter a data column followed by a subgroup indicator. If the subgroups are in
rows, omit the arguments on the main command line and use the RSUB subcommand to enter the data. For
details, go to How to enter subgroup data on page 1163. The range of the data in each subgroup is calculated and
plotted on the chart.
The process standard deviation (sigma) can be estimated two ways. The default method for RCHART is to base
the estimate on the average of the subgroup ranges with the RBAR subcommand. You can alternatively use the
pooled standard deviation or enter an historical value with the SIGMA subcommand.
You can run the first four of the eight common tests for special causes. Use the TEST subcommand to specify
which tests to use. To adjust the sensitivity of the tests, use the DEFTEST subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
461
Minitab Statistical Software Quality and Process Improvement
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
SIGMA K
For variables control charts, the process is assumed to produce data from a stable population that often follows
a normal distribution. The mean and standard deviation of a population distribution are called m and s, respectively.
MU and SIGMA can be used to specify values for these parameters. The values you enter may be either actual
known process parameters, or they may be estimates obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If m and s are not specified, they are estimated from the data.
462
Minitab Statistical Software Quality and Process Improvement
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating s involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
463
Minitab Statistical Software Quality and Process Improvement
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
Note RCHART supports only tests 1 through 4.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
464
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
465
Minitab Statistical Software Quality and Process Improvement
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
466
Minitab Statistical Software Quality and Process Improvement
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
SCHART: Session command for creating an S chart
SCHART [C...C E]
Creates a control chart for subgroup standard deviations, with subgroup size = E.
If the subgroups are in columns, enter a data column followed by a subgroup indicator. If the subgroups are in
rows, omit the arguments on the main command line, and use the RSUB subcommand to enter the data. For
details, go to How to enter subgroup data on page 1163. The standard deviation of the data in each subgroup is
calculated and plotted on the chart.
The process standard deviation (sigma) can be estimated two ways. The default method uses the average of the
subgroup standard deviations with the SBAR subcommand. You can alternatively base the estimate on the pooled
standard deviation or enter an historical standard deviation with the SIGMA subcommand.
You can run the first four of the eight common tests for special causes. Use the TEST subcommand to specify
which tests to use. To adjust the sensitivity of the tests, use the DEFTEST subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
467
Minitab Statistical Software Quality and Process Improvement
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
SIGMA K
For variables control charts, the process is assumed to produce data from a stable population that often follows
a normal distribution. The mean and standard deviation of a population distribution are called μ and σ, respectively.
SIGMA can be used to specify values for these parameters. The values you enter may be either actual known
process parameters, or they may be estimates obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
468
Minitab Statistical Software Quality and Process Improvement
If you do not specify μ and σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ. The pooled standard deviation is the most efficient method
of estimating standard deviation when you can assume constant variation across subgroups.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating s involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
469
Minitab Statistical Software Quality and Process Improvement
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
Note RCHART supports only tests 1 through 4.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
470
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
471
Minitab Statistical Software Quality and Process Improvement
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
472
Minitab Statistical Software Quality and Process Improvement
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
ZONE: Session command for creating a zone chart
ZONE [C...C E]
Creates a zone chart, with subgroup size = E.
ZONE can be used to plot a chart based on subgroup means or individual observations. The command is entered
different ways, depending on the structure of your data. For more information, go to How to enter subgroup data
on page 1163.
When the subgroup size is greater than one, the mean of all the observations in each subgroup is calculated. A
point is plotted on the zone chart for each subgroup mean. Minitab generates a standardized zone chart when
subgroup sizes are unequal. The process standard deviation (sigma) is estimated by a pooled standard deviation.
You can optionally enter an historical value for the process standard deviation with the SIGMA subcommand.
Base your estimate on the average of subgroup ranges with the RBAR subcommand. Or base your estimate on
the average of the subgroup standard deviations with the SBAR subcommand.
When the subgroup size is equal to one, a point is plotted on the zone chart for each individual observation.
Sigma is estimated using a moving range of length two. You can optionally estimate sigma based on the median
of the moving range with the MMR subcommand. Or specify a moving range of a different length with the RSPAN
subcommand. Enter historical values of sigma with the SIGMA subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
473
Minitab Statistical Software Quality and Process Improvement
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
474
Minitab Statistical Software Quality and Process Improvement
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA K...K
SIGMA C
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
475
Minitab Statistical Software Quality and Process Improvement
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
AMR
Specifies the average moving range to estimate σ when subgroup size = 1.
MMR
Specifies the median moving range to estimate σ when subgroup size = 1.
SRMSSD
Specifies the square root of half the mean of the squared successive differences to estimate σ when subgroup
size = 1.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating σ involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. Use RSPAN only when you want to change the length
of the moving range from the default of 2. K must be < 100. RSPAN is ignored when the subgroup size is less
than 1.
Weights/Reset
RESET
Resets the cumulative score to zero following each out of control signal. When a process goes out of control, an
attempt should be made to find and eliminate the cause of the problem. If the problem has been corrected, the
cumulative score should be reset to zero.
WEIGHT K K K K
Use WEIGHT to specify the weights or scores assigned to points in each zone. For example, WEIGHT 0 3 6 9
assigns a 0 to Zone 1, 3 to Zone 2, 6 to Zone 3, and 9 to Zone 4. The weight assigned to Zone 4 is also used as
the critical value for determining when a process is out of control. In this case, the critical value would be 9. If you
do not use WEIGHT, the default scores are 0, 2, 4, and 8.
Weights must be => 0, but do not need to be integers. When non-integer weights are used, ZONE rounds the
scores displayed on the chart. Store the exact scores with SCORES.
476
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX C
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
477
Minitab Statistical Software Quality and Process Improvement
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
478
Minitab Statistical Software Quality and Process Improvement
Variables Charts for Individuals Data
IMRCHART: Session command for creating an I-MR chart
IMRCHART C...C
Draws an I chart (individual observations) and an MR chart (moving range) chart in the same graph.
Enter a column of individual observations. The chart for individual observations is in the upper half of the graph.
The chart for moving ranges is in the lower half. Seeing both charts together allows you to examine both process
level and process variation at the same time.
The estimate of sigma is based on MR / d2, the average of the moving range divided by an unbiasing constant.
By default, the moving range is of length 2, since consecutive values have the greatest chance of being alike. Use
the RSPAN subcommand to change the length of the moving range. Alternatively, use the MMR subcommand
to estimate sigma using the median of the moving range. Enter historical values of sigma with the SIGMA
subcommand.
You can run all eight tests for special causes for the I portion of the chart. Only the first four tests are used with
the MR portion. You can adjust the sensitivity of the tests with the DEFTEST subcommand.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
479
Minitab Statistical Software Quality and Process Improvement
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA K
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
480
Minitab Statistical Software Quality and Process Improvement
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
AMR
Specifies the average moving range to estimate σ when subgroup size = 1.
MMR
Specifies the median moving range to estimate σ when subgroup size = 1.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
481
Minitab Statistical Software Quality and Process Improvement
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating s involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. Use RSPAN only when you want to change the length
of the moving range from the default of 2. K must be < 100. RSPAN is ignored when the subgroup size is less
than 1.
When OMIT or ESTIMATE are used with RSPAN, any moving ranges which include omitted data are excluded from
the calculations.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOLOWER K
Sets lower control limit bound for I chart.
LOUPPER K
Sets upper control limit bound for I chart.
VALOWER K
Sets lower control limit bound for MR chart.
VAUPPER K
Sets upper control limit bound for MR chart.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
482
Minitab Statistical Software Quality and Process Improvement
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
483
Minitab Statistical Software Quality and Process Improvement
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
484
Minitab Statistical Software Quality and Process Improvement
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
ZMRCHART: Session command for creating a Z-MR chart
ZMRCHART C...C E
Generates control charts for standardized individual observations (Z) and moving ranges (MR) on measurement
data from a short run process, with part indicators = E.
ZMRCHART displays a chart for standardized individual observations (Z) above a chart for moving ranges (MR).
To create a Z-MR chart, type ZMRCHART followed by a data column and a column that contains the part/product
name or number for each measurement. The columns must have the same number of rows. Thus, each row
contains a measurement, and a part or product name. The part/product name column can contain text or numeric
data. The part/product data defines the groupings for estimating process parameters. In addition, each time
Minitab encounters a change in the part/product name column a new run is defined. You can use the SET on
page 80 command to enter patterned data for the part/product number. For more information, go to Entering
patterned data for the SET session command on page 1143.
ZMRCHART standardizes the measurement data by subtracting the mean and dividing the result by the standard
deviation. Standardizing allows data collected from different runs to be evaluated by interpreting a single control
chart. You can estimate the means and standard deviations from the data, or supply historical values using the
CENTER and SPREAD subcommands.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
485
Minitab Statistical Software Quality and Process Improvement
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
486
Minitab Statistical Software Quality and Process Improvement
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
CENTER C...C
CENTER K...K
Use CENTER to enter historical values to standardize the data. The data is standardized by subtracting the mean—to
center the data—and dividing by the standard deviation. When you use CENTER, Minitab uses the data given
with the column or constant argument to standardize the data rather than estimates obtained from the
measurement data. You must enter a value for each observation in the data column. Thus, the CENTER column
must be the same length as the data column.
You can use CENTER to enter a historical mean for each part/product. Using historical means allows you to compare
your process with past performance. When you use known means to center the data, the chart reflects whether
the process is functioning as it has in the past with respect to location. That is, the chart shows whether each
part/product mean is the same as previously established. When the process is functioning the same in respect to
location, the values are distributed (equally) around the center line.
You can also use nominal specifications—target values—for each part/product to center the data. Using nominal
specifications to center the data allows you to compare your process to desired performance. The nominal
specifications are established target values for the dimension of interest for each part/product. When you use
nominal specifications to center the data, the chart reflects whether the process is producing parts/products which
are on target, or whether the process is biased.
SPREAD C...C
SPREAD K...K
Use SPREAD to use historical values to estimate standard deviation.
Estimate
SEPARATE
SEPARATE estimates standard deviation for each run independently.
POOLED
POOLED combines the data from runs of the same part together, then estimates standard deviation for that part.
This is repeated to estimate standard deviation for all parts.
EQUAL
EQUAL pools all the data—across runs and parts—to obtain a common estimate of standard deviation.
PROP
PROP takes the natural log of the data, then pools the transformed data--across all runs and all parts--to obtain
a common estimate of standard deviation for the transformed data. The natural log transformation stabilizes the
variation in cases where variation increases as the size of the measurement increases.
487
Minitab Statistical Software Quality and Process Improvement
AMR
Use to base the standard deviation estimate on the average of the moving range divided by an unbiasing constant.
MMR
Use to base the standard deviation estimate on the median of the moving range.
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. K must be < 100.
Split
SPLIT [K]
Split series by runs (when K is not specified) or by subset (when K is specified).
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
VALOWER K
Sets lower control limit bound for MR chart.
VAUPPER K
Sets upper control limit bound for MR chart.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
488
Minitab Statistical Software Quality and Process Improvement
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
ZMRCHART supports all 8 tests.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
489
Minitab Statistical Software Quality and Process Improvement
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
Storage
LOCATION C
Stores means.
VARIATION C
Stores standard deviations.
PPOINTS C C
Stores plotted points.
CENLINE C C
Stores center line values, one row for each plotted point.
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
ICHART: Session command for creating an I chart
ICHART C...C
Draws a control chart for individual observations.
Enter a column of individual observations. ICHART plots the individual observations on a chart.
The estimate of sigma is based on MR / d2, the average of the moving range divided by an unbiasing constant.
By default, the moving range is of length 2, since consecutive values have the greatest chance of being alike. Use
RSPAN to change the length of the moving range. Alternatively, use the MMR subcommand or the SRMSSD
subcommand to estimate the standard deviation or enter historical standard deviations with the SIGMA
subcommand.
You can run the eight common tests for special causes. Use the TEST subcommand to specify which tests to use.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
490
Minitab Statistical Software Quality and Process Improvement
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
491
Minitab Statistical Software Quality and Process Improvement
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA K
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
492
Minitab Statistical Software Quality and Process Improvement
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
AMR
Specifies the average moving range to estimate σ.
MMR
Specifies the median moving range to estimate σ.
SRMSSD
Specifies the square root of MSSD to estimate σ.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating s involving the standard deviation (SRMSSD).
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. K must be < 100.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
493
Minitab Statistical Software Quality and Process Improvement
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bound. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bound. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
494
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
495
Minitab Statistical Software Quality and Process Improvement
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
496
Minitab Statistical Software Quality and Process Improvement
MRCHART: Session command for creating an MR chart
MRCHART C...C
Draws an MR (moving range) control chart.
Enter a column of individual observations. The moving ranges of length K are calculated for all nonmissing data
and plotted on the chart.
The estimate of standard deviation is based on MR / d2, the average of the moving range divided by an unbiasing
constant. By default, the moving range is of length 2, since consecutive values have the greatest chance of being
alike. Use the RSPAN subcommand to change the length of the moving range. Alternatively, use the MMR
subcommand to estimate the standard deviation using the median of the moving range. Enter historical standard
deviations with the SIGMA subcommand.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
497
Minitab Statistical Software Quality and Process Improvement
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
SIGMA K...K
SIGMA C
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
498
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
AMR
Specifies the average moving range to estimate σ.
MMR
Specifies the median moving range to estimate σ.
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. K must be < 100.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
499
Minitab Statistical Software Quality and Process Improvement
UPPER K
Sets upper control limit bounds. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
500
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
501
Minitab Statistical Software Quality and Process Improvement
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
Attributes Control Charts
PDIAGNOSTIC: Session command for determining whether to use a P chart or a Laney P'
chart
PDIAGNOSTIC C E
Use this test to determine whether a traditional P chart (PCHART on page 503) or a Laney P' chart (PPRIME on
page 509) is more appropriate to chart the proportion of defectives in your sample. If the test determines that
502
Minitab Statistical Software Quality and Process Improvement
your data exhibit overdispersion or underdispersion a Laney P' chart may more accurately distinguish between
common cause variation and special cause variation.
For more information and an example of data entry, go to How to enter data for PDIAGNOSTIC, PCHART, and
PPRIMECHART on page 1161.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
PCHART: Session command for creating a P chart
PCHART C E
Draws a chart for proportion of defectives.
Each entry in the column is the number of defectives for one sample. Minitab assumes the sample came from a
binomial distribution with parameters n and p. E is the subgroup size for the sample, which can be a column (if
the subgroup size varies) or a constant (if all samples are the same size). Minitab plots the proportion of defectives,
503
Minitab Statistical Software Quality and Process Improvement
X / n, for each sample. For more information and an example of data entry, go to How to enter data for
PDIAGNOSTIC, PCHART, and PPRIMECHART on page 1161.
PCHART estimates the process proportion defective from the data by default. The process proportion is the center
line on the chart and is also used to calculated the control limits. If you have a historical value for the process
proportion defective, use the P subcommand to enter it.
The center line and control limits vary with the subgroup size in PCHART. Use the SUBGROUP subcommand to
make them constants.
You can run four common tests for special causes for PCHART. Use the TEST subcommand to specify which tests
to use.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
504
Minitab Statistical Software Quality and Process Improvement
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
P K...K
P C
For PCHART and NPCHART, the process is assumed to produce data from a population that follows a binomial
distribution. The parameters of the binomial distribution are the sample size, n, and the proportion of defectives,
p. P can be used to specify a value for the process proportion defective. The value you use may be either an actual
known process proportion, or an estimate obtained from past data.
If you use a column, it can contain different values for each stage. If you enter one constant, all historical groups
use that value; otherwise, enter a value for each historical group.
If P is not specified, it is estimated by the overall proportion of defectives in the sample.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
505
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
506
Minitab Statistical Software Quality and Process Improvement
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
507
Minitab Statistical Software Quality and Process Improvement
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores proportions, one row for each historical group.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each subgroup.
CONLIMITS C C
Stores control limit values, one row for each subgroup.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
508
Minitab Statistical Software Quality and Process Improvement
PPRIMECHART: Session command for creating a Laney P' chart
PPRIMECHART C E
Draws a Laney P' chart for proportion of defectives. The Laney P' chart is similar to a traditional P chart (PCHART
on page 503). Both charts help you to monitor the proportion of defective items that are produced by your process.
The Laney P' chart can be useful in the following situations:
You have large subgroups and your data exhibit overdispersion.
Overdispersion can cause the points on a traditional P chart to appear to be out of control when they are not.
For the Laney P' chart, the definition of common cause variation includes not only the within-subgroup variation,
but also the average variation between consecutive subgroups. If there is overdispersion, the control limits
on a Laney P' chart are wider than those of a traditional P chart. The wider control limits mean that only
important deviations in your process are identified as out of control.
Your data exhibit underdispersion.
Underdispersion, which can occur with subgroups of any size, is often caused by a lack of randomness.
Underdispersion can result in control limits that are too wide for the data. The Laney P' chart corrects for
underdispersion by calculating narrower control limits.
You can use P chart diagnostic (PDIAGNOSTIC on page 502) to test for overdispersion and underdispersion.
The calculations for the Laney P' chart include Sigma Z, which is an adjustment for overdispersion or
underdispersion. A Sigma Z value of 1 indicates that no adjustment is necessary and that the Laney P' chart is
exactly the same as a traditional P chart.
For more information and an example of data entry, go to How to enter data for PDIAGNOSTIC, PCHART, and
PPRIMECHART on page 1161.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
509
Minitab Statistical Software Quality and Process Improvement
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
P K...K
P C
The process is assumed to produce data from a population that follows a binomial distribution. The parameters
of the binomial distribution are the sample size, n, and the proportion of defectives, p. P can be used to specify
510
Minitab Statistical Software Quality and Process Improvement
a value for the process proportion defective. The value you use may be either an actual known process proportion,
or an estimate obtained from past data.
If you use a column, it can contain different values for each stage. If you enter one constant, all historical groups
use that value; otherwise, enter a value for each historical group.
If P is not specified, it is estimated by the overall proportion of defectives in the sample.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
511
Minitab Statistical Software Quality and Process Improvement
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bound. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bound. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
512
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
513
Minitab Statistical Software Quality and Process Improvement
Storage
LOCATION C
Stores proportions, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each subgroup.
CONLIMITS C C
Stores control limit values, one row for each subgroup.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
NPCHART: Session command for creating a chart for the number of defectives
NPCHART C E
Draws a chart for the number of defectives.
Each entry in the column is the number of defectives for one sample. The sample is assumed to have come from
a binomial distribution with parameters n and p. E is the subgroup size for the sample, which can be a column (if
the subgroup size varies) or a constant (if all samples are the same size). Minitab plots the number of defectives
for each sample. For more information and an example of data entry, go to How to enter data for NPCHART on
page 1160.
NPCHART estimates the process proportion defective from the data by default. The process proportion is the
center line on the NPCHART and is also used to the control limits. If you have a historical value for the process
proportion defective, use the P subcommand to enter it.
The center line and control limits vary with the subgroup size in NPCHART. Use the SUBGROUP subcommand to
make them constants.
You can run four common tests for special causes for NPCHART. Use the TEST subcommand to specify which
tests to use.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
514
Minitab Statistical Software Quality and Process Improvement
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
515
Minitab Statistical Software Quality and Process Improvement
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
P K...K
P C
For NPCHART, the process is assumed to produce data from a population that follows a binomial distribution.
The parameters of the binomial distribution are the sample size, n, and the proportion of defectives, p. P can be
used to specify a value for the process proportion defective. The value you use may be either an actual known
process proportion, or an estimate obtained from past data.
If you use a column, it can contain different values for each stage. If you enter one constant, all historical groups
use that value; otherwise, enter a value for each historical group.
If P is not specified, it is estimated by the overall proportion of defectives in the sample.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
516
Minitab Statistical Software Quality and Process Improvement
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
517
Minitab Statistical Software Quality and Process Improvement
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
518
Minitab Statistical Software Quality and Process Improvement
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores proportions, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
UPRIMECHART: Session command for creating a Laney U' chart
UPRIMECHART C E
Draws a Laney U' chart for proportion of defectives. The Laney U' chart is similar to a traditional U chart (UCHART
on page 525). Both charts help you to monitor the number of defects per unit that are produced by your process.
The Laney U' chart can be useful in the following situations:
You have large subgroups and your data exhibit overdispersion.
Overdispersion can cause the points on a traditional U chart to appear to be out of control when they are not.
For the Laney U' chart, the definition of common cause variation includes not only the within-subgroup
variation, but also the average variation between consecutive subgroups. If there is overdispersion, the control
limits on a Laney U' chart are wider than those of a traditional U chart. The wider control limits mean that only
important deviations in your process are identified as out of control.
Your data exhibit underdispersion.
Underdispersion, which can occur with subgroups of any size, is often caused by a lack of randomness.
Underdispersion can result in control limits that are too wide for the data. The Laney U' chart corrects for
underdispersion by calculating narrower control limits.
519
Minitab Statistical Software Quality and Process Improvement
You can use U chart diagnostic (UDIAGNOSTIC on page 530) to test for overdispersion and underdispersion.
The calculations for the Laney U' chart include Sigma Z, which is an adjustment for overdispersion or
underdispersion. A Sigma Z value of 1 indicates that no adjustment is necessary and that the Laney U' chart is
exactly the same as a traditional U chart.
For more information and an example of data entry, go to How to enter data for UDIAGNOSTIC, UCHART, and
UPRIMECHART on page 1163.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
520
Minitab Statistical Software Quality and Process Improvement
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C
The process is assumed to produce data from a population that follows a Poisson distribution. The mean and
variance of this distribution are both denoted by μ. MU can be used to specify a value for this parameter. The
value you enter may be either an actual known process mean, or an estimate obtained from past data.
If you use a column, it can contain different values for each stage. If you enter one constant, all historical groups
use that value. Otherwise, enter a value for each historical group.
If μ is not specified, it is estimated by the overall sample mean.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
521
Minitab Statistical Software Quality and Process Improvement
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bound. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bound. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
522
Minitab Statistical Software Quality and Process Improvement
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
523
Minitab Statistical Software Quality and Process Improvement
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores estimates of the means, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each subgroup.
CONLIMITS C C
Stores control limit values, one row for each subgroup.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
524
Minitab Statistical Software Quality and Process Improvement
UCHART: Session command for creating a U chart
UCHART C E
Draws a chart of the number of defects per unit sampled.
Each entry in the specified column is the number of defects for one sample. Minitab assumes the sample comes
from a Poisson distribution with the parameter m. E is the sample size for each sample in the column, which can
be a column (if the subgroup size varies) or a constant (if all samples are the same size). Minitab plots the number
of defects per unit, or X / n, for each sample.
UCHART estimates the process average number of defects from the data by default. The process average is the
center line on a UCHART and is also used to calculated the control limits. If you have an historical value for the
process average number of defects, use the MU subcommand to enter it.
The control limits vary with the subgroup size in UCHART. Use the SUBGROUP command to make them constants.
For examples, go to How to enter data for UDIAGNOSTIC, UCHART, and UPRIMECHART on page 1163.
You can run four common tests for special causes for UCHART. Use the TEST subcommand to specify which tests
to use.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
525
Minitab Statistical Software Quality and Process Improvement
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
P C
For CCHART and UCHART, the process is assumed to produce data from a population that follows a Poisson
distribution. The mean and variance of this distribution are both denoted by μ. MU can be used to specify a value
for this parameter. The value you enter may be either an actual known process mean, or an estimate obtained
from past data.
If you use a column, it can contain different values for each stage. If you enter one constant, all historical groups
use that value. Otherwise, enter a value for each historical group.
If μ is not specified, it is estimated by the overall sample mean.
526
Minitab Statistical Software Quality and Process Improvement
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
527
Minitab Statistical Software Quality and Process Improvement
UPPER K
Sets upper control limit bounds. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
528
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores estimates of the means, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each subgroup.
529
Minitab Statistical Software Quality and Process Improvement
CONLIMITS C C
Stores control limit values, one row for each subgroup.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
UDIAGNOSTIC: Session command for determining whether to use a U chart or a Laney U'
chart
UDIAGNOSTIC C E
Use this test to determine whether a traditional U chart (UCHART on page 525) or a Laney U' chart (UPRIMECHART
on page 519) is more appropriate to chart the number of defects per unit in your sample. If the test determines
that your data exhibit overdispersion or underdispersion a Laney U' chart may more accurately distinguish between
common cause variation and special cause variation.
For more information and an example of data entry, go to How to enter data for UDIAGNOSTIC, UCHART, and
UPRIMECHART on page 1163.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
530
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
CCHART: Session command for creating a C chart
CCHART C
Draws a chart of the number of defects.
Each entry in the specified column contains the number of defects for one sample. The sample is assumed to
have come from a Poisson distribution with parameter m. Minitab plots the number of defects, or X, for each
sample. For more information and an example of data entry, go to How to enter data for CCHART on page 1159.
CCHART estimates the process average number of defects from the data by default. The process average is the
center line on the CCHART and is also used to calculated the control limits. Use the MU subcommand to enter a
historical value for the process average number of defects.
You can run four common tests for special causes for CCHART. Use the TEST subcommand to specify which tests
to use.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
531
Minitab Statistical Software Quality and Process Improvement
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C
For CCHART, the process is assumed to produce data from a population that follows a Poisson distribution. The
mean and variance of this distribution are both denoted by μ. You can use MU to specify a value for this parameter.
You can specify either an actual known process mean, or an estimate obtained from past data.
If you use a column, it can contain different values for each stage. If you enter one constant, all historical groups
use that value. Otherwise, enter a value for each historical group.
532
Minitab Statistical Software Quality and Process Improvement
If you don't specify μ, it is estimated by the overall sample mean.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
533
Minitab Statistical Software Quality and Process Improvement
LOWER K
Sets lower control limit bounds. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart that supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
534
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores proportions, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
535
Minitab Statistical Software Quality and Process Improvement
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
Time-Weighted Control Charts
MACHART: Session command for creating a moving average chart
MACHART [C...C E]
Draws an MA (moving average) control chart.
MACHART can plot a chart based on either subgroup means or individual observations with subgroup size = E.
When plotting a chart based on subgroup means, the command is entered two ways, depending on the structure
of your data. For details, go to How to enter subgroup data on page 1163.
To plot a chart of individual observations, enter the column followed by a subgroup indicator of 1. For example,
MACHART C1 1 plots a chart of the individual observations contained in C1. To enter data for individual
observations, you must have all the data from a process in a single column. Since there are no subgroups, you
do not need a subgroup indicator column or a subgroup size.
If your data are in subgroups, then the mean of all the observations in each subgroup is calculated. Moving
averages are then formed from these means. The process standard deviation (sigma) is estimated by a pooled
standard deviation. You can optionally enter an historical value for the process standard deviation with the SIGMA
subcommand, base your estimate on the average of subgroup ranges with the RBAR subcommand, or base your
estimate on the average of the subgroup standard deviations with the SBAR subcommand.
If your data are individual observations, then moving averages are formed from the individual observations. In
this case, sigma is estimated using a moving range of length two. You can optionally estimate σ based on the
median of the moving range with the MMR subcommand. Or specify a moving range of a different length with
the RSPAN subcommand. Enter an historical value for the process standard deviation with the SIGMA subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
536
Minitab Statistical Software Quality and Process Improvement
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
537
Minitab Statistical Software Quality and Process Improvement
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA K
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
538
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
AMR
Specifies the average moving range to estimate σ when subgroup size = 1.
MMR
Specifies the median moving range to estimate σ when subgroup size = 1.
SRMSSD
Specifies the square root of half the mean of the squared successive differences to estimate σ when subgroup
size = 1.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating s involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
RSPAN K
Specifies the length of the moving range. By default, a span of two is used because consecutive values have the
greatest chance of being alike. The span must be < 100.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
539
Minitab Statistical Software Quality and Process Improvement
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
540
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
541
Minitab Statistical Software Quality and Process Improvement
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
542
Minitab Statistical Software Quality and Process Improvement
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
EWMACHART: Session command for creating an EWMA chart
EWMACHART [C...C E]
Draws an EWMA (exponentially weighted moving average) control chart.
EWMACHART can be used to plot a chart based on either subgroup means or individual observations. When
plotting a chart based on subgroup means, the command is entered two ways, depending on the structure of
your data. For details, go to How to enter subgroup data on page 1163.
To plot a chart of individual observations, enter the column followed by a subgroup indicator of 1. For example,
EWMACHART C1 1 plots a chart of the individual observations contained in C1.
If your data are in subgroups, then the mean of all the observations in each subgroup is calculated. Exponentially
weighted moving averages are then formed from these means. The process standard deviation (sigma) is estimated
by a pooled standard deviation. You can optionally enter an historical value for the process standard deviation
with the SIGMA subcommand, base your estimate on the average of subgroup ranges with the RBAR subcommand,
or base your estimate on the average of the subgroup standard deviations with the SBAR subcommand.
If your data are individual observations, then exponentially weighted moving averages are formed from the
individual observations. In this case, sigma is estimated using a moving range of length two. You can optionally
estimate σ based on the median of the moving range with the MMR subcommand. Or specify a moving range of
a different length with the RSPAN subcommand. Enter an historical value for the process standard deviation with
the SIGMA subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
543
Minitab Statistical Software Quality and Process Improvement
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Weight
WEIGHT K
Specifies the weight used in the exponentially weighted moving average. The weight must be between 0 and 1.
The default is 0.2. By changing the weight used and the number of sigmas for the control limits, you can construct
544
Minitab Statistical Software Quality and Process Improvement
a chart with very specific properties. Combinations of these two parameters are often chosen by using an ARL
(average run length) table.
Parameters
MU K...K
MU C
Specify a value for mu (denoted as μ), the mean of the population. The value that you enter can be either an
actual known process parameter or an estimate that was obtained from past data.
If you use a column, it can contain different values for each historical stage. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical stage.
If you do not specify a value, Minitab estimates it from the data.
SIGMA K...K
SIGMA C
Specify a value for sigma (denoted as σ), the standard deviation of the population. The value that you enter can
be either an actual known process parameter or an estimate that was obtained from past data.
If you use a column, it can contain different values for each historical stage. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical stage.
If you do not specify a value, Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation 2
(using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set, you
must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
545
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
AMR
Specifies the average moving range to estimate σ when subgroup size = 1.
MMR
Specifies the median moving range to estimate σ when subgroup size > 1.
SRMSSD
Specifies the square root of half the mean of the squared successive differences to estimate σ when subgroup
size > 1.
BIASED
Specifies to not use unbiasing constants when calculating the within-subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
the pooled standard deviation method of estimating σ.
RSPAN K
Specifies the length of the moving range. By default, a span of two is used because consecutive values have the
greatest chance of being alike. The span must be < 100.
S limits
SLIMITS K...K
SLIMITS C
Draws additional sigma limit lines above and below the mean at the standard deviation values that you specify.
The arguments for SLIMITS are positive numbers. Each argument you give draws two horizontal lines, one above
and one below the mean. For example, SLIMITS 2 draws control limits at two standard deviations above and
546
Minitab Statistical Software Quality and Process Improvement
below the center line. SLIMITS 1 2 3 gives three lines above and three lines below the center line at the first,
second, and third standard deviations.
LOWER K
Sets lower control limit bounds. If the calculated lower control limit is less than the lower bound, a horizontal line
labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bounds. If the calculated upper control limit is greater than the upper bound, a horizontal
line labeled UB will be drawn at the upper bound instead.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
547
Minitab Statistical Software Quality and Process Improvement
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
548
Minitab Statistical Software Quality and Process Improvement
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
549
Minitab Statistical Software Quality and Process Improvement
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
CUSUM: Session command for creating a CUSUM chart
CUSUM [C...C E]
Draws a CUSUM (cumulative sum) control chart with subgroup size = E.
Use CUSUM to plot a chart based on subgroup means or individual observations. You can enter the command
in different ways, depending on the structure of your data. For details, go to How to enter subgroup data on page
1163. When data are arranged across rows, you can optionally specify the number of models you would like. For
example, if you have data across rows c1 - c6 and you have two models (C1–C3 and C4–C6), you can enter RSUB
C1–C6 2 to produce two control charts. The number of models you specify must divide evenly into the number
of columns on the RSUB subcommand.
CUSUM plots two 1-sided CUSUMs. The upper CUSUM is for detecting upward shifts in the level of the process;
the lower CUSUM for detecting downward shifts. This chart uses an UCL and an LCL to determine when an
out-of-control situation has occurred.
Use VMASK on page 556 to plot a single 2-sided CUSUM. This chart uses a V-mask to determine when an
out-of-control situation has occurred.
The CUSUM chart is defined by two parameters, h and k. These parameters are often referred to as a "CUSUM
plan" and are specified on the PLAN subcommand. In the default chart, h is the number of standard deviations
between the center line and the control limits, and k is the allowable "slack" in the process.
If your data are in subgroups, then Minitab calculates the mean of all the observations in each subgroup, then
calculates the CUSUM statistics using the subgroup means. All subgroups must be the same size. Minitab estimates
the process standard deviation by a pooled standard deviation. You can optionally enter an historical value for
the process standard deviation with the SIGMA subcommand, base your estimate on the average of subgroup
ranges with the RBAR subcommand, or base your estimate on the average of the subgroup standard deviations
with the SBAR subcommand.
If your data are individual observations, then Minitab calculates the CUSUM statistics using the individual
observations. Minitab estimates sigma using a moving range length of 2. You can optionally estimate sigma based
on the median of the moving range with the MMR subcommand. You can also specify a moving range of a
different length with the RSPAN subcommand. Enter historical standard deviation values with the SIGMA
subcommand.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
550
Minitab Statistical Software Quality and Process Improvement
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
551
Minitab Statistical Software Quality and Process Improvement
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Target
TARGET K
Specifies a target. CUSUM statistics are cumulative deviations from this target, or nominal, specification.
Parameters
SIGMA K...K
SIGMA C
For variables control charts, the process is assumed to produce data from a stable population that often follows
a normal distribution. You can use SIGMA to specify values for the standard deviation. You can enter either actual
known process parameters, or estimates obtained from past data.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
552
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
SBAR
Use to base your estimate on the average of the subgroup standard deviations.
AMR
When plotting control charts for individual observations, the estimate of standard deviation is based on the
average of the moving range divided by an unbiasing constant.
MMR
Use to base the estimate on the median of the moving range.
SRMSSD
The SRMSSD subcommand estimates the standard deviation using the square root of half the mean of the squared
successive differences. Use this subcommand for charts which allow individual points where the standard deviation
does not have to be estimated using the moving range.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating s involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
RSPAN K
RSPAN specifies the length of the moving range. By default, Minitab uses a moving range of length 2, since
consecutive values have the greatest chance of being alike. Use RSPAN only when you want to change the length
of the moving range from the default of 2. K must be < 100.
Plan/Type
PLAN K K
Specifies a CUSUM plan, which is defined by the parameters h and k. The first value entered is h, the second is k.
Both h and k must be greater than 0. The default values are 4 and 0.5.
553
Minitab Statistical Software Quality and Process Improvement
FIR K
Uses the FIR (fast initial response) method to initialize the one-sided CUSUMs. Normally, they are initialized at 0.
If the process is out of control at startup, the CUSUMs will not detect the situation for several subgroups. The FIR
method initializes the CUSUMs at a specified number of sigma's above and below 0. This method has been shown
to reduce the number of subgroups needed to detect problems at startup.
RESET
Resets the CUSUMs to their initial values whenever an out-of-control signal is generated. When a process goes
out of control, an attempt should be made to find and eliminate the cause of the problem. If the problem has
been corrected, the CUSUMs should be reset to their initial values.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 specifies to calculate the control limits and center line as if all subgroups were of size
6. The data that are actually plotted are not affected by this subcommand.
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
554
Minitab Statistical Software Quality and Process Improvement
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, then Minitab uses data from all historical stages to find a single lambda. If you
do not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
555
Minitab Statistical Software Quality and Process Improvement
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
VMASK: Session command for creating a two-sided CUSUM chart
VMASK [C...C E]
VMASK displays a single 2-sided CUSUM, with subgroup size = E. This chart uses a V-mask to determine when
an out-of-control situation has occurred. Use CUSUM on page 550 to display a 1-sided CUSUM.
CUSUM charts are defined by two parameters, h and k. These parameters are often referred to as a "CUSUM plan"
and are specified on the PLAN subcommand. In the VMASK chart, Minitab calculates the half-width of the V-mask
(H) at the point of origination by H = h * s. The slope of the V-mask arms is defined by k. Values of h and k are
often selected from ARL (average run length) tables.
RSUB C...C
Specifies that data are in subgroups across rows.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
556
Minitab Statistical Software Quality and Process Improvement
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Target
TARGET K
Specifies a target. CUSUM statistics are cumulative deviations from this target, or nominal, specification.
557
Minitab Statistical Software Quality and Process Improvement
Parameters
SIGMA K...K
SIGMA C
For variables control charts, the process is assumed to produce data from a stable population that often follows
a normal distribution. SIGMA can be used to specify values for the standard deviation. The values you enter may
be either actual known process parameters, or they may be estimates obtained from past data.
If you use a column, it can contain different values for each historical group. If you enter one constant, all historical
stages use that value; otherwise, enter a value for each historical group.
If you do not specify σ, then Minitab estimates it from the data.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
558
Minitab Statistical Software Quality and Process Improvement
POOLED
Specifies the pooled standard deviation to estimate σ when subgroup size > 1. The pooled standard deviation is
the most efficient method of estimating standard deviation when you can assume constant variation across
subgroups.
RBAR
Specifies the average of the subgroup ranges to estimate σ when subgroup size > 1. This method is the one that
appears in many books and manuals that describe control charts. Subgroup size must be < 100 to use this
subcommand.
SBAR
Specifies the average of the subgroup standard deviations to estimate σ when subgroup size > 1.
AMR
Specifies the average moving range to estimate σ when subgroup size = 1.
MMR
Specifies the median moving range to estimate σ when subgroup size = 1.
SRMSSD
Specifies the square root of half the mean of the squared successive differences to estimate σ when subgroup
size = 1.
SUBGROUP K
If the subgroup sizes are not equal, then the control limits will not be straight lines, but will vary with the subgroup
size. The center line of charts for ranges and standard deviations also varies with the subgroup size. If the sizes
do not vary much, you may want to force the control limits to be straight lines. SUBGROUP allows you to do this.
For example, SUBGROUP 6 says to calculate the control limits and center line as if all subgroups were of size 6.
The data that are actually plotted are not affected by this subcommand.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations. The default
is to use biasing constants.
UNBIASED
Uses unbiased constants in the calculation of standard deviations. Use this subcommand only in conjunction with
methods of estimating σ involving the standard deviation (pooled standard deviation, SBAR, SRMSSD).
RSPAN K
Specifies the length of the moving range. By default, a span of two is used because consecutive values have the
greatest chance of being alike. The span must be < 100.
Plan/Type
PLAN K K
Specifies a CUSUM plan, which is defined by the parameters h and k. The first value entered is h, the second is k.
Both h and k must be greater than 0. The default values are 4 and 0.5.
VMASK K
Specifies the subgroup number to center the V-mask on. If you use 0 or do not specify K, the VMASK is placed
on the last subgroup.
559
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX C
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
560
Minitab Statistical Software Quality and Process Improvement
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores standard deviations, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores center line values, one row for each plotted point.
CONLIMITS C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
561
Minitab Statistical Software Quality and Process Improvement
Multivariate Control Charts
TSGV: Session command for creating a Tsquared-generalized variance chart
TSGV C...C E
Draws a Tsquared chart and a generalized variance chart in the same graph, with subgroup size = E. Use the
Tsquared-generalized variance chart to examine whether the process mean vector and process variability for two
or more correlated variables are in control.
You must have at least two columns of correlated data. For example, you can create a Tsquared-generalized
variance chart to investigate how the tensile strength and diameter of a fiber jointly affect the quality of a fabric.
If you have correlated variables, the use of separate control charts is misleading because the variables jointly
affect the process. If you use separate univariate control charts in a multivariate situation, type I error and the
probability of a point correctly plotting in control are not equal to their expected values. The distortion of these
values increases with the number of measurement variables.
Multivariate control charting has several advantages over creating multiple univariate charts:
The actual control region of the related variables is represented (elliptical for bivariate case).
You can maintain a specific type I error.
A single control limit determines whether the process is in control.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
562
Minitab Statistical Software Quality and Process Improvement
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
MU K...K
MU C...C
MU specifies the vector of historical means, one column for each column of data on the main command line. Any
one column may have multiple values (one for each historical group) or a single value used for all historical stages.
If using constants, there must the same number of Ks as columns of data on the main command line.
563
Minitab Statistical Software Quality and Process Improvement
SIGMA M M
SIGMA specifies the historical covariance matrix, M...M, which must be a positive definite square matrix with the
same number of rows and columns as columns of data on the main command. The matrix's diagonal elements
must be positive. Element ij must equal element ji.
If only one M is entered, then all historical stages use that pair. If you want each historical stage to use its own
covariance matrix, then enter the same number of matrices as historical stages.
NUMBER K...K
Use NUMBER to specify the number of samples used to estimate covariance.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
564
Minitab Statistical Software Quality and Process Improvement
Confidence limits
SLIMITS K...K
SLIMITS C
Draws additional confidence limits at the specified values. The arguments for SLIMITS are positive numbers.
LOLOWER K
Sets bound on lower confidence limit for Tsquared chart.
LOUPPER K
Sets bound on upper confidence limit for Tsquared chart.
VALOWER K
Sets bound on lower confidence limit for generalized variance chart.
VAUPPER K
Sets bound on upper confidence limit for generalized variance chart.
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
565
Minitab Statistical Software Quality and Process Improvement
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores covariances, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
566
Minitab Statistical Software Quality and Process Improvement
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
DECOMP C
Stores decomposed Tsquared values for out-of-control points.
TSQUARED: Session command for creating a Tsquared chart
TSQUARED C...C E
Creates a Tsquared chart, with subgroup size = E. Use the Tsquared chart to examine if the process mean vector
for two or more correlated variables is in control.
You must have at least two columns of correlated data. For example, you can create a Tsquared chart to investigate
the percentage of impurities and the concentration strength in a chemical process.
If you have correlated variables, the use of separate control charts is misleading because the variables jointly
affect the process. If you use separate univariate control charts in a multivariate situation, type I error and the
probability of a point correctly plotting in control are not equal to their expected values. The distortion of these
values increases with the number of measurement variables.
The actual control region of the related variables is represented (elliptical for bivariate case).
You can maintain a specific type I error.
A single control limit determines whether the process is in control.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
567
Minitab Statistical Software Quality and Process Improvement
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
568
Minitab Statistical Software Quality and Process Improvement
Parameters
MU K...K
MU C...C
MU specifies the vector of historical means, one column for each column of data on the main command line. Any
one column can have multiple values (one for each historical group) or a single value used for all historical stages.
If using constants, there must the same number of Ks as columns of data on the main command line.
SIGMA K
SIGMA specifies the historical covariance matrix, M...M, which must be a positive definite square matrix with the
same number of rows and columns as columns of data on the main command. The matrix's diagonal elements
must be positive. Element ij must equal element ji.
If only one M is entered, then all historical stages use that pair. If you want each historical group to use its own
covariance matrix, then enter the same number of matrices as historical stages.
NUMBER K...K
Use NUMBER to specify the number of samples used to estimate covariance.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation 2
(using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set, you
must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
569
Minitab Statistical Software Quality and Process Improvement
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation 2
(using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set, you
must enter observation 2 as the observation to omit.
Confidence limits
SLIMITS K...K
SLIMITS C
Draws additional confidence limits at the specified values. The arguments for SLIMITS are positive numbers.
UPPER K
Sets a bound on the upper confidence limit.
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
570
Minitab Statistical Software Quality and Process Improvement
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores covariances, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
571
Minitab Statistical Software Quality and Process Improvement
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C...C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
DECOMP C
Stores decomposed Tsquared values for out-of-control points.
GENVAR: Session command for creating a generalized variance chart
GENVAR C...C E
Draws a generalized variance chart with subgroup size = E. Use the generalized variance chart to examine if the
process variability for two or more correlated variables is in control.
You must have at least two columns of correlated data. For example, you can create a Tsquared-generalized
variance chart to investigate how the tensile strength and diameter of a fiber jointly affect the quality of a fabric.
If you have correlated variables, the use of separate control charts is misleading because the variables jointly
affect the process. If you use separate univariate control charts in a multivariate situation, type I error and the
probability of a point correctly plotting in control are not equal to their expected values. The distortion of these
values increases with the number of measurement variables.
Multivariate control charting has several advantages over creating multiple univariate charts:
The actual control region of the related variables is represented (elliptical for bivariate case).
You can maintain a specific type I error.
A single control limit determines whether the process is in control.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
572
Minitab Statistical Software Quality and Process Improvement
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
573
Minitab Statistical Software Quality and Process Improvement
Parameters
SIGMA M...M
SIGMA specifies the historical covariance matrix, M...M, which must be a positive definite square matrix with the
same number of rows and columns as columns of data on the main command. The matrix's diagonal elements
must be positive. Element ij must equal element ji.
If only one M is entered, then all historical stages use that pair. If you want each historical stage to use its own
covariance matrix, then enter the same number of matrices as historical stages.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
574
Minitab Statistical Software Quality and Process Improvement
Confidence limits
SLIMITS K...K
SLIMITS C
Draws additional confidence limits at the specified values. The arguments for SLIMITS are positive numbers.
LOWER K
Sets a bound on the lower confidence limit.
UPPER K
Sets a bound on the upper confidence limit.
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
575
Minitab Statistical Software Quality and Process Improvement
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
VARIATION C
Stores covariances, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
576
Minitab Statistical Software Quality and Process Improvement
TRESULTS C...C
Stores test results, one row for each plotted point. Minitab assigns each plotted point one of three values: 1
(beyond upper control limit), −1 (beyond lower control limit), 0 (in control).
MEWMA: Session command for creating a multivariate EWMA chart
MEWMA C...C E
Draws a multivariate EWMA chart, the multivariate equivalent to the EWMACHART on page 543. Use the multivariate
EWMA chart to examine small shifts in the mean vector of two or more correlated variables.
You must have at least two columns of correlated data. For example, you can create a Tsquared-generalized
variance chart to investigate how the tensile strength and diameter of a fiber jointly affect the quality of a fabric.
If you have correlated variables, the use of separate control charts is misleading because the variables jointly
affect the process. If you use separate univariate control charts in a multivariate situation, type I error and the
probability of a point correctly plotting in control are not equal to their expected values. The distortion of these
values increases with the number of measurement variables.
Multivariate control charting has several advantages over creating multiple univariate charts:
The actual control region of the related variables is represented (elliptical for bivariate case).
You can maintain a specific type I error.
A single control limit determines whether the process is in control.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
577
Minitab Statistical Software Quality and Process Improvement
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
ARL and weight
ARL K
Sets the average run length (ARL) of K to determine the upper control limit. K must be a positive number. The
default ARL is 200. The minimum allowable ARL is 1.
WEIGHT K
Specifies the weight. K must be between 0 and 1. The default is 0.1.
578
Minitab Statistical Software Quality and Process Improvement
Parameters
MU C...C
MU K...K
MU specifies the vector of historical means, one column for each column of data on the main command line. Any
one column may have multiple values (one for each historical group) or a single value used for all historical stages.
If using constants, there must the same number of K's as columns of data on the main command line.
SIGMA M...M
SIGMA specifies the historical covariance matrix, M...M, which must be a positive definite square matrix with the
same number of rows and columns as columns of data on the main command. The matrix's diagonal elements
must be positive. Element ij must equal element ji.
If only one M is entered, then all historical stages use that pair. If you want each historical group to use its own
covariance matrix, then enter the same number of matrices as historical stages.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
579
Minitab Statistical Software Quality and Process Improvement
Confidence limits
UPPER K
Sets a bound on the upper confidence limit.
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Box-Cox transformation
BOXCOX [K...K]
BOXCOX [C]
The Box-Cox transformation can be used to correct both non-normality in process data and subgroup process
variation being related to the subgroup mean. Under most conditions, it is not necessary to correct for
non-normality unless the data are highly skewed.
Minitab provides two Box-Cox transformations: a stand-alone command, and a transformation option provided
with each control chart. You can use these procedures in tandem. First, use the stand-alone command as an
exploratory tool to help you determine the best lambda value for the transformation. Then, when you enter the
control chart command, use the transformation option to transform the data at the same time you draw the chart.
You can use the Box-Cox power transformation when your data are very skewed or where the within-subgroup
variation is unstable. The transformation takes the original data to the power λ, unless λ = 0, in which case the
transformation takes the natural log.
You can use BOXCOX only with positive data.
You can use the common transformations natural log = 0) and square root = 0.5). You can also choose any
value between −5 and 5 for λ or choose to find a single optimal λ for each or all historical stages. In most cases,
you should not choose a λ outside the range of −2 and 2.
When you use this transformation, Minitab does not accept any values entered for MU or SIGMA.
When you use the Box-Cox transformation, the control chart is of the transformed data. The process parameters
(mean and standard deviation) are also calculated using the transformed data.
580
Minitab Statistical Software Quality and Process Improvement
ALL
If you use the ALL argument, Minitab uses data from all historical stages to find a single lambda. If you do
not specify any arguments, then Minitab finds the optimal value of lambda.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores means, one row for each historical stage.
VARIATION C
Stores covariances, one row for each historical stage.
PPOINTS C
Stores plotted points, one row for each subgroup.
CONLIMITS C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
SAMPSIZE C
Stores subgroup sizes, one row for each plotted point.
TRESULTS C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
581
Minitab Statistical Software Quality and Process Improvement
Rare Event Charts
GCHART: Session command for creating a G chart
GCHART C...C
Use a G chart to monitor the number of opportunities or, in many cases, the number of days between rare events,
such as infections or surgical complications.
When you monitor rare events with a traditional attribute chart, such as a P or a U chart, you need a large amount
of data to establish accurate control limits. Therefore, collecting enough rare event data to detect an adverse
change in the frequency of events may take months or even years. You do not need to collect large amounts of
data to use a G chart. The G chart is based on the geometric distribution. The G chart plots the number of
opportunities between events so you can easily detect when events occur more or less often than expected. For
more information, go to How to enter data for GCHART on page 1159.
In some situations, the actual number of opportunities between events is not known. Instead, the dates of the
events are recorded. When you use the G chart in these situations, you should verify that the number of possible
opportunities per day is fairly constant.
If you know the date and specific time of day for each event, use TCHART on page 587 to monitor time between
rare events.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
582
Minitab Statistical Software Quality and Process Improvement
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
P K...K
P C
You can enter historical data for estimating p. For example, if you have a known process parameter or an estimate
obtained from past data, enter the value(s). If you do not specify a value for p, Minitab estimates it from the data.
By default, Minitab estimates the chance of an event occurring in any particular day (or opportunity), p, from the
overall sample proportion. Then, Minitab calculates the center line and control limits using this value.
583
Minitab Statistical Software Quality and Process Improvement
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
P limits
PLIMITS K...K
PLIMITS C
Each argument in PLIMITS defines a single line to be drawn at the specified percentile. Values entered should be
percents. To get lines above and below the center line, specify matching percentiles above and below. For example,
in PLIMITS 0.1 2.5 10 90 97.55 99.99, the first 3 percentiles are below the center line, the last 3 are
above.
LOWER K
Sets lower control limit bound. K must be a positive number. If the calculated lower control limit is less than the
lower bound, a horizontal line labeled LB will be drawn at the lower bound instead.
UPPER K
Sets upper control limit bound. K must be a positive number. If the calculated upper control limit is greater than
the upper bound, a horizontal line labeled UB will be drawn at the upper bound instead.
584
Minitab Statistical Software Quality and Process Improvement
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
BENNEYAN K
Use K=1 to perform the Benneyan test. Use K=0 to not perform the Benneyan test.
The Benneyan test counts the number of consecutive plotted points equal to 0. When a point on a G chart fails
the Benneyan test, the point is marked with B. The number of points that are required to signal the Benneyan
Test is a function of the desired false alarm rate and the event probability. The false alarm rate is based on the
probability associated with the test 1 argument for a chart based on the normal distribution, such as an XBar
chart. The default test 1 argument is 3.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test for
special causes
31–6One point more than K standard deviations from
center line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
585
Minitab Statistical Software Quality and Process Improvement
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
LOCATION C
Stores estimates of the proportions, one row for each historical stage.
PPOINTS C C
Stores plotted points, one row for each subgroup.
CENLINE C C
Stores center line values, one row for each plotted point.
586
Minitab Statistical Software Quality and Process Improvement
CONLIMITS C C C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators, one row for each plotted point.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
TCHART: Session command for creating a T chart
TCHART C...C
Use a T chart to monitor the time between rare events, such as infections or surgical complications.
When you monitor rare events with a traditional variables control chart, you need a large amount of data to
establish accurate control limits. Therefore, collecting enough rare event data to respond to an adverse change
in the frequency of events may take months or even years. You do not need to collect large amounts of data to
use a T chart. The T chart is based on the Weibull distribution or the exponential distribution, and the chart plots
the time between events so you can easily detect when events occur more or less frequently than usual. For details,
go to How to enter data for TCHART on page 1161.
If you know the date but not the specific time for each event, use GCHART on page 582 to monitor the number
of complete days between rare events.
UNITS "text"
Defines the units for numeric time-between data ("Hours" or "Days").
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
STAMP: Session subcommand for specifying columns that contain time values for observations on page 1083
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
587
Minitab Statistical Software Quality and Process Improvement
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CLIMITS: Session command for specifying attributes for control limit lines on page 1006
CLINE: Session command for specifying attributes for a center line on page 1008
CONNECT: Session subcommand for connecting points with lines on page 1012
HLINE: Session subcommand for specifying attributes for historical stage lines on page 1032
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Parameters
You can base the chart on either a Weibull distribution or an exponential distribution. You can also specify historical
values for the distribution parameters if, for example, you have known process parameters or estimates that were
obtained from past data. The following table shows how to specify the distribution and parameters.
588
Minitab Statistical Software Quality and Process Improvement
Command languageDistribution
NoneA Weibull distribution and estimate the shape and scale parameters from
the data
WSHAPE X 1
WSCALE Y
A Weibull distribution with shape = X and scale = Y
WSHAPE 1
An exponential distribution, when you want to estimate the scale parameter
from the data
WSHAPE 1
WSCALE X
An exponential distribution with scale = X
If your chart includes stages, and you enter one value for a parameter, then all stages use that same parameter value.
You can also enter a separate parameter value for each stage.
Historical values between 0.5 and 2 are most practical for the shape of the Weibull distribution. Your historical scale
value for the Weibull distribution should be slightly greater than the mean of the data. For an exponential distribution,
the scale parameter is the mean.
WSHAPE K...K
WSHAPE C
Specifies the shape parameter.
WSCALE K...K
WSCALE C
Specifies the scale parameter.
Estimate
OMIT K...K
OMIT C
Use OMIT to specify subgroups to omit from the calculations for the estimates of μ and σ.
You cannot use OMIT and ESTIMATE in the same command.
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, OMIT 10:30 32 specifies to omit subgroups 10 to 30 and subgroup
32. Or suppose you have 50 subgroups, but the 24
th
is an outlier with a corrected assignable cause (that is, you
do not want to use the 24
th
in parameter estimation). You should use OMIT 24. OMIT with a column is useful in
macros.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with OMIT.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
ESTIMATE K...K
ESTIMATE C
Use ESTIMATE to list the subgroups to be used.
You cannot use OMIT and ESTIMATE in the same command.
589
Minitab Statistical Software Quality and Process Improvement
List the subgroups, or a column that contains the subgroup numbers that you want to omit. Use a colon to indicate
a range of values or columns. For example, ESTIMATE 10:30 32 specifies to use subgroups 10 to 30 and
subgroup 32.
When you use the control chart dialogs to create the chart, you can use only constants (not columns) with
ESTIMATE.
Important If you use OMIT or ESTIMATE with INCLUDE or EXCLUDE, the estimate or used samples apply to the entire data set, not
just the subsetted data. Suppose you exclude observation 1 from your analysis (using EXCLUDE 1), then decide to omit observation
2 (using OMIT 2). Because Minitab considers an omitted observation or sample (observation 1) to still be part of the entire data set,
you must enter observation 2 as the observation to omit.
P limits
PLIMITS K...K
PLIMITS C
Each argument in PLIMITS defines a single line to be drawn at the specified percentile. Values entered should be
percents. To get lines above and below the center line, specify matching percentiles above and below. For example:
PLIMITS 0.1 2.5 10 90 97.55 99.99. The first 3 percentiles are below the center line, and the last 3 are
above.
LOWER K
Sets the lower control limit bound. K must be a positive number. If the calculated lower control limit is less than
the lower bound, a horizontal line labeled LB is drawn at the lower bound instead.
UPPER K
Sets the upper control limit bound. K must be a positive number. If the calculated upper control limit is greater
than the upper bound, a horizontal line labeled UB is drawn at the upper bound instead.
Tests
TEST K...K
TEST C
Performs one or more of the eight tests for special causes. Each test detects a specific pattern in the data plotted
on the chart. The occurrence of a pattern suggests a special cause for the variation, one that should be investigated.
To adjust the sensitivity of the tests, use the DEFTEST subcommand.
To use TEST, list the numbers of the tests you want to use, or a column which contains the numbers of the tests
you want to use. For example, TEST 1 3 specifies perform tests 1 and 3. TEST 1:8 specifies do all eight tests.
TEST with a column is useful when writing macros. Test 0 will perform no tests and override any set control chart
options.
When a point fails a test, it is marked with the test number on the chart. If a point fails more than one test, the
number of the first test in your list is the number displayed on the chart.
Minitab will perform tests when subgroup sizes are unequal.
DEFTEST
Defines the sensitivity of the tests for special causes used with quality control charts.
The test definitions only apply to this chart.
590
Minitab Statistical Software Quality and Process Improvement
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
Default value
of second K
Second K:
Sensitivity of the
test
Description of the testFirst K: Test
for special
causes
31–6One point more than K standard deviations from center line1
(Minitab also draws the control limits at K standard deviations
from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations from
center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation from
center line (same side)
6
1512–15K points in a row within 1 standard deviation of center line
(either side)
7
86–10K points in a row more than 1 standard deviation from center
line (either side)
8
Stages
HPROCESS C
HPROCESS lets the user define historical stages in the process data. The control limits and center line are then
estimated independently within each stage. Stages are much like groups in other Minitab graph commands. Thus,
the HPROCESS column is like a group variable in other graph commands, with one exception—when the value
in the column changes, a new stage starts. This works the same way the subgroup column works in the control
chart commands.
HPROCESS is often done for comparative purposes. For example, suppose that a process improvement is made
at some point in time. This usually results in a reduction of the process variation. It may be of interest to draw a
control chart containing data prior to the improvement and data after the improvement so that one can directly
compare the two to see the change in process variation.
VALUES K...K
VALUES C
If you use the optional VALUES sub-subcommand, then Minitab uses the values listed in that column or list
of constants to estimate new parameters.
Display
DISPLAY K
Displays only the final K subgroups in the control chart.
591
Minitab Statistical Software Quality and Process Improvement
SPLIT [K]
Splits series by historical stages or by size.
NSESSION
Suppresses display of test results in the table under the graph.
INLABELS
Displays the center lines and control limits for each stage, inside the data region. You can specify the exact position
of particular control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
OUTLABELS
Displays the center lines and control limits for the final stage, outside the data region. You can specify the exact
position of the control limits or center lines using the POSITION / ENDPOSITION subcommands. However, it may
be easier to just move them with the pointer.
Storage
SSHAPE C
Stores the shape parameter.
SSCALE C
Stores the scale parameter.
PPOINTS C
Stores plotted points, one row for each subgroup.
CENLINE C
Stores the center line value.
CONLIMITS C C
Stores control limit values, one row for each plotted point.
STAGES C
Stores stage indicators.
TRESULTS C...C
Stores test results, one column for each test performed and one row for each plotted point. Minitab assigns each
plotted point a value: 1 (failed test) or 0 (did not fail test).
Tests for Special Causes
DEFTEST: Session command for defining the sensitivity of the tests for special causes
DEFTEST K K...K K
Defines the sensitivity of the tests for special causes that are used with control charts.
DEFTEST applies to any chart which supports the TEST subcommand. The first K in each pair corresponds to the
number of the test; the second K defines the test.
592
Minitab Statistical Software Quality and Process Improvement
Default
value of
second K
Range of acceptable
values for the second
K, the sensitivity of
the test
Description of the testFirst K, the
number of the
test for special
causes
31–6One point more than K standard deviations from center
line
1
(Minitab also draws the control limits at K standard
deviations from the center line.)
97–11K points in a row on same side of center line2
65–8K points in a row, all increasing or all decreasing3
1412–14K points in a row, alternating up and down4
22–4K out of K+1 points more than 2 standard deviations
from center line (same side)
5
43–6K out of K+1 points more than 1 standard deviation
from center line (same side)
6
1512–15K points in a row within 1 standard deviation of center
line (either side)
7
86–10K points in a row more than 1 standard deviation from
center line (either side)
8
Capability Analysis
DCAPA: Session command for performing individual distribution
identification
DCAPA [C] [C]
DCAPA [C] [K]
Fits data in a column or in subgroups across rows of several columns with 14 distributions: normal, lognormal,
3-parameter lognormal, gamma, 3-parameter gamma, exponential, 2-parameter exponential, smallest extreme
value, weibull, 3-parameter weibull, largest extreme value, logistic, loglogistic, and 3-parameter loglogistic; and
2 transformations: Box-Cox and Johnson. You can specify subgroups in another column or using a constant.
The report includes goodness-of-fit test and probability plot to assess whether a distribution fits your data.
The values in the column must be numeric. Columns can have missing values.
RSUB C...C
Specifies that the subgroup data for a variable are in rows of several columns. Columns must be the same
length. You can use this subcommand only when no column is specified with the DCAPA. For more information,
go to How to enter subgroup data on page 1163.
593
Minitab Statistical Software Quality and Process Improvement
Distributions and transformations
Use the following subcommands to specify which distributions to fit your data with.
NORMAL
The normal distribution.
LNORMAL
The lognormal distribution.
TLNORMAL
The 3-parameter lognormal distribution.
EXPONENTIAL
The exponential distribution.
TEXPONENTIAL
The 2-parameter exponential distribution.
WEIBULL
The Weibull distribution.
TWEIBULL
The 3-parameter Weibull distribution.
LEXTREMEVALUE
The largest extreme value distribution.
SEXTREMEVALUE
The smallest extreme value distribution.
GAMMA
The gamma distribution.
TGAMMA
The 3-parameter gamma distribution.
LOGISTIC
The logistic distribution.
LLOGISTIC
The loglogistic distribution.
TLLOGISTIC
The 3-parameter loglogistic distribution.
BOXCOX
Transforms the data to follow normal distribution using Box-Cox transformation. Specify the value of lambda as
K. K must be between −5 and 5. If no value is specified, Minitab estimates the optimal value of lambda from the
data. Box-Cox transformation is valid only for positive data values.
The output includes goodness-of-fit test and normal probability plot for original and transformed data for
comparison.
STORE C
Stores the transformed data in C, when data are in one column.
594
Minitab Statistical Software Quality and Process Improvement
STORE C...C
Stores the data in C...C, when data are in subgroups.
JOHNSON
Transforms the data to follow normal distribution using Johnson transformation. Specify the value of the P-value
as K. K must be between 0 and 1. If no value is specified, Minitab uses a default P-value of 0.01.
The output includes goodness-of-fit test and normal probability plot for original and transformed data for
comparison.
STORE C
Stores the transformed data in C, when data are in one column.
STORE C...C
Stores the data in C...C, when data are in subgroups.
ALL
Use ALL when you want all 14 distributions but want to specify values for the data transformations or specify
storage options. For example, if you want a specific value of lambda, say λ = 2, and you want to store the
transformed data, then use:
ALL;
BOXCOX 2;
STORE C.
Results
RDESCRIPTIVE
Displays the descriptive statistics for the data column.
RFITTESTS
RFITTEST performs a goodness-of-fit test for your choice of distribution. The session output contains
Anderson-Darling (AD), corresponding p-value (P), and likelihood ratio test p-value (LRT P).
SPVALUE C C C
SPVALUE stores the name of the distribution and corresponding p-values of the Anderson-Darling and
Anderson-Darling likelihood-ratio test in C, C, and C, respectively.
RPTILE
Specifies the percentiles to be estimated. K and values in C lie between 1 and 100.
RESTIMATE
Displays the estimated distribution parameters.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
SEPARATE
Displays one probability plot per graph. The default is 4 probability plots per graph.
595
Minitab Statistical Software Quality and Process Improvement
NOCI
Displays probability plots with no confidence intervals.
JOHNSON: Session command for applying the Johnson
transformation
JOHNSON [C]
Transforms your data to follow normal distribution when feasible. Specify a column when data are in a single
column. Use RSUB when data are in subgroup across rows of several columns.
The values in the column must be numeric and contain at least four distinct observations.
RSUB C...C
Specifies that the subgroup data for a variable are in rows of C...C. The values in the columns must be numeric
and contain at least four distinct observations.
STORE C
Stores the transformed data in column C when the input data are in one column.
STORE C...C
Stores the transformed data in subgroups in rows of C...C. The number of columns specified must equal to
that specified with RSUB.
SPARAMETERS
Stores the optimal distribution type and parameters estimates in a column. The first row in C stores distribution
type, SB, SL, or SU, the second row gamma parameter estimate, the third row eta, the fourth row epsilon,
and the five row lambda (when available).
Options
PAVLUE K
Specifies a p-value for the transformation.
BWCAPA: Session command for performing between/within
capability analysis
BWCAPA [C...C E]
Performs a capability analysis using within and between subgroup variations on data sets in C...C with subgroups
in E. Performs a capability analysis and generates a process capability report for data from a normal distribution
using both between-subgroup variation and within-subgroup variation.
If the data set is arranged in columns, specify the columns in C...C. Columns can contain numeric or text data.
Specify the subgroup size in E. E can be a column (if the subgroup size varies) or a constant (if the subgroups are
the same size). If your data are in subgroups across rows of several of columns, use RSUBS. For more information,
go to How to enter data.
The process capability report includes the following components:
A capability histogram that is overlaid with two normal curves. Minitab generates the two normal curves using
the process mean and the overall standard deviation, and the process mean and the total standard deviation.
596
Minitab Statistical Software Quality and Process Improvement
A complete table of overall and total (between- and within-subgroup) capability statistics. To calculate the
statistics, Minitab uses either the historical values that you specify or the values that it estimates from the data
for within- and between-subgroup standard deviations.
Capability statistics to assess whether the process is capable of meeting the specifications consistently.
RSUBS C...C [K]
Specifies that subgroup data for a variable are in rows of C...C. All columns must be the same length. If you
specify only one input column with RSUBS, then the subgroup size is 1. If the number of data sets is greater
than 1, then you can use K to specify the number. For more information, go to How to enter data.
USPEC C
USPEC K...K
Specifies the upper specification limit for each data set. You can specify values for a limit in a column (C) or
as constants (K...K), one for each data set used in the analysis.
Note You must enter either a value for either USPEC or LSPEC.
UBOUND C
UBOUND K...K
Specifies that the upper specification limit is a boundary in C or K...K.
LimitValues in C or K...K
The limit is not a boundary.0
The limit is a boundary.1
LSPEC C
LSPEC K...K
Specifies the lower specification limit for each data set. You can specify values for a limit in a column (C) or
as constants (K...K), one for each data set used in the analysis.
Note You must enter either a value for either USPEC or LSPEC.
LBOUND C
LBOUND K...K
Specifies that the upper specification limit is a boundary in C or K...K.
LimitValues in C or K...K
The limit is not a boundary.0
The limit is a boundary.1
Historical estimates
It is generally assumed that the data from the process follow a normal distribution. MU is the mean of this distribution.
BSIGMA is the process standard deviation between batches and WSIGMA is the process standard deviation within
subgroups. You can use these subcommands to enter known values for the process parameters, or enter previous
estimates. If you omit these subcommands, then Minitab estimates the values from the data sets.
You can specify the values in a column or as constants, one for each data set used in the analysis.
597
Minitab Statistical Software Quality and Process Improvement
MU C
MU K...K
Specifies historical values for the mean of the normal distribution for each data set in C or as K...K. If you don't
specify a value, then Minitab estimates it from the data.
BSIGMA C
BSIGMA K...K
Specifies historical values for the between-subgroup standard deviation for each data set in C or as K...K. If you
don't specify a value, then Minitab estimates it from the data.
WSIGMA C
WSIGMA K...K
Specifies historical values for the within-subgroup standard deviation for each data set in C or as K...K. If you don't
specify a value, then Minitab estimates it from the data.
Options
TARGET C
TARGET K...K
Specifies a process target value in C or as K...K, one for each data set used in the analysis. Minitab then calculates
Cpm, in addition to the standard capability statistics.
TOLER K
Specifies a value to calculate the capability statistics using an interval that is 6 standard deviations wide, 3 on
either side of the process mean. TOLER lets you change the width of this interval. For example, TOLER 12 says
to use an interval 12 standard deviations wide, 6 on either side of the process mean. This is referred to as "6-sigma
quality".
WITHIN
Performs within-subgroup capability analysis only. If you don't include this subcommand, then Minitab performs
both within-subgroup capability analysis and overall capability analysis.
OVERALL
Performs overall capability analysis only. If you don't include this subcommand, then Minitab performs both
within-subgroup capability analysis and overall capability analysis.
PERCENT
Uses percentages instead of the default parts per million (PPM).
PPM
Replaces the percentage calculations with parts per million (PPM). Use this command to get PPM calculations
after you change the default calculations to percentages.
ZBENCH
Displays benchmark Z statistics instead of the default capability statistics.
CSTAT
Displays the capability statistics when you include ZBENCH to display benchmark Z statistics.
598
Minitab Statistical Software Quality and Process Improvement
CONFIDENCE [K]
Specifies a confidence level in K to calculate the confidence intervals for Cp, Cpk, Pp, Ppk, and Cpm statistics. For
example, for a 90% confidence level, enter CONFIDENCE 90. The default value of K is 95.
ONECI
Specifies one-sided confidence intervals. The direction of the intervals depends on the statistic.
Lower bound:
Cp
Cpk
Ppk
Cpm
Z.bench
Upper bound:
Parts Per Million (PPM) < Lower Specification Limit (LSL)
PPM > Upper Specification Limit (USL)
PPM total
Percent < LSL
Percent > USL
Percent total
TWOCI
Specifies two-sided confidence intervals.
NOCI
Specifies not to include confidence intervals in the output.
Box-Cox transformation
BOXCOX [C]
BOXCOX [K...K]
Transforms the data to follow a normal distribution using the Box-Cox transformation.
You can specify lambda values that you want Minitab to use in the transformation in C or K...K, one value for each
data set used in the analysis. Values that you specify must be between –5 and 5. If you don't specify lambda values,
Minitab estimates the optimal value of lambda from the data.
Sigma estimates
AMR
Estimates the within standard deviation using the average moving range with the length that you specify with
RSPAN in K.
RSPAN K
Specifies the length that you want to use for the moving range. The maximum length is 100.
599
Minitab Statistical Software Quality and Process Improvement
RBAR
Estimates within standard deviation using the average of subgroup range method.
SBAR
Estimates within standard deviation using the averages of the subgroup standard deviation method.
MMR
Estimates within standard deviation using the median of the moving ranges with the length that you specify with
RSPAN in K.
RSPAN K
Specifies the length that you want to use for the moving range. The maximum length is 100.
SRMSSD
Estimates the within standard deviation using the square root of half of the mean of the squared successive
differences.
POOLED
Estimates the within standard deviation using the pooled standard deviation.
BIASED
Specifies to not use unbiasing constants in the calculation of the within-subgroup standard deviations. The default
is to use unbiasing constants.
UNBIASED
Specifies to use unbiasing constants in the calculation of the within-subgroup standard deviations.
OBIASED
Specifies to not use an unbiasing constant in the calculation of the overall standard deviation. The default is to
use an unbiasing constant.
OUNBIASED
Specifies to use an unbiasing constant in the calculation of the overall standard deviation.
Graphs
NOCHART
Suppresses the display of the graph. The default is to display the graph.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
600
Minitab Statistical Software Quality and Process Improvement
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Storage
NAME C
Stores the name of the columns of measurements used for the analysis.
USL C
Stores the upper specification limit.
STARGET C
Stores the target of the process.
LSL C
Stores the lower specification limit.
MEAN C
Stores the process mean.
N C
Stores the sample size used for the analysis.
601
Minitab Statistical Software Quality and Process Improvement
SDB C
Stores the between-subgroup standard deviation.
SDW C
Stores the within-subgroup standard deviation.
SDT C
Stores the between/within-subgroup standard deviation of the transformed data.
SDO C
Stores the overall standard deviation.
CP C
Stores the Cp statistic.
CPUC C
Stores the upper limit of a confidence interval for the Cp statistic.
CPLC C
Stores the lower limit of a confidence interval for the Cp statistic.
CPU C
Stores the CPU statistic.
CPL C
Stores the CPL statistic.
CPK C
Stores the Cpk statistic.
CPKU C
Stores the upper limit of a confidence interval for the Cpk statistic.
CPKL C
Stores the lower limit of a confidence interval for the Cpk statistic.
CCPK C
Stores the CCpk statistic.
PP C
Stores the Pp statistic.
PPUC C
Stores the upper limit of a confidence interval for the Pp statistic.
PPLC C
Stores the lower limit of a confidence interval for the Pp statistic.
PPU C
Stores the PPU statistic.
PPL C
Stores the PPL statistic.
602
Minitab Statistical Software Quality and Process Improvement
PPK C
Stores the Ppk statistic.
PPKU C
Stores the upper limit of a confidence interval for the Ppk statistic.
PPKL C
Stores the lower limit of a confidence interval for the Ppk statistic.
CPM C
Store the Cpm statistic.
UCPM C
Stores the upper limit of a confidence interval for the Cpm statistic.
LCPM C
Store the lower limit of a confidence interval for the Cpm statistic.
PPML C
Store the observed parts per million less than the lower specification limit.
PPMU C
Stores the observed parts per million less than the upper specification limit.
PPMT C
Stores the total parts per million beyond the specification limit.
EPLO C (C C)
Stores either the expected parts per million or the expected percentage less than the lower specification limit.
The units match the output. The calculation uses the overall variation. Minitab stores the value in the first column
that you specify. To store the confidence bound from the output, specify a second column. To store the confidence
interval from the output, specify 2 additional columns.
EPUO C (C C)
Stores either the expected parts per million or the expected percentage greater than the upper specification limit.
The units match the output. The calculation uses the overall variation. Minitab stores the value in the first column
that you specify. To store the confidence bound from the output, specify a second column. To store the confidence
interval from the output, specify 2 additional columns.
EPTO C (C C)
Stores either the expected parts per million or the expected percentage outside the specification limits. The units
match the output. The calculation uses the overall variation. Minitab stores the value in the first column that you
specify. To store the confidence bound from the output, specify a second column. To store the confidence interval
from the output, specify 2 additional columns.
EPLW C (C C)
Stores either the expected parts per million or the expected percentage less than the lower specification limit.
The units match the output. The calculation uses the within subgroup variation. Minitab stores the value in the
first column that you specify. To store the confidence bound from the output, specify a second column. To store
the confidence interval from the output, specify 2 additional columns.
EPUW C (C C)
Stores either the expected parts per million or the expected percentage greater than the upper specification limit.
The units match the output. The calculation uses the within subgroup variation. Minitab stores the value in the
first column that you specify. To store the confidence bound from the output, specify a second column. To store
the confidence interval from the output, specify 2 additional columns.
603
Minitab Statistical Software Quality and Process Improvement
EPTW C (C C)
Stores either the expected parts per million or the expected percentage outside the specification limits. The units
match the output. The calculation uses the within subgroup variation. Minitab stores the value in the first column
that you specify. To store the confidence bound from the output, specify a second column. To store the confidence
interval from the output, specify 2 additional columns.
SLAMBDA C
Stores the lambda value that Minitab uses in the Box-Cox transformation.
TUSL C
Stores the upper specification limit of the Box-Cox transformed data.
TTARGET C
Stores the target value of the Box-Cox transformed data.
TLSL C
Stores the lower specification limit of the Box-Cox transformed data.
TMEA C
Stores the mean of the Box-Cox transformed data.
TSDB C
Stores the between-subgroup standard deviation of the Box-Cox transformed data.
TSDW C
Stores the within-subgroup standard deviation of the Box-Cox transformed data.
TSDT C
Stores the total standard deviation of the Box-Cox transformed data.
TSDO C
Stores the overall standard deviation of the Box-Cox transformed data.
CAPA: Session command for performing a normal capability
analysis
CAPA [C...C E]
Performs a capability analysis based on the assumption that data come from normal population. You can also
use the BOXCOX or JOHNSON subcommand to try to transform your data to follow normal distribution. If a data
set is arranged in a column, specify the columns with subgroup size in E. E can be a column (if the subgroup size
varies) or a constant (if the subgroups are the same size.) Columns may contain numeric or text data. If your data
are in subgroups across rows of several of columns, use RSUBS. For details, go to How to enter subgroup data
on page 1163.
CAPA displays a histogram, overlaid with a normal curve generated from the process mean and standard deviation.
It also displays the locations of the process mean and the target, the natural process tolerance, and the process
specifications. Hence, the chart can be used to visually assess whether the data are normally distributed, whether
the process is centered on the target, and whether it is capable of meeting the process specifications consistently.
RSUBS C...C [K]
Specifies that the data in each row of the input columns makes up a subgroup. All columns must be the same
length. If only one input column is given with RSUB, then the subgroup size is 1.
604
Minitab Statistical Software Quality and Process Improvement
The optional K indicates the number of data sets if greater than 1. For details, go to How to enter subgroup
data on page 1163.
USPEC C
USPEC K...K
Specifies the upper specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
UBOUND C
UBOUND K...K
Specifies that the upper specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
LSPEC C
LSPEC K...K
Specifies the lower specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
LBOUND C
LBOUND K...K
Specifies that the lower specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
Historical estimates
MU C
MU K...K
Specifies the mean of the population distribution (denoted as μ or mu). The value that you enter can be either
an actual known process parameter, or an estimate obtained from past data. You can either specify one value
applicable to all the data sets or multiple values, one value for each data set used in the analysis.
You cannot use MU with a transformation.
If you do not specify μ, then Minitab estimates it from the data.
SIGMA C
SIGMA K...K
Specifies the standard deviation of the population distribution (denoted as σ or sigma). The value that you enter
can be either an actual known process parameter, or an estimate obtained from past data. You can either specify
one value applicable to all the data sets or multiple values, one value for each data set used in the analysis.
You cannot use SIGMA with a transformation.
If you do not specify σ, then Minitab estimates it from the data.
605
Minitab Statistical Software Quality and Process Improvement
Options
TARGET C
TARGET K...K
Specifies a process target value. Minitab then calculates Cpm, in addition to the standard capability statistics.
You can specify the values in a column or as constants, one value for each data set used in the analysis.
TOLER K
Specifies a value to calculate the capability statistics using an interval other than 6 standard deviations wide, 3 on
either side of the process mean. For example, TOLER 12 says to use an interval 12 standard deviations wide, 6
on either side of the process mean.
You can specify the values in a column or as constants, one value for each data set used in the analysis.
WITHIN
Use WITHIN to perform a within capability analysis only. This subcommand cannot be used with a Johnson
transformation.
The default is to conduct both within and overall capability analyses.
OVERALL
Use OVERALL to perform an overall capability analysis only. If a Johnson transformation is used, only an overall
analysis can be done so this subcommand is redundant.
The default is to conduct both within and overall capability analyses.
PERCENT
Replaces the default parts per million (PPM) calculations with percentages.
PPM
Replaces the percentage calculations with parts per million (PPM). Use this command to get PPM calculations
after you change the default calculations to percentages.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
CONFIDENCE K
Specifies a confidence level in K. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ONECI
Specifies one-sided confidence intervals. The direction of the intervals depends on the statistic.
Lower bound:
Cp
Cpk
Ppk
Cpm
606
Minitab Statistical Software Quality and Process Improvement
Z.bench
Upper bound:
Parts Per Million (PPM) < Lower Specification Limit (LSL)
PPM > Upper Specification Limit (USL)
PPM total
Percent < LSL
Percent > USL
Percent total
TWOCI
Specifies two-sided confidence intervals.
NOCI
Specifies not to include confidence intervals in the output.
Box-Cox transformation
BOXCOX [C]
BOXCOX [K...K]
Transforms the data to follow a normal distribution using Box-Cox transformation. You can also specify a value
for lambda to be used in the transformation. If no value is specified, Minitab estimates the optimal value of lambda
from the data.
You can specify the values for lambda in a column (C) or as constants (K), one value for each data set used in the
analysis. K and values in C must lie between -5 and 5.
You cannot use BOXCOX with a Johnson transformation.
Johnson transformation
JOHNSON
Selects a distribution function from Johnson system to transform each data set to follow normal distribution.
You cannot use JOHNSON with a Box-Cox transformation.
PVALUE K...K
PVALUE C
Use the optional PVALUE to change the default p-value of 0.10 to select the optimal transformation. You can
specify p-values in a column or as constants, one value for each data set used in the analysis.
Standard deviation estimates
These subcommands provide options for estimating the within process standard deviation based on the following
methods.
Except for OBIASED and OUNBIASED, you cannot use the following subcommands with a Johnson transformation.
607
Minitab Statistical Software Quality and Process Improvement
AMR
Average moving range.
RSPAN K
Use RSPAN to change the length of the moving range. The maximum length allowed is 100.
RBAR
Averages of the subgroup ranges. The maximum subgroup size allowed is 100.
SBAR
Averages of the subgroup standard deviations.
MMR
Median of the moving range.
RSPAN K
Use RSPAN to change the length of the moving range. The maximum length allowed is 100.
SRMSSD
Square root of half of the mean of the squared successive differences.
POOLED
Pooled standard deviation.
BIASED
Use BIASED to suppress the use of unbiasing constants in the calculation of the within-subgroup standard
deviations. The default is to use unbiasing constants.
UNBIASED
Use an unbiasing constant in the calculation of the within subgroup standard deviations.
OBIASED
Use OBIASED to suppress the use of an unbiasing constant in the calculation of the overall standard deviation.
The default is to use unbiasing constants.
OUNBIASED
Use an unbiasing constant in the calculation of the overall standard deviation.
Graphs
NOCHART
Suppresses the display of the graph. The default is to display the graph.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
608
Minitab Statistical Software Quality and Process Improvement
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Storage
NAME C
Stores the name of the data columns used in the analysis.
USL C
Stores the upper specification limit.
STARGET C
Stores the process target.
LSL C
Stores the lower specification limit.
609
Minitab Statistical Software Quality and Process Improvement
MEAN C
Stores the mean of the data.
N C
Stores the number of sample observations.
SDT C
Stores the within-subgroup standard deviation (produces missing values if used with the Johnson transformation).
SDO C
Stores the overall standard deviation.
CP C
Stores the Cp or Z.bench statistic.
CPUC C
Stores the upper limit of a confidence interval for the Cp or Z.Bench statistic.
CPLC C
Stores the lower limit of a confidence interval for the Cp or Z.Bench statistic.
CPU C
Stores the CPU or Z.USL statistic.
CPL C
Stores the CPL or Z.LSL statistic.
CPK C
Stores the Cpk statistic.
CPKU C
Stores the upper limit of a confidence interval for the Cpk statistic.
CPKL C
Stores the lower limit of a confidence interval for the Cpk statistic.
CCPK C
Stores the CCpk statistic.
PP C
Stores the Pp or Z.Bench statistic.
PPUC C
Stores the upper limit of a confidence interval for the Pp or Z.Bench statistic.
PPLC C
Stores the lower limit of a confidence interval for the Pp or Z.Bench statistic.
PPU C
Stores the PPU or Z.USL statistic.
PPL C
Stores the PPL or Z.LSL statistic.
610
Minitab Statistical Software Quality and Process Improvement
PPK C
Stores the Ppk statistic.
PPKU C
Stores the upper limit of a confidence interval for the Ppk statistic.
PPKL C
Stores the lower limit of a confidence interval for the Ppk statistic.
CPM C
Stores the Cpm statistic.
UCPM C
Stores the upper limit of a confidence interval for the Cpm statistic.
LCPM C
Stores the lower limit of a confidence interval for the Cpm statistic.
PPML C
Stores the observed parts per million less than the lower specification limit.
PPMU C
Stores the observed parts per million greater than the upper specification limit.
PPMT C
Stores the total parts per million beyond the specification limit.
EPLO C (C C)
Stores either the expected parts per million or the expected percentage less than the lower specification limit.
The units match the output. The calculation uses the overall variation. Minitab stores the value in the first column
that you specify. To store the confidence bound from the output, specify a second column. To store the confidence
interval from the output, specify 2 additional columns.
EPUO C (C C)
Stores either the expected parts per million or the expected percentage greater than the upper specification limit.
The units match the output. The calculation uses the overall variation. Minitab stores the value in the first column
that you specify. To store the confidence bound from the output, specify a second column. To store the confidence
interval from the output, specify 2 additional columns.
EPTO C (C C)
Stores either the expected parts per million or the expected percentage outside the specification limits. The units
match the output. The calculation uses the overall variation. Minitab stores the value in the first column that you
specify. To store the confidence bound from the output, specify a second column. To store the confidence interval
from the output, specify 2 additional columns.
EPLW C (C C)
Stores either the expected parts per million or the expected percentage less than the lower specification limit.
The units match the output. The calculation uses the within subgroup variation. Minitab stores the value in the
first column that you specify. To store the confidence bound from the output, specify a second column. To store
the confidence interval from the output, specify 2 additional columns.
EPUW C (C C)
Stores either the expected parts per million or the expected percentage greater than the upper specification limit.
The units match the output. The calculation uses the within subgroup variation. Minitab stores the value in the
first column that you specify. To store the confidence bound from the output, specify a second column. To store
the confidence interval from the output, specify 2 additional columns.
611
Minitab Statistical Software Quality and Process Improvement
EPTW C (C C)
Stores either the expected parts per million or the expected percentage outside the specification limits. The units
match the output. The calculation uses the within subgroup variation. Minitab stores the value in the first column
that you specify. To store the confidence bound from the output, specify a second column. To store the confidence
interval from the output, specify 2 additional columns.
JTYPE C
Stores the optimal distribution function type selected for Johnson transformation.
JGAMMA C
Stores the gamma parameter of a distribution function in Johnson transformation.
JETA C
Stores the eta parameter of a distribution function in Johnson transformation.
JLAMBDA C
Stores the lambda parameter of a distribution function in Johnson transformation.
JEPSILON C
Stores the epsilon parameter of a distribution function in Johnson transformation.
SLAMBDA C
Stores the value of lambda used in Box-Cox transformation.
TUSL C
Stores the Box-Cox or Johnson transformed value of the upper specification limit.
TTARGET C
Stores the Box-Cox or Johnson transformed target value.
TLSL C
Stores the Box-Cox or Johnson transformed value of the lower specification limit.
TMEA C
Stores the mean of the Box-Cox or Johnson transformed data.
TSDT C
Stores the total standard deviation of the Box-Cox or Johnson transformed data.
TSDO C
Stores the overall standard deviation of the Box-Cox or Johnson transformed data.
NNCAPA: Session command for performing a nonnormal capability
analysis
NNCAPA C...C
Generates a process capability report when your data do not follow normal distribution. The report is based on
your choice of a distribution.
The report includes a capability histogram overlaid with a distribution curve, and a table of capability statistics.
The distribution curve and the capability statistics are based on the distribution parameter. The report also includes
statistics of the process data, such as the mean, parameters, target (if you enter one), and process specifications;
and the observed and expected overall performance. So the report can be used to visually assess the distribution
612
Minitab Statistical Software Quality and Process Improvement
of the process relative to the target, whether the data follows a specified distribution, and whether the process
is capable of meeting the specifications consistently.
When using the nonnormal model, Minitab calculates the overall capability statistics, Pp, Ppk, PPU, and PPL. If no
historical values for the parameters are specified, Minitab estimates the parameters from the data using maximum
likelihood method.
RSUBS C...C [K]
Specifies that the data in each row of the input columns makes up a subgroup. All columns must be the same
length. If only one input column is given with RSUB, then the subgroup size is 1.
The optional K indicates the number of data sets if greater than 1. For details, go to How to enter subgroup
data on page 1163.
USPEC C
USPEC K...K
Specifies the upper specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
UBOUND C
UBOUND K...K
Specifies that the upper specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
LSPEC C
LSPEC K...K
Specifies the lower specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
LBOUND C
LBOUND K...K
Specifies that the lower specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
Method
MTBINDEX
Calculates the capability indices using the MTB method, also called z-score method.
ISOINDEX
Calculates the capability indices using the ISO method.
Distributions
Use the following subcommands to specify which distributions to fit your data with.
EXPONENTIAL
The exponential distribution.
613
Minitab Statistical Software Quality and Process Improvement
TEXPONENTIAL
The 2-parameter exponential distribution.
LNORMAL
The lognormal distribution.
TLNORMAL
The 3-parameter lognormal distribution.
WEIBULL
The Weibull distribution.
TWEIBULL
The 3-parameter Weibull distribution.
LEXTREMEVALUE
The largest extreme value distribution.
SEXTREMEVALUE
The smallest extreme value distribution.
GAMMA
The gamma distribution.
TGAMMA
The 3-parameter gamma distribution.
LOGISTIC
The logistic distribution.
LLOGISTIC
The loglogistic distribution.
TLLOGISTIC
The 3-parameter loglogistic distribution.
Parameters
SETS K...K
SETS C
Sets the shape parameter for the gamma and the Weibull distributions and the scale parameter for all other
distributions. Minitab calculates maximum likelihood estimates from the data for missing values.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
SETTHRESHOLD K...K
SETTHRESHOLD C
Sets the threshold parameter for the 2-parameter exponential and any 3-parameter distributions. Minitab calculates
maximum likelihood estimates from the data set for missing values.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
614
Minitab Statistical Software Quality and Process Improvement
HPARAMETERS K...K
HPARAMETERS C
HPARAMETERS C...C
Sets all the parameters in a distribution. If all data sets share the same parameter values, enter constants or a
column. The number of constants or values in a column must equal the number of parameter in a distribution. If
the data set has different parameter values, enter columns equal to the number of data sets in your analysis. The
number of entries in each column must equal the number of parameters in a distribution.
You must enter parameter values in the following order: location, shape, scale, and threshold. For example, for
3-parameter loglogistic distribution, enter values of the parameters in the following order: location, scale, and
threshold.
Options
TARGET K...K
TARGET C
Specifies a process target value. Minitab then calculates Cpm, in addition to the standard capability statistics. The
target and Cpm values are displayed in the table below the graph.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
TOLER K...K
TOLER C
Specifies a value to calculate the capability statistics using an interval other than 6 standard deviations wide, 3 on
either side of the process mean. For example, TOLER 12 says to use an interval 12 standard deviations wide, 6
on either side of the process mean. This is referred to as "6-sigma quality."
You can specify the values in a column or as constants, one value for each data set used in the analysis.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
PERCENT
Replaces the default parts per million (PPM) calculations with percentages.
PPM
Replaces the percentage calculations with parts per million (PPM). Use this command to get PPM calculations
after you change the default calculations to percentages.
Graphs
NOCHART
Suppresses the display of the graph. The default is to display the graph.
615
Minitab Statistical Software Quality and Process Improvement
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
616
Minitab Statistical Software Quality and Process Improvement
Storage
NAME C
Stores the name of the data columns used in the analysis.
LSL C
Stores the lower specification limit.
USL C
Stores the upper specification limit.
STARGET C
Stores the process target.
MEAN C
Stores the mean of the data.
N C
Stores the number of sample observations.
SSHAPE C
Stores the shape parameter of a distribution.
SSCALE C
Stores the scale parameter of a distribution.
SLOCATION C
Stores the location parameter of a distribution.
STHRESHOLD C
Stores the threshold parameter of a distribution.
PP C
Stores the Pp statistic.
PPU C
Stores the PPU or Z.USL statistic.
PPL C
Stores the PPL statistic.
PPK C
Stores the Ppk statistic.
PPML C
Stores the observed parts per million less than the lower specification limit.
PPMU C
Stores the observed parts per million greater than the upper specification limit.
PPMT C
Stores the total parts per million beyond the specification limit.
EPLO C
Stores the expected overall parts per million less than the lower specification limit.
617
Minitab Statistical Software Quality and Process Improvement
EPUO C
Stores the expected overall parts per million greater than the upper specification limit.
EPTO C
Stores the expected overall parts per million beyond the specification limits.
NPCAPA: Session command for performing a nonparametric
capability analysis
NPCAPA [C]
Generates a process capability report that makes no assumptions about the distribution of the data. Use a single
column with the main command to enter all of the data in a single column. Enter the main command without an
argument and use the RSUBS subcommand to enter data from multiple columns.
The report includes a capability histogram and a table of capability statistics. The report also includes statistics
of the process data, such as the mean, median, target (if you enter one), process specifications, and the observed
and expected overall performance. Use the histogram to visually assess whether the process is capable of meeting
the specifications consistently.
When using the nonparametric analysis, Minitab Statistical Software calculates the overall capability statistics,
Cnp, Cnpl, Cnpu, and Cnpk.
RSUBS C...C
Specifies that the data for the analysis are in multiple columns. The results are the same as if the data are all
in a single column.
USPEC K
Specifies the upper specification limit. The analysis requires at least 1 specification limit.
LSPEC K
Specifies the lower specification limit. The analysis requires at least 1 specification limit.
Options
TARGET K
Specifies a process target value. Minitab Statistical Software then includes a reference line for the target on the
histogram. The target is also in the table of process data.
TOLER K
Specifies a tolerance value to use to calculate the capability statistics. The value that you specify is a number of
standard deviations around the mean in a normal distribution. The value defines percentiles. The analysis uses
the corresponding empirical percentiles from the data to calculate the tolerance. For example, a value of 6 defines
percentiles that are 3 standard deviations to either side of the mean for a normal distribution. In a normal
distribution, 3 standard deviations below the mean is the 0.15 percentile and 3 standard deviations above the
mean is the 99.85 percentile. The analysis uses 0.15 empirical percentile and the 99.85 empirical percentile to
calculate the capability statistics.
618
Minitab Statistical Software Quality and Process Improvement
The default value if you do not specify the subcommand depends on the value in File > Options > Control Charts
and Quality Tools > Capability Analysis. The value with the default installation of Minitab Statistical Software
is 6.
PERCENT
Displays the observed performance statistics in percentages. Specify only 1 of PERCENT and PPM.
PPM
Displays the observed performance statistics in parts per million (PPM). Specify only 1 of PERCENT and PPM.
ONECI
Specifies one-sided, upper confidence intervals for the observed performance statistics.
TWOCI
Specifies two-sided confidence intervals for the observed performance statistics.
NOCI
Specifies not to include confidence intervals in the output.
CONFIDENCE K
Specifies a confidence level in K. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
Graphs
NOCHART
Suppresses the display of the graph. The default is to display the graph.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify displays in the
navigator, on the output tab, and at the top of the output above the graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
619
Minitab Statistical Software Quality and Process Improvement
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Storage
NAME C
Stores the name of the data columns used in the analysis.
LSL C
Stores the lower specification limit that you specify with LSPEC.
USL C
Stores the upper specification limit that you specify with USPEC.
STARGET C
Stores the process target that you specify with TARGET.
MEAN C
Stores the mean of the data.
MEDIAN C
Stores the median of the data.
N C
Stores the number of sample observations.
SDO C
Stores the sample standard deviation.
CNP C
Stores the Cnp statistic.
620
Minitab Statistical Software Quality and Process Improvement
CNPU C
Stores the Cnpu statistic.
CNPL C
Stores the Cnpl statistic.
CNPK C
Stores the Cnpk statistic.
PPML C (C C)
Stores the observed parts per million or percent less than the lower specification limit. The units match the output.
Minitab stores the value in the first column that you specify. To store the confidence bound from the output,
specify a second column. To store the confidence interval from the output, specify 2 additional columns.
PPMU C (C C)
Stores the observed parts per million or percent greater than the upper specification limit. The units match the
output. Minitab stores the value in the first column that you specify. To store the confidence bound from the
output, specify a second column. To store the confidence interval from the output, specify 2 additional columns.
PPMT C (C C)
Stores the total parts per million or percent beyond the specification limit. The units match the output. Minitab
stores the value in the first column that you specify. To store the confidence bound from the output, specify a
second column. To store the confidence interval from the output, specify 2 additional columns.
ATCAPA: Session command for performing an automated
capability analysis
ATCAPA [C E]
Generates a process capability report that automatically selects whether to use a distribution, a transformation,
or to make no parametric assumptions about the data. If a data set is arranged in a column, specify the column
with subgroup size in E. E can be a column (if the subgroup size varies) or a constant (if the subgroups are the
same size.) Subgroup columns may contain numeric, text or date/time data. If your data are in subgroups across
rows of several of columns, use RSUBS. For details, go to How to enter subgroup data on page 1163.
The report includes a histogram and the capability statistics for the method that the analysis selected. The report
also includes statistics of the process data, such as the mean, median, target (if you enter one), process specifications,
and the observed performance. Use the histogram to visually assess whether the process is capable of meeting
the specifications consistently.
RSUBS C...C
Specifies that the data in each row of the input columns makes up a subgroup. All columns must be the same
length. If only one input column is given with RSUB, then the subgroup size is 1.
USPEC K
Specifies the upper specification limit. Every capability analysis requires at least 1 specification limit.
LSPEC K
Specifies the lower specification limit. Every capability analysis requires at least 1 specification limit.
621
Minitab Statistical Software Quality and Process Improvement
Methods
The ATCAPA command has 3 modes.
Specify only the AUTO subcommand
Using the same order as in the list of subcommands and in the table of results, the analysis displays results for
the first method that provides reasonable results. If none of the distributions or transformations provides a
reasonable fit for the data, then the analysis provides results for a nonparametric method. The analysis also displays
a table of statistics about the other methods.
Specify only a subcommand for a method
The analysis displays capability results for the method.
Specify the AUTO subcommand and a subcommand for a method
The analysis displays capability results for the method and a table of statistics about the other methods. Specify
only one subcommand for a distribution or transformation.
AUTO
Automatically select a method to use to calculate the capability statistics.
NORMAL
Calculate alternative results with the normal distribution.
WEIBULL
Calculate alternative results with the Weibull distribution.
LNORMAL
Calculate alternative results with the lognormal distribution.
SEXTREMEVALUE
Calculate alternative results with the smallest extreme value distribution.
LEXTREMEVALUE
Calculate alternative results with the largest extreme value distribution.
GAMMA
Calculate alternative results with the gamma distribution.
LOGISTIC
Calculate alternative results with the logistic distribution.
LLOGISTIC
Calculate alternative results with the loglogistic distribution.
EXPONENTIAL
Calculate alternative results with the exponential distribution.
TWEIBULL
Calculate alternative results with the 3-parameter Weibull distribution.
TLNORMAL
Calculate alternative results with the 3-parameter lognormal distribution.
TGAMMA
Calculate alternative results with the 3-parameter gamma distribution.
622
Minitab Statistical Software Quality and Process Improvement
TLLOGISTIC
Calculate alternative results with the 3-parameter loglogistic distribution.
TEXPONENTIAL
Calculate alternative results with the 2-parameter exponential distribution.
BOXCOX [K]
Calculate alternative results with the Box-Cox transformation. Specify K to provide λ for the transformation. When
you do not specify λ, then the analysis calculates the optimal λ value.
JOHNSON [K] [K] [K] [K] [K]
Calculate alternative results with the Johnson transformation. To have the analysis fit the Johnson transformation,
do not enter any arguments.
To perform the analysis for a specific Johnson Transformation, specify the arguments. The first argument specifies
the family of the transformation. Specify the family with one of the following numbers.
1: S
B
2: S
L
3: S
U
The last 4 arguments provide the coefficients for the transformation function in the following order:
1. γ
2. η
3. ε
4. λ
Insert a value of λ only when the transformation family is S
B
or S
U
. The following table summarizes the
transformations families:
RangeTransformation functionJohnson family
η, λ > 0, –∞ < γ < , –∞ < ε < ∞, ε < x < ε + λγ + η ln [(x ε) / + ε x)]S
B
η > 0, –∞ < γ < ∞, –∞ < ε < ∞, ε < xγ + η ln (x ε)S
L
η, λ > 0, –∞ < γ < ∞, –∞ < ε < ∞, –∞ < x < γ + η Sinh
–1
[(x ε) / λ] , where
Sinh
–1
(x) = ln [x + sqrt (1 + x
2
)]
S
U
NPAR
Calculate alternative results with a nonparametric method. Nonparametric methods do not make assumptions
about the distribution of the data.
Options
TARGET K
Specifies a process target value. The results include the target. If the analysis selects a method that uses the target
to calculate a capability statistic, like Cpm, then the results include such statistics.
TOLER K
Specifies a value to use in the estimation if the spread of the process. Specify a value such that 0 < K ≤8. The
application of the value differs slightly among the methods. For example, for an analysis that uses the normal
623
Minitab Statistical Software Quality and Process Improvement
distribution, 6 specifies that the process spread is an interval 6 standard deviations wide, 3 on either side of the
process mean. Other methods use intervals that produce comparable measures of capability.
ALPHA K
Specifies the significance level for the selection of the method. Specify a value such that 0.01 K 0.25. By default,
the analysis uses a significance level of 0.05. The analysis selects the first distribution or transformation that
produces a p-value greater than the significance level. The analysis selects a method even when the method does
not produce an exact p-value, such as when the result is that the p-value > 0.25. If no parametric method achieves
the significance level, the analysis uses a nonparametric method.
PERCENT
Replaces the default parts per million (PPM) calculations with percentages.
PPM
Replaces the percentage calculations with parts per million (PPM). Use this command to get PPM calculations
after you change the default calculations to percentages.
CONFIDENCE K
Specifies a confidence level in K. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ONECI
Specifies one-sided confidence intervals. The direction of the intervals depends on the statistic. If a larger
value indicates a more capable process, then the results include a lower bound. For example, the results
include a lower bound for Pp.
If a lower value indicates a more capable process, then the results include an upper bound. For example, the
results include an upper bound for the total parts per million out of specification.
TWOCI
Specifies two-sided confidence intervals.
NOCI
Specifies not to include confidence intervals in the output.
Graphs
NOCHART
Suppresses the display of the graph. The default is to display the graph.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
624
Minitab Statistical Software Quality and Process Improvement
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Storage
The ATCAPA command does not store all of the statistics for a method. To store more statistics, use a capability analysis
command that specifies the method.
NAME C
Stores the name of the data columns used in the analysis.
USL C
Stores the upper specification limit.
STARGET C
Stores the process target.
LSL C
Stores the lower specification limit.
MEAN C
Stores the mean of the data.
625
Minitab Statistical Software Quality and Process Improvement
MEDIAN C
Stores the median of the data.
N C
Stores the number of sample observations.
SDT C
Stores the within-subgroup standard deviation when the method uses the normal distribution or the Box-Cox
transformation. Stores a missing for the other methods.
SDO C
Stores the overall standard deviation.
PPMT C
Stores the total parts per million beyond the specification limits or the percent outside of the specification limits.
The units depend on the specifications for the analysis.
DISTRIBUTION C
Stores the name of the method that the analysis selects.
CP C
Stores the Cp statistic when the method produces that statistic. Stores a missing value otherwise.
CPK C
Stores the Cpk statistic when the method produces that statistic. Stores a missing value otherwise.
PP C
Stores the Pp statistic or Cnp statistic when the method produces that statistic. Stores a missing value otherwise.
PPK C
Stores the Ppk statistic or Cnpk statistic when the method produces that statistic. Stores a missing value otherwise.
MCAPA: Session command for performing a normal capability
analysis for multiple variables
MCAPA C...C
Generates a process capability report when each of the continuous variables follows a normal distribution. You
can also use the BOXCOX or JOHNSON subcommand to try to transform your data to follow normal distribution.
MCAPA allows you to compare the results for multiple variables or when a grouping variable is associated with
a continuous variable. For example, you want to compare the width of parts from the same process before and
after a process improvement.
Displays a capability histogram overlaid with a normal curve and displays capability statistics. The distribution
curve is generated from the distribution parameters.
The command is entered differently depending on how the data is structured in the worksheet. For details, go to
How to enter subgroup data on page 1163. The report that MCAPA produces a histogram, overlaid with a normal
curve generated from the process mean and standard deviation. It also displays the locations of the process mean
and target, the natural process tolerance, and the process specifications. So you can use the chart to visually
assess whether the data are normally distributed, whether the process is centered on the target, and whether it
is capable of meeting the process specifications consistently.
626
Minitab Statistical Software Quality and Process Improvement
If you have data in subgroups, MCAPA uses the pooled standard deviation to estimate the standard deviation by
default. Use the RBAR subcommand to base the estimate on subgroup ranges. If you use RBAR, the maximum
subgroup size allowed is 100.
For individual observations, the default estimate of sigma is based on the average of the moving range of length
2. Use the MMR subcommand to use the median of the moving range. Use the RSPAN subcommand to change
the length of the moving range. The maximum length allowed is 50. Use the SRMSSD subcommand to estimate
the standard deviation using the square root of half the mean of the squared successive differences.
BY C...C
Specifies the grouping columns in C...C. Columns may contain numeric or text data. If you use BY subcommand
you can only enter only one column with MCAPA command.
BETWEEN
Specifies the use of both between and within subgroup variations for analysis. You cannot use this
subcommand with a Johnson transformation.
Subgroup size
Specifies the subgroup size of variables specified with MCAPA command or groups in BY subcommand. You can enter
one subgroup size applicable to all variables, one value entered as a constant or in a row of a column for each variable,
or one subgroup ID column for each variable.
SIZE K
Specifies the subgroup size for all variables or groups as K
SIZE K...K
Specifies the subgroup size for each variables or groups as K...K
SIZE C
Specifies the subgroup ID column C for all variables or groups
SIZE C...C
Specifies the subgroup ID column for each multiple variables or groups in C...C
Specification limits
Use USPEC and LSPEC to specify a value for the upper and lower specification limits, respectively. You must enter at
least one of these.
Use the optional UBOUND and LBOUND to specify the limits as boundaries. K or the values in C are 1 or 0, indicating
whether the corresponding limits are boundaries.
If all data sets share the same specification limit, specify a constant or a column with one value. If the data sets have
different specification limits, specify a value for each data set in a column or as constants.
USPEC K
USPEC K...K
USPEC C
Specifies the upper specification limit.
UBOUND [K]
Specifies the upper specification limit as the boundary as K, applicable to all variables or groups. K takes
values 1 or 0.
627
Minitab Statistical Software Quality and Process Improvement
UBOUND [K...K]
Specifies the upper specification limit as the boundary as K, one K for each variable or group. K takes values
1 or 0.
UBOUND [C]
Specifies the upper specification limit as the boundary in C. Values in C are 1 and/or 0.
LSPEC K
LSPEC K...K
LSPEC C
Specifies the lower specification limit.
LBOUND [K]
Specifies the lower specification limit as the boundary as K, applicable to all variables or groups. K takes
values 1 or 0.
LBOUND [K...K]
Specifies the lower specification limit as the boundary as K, one K for each variable or group. K takes values
1 or 0.
LBOUND [C]
Specifies the lower specification limit as the boundary in C. Values in C are 1 and/or 0.
Historical estimates
It is generally assumed that the data from the process follows a normal distribution. MU is the mean of this distribution.
BSIGMA is the process standard deviation between batches and WSIGMA is the process standard deviation within
subgroups. You can use these subcommands to enter known values for the process parameters, or enter previous
estimates. For BSIGMA, the BETWEEN subcommand must be issued.
You can specify the values in a column or as constants. one value applicable to all variables or groups or one value for
each variable or group as a list of constants or a column.
If all data sets share the same process parameter values, specify a constant or a column with one value. If the data sets
have different process parameter values, specify a value for each data set in a column or as constants.
You cannot use these subcommands with a transformation.
MU K
MU K...K
MU C
Specifies the mean of the normal distribution.
WSIGMA K
WSIGMA K...K
WSIGMA C
Specifies the historical values for the within-subgroup standard deviation.
628
Minitab Statistical Software Quality and Process Improvement
BSIGMA K
BSIGMA K...K
BSIGMA C
Specifies the historical values for the between-subgroup standard deviation.
Standard deviation estimates
These subcommands provide options for estimating the within-subgroup process standard deviation based on the
following methods.
AMR
Average moving range.
RSPAN K
Use RSPAN to change the length of the moving range. The maximum length allowed is 100.
RBAR
Averages of the subgroup ranges. The maximum subgroup size allowed is 100.
SBAR
Averages of the subgroup standard deviations.
MMR
Median of the moving range.
RSPAN K
Use RSPAN to change the length of the moving range. The maximum length allowed is 100.
SRMSSD
Square root of half of the mean of the squared successive differences.
POOLED
Pooled standard deviation.
BIASED
Specifies to not use unbiasing constants when calculating the within-subgroup standard deviations. The default
is to use unbiasing constants.
UNBIASED
Specifies to use unbiasing constants when calculating the within subgroup standard deviations.
OBIASED
Specifies to not use an unbiasing constant when calculating the overall standard deviation.
OUNBIASED
Specifies to use an unbiasing constant when calculating the overall standard deviation.
629
Minitab Statistical Software Quality and Process Improvement
Box-Cox transformation
BOXCOX [K]
BOXCOX [K...K]
BOXCOX [C]
Transforms the data to follow a normal distribution using Box-Cox transformation. You can also specify a value
for lambda to be used in the transformation. If no value is specified, Minitab estimates the optimal value of lambda
from the data.
If all data sets share the same lambda value, specify a constant (K) or a column (C) with one value. If the data sets
have different lambda values, specify a value for each data set in a column or as constants. K and values in C must
lie between -5 and 5.
These subcommands cannot be used with a Johnson transformation.
Johnson transformation
JOHNSON
Selects a distribution function from Johnson system to transform each data set to follow normal distribution.
These subcommands cannot be used with a Box-Cox transformation.
PVALUE K...K
PVALUE C
Use the optional PVALUE to change the default p-value of 0.10 to select the optimal transformation. You can
specify p-values in a column or as constants, one value for each data set used in the analysis. These
subcommands cannot be used with a Box-Cox transformation.
Options
TARGET K
TARGET K...K
TARGET C
Specifies a process target value. Minitab then calculates Cpm, in addition to the standard capability statistics.
However, if JOHNSON is issued, then Minitab only displays the target in the process data table and capability
histogram.
If all data sets share the same target value, specify a constant or a column with one value. If the data sets have
different target values, specify a value for each data set in a column or as constants.
TOLER K
TOLER K...K
TOLER C
By default, calculates the capability statistics using an interval that is 6 standard deviations wide, 3 on either side
of the process mean. TOLER lets you change the width of this interval. For example, TOLER 12 says to use an
interval 12 standard deviations wide, 6 on either side of the process mean. This is referred to as "6-sigma quality.
If all data sets share the same tolerance, specify a constant or a column with one value. If the data sets have
different tolerance, specify a value for each data set in a column or as constants.
630
Minitab Statistical Software Quality and Process Improvement
CONFIDENCE [K]
Specifies a confidence level other than the default value of 95.0. Specify any value between 0 and 100. Minitab
calculates the confidence intervals for Cp, Cpk, Pp, Ppk, and Cpm statistics.
ONECI
Specifies one-sided confidence intervals. The direction of the intervals depends on the statistic.
Lower bound:
Cp
Cpk
Ppk
Cpm
Z.bench
Upper bound:
Parts Per Million (PPM) < Lower Specification Limit (LSL)
PPM > Upper Specification Limit (USL)
PPM total
Percent < LSL
Percent > USL
Percent total
TWOCI
Specifies two-sided confidence intervals.
NOCI
Specifies not to include confidence intervals in the output.
WITHIN
Use WITHIN to perform a within capability analysis only. This subcommand cannot be used with a Johnson
transformation.
The default is to conduct both within and overall capability analyses.
OVERALL
Use OVERALL to perform an overall capability analysis only. If a Johnson transformation is used, only an overall
analysis can be done so this subcommand is redundant.
The default is to conduct both within and overall capability analyses.
PERCENT
Replaces the default parts per million (PPM) calculations with percentages.
PPM
Replaces the percentage calculations with parts per million (PPM). Use this command to get PPM calculations
after you change the default calculations to percentages.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
631
Minitab Statistical Software Quality and Process Improvement
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
Results
BRIEF K
Controls the amount of output with a value in K.
Output that is displayedValue of K
No output is displayed.0
All output is displayed.2
Graphs
GHISTOGRAM
Displays a histogram with a density function.
DSCALING
Use DSCALING to have different X-axis scaling for all the variables.
MINIMUM K
MINIMUM K...K
MINIMUM C
Use MINIMUM and MAXIMUM to enter the range in which the data are plotted in the histogram. If no value
is entered, the range for each variable is determined by its data.
MAXIMUM K
MAXIMUM K...K
MAXIMUM C
Use MINIMUM and MAXIMUM to enter the range in which the data are plotted in the histogram. If no value
is entered, the range for each variable is determined by its data.
GNORMAL
Displays a normal probability plot for each variable or group.
Storage
NAME C
Stores the names of the data columns used in the analysis or the levels of the by variable that define the different
variables.
USL C
Stores the upper specification limit for each variable.
STARGET C
Stores the process target for each variable.
632
Minitab Statistical Software Quality and Process Improvement
LSL C
Stores the lower specification limit for each variable.
MEAN C
Stores the mean of the data for each variable.
N C
Stores the number of sample observations for each variable.
SDB C
Stores the between-subgroup standard deviation for each variable.
SDW C
Stores the within-subgroup standard deviation for each variable.
SDT C
Stores the within standard deviation for each variable when the analysis is performed for within subgroups variation
(default) or stores the total standard deviation for each variable when the analysis is performed for between and
within subgroup variation.
SDO C
Stores the overall standard deviation for each variable.
CP C
Stores the Cp or Z.bench statistic for each variable.
CPUC C
Stores the upper limit of a confidence interval for the Cp or Z.Bench statistic for each variable.
CPLC C
Stores the lower limit of a confidence interval for the Cp or Z.Bench statistic for each variable.
CPU C
Stores the CPU or Z.USL statistic for each variable.
CPL C
Stores the CPL or Z.LSL statistic for each variable.
CPK C
Stores the Cpk statistic for each variable.
CPKU C
Stores the upper limit of a confidence interval for the Cpk statistic for each variable.
CPKL C
Stores the lower limit of a confidence interval for the Cpk statistic for each variable.
CCPK C
Stores the CCpk statistic for each variable.
PP C
Stores the Pp or Z.Bench statistic for each variable.
PPUC C
Stores the upper limit of a confidence interval for the Pp or Z.Bench statistic for each variable.
633
Minitab Statistical Software Quality and Process Improvement
PPLC C
Stores the lower limit of a confidence interval for the Pp or Z.Bench statistic for each variable.
PPU C
Stores the PPU or Z.USL statistic for each variable.
PPL C
Stores the PPL or Z.LSL statistic for each variable.
PPK C
Stores the Ppk statistic for each variable.
PPKU C
Stores the upper limit of a confidence interval for the Ppk statistic for each variable.
PPKL C
Stores the lower limit of a confidence interval for the Ppk statistic for each variable.
CPM C
Stores the Cpm statistic for each variable.
UCPM C
Stores the upper limit of a confidence interval for the Cpm statistic for each variable.
LCPM C
Stores the lower limit of a confidence interval for the Cpm statistic for each variable.
PPML C
Stores the observed parts per million less than the lower specification limit for each variable.
PPMU C
Stores the observed parts per million greater than the upper specification limit for each variable.
PPMT C
Stores the total parts per million beyond the specification limit for each variable.
EPLO C (C C)
Stores either the expected parts per million or the expected percentage less than the lower specification limit for
each variable. The units match the output. The calculation uses the overall variation. Minitab stores the value in
the first column that you specify. To store the confidence bound from the output, specify a second column. To
store the confidence interval from the output, specify 2 additional columns.
EPUO C (C C)
Stores either the expected parts per million or the expected percentage greater than the upper specification limit
for each variable. The units match the output. The calculation uses the overall variation. Minitab stores the value
in the first column that you specify. To store the confidence bound from the output, specify a second column. To
store the confidence interval from the output, specify 2 additional columns.
EPTO C (C C)
Stores either the expected parts per million or the expected percentage outside the specification limits for each
variable. The units match the output. The calculation uses the overall variation. Minitab stores the value in the
first column that you specify. To store the confidence bound from the output, specify a second column. To store
the confidence interval from the output, specify 2 additional columns.
634
Minitab Statistical Software Quality and Process Improvement
EPLW C (C C)
Stores either the expected parts per million or the expected percentage less than the lower specification limit for
each variable. The units match the output. The calculation uses the within subgroup variation. Minitab stores the
value in the first column that you specify. To store the confidence bound from the output, specify a second column.
To store the confidence interval from the output, specify 2 additional columns.
EPUW C (C C)
Stores either the expected parts per million or the expected percentage greater than the upper specification limit
for each variable. The units match the output. The calculation uses the within subgroup variation. Minitab stores
the value in the first column that you specify. To store the confidence bound from the output, specify a second
column. To store the confidence interval from the output, specify 2 additional columns.
EPTW C (C C)
Stores either the expected parts per million or the expected percentage outside the specification limits for each
variable. The units match the output. The calculation uses the within subgroup variation. Minitab stores the value
in the first column that you specify. To store the confidence bound from the output, specify a second column. To
store the confidence interval from the output, specify 2 additional columns.
JTYPE C
Stores the optimal distribution function type selected for Johnson transformation for each variable.
JGAMMA C
Stores the gamma parameter of a distribution function in Johnson transformation for each variable.
JETA C
Stores the eta parameter of a distribution function in Johnson transformation for each variable.
JLAMBDA C
Stores the lambda parameter of a distribution function in Johnson transformation for each variable.
JEPSILON C
Stores the epsilon parameter of a distribution function in Johnson transformation for each variable.
SLAMBDA C
Stores the value of lambda used in Box-Cox transformation for each variable.
TUSL C
Stores the Box-Cox transformed value of the upper specification limit for each variable.
TTARGET C
Stores the Box-Cox transformed target value for each variable.
TLSL C
Stores the Box-Cox transformed value of the lower specification limit for each variable.
TMEA C
Stores the mean of the Box-Cox transformed data for each variable.
TSDB C
Stores the Box-Cox transformed value of between-subgroup standard deviation for each variable.
TSDW C
Stores the Box-Cox transformed value of within-subgroup standard deviation for each variable.
635
Minitab Statistical Software Quality and Process Improvement
TSDT C
Stores the total standard deviation of the Box-Cox transformed data for each variable.
TSDO C
Stores the overall standard deviation of the Box-Cox transformed data for each variable.
MNCAPA: Session command for performing nonnormal capability
analysis for multiple variables
MNCAPA C...C
Generates a process capability report when each of the continuous variables follows a nonnormal distribution or
to compare the results for multiple variables when a grouping variable is associated with a continuous variable.
For example, you want to compare the width of parts from the same process before and after a process
improvement.
The command is entered differently depending on how the data is structured in the worksheet. For details, go to
How to enter subgroup data on page 1163. The report includes a capability histogram overlaid with a distribution
curve, and a table of overall capability statistics. The distribution curve is generated from the distribution parameters.
The report also includes statistics of the process data, such as the mean, parameters, target (if you enter one),
and process specifications; the overall capability; and the observed and expected overall performance. So the
report can be used to visually assess the distribution of the process relative to the target, whether the data follow
a nonnormal distribution, and whether the process is capable of meeting the specifications consistently.
When using the nonnormal model, Minitab calculates the overall capability statistics, Pp, Ppk, PPU, and PPL. The
calculations are based on maximum likelihood estimates of the parameters for the specified distribution, rather
than mean and variance estimates as in the normal case.
BY C...C
Specifies the grouping columns in C...C. If you use this subcommand, only one variable can be specified with
MNCAPA.
USPEC K
USPEC K...K
USPEC C
Specifies the upper specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
UBOUND [K]
UBOUND [K...K]
UBOUND [C]
Specifies that the upper specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
636
Minitab Statistical Software Quality and Process Improvement
LSPEC K
LSPEC K...K
LSPEC C
Specifies the lower specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
LBOUND [K]
LBOUND [K...K]
LBOUND [C]
Specifies that the lower specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
Method
MTBINDEX
Calculates the capability indices using the MTB method, also called z-score method.
ISOINDEX
Calculates the capability indices using the ISO method.
Distributions
Use the following subcommands to specify which distributions to fit your data with.
EXPONENTIAL
The exponential distribution.
TEXPONENTIAL
The 2-parameter exponential distribution.
LNORMAL
The lognormal distribution.
TLNORMAL
The 3-parameter lognormal distribution.
WEIBULL
The Weibull distribution.
TWEIBULL
The 3-parameter Weibull distribution.
LEXTREMEVALUE
The largest extreme value distribution.
SEXTREMEVALUE
The smallest extreme value distribution.
637
Minitab Statistical Software Quality and Process Improvement
GAMMA
The gamma distribution.
TGAMMA
The 3-parameter gamma distribution.
LOGISTIC
The logistic distribution.
LLOGISTIC
The loglogistic distribution.
TLLOGISTIC
The 3-parameter loglogistic distribution.
Parameters
SETS K
SETS K...K
SETS C
Sets the shape parameter for the gamma and the Weibull distributions and the scale parameter for all other
distributions. Minitab calculates maximum likelihood estimates from the data for missing values.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
SETTHRESHOLD K
SETTHRESHOLD K...K
SETTHRESHOLD C
Sets the threshold parameter for the 2-parameter exponential and any 3-parameter distributions. Minitab calculates
maximum likelihood estimates from the data set for missing values.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
HPARAMETERS K...K
HPARAMETERS C
HPARAMETERS C...C
Sets all the parameters in a distribution. If all data sets share the same parameter values, enter constants or a
column. The number of constants or values in a column must equal the number of parameter in a distribution. If
the data set has different parameter values, enter columns equal to the number of data sets in your analysis. The
number of entries in each column must equal the number of parameters in a distribution.
You must enter parameter values in the following order: location, shape, scale, and threshold. For example, for
3-parameter loglogistic distribution, enter values of the parameters in the following order: location, scale, and
threshold.
638
Minitab Statistical Software Quality and Process Improvement
Options
TARGET K
TARGET K...K
TARGET C
Specifies a process target value. Minitab then calculates Cpm, in addition to the standard capability statistics.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
TOLER K
TOLER K...K
TOLER C
Specifies a value to calculate the capability statistics using an interval other than 6 standard deviations wide, 3 on
either side of the process mean. For example, TOLER 12 says to use an interval 12 standard deviations wide, 6
on either side of the process mean. This is referred to as "6-sigma quality."
You can specify the values in a column or as constants, one value for each data set used in the analysis.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
PERCENT
Replaces the default parts per million (PPM) calculations with percentages.
PPM
Replaces the percentage calculations with parts per million (PPM). Use this command to get PPM calculations
after you change the default calculations to percentages.
Graphs
GHISTOGRAM
Displays a histogram with a density function for each variable.
DSCALING
Use DSCALING to have different X-axis scaling for all the variables.
MINIMUM K
MINIMUM K...K
MINIMUM C
Use MINIMUM and MAXIMUM to enter the range in which the data are plotted in the histogram. If no value
is entered, the range for each variable is determined by its data.
If all the data sets share the same p-value, specify a constant or a column with one value. If the data sets
have different p-values, specify a value for each data set in a column or as constants.
639
Minitab Statistical Software Quality and Process Improvement
MAXIMUM K
MAXIMUM K...K
MAXIMUM C
Use MINIMUM and MAXIMUM to enter the range in which the data are plotted in the histogram. If no value
is entered, the range for each variable is determined by its data.
If all the data sets share the same p-value, specify a constant or a column with one value. If the data sets
have different p-values, specify a value for each data set in a column or as constants.
GPPLOT
Displays a probability plot for the specified distribution.
NOCHART
Suppresses the display of the graph. The default is to display the graph.
WTITLE
WTITLE specifies the command title of the resulting graph.
Storage
NAME C
Stores the names of the data columns used in the analysis or the levels of the by variable that define the different
variables.
USL C
Stores the upper specification limit for each variable.
STARGET C
Stores the process target for each variable.
LSL C
Stores the lower specification limit for each variable.
MEAN C
Stores the mean of the data for each variable.
N C
Stores the number of sample observations for each variable.
SSHAPE C
Stores the shape parameter of a distribution for each variable.
SSCALE C
Stores the scale parameter of a distribution for each variable.
SLOCATION C
Stores the location parameter of a distribution for each variable.
STHRESHOLD C
Stores the threshold parameter of a distribution for each variable.
640
Minitab Statistical Software Quality and Process Improvement
PP C
Stores the Pp or Z.Bench statistic for each variable.
PPU C
Stores the PPU or Z.USL statistic for each variable.
PPL C
Stores the PPL or Z.LSL statistic for each variable.
PPK C
Stores the Ppk statistic for each variable.
PPML C
Stores the observed parts per million less than the lower specification limit for each variable.
PPMU C
Stores the observed parts per million greater than the upper specification limit for each variable.
PPMT C
Stores the total parts per million beyond the specification limit for each variable.
EPLO C
Stores either the expected parts per million or the expected percentage less than the lower specification limit for
each variable. The units match the output. The calculation uses the overall variation.
EPUO C
Stores either the expected parts per million or the expected percentage greater than the upper specification limit
for each variable. The units match the output. The calculation uses the overall variation.
EPTO C
Stores either the expected parts per million or the expected percentage outside the specification limits for each
variable. The units match the output. The calculation uses the overall variation.
BWSIXPAC: Session command for Between/Within Capability
Sixpack
BWSIXPAC C...C [E]
Creates a capability report based on the assumption that the data are from normal distribution using both
between-subgroup and within-subgroup standard deviations. The report includes the following:
The individuals, moving range, and R or S charts, to verify whether the process is in control.
The histogram and normal probability plot, to verify that the data are normally distributed.
The capability plot, to give you a graphical view of the process variability compared to the specifications.
Minitab displays the values to the right of this plot.
The between/within and overall capability statistics, to help you assess whether a process is in control and is
capable of producing output that consistently meets the specifications.
If a data set is arranged in a column, specify the column with BWSIXPACK with subgroup size in E. E can be a
column (if the subgroup size varies) or a constant (if the subgroups are the same size.) Columns may contain
numeric or text data. If your data are in subgroups across rows of several of columns, use RSUBS. For more
information, go to How to enter subgroup data on page 1163.
641
Minitab Statistical Software Quality and Process Improvement
Minitab determines which chart to display based on the subgroup size. For individual observations, an I-MR chart
is displayed. For subgroup size between 2 and 8, an Xbar-R chart is displayed. For subgroup size > 8, an Xbar-S
chart is displayed.
RSUBS C...C [K]
Specifies that the data in each row of the input columns makes up a subgroup. All columns must be the same
length. If only one input column is given with RSUBS, then the subgroup size is 1. The optional K indicates
the number of data sets if greater than 1. For more information, go to How to enter subgroup data on page
1163.
USPEC C
USPEC K...K
Specifies the upper specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
UBOUND C
UBOUND K...K
Specifies that the upper specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
LSPEC C
LSPEC K...K
Specifies the lower specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
LBOUND C
LBOUND K...K
Specifies that the lower specification is a bound. K or the values in C are 1 or 0, which indicates whether
the corresponding limit is a boundary.
Historical estimates
It is generally assumed that the data from the process follow a normal distribution. MU is the mean of this distribution.
BSIGMA is the process standard deviation between batches and WSIGMA is the process standard deviation within
subgroups. You can use these subcommands to enter known values for the process parameters, or enter previous
estimates. If these subcommands are omitted, Minitab estimates the values from the data set.
You can specify the values in a column or as constants, one for each data set used in the analysis.
MU C
MU K...K
Specifies historical values for the mean of the normal distribution.
BSIGMA C
BSIGMA K...K
Specifies historical values for the between-subgroup standard deviation.
642
Minitab Statistical Software Quality and Process Improvement
WSIGMA C
WSIGMA K...K
Specifies historical values for the within-subgroup standard deviation.
Options
TARGET C
TARGET K...K
Specifies the target values for each data set.
TOLER K
Specifies to calculate the capability statistics using an interval specified as K.
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
Box-Cox transformation
BOXCOX [C]
BOXCOX K...K
Transforms the data to follow a normal distribution using Box-Cox transformation. You can also specify a value
for lambda to be used in the transformation. If no value is specified, Minitab estimates the optimal value of lambda
from the data.
You can specify the values for lambda in a column (C) or as constants (K), one value for each data set used in the
analysis. K and values in C must lie between −5 and 5.
Standard deviation estimates for capability statistics
OBIASED
Specifies to not use an unbiasing constant when calculating the overall standard deviation.
OUNBIASED
Specifies to use an unbiasing constant when calculating the overall standard deviation.
AMR
Estimates the between-subgroup standard deviation using the average moving range method using the length
specified with RSPAN as K.
MMR
Estimates the between-subgroup standard deviation using the median of the moving ranges method using the
length specified with RSPAN as K.
SRMSSD
Estimates the between-subgroup standard deviation using the square root of half of the mean of the squared
successive differences.
643
Minitab Statistical Software Quality and Process Improvement
RBAR
Estimates the within-subgroup standard deviation using the average of subgroup range method.
SBAR
Estimates the within-subgroup standard deviation using the average of the subgroup standard deviation method.
POOLED
Estimates the within-subgroup standard deviation using the pooled standard deviation.
Standard deviation estimates for control charts
CCAMR
Estimates standard deviation between subgroups using the average moving range method using the length
specified with RSPAN as K.
CCMMR
Estimates standard deviation between subgroups using the median of the moving ranges method using the length
specified with RSPAN K.
CCRBAR
When the subgroup size <= 8, CCRBAR estimates the within-subgroup standard deviation using the average of
subgroup range method.
CCSSBAR
When the subgroup size <= 8, CCSSBAR estimates the within-subgroup standard deviation using the average of
the subgroup standard deviation method.
CCSPOOLED
When the subgroup size <= 8, CCSPOOLED estimates the within-subgroup standard deviation using the pooled
standard deviation.
CCSBAR
When the subgroup size > 8, CCSBAR estimates the within-subgroup standard deviation using the average of the
subgroup standard deviation method.
CCPOOLED
When the subgroup size > 8, CCPOOLED estimates the within-subgroup standard deviation using the pooled
standard deviation.
Standard deviation estimates for both capability statistics and control charts
RSPAN K
Specifies the length of the moving range for AMR, MMR, CCAMR, and CCMMR.
BIASED
Specifies to not use unbiasing constants when calculating the within-subgroup standard deviations.
UNBIASED
Specifies to use unbiasing constants when calculating the within subgroup standard deviations.
644
Minitab Statistical Software Quality and Process Improvement
Tests for special causes
TEST K...K
Specifies one or more of the eight tests for special causes, where K takes values 1, 2, 3, 4, 5, 6, 7, and 8. Each K
corresponds to a test.
Each test detects a specific pattern in the data plotted on the chart. The occurrence of a pattern suggests a special
cause for the variation, one that should be investigated.
When any point fails one of the eight tests, Minitab displays the information in the output.
TestK
One point more than 3 standard deviation from center line1
Nine points in a row on same side of center line2
Six points in a row, all increasing or all decreasing3
Fourteen points in a row, alternating up and down4
Two out of three points more than 2 standard deviation from center line (same side)5
Four out of five points more than 1 standard deviation from center line (same side)6
Fifteen points in a row within 1 standard deviation of center line (either side)7
Eight points in a row more than 1 standard deviation from center line (either side)8
Graphs
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
645
Minitab Statistical Software Quality and Process Improvement
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
SIXPACK: Session command for Normal Capability Sixpack
SIXPACK [C...C E]
Generates a capability report based on the assumption that the data are from normal distribution. You can also
use the BOXCOX or JOHNSON subcommand to try to transform your data to follow a normal distribution. The
report includes the following:
X, R, and run charts, to verify that the process is in a state of control.
A histogram and a normal probability plot, to verify that the data are normally distributed.
A capability plot, for a graphical view of the process variability compared to the specifications.
Capability statistics Cp, CPU, CPL, Cpk, and benchmark Z values, to help you assess whether a process is in
control and is capable of producing output that consistently meets the specifications.
If a data set is arranged in a column, specify the column with SIXPACK with subgroup size in E. E can be a column
(if the subgroup size varies) or a constant (if the subgroups are the same size.) If your data are in subgroups across
rows of several of columns, use RSUBS. For more information, go to How to enter subgroup data on page 1163.
By default, Minitab determines which control charts to display based on the subgroup size. For individual
observations, an I chart and an MR chart are displayed. For subgroup size between 2 and 8, an Xbar chart and an
R chart are displayed. For subgroup size greater than 8, an Xbar chart and an S chart are displayed. The CCRBAR
and CCSBAR subcommands can be used to force the display of an R chart or an S chart, respectively, for all
subgroup sizes greater than 1.
RSUBS C...C [K]
Specifies that the data in each row of the input columns makes up a subgroup. All columns must be the same
length. If only one input column is given with RSUB, then the subgroup size is 1. The optional K indicates the
number of data sets if greater than 1. For more information, go to How to enter subgroup data on page 1163.
646
Minitab Statistical Software Quality and Process Improvement
USPEC C
USPEC K...K
Specifies the upper specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
LSPEC C
LSPEC K...K
Specifies the lower specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
TARGET C
TARGET K...K
Specifies a process target value. Minitab then calculates Cpm, in addition to the standard capability statistics.
You can specify values in a column or as constants, one value for each data set used in the analysis.
Historical estimates
It is generally assumed that the data from the process follow a normal distribution. MU is the mean of this distribution.
BSIGMA is the process standard deviation between batches and WSIGMA is the process standard deviation within
subgroups. You can use these subcommands to enter known values for the process parameters, or enter previous
estimates. If these subcommands are omitted, Minitab estimates the values from the data set.
You can specify the values in a column or as constants, one for each data set used in the analysis.
You cannot use these subcommands with JOHNSON or BOXCOX.
MU C
MU K...K
Specifies historical values for the mean of the normal distribution.
SIGMA C
SIGMA K...K
Specifies historical values for the standard deviation of the normal distribution.
Options
TEST K...K
Specifies one or more of the eight tests for special causes, where K takes values 1, 2, 3, 4, 5, 6, 7, and 8. Each K
corresponds to a test.
Each test detects a specific pattern in the data plotted on the chart. The occurrence of a pattern suggests a special
cause for the variation, one that should be investigated.
When any point fails one of the eight tests, Minitab displays the information in the output.
TestK
One point more than 3 standard deviation from center line1
647
Minitab Statistical Software Quality and Process Improvement
TestK
Nine points in a row on same side of center line2
Six points in a row, all increasing or all decreasing3
Fourteen points in a row, alternating up and down4
Two out of three points more than 2 standard deviation from center line (same side)5
Four out of five points more than 1 standard deviation from center line (same side)6
Fifteen points in a row within 1 standard deviation of center line (either side)7
Eight points in a row more than 1 standard deviation from center line (either side)8
BREAKOUT K
Specifies the number of subgroups or observations to display in the run chart. The default number is 25.
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
Box-Cox transformation
BOXCOX [C]
BOXCOX [K...K]
Transforms the data to follow a normal distribution using Box-Cox transformation. You can also specify a value
for lambda to be used in the transformation. If no value is specified, Minitab estimates the optimal value of lambda
from the data.
You can specify the values for lambda in a column (C) or as constants (K), one value for each data set used in the
analysis. K and values in C must lie between −5 and 5.
You cannot use BOXCOX with JOHNSON.
Johnson transformation
JOHNSON
Selects a distribution function from the Johnson system to transform data in each column to follow a normal
distribution.
You cannot use JOHNSON with BOXCOX.
PVALUE K...K
PVALUE C
Use the optional PVALUE to change the default p-value of 0.10 to select the optimal transformation. You can
specify p-values in a column or as constants, one value for each data set used in the analysis.
648
Minitab Statistical Software Quality and Process Improvement
Standard deviation estimates for capability statistics
OBIASED
Specifies to not use an unbiasing constant when calculating the overall standard deviation.
You can use this subcommand with JOHNSON.
OUNBIASED
Specifies to use an unbiasing constant when calculating the overall standard deviation.
You can use this subcommand with JOHNSON.
AMR
When the subgroup size = 1, AMR estimates the between-subgroup standard deviation using the average moving
range method using the length specified with RSPAN as K.
You cannot use this subcommand with JOHNSON.
MMR
When the subgroup size = 1, MMR estimates the between-subgroup standard deviation using the median of the
moving ranges method using the length specified with RSPAN as K.
You cannot use this subcommand with JOHNSON.
SRMSSD
When the subgroup size = 1, SRMSSD estimates the between-subgroup standard deviation using the square root
of half of the mean of the squared successive differences.
You cannot use this subcommand with JOHNSON.
RBAR
When the subgroup size > 1, RBAR estimates the within-subgroup standard deviation using the average of
subgroup range method.
You cannot use this subcommand with JOHNSON.
SBAR
When the subgroup size > 1, SBAR estimates the within-subgroup standard deviation using the average of the
subgroup standard deviation method.
You cannot use this subcommand with JOHNSON.
POOLED
When the subgroup size > 1, POOLED estimates the within-subgroup standard deviation using the pooled standard
deviation.
You cannot use this subcommand with JOHNSON.
649
Minitab Statistical Software Quality and Process Improvement
Standard deviation estimates for control charts
CCAMR
Estimates the between-subgroup standard deviation using the average moving range method using the length
specified with RSPAN as K.
CCMMR
Estimates the between-subgroup standard deviation using the median of the moving ranges method using the
length specified with RSPAN K.
CCRBAR
When the subgroup size <= 8, CCRBAR estimates the within-subgroup standard deviation using the average of
subgroup range method.
CCSSBAR
When the subgroup size <= 8, CCSSBAR estimates the within-subgroup standard deviation using the average of
the subgroup standard deviation method.
CCSPOOLED
When the subgroup size <= 8, CCSPOOLED estimates the within-subgroup standard deviation using the pooled
standard deviation.
CCSBAR
When the subgroup size > 8, CCSBAR estimates the within-subgroup standard deviation using the average of the
subgroup standard deviation method.
CCPOOLED
When the subgroup size > 8, CCSPOOLED estimates the within-subgroup standard deviation using the pooled
standard deviation.
Standard deviation estimates for both capability statistics and control charts
RSPAN K
Specifies the length of the moving range for AMR, MMR, CCAMR, and CCMMR.
BIASED
Specifies to not use unbiasing constants when calculating the within-subgroup standard deviations.
UNBIASED
Specifies to use unbiasing constants when calculating the within subgroup standard deviations.
Graphs
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
650
Minitab Statistical Software Quality and Process Improvement
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
NNSIXPACK: Session command for Nonnormal Capability
Sixpack
NNSIXPACK C...C
Generates a capability report based on the assumption that the data follows a nonnormal distribution. The report
combines the following information into a single display:
An Xbar chart (or I chart for individual observations)
An R or S chart (or MR chart for individual observations)
651
Minitab Statistical Software Quality and Process Improvement
A run chart of the last 25 subgroups (or last 25 observations)
A histogram of the process data
A distribution probability plot
A process capability plot
Overall capability statistics Pp, Ppk, and distribution parameters
The Xbar, R, and run charts can be used to verify that the process is in a state of control. The histogram and
distribution probability plot can be used to verify that the data approximate a specified distribution. Lastly, the
capability plot gives a graphical view of the process variability compared to the specifications. Combined with
the capability statistics, this information can help you assess whether your process is in control and can produce
output that consistently meets the specifications.
When using the nonnormal model, Minitab only calculates the overall capability statistics, Pp and Ppk. The
calculations are based on maximum likelihood estimates of the distribution parameters for the specified distribution,
rather than mean and variance estimates as in the normal case.
RSUBS C...C [K]
Specifies that the data in each row of the input columns makes up a subgroup. All columns must be the same
length. If only one input column is given with RSUB, then the subgroup size is 1.
The optional K indicates the number of data sets if greater than 1. For details, go to How to enter subgroup
data on page 1163.
USPEC C
USPEC K...K
Specifies the upper specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
LSPEC C
LSPEC K...K
Specifies the lower specification limit.
Important You must enter either an upper specification limit in USPEC or a lower specification limit in LSPEC.
Method
MTBINDEX
Calculates the capability indices using the MTB method, also called z-score method.
ISOINDEX
Calculates the capability indices using the ISO method.
Distributions
Use the following subcommands to specify which distributions to fit your data with.
EXPONENTIAL
The exponential distribution.
652
Minitab Statistical Software Quality and Process Improvement
TEXPONENTIAL
The 2-parameter exponential distribution.
LNORMAL
The lognormal distribution.
TLNORMAL
The 3-parameter lognormal distribution.
WEIBULL
The Weibull distribution.
TWEIBULL
The 3-parameter Weibull distribution.
LEXTREMEVALUE
The largest extreme value distribution.
SEXTREMEVALUE
The smallest extreme value distribution.
GAMMA
The gamma distribution.
TGAMMA
The 3-parameter gamma distribution.
LOGISTIC
The logistic distribution.
LLOGISTIC
The loglogistic distribution.
TLLOGISTIC
The 3-parameter loglogistic distribution.
Parameters
SETS K...K
SETS C
Sets the shape parameter for the gamma and the Weibull distributions and the scale parameter for all other
distributions. Minitab calculates maximum likelihood estimates from the data for missing values.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
SETTHRESHOLD K...K
SETTHRESHOLD C
Sets the threshold parameter for the 2-parameter exponential and any 3-parameter distributions. Minitab calculates
maximum likelihood estimates from the data set for missing values.
You can specify values for the parameters in a column or as constants, one value for each data set used in the
analysis.
653
Minitab Statistical Software Quality and Process Improvement
HPARAMETERS K...K
HPARAMETERS C
HPARAMETERS C...C
Sets all the parameters in a distribution. If all data sets share the same parameter values, enter constants or a
column. The number of constants or values in a column must equal the number of parameter in a distribution. If
the data set has different parameter values, enter columns equal to the number of data sets in your analysis. The
number of entries in each column must equal the number of parameters in a distribution.
You must enter parameter values in the following order: location, shape, scale, and threshold. For example, for
3-parameter loglogistic distribution, enter values of the parameters in the following order: location, scale, and
threshold.
Standard deviation estimates for control charts
RSPAN K
Specifies the length of the moving range for CCAMR and CCMMR.
BIASED
Specifies to not use unbiasing constants when calculating the within subgroup standard deviations.
UNBIASED
Specifies to use unbiasing constants when calculating the within subgroup standard deviations.
Standard deviation estimates for control charts, when subgroup size = 1
CCAMR
Estimates the within-subgroup standard deviation using the average moving range method using the length
specified with RSPAN as K.
CCMMR
Estimates the within-subgroup standard deviation using the median of the moving ranges method using the
length specified with RSPAN K.
Standard deviation estimates for control charts, when 1 < subgroup size <= 8
CCRBAR
Estimates the within-subgroup standard deviation using the average of subgroup range method.
CCSSBAR
Estimates the within-subgroup standard deviation using the average of the subgroup standard deviation method.
CCSPOOLED
Estimates the within-subgroup standard deviation using the pooled standard deviation.
Standard deviation estimates for control charts, when subgroup size > 8
CCSBAR
Estimates the within-subgroup standard deviation using the average of the subgroup standard deviation method.
654
Minitab Statistical Software Quality and Process Improvement
CCPOOLED
Estimates the within-subgroup standard deviation using the pooled standard deviation.
Options
BREAKOUT K
Specifies the number of subgroups or observations to display in the run chart. The default number is 25.
TOLER K...K
TOLER C
Specifies a value to calculate the capability statistics using an interval other than 6 standard deviations wide, 3 on
either side of the process mean. For example, TOLER 12 says to use an interval 12 standard deviations wide, 6
on either side of the process mean. This is referred to as "6-sigma quality."
You can specify the values in a column or as constants, one value for each data set used in the analysis.
CSTAT
Displays the capability statistics when the default preference is set to display the benchmark Z statistics.
ZBENCH
Displays benchmark Z statistics rather than the default capability statistics.
Graph
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
655
Minitab Statistical Software Quality and Process Improvement
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
BCAPA: Session command for performing binomial capability
analysis
BCAPA C...C E
Generates a process capability report for data from a binomial distribution. E is the sample size for each data set,
which can be a column (if subgroup size varies) or a constant (if all samples are the same size). For more information,
go to How to enter data for PDIAGNOSTIC, PCHART, and PPRIMECHART on page 1161.
The report includes the following:
A P chart, to verify that the process was in a state of control at the time the report was generated.
A chart of cumulative %defective, to verify that you collected data from enough samples to have a stable
estimate of the %defective.
A histogram of %defective, to display the overall distribution of the %defectives from the samples collected.
A defective rate plot, to verify that the %defective is not influenced by the number of items that were sampled.
If an observation is missing, there is a gap in the P chart where that subgroup would have been plotted. The other
plots and charts simply exclude the missing observation.
In the P chart, the control limits are a function of the subgroup size. In general, the control limits are further from
the centerline for smaller subgroups than they are for larger ones. When you have unequal subgroup sizes, the
plot of %defective versus sample size helps you verify that there is no relationship between the two. For example,
if you tend to have a smaller %defective when more items are sampled, this could be caused by fatigued inspectors,
a common problem. The subgroup size has no bearing on the other charts, since they display only the %defective.
656
Minitab Statistical Software Quality and Process Improvement
TARGET C
TARGET K...K
Specifies a process target value, which can be in a column or as list of constants. The number of rows in a
column and constants must equal the number of columns listed with the main command.
P C
P K...K
Specify historical values for the proportions of defectives, which can be in a column or as list of constants.
The number of rows in a column and constants must equal the number of columns listed with the main
command.
TEST K...K
Specifies one or more of the four tests for special causes, where K takes values 1, 2, 3, and 4. Each value of
K corresponds to a test.
TestValue of K
One point more than 3 standard deviations from center line1
Nine points in a row on same side of center line2
Six points in a row, all increasing or all decreasing3
Fourteen points in a row, alternating up and down4
Each test detects a specific pattern in the data plotted on the chart. The occurrence of a pattern suggests a
special cause for the variation, one that should be investigated. When any point fails one of the four tests,
Minitab displays the information in the output.
Graphs
NOCHART
Suppresses the display of the graph. The default is to display the graph.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
657
Minitab Statistical Software Quality and Process Improvement
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Storage
NAME C
Stores column names used in the analysis.
PAVERAGE C
Stores the average proportion of defectives.
PALC C
Stores the lower limit of the confidence interval for the average proportion of defectives.
PAUC C
Stores the upper limit of the confidence interval for the average proportion of defectives.
PDEFECTIVE C
Stores the percent defective.
PDLC C
Stores the lower limit of the confidence interval for the percent defectives.
PDUC C
Stores the upper limit of the confidence interval for the percent defectives.
658
Minitab Statistical Software Quality and Process Improvement
PDTARGET C
Stores the target percent of defectives.
PPM C
Stores the parts per million defective.
PPML C
Stores the lower limit of the confidence interval for the parts per million defectives.
PPMU C
Stores the upper limit of the confidence interval for the parts per million defectives.
ZPROCESS C
Stores the process Z.
ZPLC C
Stores the lower limit of the confidence interval for the process Z.
ZPUC C
Stores the upper limit of the confidence interval for the process Z.
PCAPA: Session command for performing a Poisson capability
analysis
PCAPA C...C E
Generates a process capability report for data from a Poisson distribution. E is the subgroup size for each data
set, which can be a column (if subgroup size varies) or a constant (if the subgroups are the same size). For more
information, go to How to enter data for UDIAGNOSTIC, UCHART, and UPRIMECHART on page 1163.
The report includes:
A U chart, to verify that the process was in a state of control at the time the report was generated. Note: if the
samples are all the same size, there are two cases to consider. First, if all the samples have more than 1 unit
of size. In that case, a U chart is still preferred because it charts the number of defects per unit, whereas a C
chart plots the number of defects only. Defects per unit is more informative than just defects. If the samples
all have 1 unit of size, then a U chart and a C chart are exactly the same.
A chart of cumulative mean DPU, to verify that you collected data from enough samples to have a stable
estimate of the mean.
A histogram of DPU, to display the overall distribution of the defects per unit from the samples collected.
A defect rate plot, to verify that DPU is not influenced by the size of the items sampled.
If an observation is missing, there is a gap in the U chart where that subgroup would have been plotted. The other
plots and charts simply exclude the missing observation.
In the U chart, the control limits are a function of the subgroup size. In general, the control limits are further from
the centerline for smaller subgroups than they are for larger ones. When you do have unequal subgroup size, the
plot of DPU versus sample size will permit you to verify that there is no relationship between the two. For example,
if you tend to have a smaller DPU when more items are sampled, this could be caused by fatigued inspectors, a
common problem. The subgroup size has no bearing on the other charts, since they only display the DPU.
659
Minitab Statistical Software Quality and Process Improvement
TARGET C
TARGET K...K
Specifies the target values for each data set.
Historical estimates
MU C
MU K...K
The process is assumed to produce data from a population that follows a Poisson distribution. The mean and
variance of this distribution are both m. MU specifies a value for this parameter. You can specify the values for
this parameter in a column or as list of constants, where each values corresponds to the columns listed in the
main command.
Tests for special causes
TEST K
Specifies one or more of the four tests for special causes, where K takes values 1, 2, 3, and 4. Each value of K
corresponds to a test.
TestValue of K
One point more than 3 standard deviations from center line1
Nine points in a row on same side of center line2
Six points in a row, all increasing or all decreasing3
Fourteen points in a row, alternating up and down4
Each test detects a specific pattern in the data plotted on the chart. The occurrence of a pattern suggests a special
cause for the variation, one that should be investigated. When any point fails one of the four tests, Minitab displays
the information in the output.
Graph
NOCHART
Suppresses the display of the graph. The default is to display the graph.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
WTITLE "title"
You can use WTITLE as a subcommand with LAYOUT and all graphs. The title that you specify becomes the
command title of the resulting graph.
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
660
Minitab Statistical Software Quality and Process Improvement
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
Storage
NAME C
Stores the names of the data columns used in the analysis.
DEFECTS C
Stores the mean number of defects.
DEFL C
Stores the lower limit of the confidence interval for the mean number of defects.
DEFU C
Stores the upper limit of the confidence interval for the mean number of defects.
661
Minitab Statistical Software Quality and Process Improvement
DPU C
Stores the mean defects per unit.
DPUL C
Stores the lower limit of the confidence interval for the mean defects per unit.
DPUU C
Stores the upper limit of the confidence interval for the mean defects per unit.
DMINIMUM C
Stores the minimum number of defects per unit.
DMAXIMUM C
Stores the maximum number of defects per unit.
DTARGET C
Stores the target defects per unit.
Tolerance Intervals
TOLINTERVALS: Session command for calculating tolerance
intervals
TOLINTERVALS C...C
TOLINTERVALS K K K
Computes a range of values for a specific quality characteristic of a product that likely covers a specified proportion
of future product output. Alternatively, a lower or upper limit may be constructed such that the specified proportion
will be greater than or less than the limit. Tolerance intervals specify both a population proportion and a confidence
level. They are frequently used to detect excessive variation by comparing client requirements to tolerance limits
that cover a proportion of the population that is acceptable to the manufacturer.
TOLINTERVALS C...C calculates exact parametric and nonparametric tolerance intervals for each variable C...C.
TOLINTERVALS K K K calculates tolerance intervals using summarized values for the sample size, mean, and
standard deviation.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
PPERCENT K
Specifies the minimum percentage of the population covered by the tolerance interval. K is typically any number
in the interval [0.000001, 99.9999]. However, if K < 0.999999, then a population percentage of K*100 is assumed.
The default value is 95.
662
Minitab Statistical Software Quality and Process Improvement
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
Graphs
GTIPLOT
Displays a tolerance interval plot for each sample. Each plot consists of a histogram and two interval plots based
on the normal and nonparametric tolerance intervals.
Results
Each of the following subcommands displays a table in the output. If you do not use any of these subcommands, all
the output is displayed.
TMETHOD
Displays the method table that contains the hypotheses and significance level.
TSTATISTICS
TSTATISTICS displays the sample size and point estimates of the mean and standard deviation for each population.
TTOLINTERVAL
TTOLINTERVAL displays both the normal and nonparametric tolerance intervals.
Storage
SPTLIMITS C C
SPTLIMITS stores the limits for the tolerance intervals that are calculated using the normal method.
The lower limits is stored in the first column C and the upper limit is stored in the second column C. If ITYPE is
specified as –1 or 1, then specify only one column C.
SNPTLIMITS C C
SNPTLIMITS stores the limits for the tolerance intervals that are calculated using the nonparametric method.
The lower limits is stored in the first column C and the upper limit is stored in the second column C. If ITYPE is
specified as –1 or 1, then specify only one column C.
STFACTOR C
Stores the tolerance factor for the normal method, also known as the k factor, for each variable. The values are
stored in column C.
663
Minitab Statistical Software Quality and Process Improvement
NNTINTERVALS: Session command for calculating tolerance
intervals
NNTINTERVALS C...C
Computes a range of values for a specific quality characteristic of a product that likely covers a specified minimum
percentage of current or future product output. Alternatively, a lower or upper limit may be constructed such that
the specified proportion will be greater than or less than the limit. Tolerance intervals specify both a population
proportion and a confidence level. They are frequently used to detect excessive variation by comparing client
requirements to tolerance limits that cover a proportion of the population that is acceptable to the manufacturer.
NNTINTERVALS C...C calculates exact parametric and nonparametric tolerance intervals for each variable C...C.
PPERCENT K
Specifies the minimum percentage of the population covered by the tolerance interval. K is typically any
number in the interval [0.000001, 99.9999]. However, if K < 0.999999, then a population percentage of K*100
is assumed. The default value is 95.
Distributions
EXPONENTIAL
Assumes that the data follow an exponential distribution.
LNORMAL
Assumes that the data follow a lognormal distribution.
WEIBULL
Assumes that the data follow a Weibull distribution.
SEXTREMEVALUE
Assumes that the data follow a smallest extreme value distribution.
LEXTREMEVALUE
Assumes that the data follow a largest extreme value distribution.
GAMMA
Assumes that the data follow a gamma distribution.
LOGISTIC
Assumes that the data follow a logistic distribution.
LLOGISTIC
Assumes that the data follow a loglogistic distribution.
NOPARA
Assumes the data do not follow any specific distribution. Minitab provides only a nonparametric interval.
664
Minitab Statistical Software Quality and Process Improvement
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
Graphs
GTIPLOT
Displays a tolerance interval plot for each sample. Each plot consists of a histogram and two interval plots based
on the parametric and nonparametric tolerance intervals.
Results
Each of the following subcommands displays a table in the output. If you do not use any of these subcommands, all
the output is displayed.
TMETHOD
Displays the method table that contains the hypotheses and significance level.
TSTATISTICS
TSTATISTICS displays the sample size and point estimates of the mean and standard deviation for each population.
TESTIMATE
TESTIMATE displays the estimated values of the distribution parameters.
TTOLINTERVAL
TTOLINTERVAL displays both the parametric and nonparametric tolerance intervals.
Storage
SPTLIMITS C C
SPTLIMITS stores the limits for the tolerance intervals that are calculated using the parametric method.
The lower limits is stored in the first column C and the upper limit is stored in the second column C. If ITYPE is
specified as –1 or 1, then specify only one column C.
SNPTLIMITS C C
SNPTLIMITS stores the limits for the tolerance intervals that are calculated using the nonparametric method.
The lower limits is stored in the first column C and the upper limit is stored in the second column C. If ITYPE is
specified as –1 or 1, then specify only one column C.
665
Minitab Statistical Software Quality and Process Improvement
STFACTOR C
Stores the tolerance factor for the parametric method, also known as the k factor, for each variable. The values
are stored in column C.
Measurement Systems Analysis
TOGAGE: Session command for performing a Type 1 gage study
TOGAGE C
Performs a Type 1 gage study on measurements from a single part. The argument specifies the numeric column.
Reference value
REFERENCE K
Specifies the reference value for the single part. Reference value must be numeric.
Tolerance limits
Important You must use one of the following tolerance limit subcommands.
TOLERANCE K (K)
Specifies the tolerance range, which is USL–LSL or USL–0, when both limits are known or a natural zero exists. You
must specify tolerance to calculate the capability indices.
USL K
Use when only the upper specification limit is known. Minitab does not calculate capability indices unless both
specifications are given.
LSL K
Use when only the lower specification limit is known. Minitab does not calculate capability indices unless both
specifications are given.
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
666
Minitab Statistical Software Quality and Process Improvement
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
Options
CGCONSTANT K
Specifies the percent of tolerance used for calculating the capability indices, Cg and CgK. K is a constant and must
be a positive number. The default value of K is 20.
STUDYVAR K
Specifies the constant to multiply by sigma for the gage variation. K is a constant and must be a positive number.
The default value of K is 6.
RESOLUTION K
Specifies the gage resolution value. K is a constant and must be a positive number. If you do not use this
subcommand, Minitab does not display the resolution output.
NOBIASTEST
Suppresses the testing of bias=0.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GAWORKSHEET: Session command for creating a gage R&R study
worksheet
GAWORKSHEET K K K
Creates a Gage R&R Study Worksheet (or Attribute Agreement Analysis Worksheet) with Parts (Samples), Operators
(Appraisers), Run Order, and Standard Order columns. The first K is the number of parts (samples). The second K
is the number of operators (appraisers). The third K is the number of replicates.
PARTS K...K
PARTS "text"..."text"
PARTS C
Specifies part names for all K parts, the first number specified with GAWORKSHEET. By default, the part names
are "1", "2", ... "K". If you use a column of part names, each value must be distinct.
OPERATORS K...K
OPERATORS "text"
Specifies operator names for all K operators, the second number specified with GAWORKSHEET. By default,
the operator names are "1", "2", ... "K".
667
Minitab Statistical Software Quality and Process Improvement
Options
NSTANDARD K...K
NSTANDARD C
Specifies the numeric standard values for samples in Attribute Agreement Analysis. Arguments must be numeric
values and the number of standard values must be equal to the number of samples specified with GAWORKSHEET.
When the standards are stored in a column, the number of values must equal the number of samples. This
subcommand cannot be used if TSTANDARD has been issued.
REFERENCE K
Specifies a reference level out of the two standard values to define the value order for the stored binary
standard value column. This subsubcommand is only valid with binary data. If the standard has more than
two levels, REFERENCE is ignored.
TSTANDARD "text"..."text"
TSTANDARD C
Specifies the text standard values for samples in Attribute Agreement Analysis. Arguments must be text values
and the number of standard values must be equal to the number of samples specified with GAWORKSHEET. When
the standards are stored in a column, the number of values must equal the number of samples. This subcommand
cannot be used if NSTANDARD has been issued.
REFERENCE "text"
Specifies a reference level out of the two standard values to define the value order for the stored binary
standard value column. This subsubcommand is only valid with binary data. If the standard has more than
two levels, REFERENCE is ignored.
RANDOMIZE (K)
Completely randomizes the run order. To generate the same random sample, you can optionally set the base, K.
K is a numeric value.
WRANDOMIZE (K)
Randomizes the run order within each operator. To generate the same random sample, you can optionally set
the base, K. K is a numeric value.
RSOPERATOR
When randomizing the run order within operator (WRANDOMIZE), this subcommand randomizes the order
of operators. Without this subcommand, Operator 1 is always listed first, Operator 2 is second, and so on.
SORDER C
Stores the standard order in the worksheet. You can designate the column to store it in and name the column.
RORDER C
Stores the run order in the worksheet. You can designate the column to store it in and name the column.
XMATRIX C C (C)
Stores the part and operator names in the worksheet. Optionally, stores standard values for each sample in an
Attribute Agreement Analysis worksheet. You can designate and name the storage columns.
Results
RTABLE
Displays a summary table in the output.
668
Minitab Statistical Software Quality and Process Improvement
RNGAGE: Session command for creating gage run chart
RNGAGE
Plots the response values by operator and part number.
You can use this chart to quickly assess the differences in measurements between different operators and parts.
A stable process would give you a random horizontal scattering of points. With an operator or part effect, you
would see some kind of pattern or patterns in the plot.
A horizontal reference line is drawn at the mean of all observations. Use the MU subcommand to enter your own
value for the reference line.
Type the command as shown with example data in C1–C3.
RNGAGE;
PARTS C1;
OPERS C2;
RESPONSE C3.
Measurement data
PARTS C (required)
Specifies the part names or numbers. Part numbers can be text or numeric.
OPERS C
Specifies the operator names or numbers. Operators can be text or numeric.
TRIALS C
Specifies trial numbers.
A gage R&R study usually consists of several operators taking a series of measurements on each of several parts
with a common gage. It is often recommended that the order of runs in the gage R&R experiment be randomized
to reduce the effects of systematic errors. If TRIAL is not used, the first value encountered in each part by operator
combination is taken to be the first trial, the second part encountered with the same part and operator is taken
to be the second trial, and so on. If the actual order of the trials is different, you should use TRIAL to designate
the order. When designating the order, specify the order within the particular set of part and operator values, not
the order within the whole experiment.
RESPONSE C (required)
Specifies the observed measurements.
MU K
Specifies a value for the horizontal reference line on the Gage Run Chart. By default, the reference line is the mean
of all observations.
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
669
Minitab Statistical Software Quality and Process Improvement
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
GTOL "text"
Specifies the gage tolerance in the label on the output. If you do not use this subcommand, the label will contain
a blank line.
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
Options
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
MGAGE: Session command for performing an expanded gage
R&R study
MGAGE C = Terms
Use an expanded gage R&R study when you want to assess the variation due to Part, Operator (optional), and a
maximum of eight additional factors (optional). All factors can be fixed or random, crossed or nested, and text or
numeric. The design can be balanced or unbalanced.
This method breaks down the gage variation into reproducibility and repeatability. You may also add other main
and interaction effects to Reproducibility in addition to, or instead of, Operator and Operator by Part. Optionally,
you can specify terms in addition to Part to calculate part-to-part variation.
The main command to perform a gage R&R study for multiple factors is MGAGE C = Terms, where C is the numeric
measurement column (response). Both the response and term columns must have the same length. For more
information, go to How to specify the model in MGAGE on page 1170.
Measurement data
PARTS C (required)
Specifies the part names or numbers. Part numbers can be text or numeric. The column must be specified by
MGAGE.
OPERATORS C (optional)
Specifies the operator names or numbers. Operators can be text or numeric. If used, the column must be specified
by MGAGE.
670
Minitab Statistical Software Quality and Process Improvement
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
Options
FIXED C...C (optional)
Specifies which factors are fixed. By default, all factors are random. If used, the column or columns must be
specified by MGAGE. Do not include interaction terms or nested factors.
VARPART terms (optional)
Specifies the terms to define Part-to-Part variation. Without this subcommand, the Part-to-Part variation is defined
by Part term alone. Operator term is not allowed. If used, the column or columns must be specified by MGAGE.
STUDYVAR K
Specifies the multiple used in the Study Var (K * SD) column of the output. The default multiple is 6, which is the
number of standard deviations needed to capture 99% of your process measurements.
SIGMA K
Specifies a historical standard deviation (σ).
VHIST
Estimate the total process variation with the historical standard deviation. When you specify a historical
standard deviation, Minitab uses this option by default.
VSTUDY
Calculate the total process variation with the parts in the study. The output table that displays the percentage
contributions will include a %Process column when you use this subcommand. This column displays the
percentage of the process (σ) that is taken up by each variance component.
TOLER K
Specifies a tolerance range. The output table that displays the percentage contributions will include a %Tolerance
column when you use this subcommand. This column displays the percentage of tolerance taken up by each
variance component.
LSL K
Specifies the lower specification limit when no upper specification limit exists. The output table that displays the
percentage contributions will include a %Tolerance column when you use this subcommand. This column displays
the percentage of tolerance taken up by each variance component.
671
Minitab Statistical Software Quality and Process Improvement
USL K
Specifies the upper specification limit when no lower specification limit exists. The output table that displays the
percentage contributions will include a %Tolerance column when you use this subcommand. This column displays
the percentage of tolerance taken up by each variance component.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
PVALUE K
Specifies the alpha level to determine which interaction terms are insignificant. K is typically any number between
0 and 1. However, if K > 0.999999, alpha = K /100. The default is 0.25.
NOPCONTRIBUTION
Suppresses the %Contribution output and the corresponding bars in the Variance Components graph.
NOPSTUDYVAR
Suppresses the %Study Var output and the corresponding bars in the Variance Components graph.
Results
TFACTINFO
Displays the factor information table.
TANOVA
Displays ANOVA tables.
TVARCOMP
Displays the variance component table.
TSTUDYVAR
Displays the study variance and tolerance table.
TDCATEGORY
Displays the number of distinct categories.
TRISK
Displays the conditional and joint probability of misclassification tables.
Graphs
GVARCOMP
Displays a graphical representation of the Gage R&R.
GXBARR C [C]
Displays Xbar and R Charts. One or two Cs are required. These columns cannot include Part and all columns must
be specified by MGAGE.
GFMAIN C...C
Displays the measurements by single factor plots. At least one C is required and all columns must be specified
by MGAGE.
672
Minitab Statistical Software Quality and Process Improvement
GFINT C...C
Displays two-way interaction plots. Minitab draws a single interaction plot if you enter two factors, or multiple
interaction plots if you enter more than two factors. At least two Cs are required and no nested factors are allowed
as arguments. All columns must be specified by MGAGE.
SEPARATE
Displays all graphs, except Xbar and R chart, separately. By default, MGAGE produces layouts of 6 graphs in one
frame.
Storage
SVARCOMP C C
Stores the variance component and percent contribution for each source listed in an ANOVA table in C and C,
respectively.
SSTDDEV C
Stores the standard deviation for each source listed in an ANOVA table in C.
SSTUDYVAR C C
Stores the study variation and the percent study variation for each source listed in an ANOVA table in C and C,
respectively.
SPROCESS C
Stores the %Process values in C. This subcommand is ignored if SIGMA is not issued.
STOLERANCE C
Stores the %Tolerance values in C. This subcommand is ignored if TOLER, LSL, or USL is not issued.
LNGAGE: Session command for performing a gage linearity and
bias study
LNGAGE
Performs a gage linearity and bias study.
A gage linearity and bias study tells you how accurate your measurements are through the expected range of the
measurements. It answers the question, "Does my gage have the same accuracy for all sizes of objects being
measured?" A gage accuracy study examines the difference between the observed average measurement and a
reference value. A gage accuracy study answers the question, "How accurate is my gage when compared to a
master value?"
Both studies are done by selecting parts whose measurements cover the normal range of values for a particular
process, measuring the parts with a master system, then having an operator make several measurements on each
part using a common gage. Minitab subtracts each measurement taken by the operator from the reference
measurement, then calculates, for each part, an average deviation from the master measurement.
To calculate the linearity of the gage, Minitab finds the best-fit line relating the average deviations to the reference
measurements. Then,
Linearity = | slope | * process standard deviation
Generally, the closer the slope is to zero, the better the gage linearity. Linearity can also be expressed as a
percentage of the process variation by multiplying the slope of the line by 100.
673
Minitab Statistical Software Quality and Process Improvement
To calculate the accuracy of the gage, Minitab combines the deviations from the reference measurement for all
parts. The mean of this combined sample is the gage accuracy. Accuracy can also be expressed as a percentage
of the overall process variation by dividing the mean deviation by the process standard deviation, and multiplying
by 100.
Type the command as shown with example data in C1-C3.
LNGAGE;
PARTS C1;
REFERENCE C2;
RESPONSE C3
SIGMA 14.1941.
Linearity data
PARTS C (required)
Specifies the part names or numbers. Part numbers can be text or numeric.
REFERENCE C (required)
Specifies the reference values.
RESPONSE C (required)
Specifies the observed measurements.
SIGMA K
Specifies a historical standard deviation (σ). The table in the output that displays the percentage contributions
will include a %Process column when you use this subcommand. This column displays the percentage of the
process (σ) taken up by each variance component.
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
GTOL "text"
Specifies the gage tolerance in the label on the output. If you do not use this subcommand, the label will contain
a blank line.
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
674
Minitab Statistical Software Quality and Process Improvement
Options
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
STDEV
Specifies the sample standard deviation to estimate the repeatability standard deviation. If you do not use STDEV,
Minitab estimates the repeatability standard deviation using the sample range.
GAGERR: Session command for performing a crossed gage R&R
study
GAGERR
Performs a gage R&R analysis using the ANOVA method or the Xbar and R method.
The Xbar and R method breaks down the gage variation into reproducibility and repeatability. The ANOVA method
examines the Operator by Part effect component of Reproducibility.
Measurement data
PARTS C (required)
Specifies the part names or numbers. Part numbers can be text or numeric.
OPERS C
Specifies the operator names or numbers. Operator names can be text or numeric. This subcommand is optional
for GAGERR when the ANOVA method is used, but required for GAGERR when XBAR is used.
RESPONSE C (required)
Specifies the observed measurements.
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
GTOL "text"
Specifies the gage tolerance in the label on the output. If you do not use this subcommand, the label will contain
a blank line.
675
Minitab Statistical Software Quality and Process Improvement
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
Options
XBAR
Specifies the Xbar and R method, which breaks down the overall variation into three categories: part-to-part,
repeatability, and reproducibility. If you do not enter the XBAR subcommand, Minitab uses the ANOVA method.
The ANOVA method goes one step further and breaks down reproducibility into its operator and operator-by-part
components.
STUDYVAR K
Specifies the multiple used in the Study Var (K * SD) column of the output. The default multiple is 6, which is the
number of standard deviations needed to capture 99% of your process measurements.
SIGMA K
Specifies a historical standard deviation (σ).
VHIST
Estimate the total process variation with the historical standard deviation. When you specify a historical
standard deviation, Minitab uses this option by default.
VSTUDY
Calculate the total process variation with the parts in the study. The output table that displays the percentage
contributions will include a %Process column when you use this subcommand. This column displays the
percentage of the process (σ) that is taken up by each variance component.
SPROCESS C
Stores the process variation for each source in an ANOVA table in C.
TOLER C
Specifies a tolerance range. The output table that displays the percentage contributions will include a %Tolerance
column when you use this subcommand. This column displays the percentage of tolerance taken up by each
variance component.
STOLERANCE C
Stores the process tolerance for each source in an ANOVA table in C.
LSL K
Specifies the lower specification limit of the process. The output table that displays the percentage contributions
will include a %Tolerance column when you use this subcommand. This colualphamn displays the percentage of
tolerance taken up by each variance component.
USL K
Specifies the upper specification limit of the process. The output table that displays the percentage contributions
will include a %Tolerance column when you use this subcommand. This column displays the percentage of tolerance
taken up by each variance component.
PVALUE K
Specifies the p-value used to eliminate the interaction term from a two-way ANOVA model when the ANOVA
method is used to calculate Gage variance components. The default p-value is 0.25.
676
Minitab Statistical Software Quality and Process Improvement
RISK
Calculates the joint and conditional probabilities of misclassification when an upper specification, lower specification,
or both are specified.
SEPARATE
Displays each graph separately. By default, GAGERR produces layouts of 6 graphs in one frame.
TITLE "text"
Specifies a title for the graph. When you omit this subcommand, Minitab displays a default title.
NOPCONTRIBUTION
Suppresses the %Contribution output and the corresponding bars in the Variance Components graph.
NOPSTUDYVAR
Suppresses the %Study Var output and the corresponding bars in the Variance Components graph.
Storage
SVARCOMP C C
Stores the variance component and percent contribution for each source listed in an ANOVA table in C and C.
SSTDEV C
Stores the standard deviation for each source listed in an ANOVA table in C.
SSTUDYVAR C C
Stores the study variation and the percent study variation for each source listed in an ANOVA table in C and C.
SDISTINCT C
Stores the number of distinct categories that the process is able to distinguish in C.
Confidence intervals
CONFIDENCE K
Specifies a confidence level in K. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95. CONFIDENCE is ignored if XBAR is issued.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
SIVARCOMP C [C]
Stores the confidence limits for the variance components for each source listed in an ANOVA table in C and C.
Use two arguments for a two-sided confidence interval and one for a one-sided interval.
677
Minitab Statistical Software Quality and Process Improvement
SIPVARCOMP C [C]
Stores the confidence limits for the %contribution of the variance components for each source listed in an ANOVA
table in C and C. Use two arguments for a two-sided confidence interval and one for a one-sided interval.
SISTDDEV C [C]
Stores the confidence limits for the standard deviations for each source listed in an ANOVA table in C and C. Use
two arguments for a two-sided confidence interval and one for a one-sided interval.
SISV C [C]
Stores the confidence limits for the study variation for each source listed in an ANOVA table in C and C. Use two
arguments for a two-sided confidence interval and one for a one-sided interval.
SIPSV C [C]
Stores the confidence limits for the %study variation for each source listed in an ANOVA table in C and C. Use
two arguments for a two-sided confidence interval and one for a one-sided interval.
SITOLERANCE C [C]
Stores the confidence limits for the %tolerance for each source listed in an ANOVA table in C and C. Use two
arguments for a two-sided confidence interval and one for a one-sided interval.
SIPROCESS C [C]
Stores the confidence limits for the %process values for each source listed in an ANOVA table in C and C. Use
two arguments for a two-sided confidence interval and one for a one-sided interval.
SIDSTINCT C [C]
Stores the confidence limits for the number of distinct categories in C and C. Use two arguments for a two-sided
confidence interval and one for a one-sided interval.
WHEELER: Session command for performing a crossed Evaluate
Measurement Process (EMP) study
WHEELER
Performs an Evaluate Measurement Process (EMP) study using the ANOVA method or the Xbar and R method.
The Xbar and R method breaks down the gage variation into reproducibility and repeatability. The ANOVA method
also examines the Operator by Part component of Reproducibility.
Measurement data
PARTS C
Specifies the part names or numbers. Part numbers can be text or numeric.
OPERATORS C
Specifies the operator names or numbers. Operator names can be text or numeric. This subcommand is optional
when the ANOVA method is used, but required when XBAR is used.
RESPONSE C
Specifies the observed measurements.
678
Minitab Statistical Software Quality and Process Improvement
Options
ANOVA
Specifies the ANOVA method, which breaks down the overall variation into four categories: part-to-part,
repeatability, reproducibility, and the repeatability by reproducibility. If you do not enter the XBAR subcommand
or the ANOVA subcommand, then Minitab uses the ANOVA method.
XBAR
Specifies the Xbar and R method, which breaks down the overall variation into three categories: part-to-part,
repeatability, and reproducibility. If you do not enter the XBAR subcommand or the ANOVA subcommand, then
Minitab uses the ANOVA method. The ANOVA method goes one step further and breaks down reproducibility
into its operator and operator-by-part components.
LSL K
Specifies the lower specification limit of the process. When you specify at least 1 specification limit and use the
ANOVA method, then the TRISK subcommand adds a table that shows the probabilities of misclassification.
USL K
Specifies the upper specification limit of the process. When you specify at least 1 specification limit and use the
ANOVA method, then the TRISK subcommand adds a table that shows the probabilities of misclassification.
SIGMA K
Specifies a historical standard deviation (σ). The analysis uses the historical standard deviation to calculate
probabilities of misclassification. Probabilities of misclassification require at least 1 specification limit and the use
of the ANOVA method.
ALPHA K
Specifies the significance level for the decision limits on the ANOME and ANOMR charts. The default value is 0.05.
Specify a value between 0 and 0.5.
INCREMENT K
By default, the analysis calculates the measurement increment from the data. Use this subcommand to specify a
measurement increment. For example, the gage that you use reports results in the tenths place, but records
measurements only to the nearest half, such as 1.0 and 1.5. Then, specify that the increment is 0.5. Specify a
positive value.
Graphs
GREPEAT
Displays the repeatability plot of the part measurements. The measurements are by operator if the analysis specifies
the operators. When the number of measurements on a single part is 8 or less, the chart displays the ranges of
the measurements. For larger sample sizes, the chart displays the standard deviations.
GSIGNAL
Displays the signal-to-noise plot of the mean part measurements. The measurements are by operator if the analysis
specifies the operators.
GPARALLELISM
Displays the parallelism plot of the part measurements. The measurements are by operator. The analysis ignores
this subcommand if the analysis does not specify the operators.
GVARIANCE
Displays the plot of the contributions of the variance components.
679
Minitab Statistical Software Quality and Process Improvement
GMAIN
Displays the plot of the main effect of different operators. The analysis ignores this subcommand if the analysis
does not specify the operators.
GMRANGE
Displays the plot of the average ranges of different operators. The analysis ignores this subcommand if the analysis
does not specify the operators.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TVARCOMP
Displays the variance components table.
TESTAT
Displays the EMP statistics table and the gage classification table.
TRISK
Displays tables that show the conditional and joint probability of misclassification tables. The analysis calculates
the probabilities of misclassification when the analysis uses the ANOVA method and the analysis includes at least
1 specification limit.
TRESO
Displays the effective resolution table.
STORAGE
SVARCOMP C
Stores the variance components in C. This statistic is the Variance column from the Variance Components table.
SPCONTRIBUTION C
Stores the percent of the total variation for the variance components in C. This statistic is the %Total column from
the Variance Components table.
SSTDDEV C
Stores the standard deviations for the variance components in C. This statistic is the StdDev column from the
Variance Components table.
NTGAGE: Session command for performing a nested gage R&R
study
NTGAGE
Use a nested gage R&R study to assess the variation in your measurement system when every operator cannot
measure all parts.
If you need to use destructive testing, then you must be able to assume that all parts within a single batch are
identical enough to claim that they are the same part. If you are unable to make that assumption, then part-to-part
variation within a batch will mask the measurement system variation. If you can make that assumption, then your
680
Minitab Statistical Software Quality and Process Improvement
choice of using a crossed gage R&R study or a nested gage R&R study depends on how your measurement
process is set up. If all operators measure parts from each batch, then use a crossed or expanded study. If each
batch is measured by only a single operator, then use a nested or expanded study. In fact, whenever operators
measure unique parts, the design is nested.
Measurement data
PARTS C (required)
Specifies the part names or numbers. Part numbers can be text or numeric.
OPERS C (required)
Specifies the operator names or numbers. Operator names can be text or numeric.
RESPONSE C (required)
Specifies the observed measurements.
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
GTOL "text"
Specifies the gage tolerance in the label on the output. If you do not use this subcommand, the label will contain
a blank line.
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
Options
STUDYVAR K
Specifies the multiple used in the Study Var (K * SD) column of the output. The default multiple is 6, which is the
number of standard deviations needed to capture 99% of your process measurements.
SIGMA K
Specifies a historical standard deviation (σ).
681
Minitab Statistical Software Quality and Process Improvement
VHIST
Estimate the total process variation with the historical standard deviation. When you specify a historical
standard deviation, Minitab uses this option by default.
VSTUDY
Calculate the total process variation with the parts in the study. The output table that displays the percentage
contributions will include a %Process column when you use this subcommand. This column displays the
percentage of the process (σ) that is taken up by each variance component.
SPROCESS C
Stores the process variation for each source in an ANOVA table in C.
TOLER C
Specifies a tolerance range. The output table that displays the percentage contributions will include a %Tolerance
column when you use this subcommand. This column displays the percentage of tolerance taken up by each
variance component.
STOLERANCE C
Stores the process tolerance for each source in an ANOVA table in C.
LSL K
Specifies the lower specification limit when no upper specification limit exists. The output table that displays the
percentage contributions will include a %Tolerance column when you use this subcommand. This column displays
the percentage of tolerance taken up by each variance component.
USL K
Specifies the upper specification limit when no lower specification limit exists. The output table that displays the
percentage contributions will include a %Tolerance column when you use this subcommand. This column displays
the percentage of tolerance taken up by each variance component.
RISK
Calculates the joint and conditional probabilities of misclassification when an upper specification, lower specification,
or both are specified.
SEPARATE
Displays each graph separately. By default, NTGAGE produces layouts of 6 graphs in one frame.
TITLE "text"
Specifies a title for the graph. When you omit this subcommand, Minitab displays a default title.
NOPCONTRIBUTION
Suppresses the %Contribution output and the corresponding bars in the Variance Components graph.
NOPSTUDYVAR
Suppresses the %Study Var output and the corresponding bars in the Variance Components graph.
Storage
SVARCOMP C C
Stores the variance components and %contribution in C and C.
SSTDEV C
Stores the standard deviations in C.
682
Minitab Statistical Software Quality and Process Improvement
SSTUDYVAR C C
Stores the study variation and percent %study variation in C and C.
SDISTINCT C
Stores the number of distinct categories in C.
Confidence intervals
CONFIDENCE K
Specifies a confidence level in K. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95. Displays confidence intervals for the variability measures with a confidence level of K. CONFIDENCE
is ignored if XBAR is issued.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
SIVARCOMP C [C]
Stores the confidence limits for the variance components for each source listed in an ANOVA table in C and C.
Use two arguments for a two-sided confidence interval and one for a one-sided interval.
SIPVARCOMP C [C]
Stores the confidence limits for the %contribution of the variance components for each source listed in an ANOVA
table in C and C. Use two arguments for a two-sided confidence interval and one for a one-sided interval.
SISTDDEV C [C]
Stores the confidence limits for the standard deviations for each source listed in an ANOVA table in C and C. Use
two arguments for a two-sided confidence interval and one for a one-sided interval.
SISV C [C]
Stores the confidence limits for the study variation for each source listed in an ANOVA table in C and C. Use two
arguments for a two-sided confidence interval and one for a one-sided interval.
SIPSV C [C]
Stores the confidence limits for the %study variation for each source listed in an ANOVA table in C and C. Use
two arguments for a two-sided confidence interval and one for a one-sided interval.
SITOLERANCE C [C]
Stores the confidence limits for the %tolerance for each source listed in an ANOVA table in C and C. Use two
arguments for a two-sided confidence interval and one for a one-sided interval.
SIPROCESS C [C]
Stores the confidence limits for the %process values for each source listed in an ANOVA table in C and C. Use
two arguments for a two-sided confidence interval and one for a one-sided interval.
SIDSTINCT C [C]
Stores the confidence limits for the number of distinct categories in C and C. Use two arguments for a two-sided
confidence interval and one for a one-sided interval.
683
Minitab Statistical Software Quality and Process Improvement
LONGMETHOD: Session command for performing an attribute
gage study (analytic method)
LONGMETHOD
Performs an attribute gage study (analytic method).
Attribute gage study data
PARTS C (required)
Specifies the part names or numbers. Part numbers can be text or numeric.
REFERENCE C
Specifies the reference value column for each part. Reference values must be numeric. Structure raw data so that
each row contains the part name or number, reference value, and binary response. Structure summarized data
so that each row contains the part name or number, reference value, and summarized count.
RESPONSE C (K)
RESPONSE (C)
RESPONSE C specifies the binary column of raw data. The values in this column can be numeric or text.
RESPONSE C (K) or RESPONSE C (C) specifies the summarized count column and the number of times each part
is examined (a constant or column). If all parts are examined the same number of times, K represents the number
of trials. If the parts are examined a different number of times, you must create a column that contains the number
of trials.
ATTRIBUTE K
Specifies the attribute (or standard). This value must be the same data type as the response and must match one
of the two distinct response values.
For summarized data, ATTRIBUTE K is optional. If ATTRIBUTE is not specified, the default is "Acceptance".
Tolerance limits
USELOW
Specifies the use of the lower limit to calculate bias and repeatability. You must use either USELOW or USEHIGH.
USEHIGH
Specifies the use of the upper limit to calculate bias and repeatability. You must use either USELOW or USEHIGH.
TOLERANCE K (K)
Specifies the tolerance limit or limits for accepting or rejecting the product.
If one argument is given, K is the tolerance limit corresponding to the USELOW or USEHIGH subcommand. If two
arguments are given, the first K is the lower limit and second K is the upper limit. The first K must be less than the
second K.
684
Minitab Statistical Software Quality and Process Improvement
Gage information
GAGE "text"
Specifies the name of your gage in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
DATE K
Specifies the date that the analysis is performed in the label on the output. K is a constant and a text value. If you
do not use this subcommand, the label will contain a blank line.
USER "text"
Specifies the user name in the label on the output. If you do not use this subcommand, the label will contain a
blank line.
GTOL "text"
Specifies the gage tolerance in the label on the output. If you do not use this subcommand, the label will contain
a blank line.
MISC "text"
Specifies any miscellaneous notes in the label on the output. If you do not use this subcommand, the label will
contain a blank line.
Options
REGTEST
Specifies the regression method to test for bias in the attribute gage system. If you do not include this subcommand,
the AIAG method is used to test bias. You must have at least 20 trials per part to perform the AIAG method.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
ATGAGE: Session command for performing an attribute agreement
analysis
ATGAGE
Use attribute agreement analysis to assess the agreement of nominal or ordinal ratings given by multiple appraisers
for both nominal and ordinal data. The measurements are subjective ratings by people rather than direct physical
measurements. Examples include:
Automobile performance ratings
Classification of fabric quality as good or bad
Ratings of coffee color, aroma, and taste on a 1–10 scale
In these situations, quality characteristics are difficult to define and assess. To obtain meaningful classifications,
more than one appraiser should classify the response measure. If the appraisers agree, the possibility exists that
the ratings are accurate. If the appraisers disagree, rating usefulness is limited.
685
Minitab Statistical Software Quality and Process Improvement
Agreement data
SAMPLES C
Specifies the sample column. Values can be numeric or text. Must be used in conjunction with APPRAISERS
subcommand, and data must be stacked.
APPRAISERS C
Specifies the appraiser column. Values can be numeric or text. Must be used in conjunction with SAMPLES
subcommand, and data must be stacked.
UNSTACK K K
Specifies that the data are in unstacked format. The first K is the number of appraisers, the second K is the number
of trials for each appraiser. Each K must be a positive integer. Cannot be used in conjunction with SAMPLES or
APPRAISERS subcommands.
NAMES C
NAMES K K
Specifies the names of the appraisers for unstacked data (the default is Appraiser 1, ..., Appraiser k). The number
of rows in the column (or the number of constants) must equal the number of appraisers. The argument can be
text or numeric. If no names are specified and there is only one trial per appraiser, the column names are used
as the appraiser's names.
This subcommand is ignored if the data are stacked.
RESPONSE C
RESPONSE C...C
Specifies the response column. When used in conjunction with SAMPLES and APPRAISERS (stacked data) a single
column must be specified. When used in conjunction with UNSTACK (unstacked), the number of arguments must
equal the number of appraisers times the number of trials.
The response column or columns can either be numeric or text.
The design must be balanced. (There must be the same number of trials because each appraiser must evaluate
each sample the same number of times.)
For more information, go to Data requirements and formats for attribute agreement analysis on page 1138.
ATTRIBUTE C
Specifies the attribute (or standard) for each sample if known.
Must be the same data type as the response. Missing attributes are not allowed.
ORDINAL
Specifies that the data are ordinal with more than two levels.
To specify the value order for a text response column, right-click the column, then choose Column Properties >
Value Order. Value ordering for all text response columns must be the same.
The value ordering for the attribute (standard) column must be the same as for the response column or columns.
686
Minitab Statistical Software Quality and Process Improvement
Information about the attribute agreement analysis
DATE "text"
Specifies the date that the attribute gage analysis is performed. K is a constant and text value.
USER "text"
Specifies the name of the user who does the analysis. K is a constant and text value.
PRODUCT "text"
Specifies the product name.
MISC "text"
Specifies information that is not included by DATE, USER, and PRODUCT. K is a constant and text value.
Options
COHEN
Calculates Cohen's alpha when appropriate. Minitab will calculate Cohen's kappa when two appraisers rate a
single trial or when each appraiser rates two trials.
DISAGREEMENT
Displays the disagreement table. Minitab displays how often each appraiser's assessments differ from each known
standard or attribute value. Must be used in conjunction with ATTRIBUTE subcommand.
CONFIDENCE K
Specifies a confidence level in K for the interval estimation of the percentage agreement within appraisers, and
between each appraiser and the known standard. For example, for a 90% confidence level, enter CONFIDENCE
90. The default value of K is 95.
Graphs
GAPPRAISER
Specifies the graph of the matched proportions for each appraiser when the number of replicates for each appraiser
is more than one. If there is no replicate, and GAPPRAISER is entered, no graph is created, and a message of "No
graph is made when no repeated ratings are given by each appraiser" will appear in the output.
GATTRIBUTE
Specifies the graph of the matched proportions between the ratings of each appraiser and the attribute when
attribute is known. If the attribute is unknown, and GATTRIBUTE is entered, then no graph is created, and a message
of "No graph of the matched proportions between the ratings for each appraiser and the attribute is made when
the attribute for each sample is unknown." will appear in the output.
ONEDOC
Displays both plots together.
Results
BRIEF K
Controls the amount of output with a value in K.
687
Minitab Statistical Software Quality and Process Improvement
Output that is displayedValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays percentages.1
Minitab displays percentages, and kappa and Kendall's (ordinal data) coefficient tables.2
Acceptance Sampling
AASA: Session command for acceptance sampling by attributes
AASA K
Creates or compares attributes acceptance sampling plans using fraction defective or defects per unit to represent
lot/process quality.
Representation of lot/process qualityValue of K
Fraction defective1
Defects per unit2
Create plans
Creates a sampling plan based on the criteria you enter.
CREATE
Creates a sampling plan based on plan criteria.
ALPHA K
Specifies the probability that a lot will meet the AQL and will not be accepted, also known as the producer's
risk. You can specify K as 0<K<1. The default value of K is 0.05.
UBALPHA K
Specifies the maximum alpha allowed.
BETA K
Specifies the probability that a lot will exceed the RQL and will still be accepted, also known as the consumer's
risk. You may specify K as 0<K<1. The default value of K is 0.10.
UBBETA K
Specifies the maximum beta allowed.
Compare plans
Compares several user defined sampling plans.
You can vary sample sizes (SIZE) and/or acceptance numbers (ANUMBER):
Specify one sample size and several acceptance numbers to examine the effect of varying only the acceptance
number.
688
Minitab Statistical Software Quality and Process Improvement
Specify multiple sample sizes with only one acceptance number to examine the effect of varying only sample size.
Specify combinations of sample size and acceptance number to examine specific paired combinations. Use the
same number of sample sizes and acceptance numbers.
COMPARE
Compares several user defined sampling plans.
SIZE K...K
Specifies the sample sizes of the plans you wish to compare.
ANUMBER K...K
Specifies the accept number (number of defective units or total defects allowed) of the plans you wish to
compare.
Plan criteria
AQL K
Specifies the acceptable quality level. AQL is required when you create plans, but optional when you compare
plans.
RQL K
Specifies the rejectable quality level. RQL is required when you create plans, but optional when you compare
plans.
LOTSIZE K (optional)
Specifies the lot size. The lot size is required for the ATI and AOQ curves.
HYPERGEOMETRIC
Specifies to use the hypergeometric distribution when creating/comparing sampling plans of isolated lots when
you have go / no go defectives data. You must also specify the lot size in this case.
By default, Minitab uses the binomial distribution to create sampling plans and compare sampling plans for go/no
go data.
To correctly use the binomial distribution, Minitab assumes that the sample comes from a large lot or from a
stream of lots randomly that are selected from an ongoing process. However, if the lot of products that you are
sampling from is an isolated lot of finite size—for example, you receive one special order shipment of 500
labels—then the exact distribution for calculating the probability of acceptance is the hypergeometric distribution.
Measurement type
PROPORTION
Choose to use proportion defective or defects per unit to represent the quality of a lot. If you choose proportion,
enter the plan AQL and RQL in proportions. For example, AQL = 0.02 and RQL = 0.08.
PERCENT
Choose to use percent defectives or defects per hundred units to represent the quality of a lot. If you choose
percent, enter the plan AQL and RQL in percents. For example, AQL = 2.0 and RQL = 8.0.
PPM
Choose to use proportion defectives per million or defects per million units to represent the quality of a lot. If
you choose ppm, enter the plan AQL and RQL in ppm. For example, AQL = 200 and RQL = 800.
689
Minitab Statistical Software Quality and Process Improvement
Graphs
GOC
Creates an operating characteristic (OC) curve, which describes the discriminatory power of an acceptance sampling
plan. The OC curve plots the probabilities of accepting a lot versus the fraction defective.
GAOQ
Creates an average outgoing quality (AOQ) curve, which approximates the relationship between the quality of
the incoming material and the quality of the outgoing material, assuming that rejected lots will be 100% inspected
and defective items will be reworked and inspected again (rectifying inspection).
The average outgoing quality depends on the incoming quality, the probability that the lot will be accepted, and
the sample size and the lot size.
GATI
Creates an average total inspection (ATI) curve, which approximates the relationship between the quality of the
incoming material and the number of items that need to be inspected, assuming that rejected lots will be 100%
inspected and defective items will be reworked and inspected again (rectifying inspection).
The average total inspection per lot depends on the incoming quality, the probability that the lot will be accepted,
and the sample size and the lot size.
ONEGRAPH
Displays all graphs on one graph.
Options
DEFECTIVES K...K
Calculates the probability of acceptance for additional defective levels, specified by K...K.
Storage
SSIZE C
Stores the sample size.
SANUMBER C
Stores the accept number.
SDEFECTIVES C
Stores the defectives/defect levels. When you use this command, Minitab stores the AQL, RQL, and any additional
defective levels specified with DEFECTIVES.
SPACCEPT C
Stores the probability of accepting values. When you use this command, Minitab stores the acceptance values
associated with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
SPREJECT C
Stores the probability of rejecting values. When you use this command, Minitab stores the acceptance values
associated with the AQL, RQL, and any additional defective levels specified with DEFECTIVES. The probability of
rejecting is 1 the probability of accepting.
690
Minitab Statistical Software Quality and Process Improvement
SAOQ C
Stores the average outgoing quality values. When you use this command, Minitab stores the AOQ values associated
with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
SATI C
Stores the average total inspection values. When you use this command, Minitab stores the ATI values associated
with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
VASAMPLING: Session command for creating or comparing
variables acceptance plans
VASAMPLING
Creates a variables acceptance sampling plan based on the criteria of AQL, RQL, and lot size. This sampling plan
tells you how many units to sample and what the accept/reject criteria is in terms of critical distances.
Create plans
Creates a sampling plan based on the criteria you enter.
CREATE
Creates a sampling plan based on plan criteria.
ALPHA K
Specifies the probability that a lot will meet the AQL and will not be accepted. You can specify K as 0<K<1.
If you do not specify K, the default is K=0.05.
BETA K
Specifies the probability that a lot will exceed the RQL and still be accepted. You can specify K as 0<K<1. If
you do not specify K, the default is K=0.10.
Compare plans
Compares several user defined sampling plans.
You can vary sample sizes (SIZE) and/or critical distances (CDISTANCE):
Specify one sample size and several critical distances to consider the effect of varying only critical distance.
Specify multiple sample sizes with only one acceptance number to consider the effect of varying only sample size.
Specify combinations of sample size and critical distance to consider specific paired combinations. Use the same
number of sample sizes and critical distances.
COMPARE
Compares several user defined sampling plans.
SIZE K...K
Specifies the sample sizes of the plans you wish to compare.
CDISTANCE K...K
Specifies the critical distances (criteria to accept or reject a lot) of the plans you wish to compare.
691
Minitab Statistical Software Quality and Process Improvement
Plan criteria
LSPEC K
Specifies the lower specification limit for the measurements. You must enter at least one specification limit.
USPEC K
Specifies the upper specification limit for the measurements. You must enter at least one specification limit.
SIGMA K
Optionally, specifies the standard deviation.
AQL K
Specifies the acceptable quality level. Is required when creating plans, but optional when comparing plans.
RQL K
Specifies the rejectable quality level. Is required when creating plans, but optional when comparing plans.
LOTSIZE K
Optionally, specifies the lot size. The lot size is required for the ATI and AOQ curves.
Measurement type
PROPORTION
Choose to use proportion defective or defects per unit to represent the quality of a lot. If you choose proportion,
enter the plan AQL and RQL in proportions. For example, AQL = 0.02 and RQL = 0.08.
PERCENT
Choose to use percent defectives or defects per hundred units to represent the quality of a lot. If you choose
percent, enter the plan AQL and RQL in percents. For example, AQL = 2.0 and RQL = 8.0.
PPM
Choose to use proportion defectives per million or defects per million units to represent the quality of a lot. If
you choose ppm, enter the plan AQL and RQL in ppm. For example, AQL = 200 and RQL = 800.
Graphs
GOC
Creates an operating characteristic (OC) curve, which describes the discriminatory power of an acceptance sampling
plan. The OC curve plots the probabilities of accepting a lot versus the fraction defective.
GAOQ
Creates an average outgoing quality (AOQ) curve, which approximates the relationship between the quality of
the incoming material and the quality of the outgoing material, assuming that rejected lots will be 100% inspected
and defective items will be reworked and inspected again (rectifying inspection).
The average outgoing quality depends on the incoming quality, the probability that the lot will be accepted, and
the sample and lot sizes.
GATI
Creates an average total inspection (ATI) curve, which approximates the relationship between the quality of the
incoming material and the number of items that need to be inspected, assuming that rejected lots will be 100%
inspected and defective items will be reworked and inspected again (rectifying inspection).
692
Minitab Statistical Software Quality and Process Improvement
The average total inspection per lot depends on the incoming quality, the probability that the lot will be accepted,
and the sample and lot sizes.
GAREGION
Creates an acceptance region plot, which allows you to see the region of sample means and sample standard
deviations for which you will accept a lot, when both specifications are given and the standard deviation is unknown.
ONEGRAPH
Displays all graphs on one graph.
Options
DEFECTIVES K...K
Calculates probability of acceptance for additional defective levels, specified by K...K.
WALLIS
Specify to use the approximation procedure proposed by Wallis to calculate the maximum standard deviation.
This option is only available when you specify a value for both LSPEC and USPEC, but do not specify a value with
SIGMA. If you issue WALLIS and the previous conditions are not met, Minitab ignores the subcommand.
Storage
SSIZE C
Stores sample size in worksheet, in column C.
SANUMBER C
Stores accept number in worksheet, in column C.
SDEFECTIVES C
Stores the defectives/defect levels in worksheet, in column C. When this command is issued, Minitab stores the
AQL, RQL, and any additional defective levels specified with DEFECTIVES.
SPACCEPT C
Stores the probability of accepting values in worksheet, in column C. When this command is issued, Minitab stores
the acceptance values associated with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
SPREJECT C
Stores the probability of rejecting values in worksheet, in column C. When this command is issued, Minitab stores
the acceptance values associated with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
The probability of rejecting is 1 the probability of accepting.
SAOQ C
Stores the average outgoing quality values in the worksheet, in column C. When this command is issued, Minitab
stores the AOQ values associated with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
SATI C
Stores the average total inspection values in the worksheet, in column C. When this command is issued, Minitab
stores the ATI values associated with the AQL, RQL, and any additional defective levels specified with DEFECTIVES.
693
Minitab Statistical Software Quality and Process Improvement
ARDECISION: Session command for accepting or rejecting an
entire lot
ARDECISION
Allows you to enter actual measurements from a sample and determine whether you should accept or reject the
entire lot based on sampling plan criteria.
Plan criteria
LSPEC K
Specifies the lower specification limit for the measurements. You must enter at least one specification limit.
USPEC K
Specifies the upper specification limit for the measurements. You must enter at least one specification limit.
SIGMA K
Optionally, specifies the standard deviation.
CDISTANCE K
Specifies the critical distance K, that is calculated from creating the sampling plan, and uses K to accept or reject
a lot. K is a positive number.
WALLIS
Specify to use the approximation procedure proposed by Wallis to calculate the maximum standard deviation.
This option is only available when you specify a value for both LSPEC and USPEC, but do not specify a value with
SIGMA. If you issue WALLIS and the previous conditions are not met, Minitab ignores the subcommand.
694
Minitab Statistical Software Quality and Process Improvement
Reliability/Survival
Test Plans
DTESTPLAN: Session command for creating a demonstration test
plan
DTESTPLAN K...K
Generates a demonstration test plan with a maximum number of K failures allowed.
A demonstration test plan is to show that you have met a reliability specification or that a redesigned system has
suppressed or significantly reduced the occurrence of a known cause of failure. In a demonstration test, you verify
that only a certain number of failures occur in a set amount of test time.
Minimum value to be demonstrated
SCLOCATION K
Specifies the scale parameter for the Weibull or exponential distribution, or the location parameter for the other
distributions.
PTILE K
Specifies the percentile for the given percent. The argument of PTILE is the percent and the argument of TIME is
the percentile.
TIME K
Demonstrates that the specified percentile exceeds K. The argument of time is the percentile.
RELIABILITY K
Specifies the reliability goal as K at time K.
TIME K
Demonstrates that the reliability exceeds the specified value at time K. The argument of time is the percentile.
MTTF K
Specifies the mean time to failure as K.
Sample sizes or testing times
Specifies either sample sizes or testing times.
SAMPLE K...K
Specifies the sample size for each test plan. Minitab calculates the corresponding testing time.
TTIME K...K
Specifies the testing time for each test plan. Minitab calculates the corresponding sample sizes.
695
Minitab Statistical Software Reliability/Survival
Planning distributions
Specifies the assumed distribution of failure data to be collected.
WEIBULL
Weibull distribution.
EXPONENTIAL
Exponential distribution.
SEXTREMEVALUE
Smallest extreme value distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal (base e) distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
SHSCALE K
Specifies the assumed parameter. For the Weibull distribution, K is the shape. For all other distributions, K is the
scale. Do not use the SHSCALE subcommand with the exponential distribution.
Graphs
GPOPGRAPH
Displays the probability of passing a test plan graph.
OVMAXFAILURES
Use if you have requested more than one test plan (maximum number of failures) and you want to overlay
the probability of passing each test plan on the same graph.
XMINIMUM K
Specify the minimum improvement ratio or amount of improvement to be displayed on the x-axis.
The x-axis is in terms of the ratio of improvement for the Weibull, lognormal, exponential, and loglogistic
distributions. It is in terms of the amount of improvement for the normal, logistic, and extreme value
distributions.
XMAXIMUM K
Specify the maximum improvement ratio or amount of improvement to be displayed on the x-axis.
The x-axis is in terms of the ratio of improvement for the Weibull, lognormal, exponential, and loglogistic
distributions. It is in terms of the amount of improvement for the normal, logistic, and extreme value
distributions.
696
Minitab Statistical Software Reliability/Survival
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ETESTPLAN: Session command for creating an estimation test plan
ETESTPLAN
Generates an estimation test plan.
An estimation test plan indicates the number of test units that you need to estimate percentiles or reliabilities
with a specified degree of precision.
Parameter to be estimated
EPTILE K
Estimates a specific percentile at K.
ERELIABILITY K
Estimates a specific reliability. K is the corresponding time.
Precisions
DUPPER is the same as DLOWER only when the CI is symmetric about the MLE. For example, any confidence interval
for the K
th
percentile in a location-scale model is symmetric about the MLE.
DLOWER K...K
The precision given as the distance between the MLE and the lower bound of the confidence interval.
DUPPER K...K
The precision given as the distance between the MLE and the upper bound of the confidence interval
Planning distributions
Specifies the assumed distribution of failure data to be collected.
WEIBULL
Weibull distribution.
EXPONENTIAL
Exponential distribution.
SEXTREMEVALUE
Smallest extreme value distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal (base e) distribution.
697
Minitab Statistical Software Reliability/Survival
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
Planning values
Specify the planning values. You must provide exactly two planning values for all distributions except the exponential.
SHSCALE K
Specifies the planning value for the shape parameter (Weibull distribution) or scale parameter (other distributions).
You cannot use SHSCALE with the exponential distribution.
SETS K
Specifies the true value of the known parameter. You cannot use SHSCALE and SETS simultaneously. You cannot
use SETS with the exponential distribution.
SCLOCATION
Specifies the planning value for the scale parameter (Weibull or exponential distributions) or location parameter
(other distributions).
PTILE K [K]
Specifies the planning values for the percentiles. Specifies the percentile for the given percent. The arguments of
PTILE are the percents and the arguments of TIME are the percentile. You can provide either one or two planning
values for the percentiles. If PTILE has two arguments, then you cannot use SETS or SCLOCATION.
TIME K [K]
Specifies the planning value for the percentile as K.
Right censoring
UPTIME C...C
UPTIME K...K
Use for Type I censoring on the right (Time Censoring). Censored observations are those whose failure times are
greater than or equal to the UPTIME value.
If a column has more than one row, each row value is the censoring time for each group in a multiple censoring
scheme.
If constants are specified, Minitab assumes a singly censoring scheme, where each constant is a replicate.
If none of the censoring commands (UPTIME, UPFAIL, or NINSPECTIONS) are specified, the data to be collected
is assumed to be uncensored.
UPFAIL C...C
UPFAIL K...K
Use for Type II censoring on the right (Failure Censoring). Specify the upper cutoff for the number of failures.
Censored observations are those at the upper cutoff point and all subsequent observations.
If a column has more than one row, each row value is the censoring percent failure for each group in a multiple
censoring scheme.
If constants are specified, Minitab assumes a singly censoring scheme, where each constant is a replicate.
698
Minitab Statistical Software Reliability/Survival
If none of the censoring commands (UPTIME, UPFAIL, or NINSPECTIONS) are specified, the data to be collected
is assumed to be uncensored.
PRPBROUP C...C
Each column contains the expected percent of units run per group. The rows in each column must sum to 100.
The arguments are paired with the column arguments of UPTIME or UPFAIL when your data are multiply censored.
In this case, if PRPGROUP is not specified, Minitab assumes an equal percent of units run in each group.
Interval censoring
NINSPECTIONS K
Specifies the number of inspections for interval-censored data. You must provide exactly one of the following
subcommands. If none of the censoring commands (UPTIME, UPFAIL, or NINSPECTIONS) are specified, the data
to be collected is assumed to be uncensored.
You cannot use this subcommand with UPTIME, UPFAIL, or PRPGROUP.
ESITIMES K
Specifies equally spaced inspection times. K is the last inspection time.
EPITIMES K
Specifies inspection intervals containing an equal percent of units failing. K is the expected percent of failures
in the entire life test.
ESILTIMES K K
Specifies equally spaced inspections in log times. The arguments are the first and last inspection times,
respectively.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
TWOSIDED
Indicates that the precision corresponds to a two-sided confidence interval. By default, Minitab assumes a one-sided
confidence interval.
ALTTESTPLAN: Session command for creating an accelerated life
test plan
ALTTESTPLAN
Generates an accelerated life test plan.
Use an accelerated life test plan to estimate the standard error of percentiles and reliabilities when you know the
number of units that are available to test, or when you want to calculate the number of test units that you need
to estimate percentiles or reliabilities with a specified degree of precision.
699
Minitab Statistical Software Reliability/Survival
Parameter to be estimated
EPTILE K
Specifies that you want to estimate the K
th
percentile.
ERELIABILITY K
Specifies that you want to estimate the reliability at time K.
Sample sizes or precisions
Specifies precisions or sample sizes. You must provide exactly one of the following subcommands.
DUPPER is the same as DLOWER only when the CI is symmetric about the MLE. For example, any confidence interval
for the K
th
percentile in a location-scale model is symmetric about the MLE.
SAMPLE K...K
The available total sample size.
DLOWER K...K
The precision given as the distance between the MLE and the lower bound of the confidence interval.
DUPPER K...K
The precision given as the distance between the MLE and the upper bound of the confidence interval.
Planning distributions
Specifies the assumed distribution of failure data to be collected.
WEIBULL
Weibull distribution.
EXPONENTIAL
Exponential distribution.
SEXTREMEVALUE
Smallest extreme value distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal (base e) distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
Relationships
Specifies the relationship between failure times or log failure times and the accelerating variable.
ARRHENIUS
Arrhenius relationship.
700
Minitab Statistical Software Reliability/Survival
POWER
Power relationship (also called ln relationship).
LINEAR
Linear relationship.
INVTEMP
Inverse temperature relationship.
Planning values
Specify the planning values. You must provide exactly two planning values for all distributions except the exponential.
SHSCALE K
Specifies the planning value for the shape parameter (Weibull distribution) or scale parameter (other distributions).
You cannot use SHSCALE with the exponential distribution.
SETS K
Specifies the true value of the known parameter. You cannot use SHSCALE and SETS simultaneously. You cannot
use SETS with the exponential distribution.
SCLOCATION
Specifies the planning value for the scale parameter (Weibull or exponential distributions) or location parameter
(other distributions).
PTILE K [K]
Specifies the K
th
percentile as the planning value The arguments of PTILE are the percents, and the arguments of
TIME are the percentile. You can provide either one or two planning values for the percentiles. If PTILE has two
arguments, then you cannot use SETS or SCLOCATION.
TIME K [K]
Specifies the planning value for the percentile as K.
STRESS K [K]
Specifies the stress value for the percentile as K.
Stresses
DSTRESS K
Specifies the design stress value as K.
TSTRESSES K...K
TSTRESSES C...C
Specifies the fixed test stresses as follows:
Use constant arguments (K...K) to represent the test stress values in a single test plan.
Use column arguments (C...C) to represent a set of test stress values for a collection of test plans. Columns
must be the same length.
You must also specify either ALLOCATIONS or INCRANGES.
701
Minitab Statistical Software Reliability/Survival
ALLOCATIONS K...K
ALLOCATIONS C...C
Specifies the percent allocations of units to the test stress levels. You must provide the test stresses in order from
the lowest level (not necessarily the lowest value) to the highest level (not necessarily the highest value). As a
result, the stress values—including the design stress value—are either increasing or decreasing.
Use constant arguments (K...K) to represent the percent allocations in a single test plan.
Use column arguments (C...C) to represent the percent allocations for a set of test stress values for a collection
of test plans. Columns of allocations and test stresses must be the same length.
INCRANGES K
Searches for the best allocation of test units to stress levels by including prefixed ranges in the search space. K is
the step length Minitab uses to search through ranges of proportions in order to optimize the proportionate
allocation of units to the test stress levels. Small K values widen the search space and as a result, the optimization
process becomes more computationally intensive. The default value is 0.05.
NBESTPLANS K
Specifies the number of test plans displayed in the output in addition to those specified using the ALLOCATIONS
subcommand. By default, Minitab displays the three best plans.
Right censoring
UPTIME K...K
Use for Type I censoring on the right (Time Censoring). Censored observations are those whose failure times are
greater than or equal to the UPTIME value. Each argument of UPTIME represents the censoring times associated
with a stress level. The first argument corresponds to the censoring time at the lowest test stress level, the second
argument corresponds to the censoring time at the second test stress level, and so on.
If none of the censoring commands (UPTIME, UPFAIL, or NINSPECTIONS) are specified, the data to be collected
is assumed to be uncensored.
UPFAIL K...K
Use for Type II censoring on the right (Failure Censoring). Specify the upper cutoff for the percent failures. Censored
observations are those at the upper cutoff point and all subsequent observations. The arguments of UPFAIL
represent the percent of failures corresponding to each stress level. The first argument corresponds to percent
failures at the lowest test stress level, the second argument corresponds to percent failures at the second test
stress level, and so on.
If none of the censoring commands (UPTIME, UPFAIL, or NINSPECTIONS) are specified, the data to be collected
is assumed to be uncensored.
Interval censoring
NINSPECTIONS K
Specifies the number of inspections for interval-censored data. You must provide exactly one of the following
subcommands. If none of the censoring commands (UPTIME, UPFAIL, or NINSPECTIONS) are specified, the data
to be collected is assumed to be uncensored.
You cannot use this subcommand with UPTIME, UPFAIL, or PRPGROUP.
702
Minitab Statistical Software Reliability/Survival
ESITIMES K
Specifies equally spaced inspection times. K is the last inspection time for each test stress level. The first
argument is the last inspection time at the lowest test stress level, the second argument is the last inspection
at the second test stress level, and so on.
EPITIMES K
Specifies inspection intervals containing an equal percent of units failing. K is the expected percent of failures
for each test stress level. The first argument is the percent failures at the lowest test stress level, the second
argument is the percent failures at the second test stress level, and so on.
ESILTIMES K K
Specifies equally spaced inspections in log times. The two arguments are the first and last inspection times,
respectively for each test stress level. ESILTIMES must have exactly twice as many arguments as there are
test stress levels. The first set of arguments are the first inspection time at the lowest test stress level, the
first inspection time at the second test stress level, and so on. The second set of arguments are the last
inspection time at the lowest test stress level, the last inspection time at the second test stress level, and so
on.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
TWOSIDED
Indicates that the precision corresponds to a two-sided confidence interval. By default, Minitab assumes a one-sided
confidence interval.
Distribution Analysis (Right Censoring)
RDIDENTIFICATION: Session command for creating a distribution
ID plot
RDIDENTIFICATION C...C
Generates probability plots for right-censored/uncensored, failure (or survival) data.
Use RDIDENTIFICATION to plot up to eleven different probability plots (with distributions chosen from smallest
extreme value, Weibull, three-parameter Weibull, exponential, two-parameter exponential, normal, lognormal,
three-parameter lognormal, logistic, loglogistic, and three-parameter loglogistic) to help you determine which
of these distributions best fits your data. Usually this is done by comparing how closely the plot points lie to the
best-fit lines—in particular, points in the tails of the distribution.
The sample data are the individual failure times. For example, you may have collected samples of failure times
under different temperatures, or under varying conditions of any combination of stress variables. The data can
be singly censored on the right, with censoring of either type I (time censoring) of type II (failure censoring). You
can also supply censor columns for multiple censored data, where a 0 denotes a censored observation and a 1
denotes a failure time.
You can have up to 50 input columns, or samples.
703
Minitab Statistical Software Reliability/Survival
FREQUENCY C...C
Specifies the number of occurrences of a row of data. Frequency columns are useful for data where you have
large numbers of observations with common failure and censoring times.
BY C
For stacked data, C is the variable that defines the groups. Use one By variable to represent your groups.
Censoring options
CENSOR C...C
If you have multiple right censored data, CENSOR specifies which observations are censored.
Use two distinct values in each censoring columns, C...C, as indicator variables for censored observations. By
default, the lowest numeric value or the lowest ASCII value for text columns is the censoring value. You can specify
which value is the censoring value by using the CVALUE subcommand. The censored observations are assumed
to be right censored while the uncensored observations are considered exact failure times.
CVALUE K
This subcommand allows you to specify the censoring value, K, which is the value in the censoring column that
defines a censored observation.
UPTIME K
If you have Type I censoring on the right (time censoring), UPTIME specifies the upper cutoff for failure time.
If you have more than one data column, the same cutoff point will be used for all data columns. Observations
whose failure times are greater than or equal to the upper cutoff are considered to be censored, observations
whose failure times are not greater than the upper cutoff are uncensored. For example, UPTIME 500 specifies
to make all observations whose failure times are > 500 censored, and all observations whose failure times are <
500 uncensored.
UPFAIL K
If you have Type II censoring on the right (failure censoring), then UPFAIL specifies the upper cutoff for the number
of failures. This command applies only to single censoring.
If you have more than one data column, the same cutoff point is used for all data columns. The observation at
the upper cutoff point, and all subsequent observations, are considered to be censored. Observations prior to
the upper cutoff point are uncensored. For example, UPFAIL 20 specifies to make all (ordered) observations
starting with the 20
th
observations censored, and all (ordered) observations prior to the 20
th
observation uncensored.
Estimation methods
PTILES K...K
The percents K that define the additional percentiles to be estimated.
LSXY
Use LSXY to estimate parameters using least squares (failure time (X) on rank (Y)) method.
MLE
Use MLE to estimate parameters using maximum likelihood method.
704
Minitab Statistical Software Reliability/Survival
Distributions
Use the following subcommands to create distribution plots of the following distributions.
SEXTREMEVALUE
Smallest extreme value distribution.
WEIBULL
Weibull distribution.
TWEIBULL
Three-parameter Weibull distribution.
EXPONENTIAL
Exponential distribution.
TEXPONENTIAL
Two-parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal distribution.
TLNORMAL
Three-parameter lognormal distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Loglogistic distribution.
TLLOGISTIC
Three-parameter loglogistic distribution.
Probability plot options
Use one of the following subcommands to specify how plot points are determined. Minitab uses the median rank
(Benard) method as the default, if you do not specify one of these subcommands.
MEDRANK
Median ranks (Benard) method.
HJ
Herd-Johnson method.
MKM
Modified Kaplan-Meier method.
KM
Kaplan-Meier method.
ALLPTS
For identical failure times, ALLPTS plots the cumulative percents for each occurrence of a failure time.
705
Minitab Statistical Software Reliability/Survival
AVEPTS
For identical failure times, AVEPTS plots the median cumulative percent of identical failure times.
MAXPTS
For identical failure times, MAXPTS plots the maximum cumulative percent of identical failure times.
Graph options
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
SEPARATE
Displays each graph of different variables or By variable in a separate graph. Minitab overlays graphs, if you omit
this subcommand.
XMINIMUM K
For the endpoints of the x-axis, XMINIMUM specifies the minimum value, K, along the x-axis.
XMAXIMUM K
For the endpoints of the x-axis, XMAXIMUM specifies the maximum value, K, along the x-axis.
RDOVIEW: Session command for creating a layout of distribution
plots
RDOVIEW C...C
Generates distribution plots of specified distributions for right-censored, failure time data, specified in columns
C...C.
RDOVIEW generates a layout of distribution plots for data for up to 50 samples of individual failure times. For
example, you may have collected samples of failure times under different temperatures, or under varying conditions
of any combination of stress variables. The data can be singly censored on the right, with censoring of either type
I (time censoring) of type II (failure censoring). You can also supply censor columns for multiple censored data,
where a 0 denotes a censored observation and a 1 denotes a failure time.
If you choose a parametric analysis, Minitab displays four different ways of describing the distribution of failure
time data in each sample - a probability density function plot, a probability plot, a survival plot, and a hazard plot.
The probability plot displays (usually transformed) estimates of the cumulative distribution function F(y) versus
(usually transformed) failure time. The survival plot displays the survival or reliability function 1-F(y) vs. failure
time. The hazard plot displays the hazard function f(y)/(1-F(y)) versus failure time.
If you choose a nonparametric analysis, Minitab displays a survival plot and a hazard plot.
FREQUENCY C...C
Specifies the number of occurrences of a row of data. Frequency columns are useful for data where you have
large numbers of observations with common failure and censoring times.
BY C
For stacked data, C is the variable that defines the groups. Use one By variable to represent your groups.
706
Minitab Statistical Software Reliability/Survival
Censoring options
CENSOR C...C
If you have multiple right censored data, CENSOR specifies which observations are censored.
Use two distinct values in each censoring columns, C...C, as indicator variables for censored observations. By
default, the lowest numeric value or the lowest ASCII value for text columns is the censoring value. You can specify
which value is the censoring value by using the CVALUE subcommand. The censored observations are assumed
to be right censored while the uncensored observations are considered exact failure times.
CVALUE K
Specifies the censoring value, K, which is the value in the censoring column that defines a censored observation.
UPTIME K
If you have Type I censoring on the right (time censoring), UPTIME specifies the upper cutoff for failure time.
If you have more than one data column, the same cutoff point will be used for all data columns. Observations
whose failure times are greater than or equal to the upper cutoff are considered to be censored, observations
whose failure times are not greater than the upper cutoff are uncensored. For example, UPTIME 500 says to make
all observations whose failure times are > 500 censored, all observations whose failure times are < 500 uncensored.
UPFAIL K
If you have Type II censoring on the right (failure censoring), UPFAIL specifies the upper cutoff for the number of
failures. This command applies only to single censoring.
If you have more than one data column, the same cutoff point will be used for all data columns. The observation
at the upper cutoff point, and all subsequent observations, are considered to be censored. Observations prior to
the upper cutoff point are uncensored. For example, UPFAIL 20 says to make all (ordered) observations starting
with the 20th observations censored, all (ordered) observations prior to the 20th observation uncensored.
Parametric estimation methods
LSXY
Use LSXY to estimate parameters using least squares (failure time (X) on rank (Y)) method.
MLE
Use MLE to estimate parameters using maximum likelihood method.
Nonparametric estimation methods
KMESTIMATE
Specifies the Kaplan-Meier method for nonparametric estimates.
INTBY K K
Specifies the intervals for the actuarial method. The intervals are created from 0 to K by K.
Distributions
Use the following subcommands to create distribution plots of the following distributions.
SEXTREMEVALUE
Smallest extreme value distribution.
707
Minitab Statistical Software Reliability/Survival
WEIBULL
Weibull distribution.
TWEIBULL
Three-parameter Weibull distribution.
EXPONENTIAL
Exponential distribution.
TEXPONENTIAL
Two-parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal distribution.
TLNORMAL
Three-parameter lognormal distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Loglogistic distribution.
TLLOGISTIC
Three-parameter loglogistic distribution.
Probability plot options
Use one of the following subcommands to specify how plot points are determined. Minitab uses the median rank
(Benard) method as the default, if you do not specify one of these subcommands.
MEDRANK
Median ranks (Benard) method.
HJ
Herd-Johnson method.
MKM
Modified Kaplan-Meier method.
KM
Kaplan-Meier method.
ALLPTS
For identical failure times, ALLPTS plots the cumulative percents for each occurrence of a failure time.
AVEPTS
For identical failure times, AVEPTS plots the median cumulative percent of identical failure times.
MAXPTS
For identical failure times, MAXPTS plots the maximum cumulative percent of identical failure times.
708
Minitab Statistical Software Reliability/Survival
Graph options
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
SEPARATE
Displays each graph of different variables or By variable in a separate graph. Minitab overlays graphs, if you omit
this subcommand.
XMINIMUM
For the endpoints of the x-axis, XMINIMUM specifies the minimum value, K, along the x-axis.
XMAXIMUM
For the endpoints of the x-axis, XMAXIMUM specifies the maximum value, K, along the x-axis.
LTEST: Session command for parametric or nonparametric
distribution analysis
LTEST C...C
LTEST fits a smallest extreme value, Weibull, three-parameter Weibull, exponential, two-parameter exponential,
normal, lognormal, three-parameter lognormal, logistic, loglogistic, or three-parameter loglogistic distribution
to the data that you specify in columns C...C.
From the distribution that you chose, estimate percentiles, survival probabilities, cumulative failure probabilities,
evaluate the appropriateness of the chosen distribution, make survival, cumulative failure, hazard and probability
plots, and so on. Your data can be right censored or exact failure times. You can have multiple failure modes.
If no distribution fits your data, then Minitab provides nonparametric estimates of survival probabilities, hazard
function, and so on.
NOPARAMETRIC
When no distribution fits your data, Minitab provides nonparametric estimates of survival probabilities, hazard
function, and so on.
Nonparametric estimation methods are Kaplan-Meier and Actuarial methods.
FREQUENCY C...C
Specifies the number of occurrences of a row of data. Frequency columns are useful for data where you have
large numbers of observations with common failure and censoring times.
BY C
For stacked data, C is the variable that defines the groups. Use one By variable to represent your groups.
Censoring options
CENSOR C...C
If you have multiple right censored data, CENSOR specifies which observations are censored.
Use two distinct values in each censoring columns, C...C, as indicator variables for censored observations. By
default, the lowest numeric value or the lowest ASCII value for text columns is the censoring value. You can specify
which value is the censoring value by using the CVALUE subcommand. The censored observations are assumed
to be right censored while the uncensored observations are considered exact failure times.
709
Minitab Statistical Software Reliability/Survival
CVALUE K
This subcommand allows you to specify the censoring value, K, which is the value in the censoring column that
defines a censored observation.
UPTIME C
If you have Type I censoring on the right (time censoring), UPTIME specifies the upper cutoff for failure time.
If you have more than one data column, the same cutoff point will be used for all data columns. Observations
whose failure times are greater than or equal to the upper cutoff are considered to be censored, observations
whose failure times are not greater than the upper cutoff are uncensored. For example, UPTIME 500 says to make
all observations whose failure times are >= 500 censored, all observations whose failure times are < 500 uncensored.
UPFAIL K
If you have Type II censoring on the right (failure censoring), UPFAIL specifies the upper cutoff for the number of
failures. This command applies only to single censoring.
If you have more than one data column, the same cutoff point will be used for all data columns. The observation
at the upper cutoff point, and all subsequent observations, are considered to be censored. Observations prior to
the upper cutoff point are uncensored. For example, UPFAIL 20 says to make all (ordered) observations starting
with the 20th observations censored, all (ordered) observations prior to the 20th observation uncensored.
Distributions
Use these subcommands to analyze data assuming one of these distributions.
SEXTREMEVALUE
Smallest extreme value distribution.
WEIBULL
Weibull distribution.
TWEIBULL
Weibull distribution.
EXPONENTIAL
Exponential distribution.
TEXPONENTIAL
2-parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal (base e) distribution.
TLNORMAL
Lognormal (base e) distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
710
Minitab Statistical Software Reliability/Survival
Failure modes
FMODE C...C
Estimates overall system reliability and component reliability when multiple causes of failure, identified in columns,
C...C, are present.
KEEP K...K
KEEP "text"
Specifies which failure modes to include in the analyses.
There may be times when you are only interested in analyzing some of the possible failure modes. For
example, you may wish to analyze the overall system reliability with only 1 of the 3 possible failure modes.
Use K to specify the number representing the failure modes you want to keep in the analysis.
Use text in double quotes representing the name of the failure modes you want to keep in the analysis.
ELIMINATE K...K
ELIMINATE "text"
Specifies which failure modes to exclude from the analyses.
There may be times when you are only interested in analyzing some of the possible failure modes. For
example, you may wish to analyze the overall system reliability with only 2 of the 3 possible failure modes.
Use K to specify the number representing the failure modes you want to eliminate from the analysis.
Use text in double quotes representing the name of the failure modes you want to eliminate from the
analysis.
CDISTRIBUTION K...K "text"
CDISTRIBUTION "text" "text"
Specifies which failure modes to change the distribution of, and which distribution to use. For example, to
change the distribution of failure mode A to exponential, type "A" "EXPONENTIAL".
Change the distribution of a failure mode from the assumed overall distribution when a particular failure
mode is well modeled by a specific distribution. For example, you specify LTEST; WEIBULL, for the overall
system, but change the distribution for failure mode 1 to be lognormal and for failure mode 2 to be normal.
Choose from the distributions described above.
Use K to specify the number representing the failure modes you want to change the distribution for
analysis, then type the distribution in double quotes (for example, "EXPONENTIAL").
Use text in double quotes representing the name of the failure modes you want to change the distribution
for analysis, then type the distribution in double quotes (for example, "EXPONENTIAL").
RINDANALYSES
Displays results for individual failure modes, according to the options specified by BRIEF.
SINDANALYSES
Stores results for individual failure modes.
Parametric estimation methods
Choose either the LSXY or MLE parametric estimation method.
711
Minitab Statistical Software Reliability/Survival
LSXY
Use LSXY to estimate parameters using least squares (failure time (X) on rank (Y)) method.
MLE
Use MLE to estimate parameters using maximum likelihood method.
COMSHAPE
Use COMSHAPE to assume common shape parameter.
COMSCALE
Use COMSCALE to assume common scale parameter.
TIMES K...K
TIMES C
Calculate the survival probabilities or cumulative failure probabilities for times K...K or C
ECFPROBABILITY
Choose to estimate cumulative failure probabilities instead of survival probabilities.
STIME
Stores the times associated with the survival probabilities or cumulative failure probabilities.
SURVPROBABILITY C...C
Stores the survival probability for T. Where T is given on the TIME subcommand.
CLSURVPROBABILITY C...C
Stores the upper and lower confidence limits of the survival probability.
CFPROBABILITY C...C
Stores the cumulative failure probability for T. Where T is given on the TIME subcommand.
CLCFPROBABILITY C...C
Stores the upper and lower confidence limits of the cumulative failure probability.
PTILES K...K
PTILES C
The percents K which define the additional percentiles to be estimated.
You can enter individual percents (0 < P < 100) or a column of percents.
Bayes analysis
Choose to set the shape (SETSHAPE) or scale (SETSCALE) parameters depending on your distribution.
For the Weibull distribution, estimate the scale parameter while keeping the shape parameter fixed. The number
of arguments must be 1 or equal to the number of variables. If there is 1 argument then all distributions will have
the same shape parameter.
For all distributions except the Weibull distribution, estimate the location parameter while keeping the scale
parameter fixed. The number of arguments must be 1 or equal to the number of variables. If there is 1 argument
then all distributions will have the same scale parameter.
712
Minitab Statistical Software Reliability/Survival
SETSHAPE K...K
Sets the value for the shape parameter of the Weibull distribution for up to 50 response variables. Enter a list of
values, K...K, for the shape that is equal in length to the number of variables.
SETSCALE K...K
Sets the value for the scale parameter for up to 50 response variables. Enter a list of values, K...K, for the scale that
is equal in length to the number of variables.
SETTHRESHOLD K...K
Sets the value for the threshold parameter for up to 50 response variables. Enter a list of values, K...K, for the
threshold that is equal in length to the number of variables.
For all distributions with threshold parameters (three-parameter Weibull, two-parameter exponential,
three-parameter lognormal, and three-parameter loglogistic) you can fix the threshold parameter.
The threshold parameter you set must be < the minimum data value.
Nonparametric estimation methods
Use KMESTIMATE, INTBY, or INTENDPOINTS as the nonparametric estimation method.
KMESTIMATE
Use the Kaplan-Meier method for nonparametric estimates.
INTBY K K
Specify the intervals for the actuarial method. The intervals are created from 0 to K by K.
INTENDPOINTS K K
Specify the endpoints of the intervals for the actuarial method. The lower endpoint is given by K, the upper
endpoint is given by K.
ECFPROBABILITY
Choose to estimate cumulative failure probabilities instead of survival probabilities.
STIME C
Stores the times associated with the nonparametric survival probabilities or cumulative failure probabilities.
SURVPROBABILITY C...C
Stores the nonparametric survival probability for T. Where T is given on the TIME subcommand.
SESURVPROBABILITY C...C
Stores the standard error of the nonparametric survival probability.
CLSURVPROBABILITY C...C
Stores the upper and lower confidence limits of the nonparametric survival probability.
CFPROBABILITY C...C
Stores the nonparametric cumulative failure probability for T. Where T is given on the TIME subcommand.
SECFPROBABILITY C...C
Stores the standard error of the nonparametric cumulative failure probability.
CLCFPROBABILITY C...C
Stores the upper and lower confidence limits of the nonparametric cumulative failure probability.
713
Minitab Statistical Software Reliability/Survival
HAZARD C...C
Stores hazard estimates.
HTIME C...C
Stores times associated with hazard estimates.
Confidence intervals
CONFIDENCE K
Specifies the percent confidence, K, for your confidence intervals.
LOWCI
Calculates one-sided, lower confidence intervals for parameter estimates and percentiles.
UPCI
Calculates one-sided, upper confidence intervals for parameter estimates and percentiles.
TWOCI
Calculates two-sided confidence intervals for parameter estimates and percentiles.
Parameter tests
TVSS K
Tests whether the shape (Weibull) or scale (other distributions) is equal to K (K>0).
TVSL K
Tests whether the scale (Weibull or exponential) or location (other distributions) is equal to K (K>0).
TVTHRESHOLD K
Tests whether the threshold (three-parameter Weibull, two-parameter exponential, three-parameter lognormal,
and three-parameter loglogistic) is equal to K (K>0).
TESS
Tests for equal shape (Weibull) or scale (other distributions).
TESL
Tests for equal scale (Weibull or exponential) or location (other distributions).
TETHRESHOLD
Tests for equal threshold (three-parameter Weibull, two-parameter exponential, three-parameter lognormal, and
three-parameter loglogistic).
Graph options
CI
Displays confidence intervals on probability and survival plots.
PPLOT
Displays a probability plot.
714
Minitab Statistical Software Reliability/Survival
MEDRANK
MEDRANK specifies the median ranks (Benard) method for the plotted points on the probability plot. Minitab
uses the median rank (Benard) method as the default, if you do not specify MEDRANK, HJ, MKM, or KM.
HJ
HJ specifies the Herd-Johnson method for the plotted points on the probability plot.
MKM
MKM specifies the modified Kaplan-Meier method for the plotted points on the probability plot.
KM
KM specifies the Kaplan-Meier method for the plotted points on the probability plot.
ALLPTS
For identical failure times, ALLPTS plots the cumulative percents for each occurrence of a failure time.
AVEPTS
For identical failure times, AVEPTS plots the median cumulative percent of identical failure times.
MAXPTS
For identical failure times, MAXPTS plots the maximum cumulative percent of identical failure times.
SPLOT
Displays a parametric or nonparametric survival plot. The nonparametric survival plot is a step function, while the
parametric survival plot is a smooth curve.
CFPLOT
Displays a parametric or nonparametric cumulative failure plot. The nonparametric cumulative failure plot is a
step function, while the parametric cumulative failure plot is a smooth curve.
HPLOT
Displays a parametric or nonparametric hazard plot. The nonparametric hazard plot is a step function, while the
parametric hazard plot is a smooth curve.
PANEL
Use PANEL and SEPARATE to perform hypothesis tests on the distribution parameters.
PANEL displays each graph of different variables or By variable in a separate panel of the graph.
SEPARATE
Use PANEL and SEPARATE to perform hypothesis tests on the distribution parameters.
SEPARATE displays each graph of different variables or By variable in a separate graph.
XMINIMUM K
For parametric distribution analysis, specify the minimum and maximum X scale for the probability, survival and
hazard plots. For nonparametric distribution analysis, specify the minimum and maximum X scale for the survival
and hazard plot.
Use XMINIMUM to specify the X-axis scale minimum.
715
Minitab Statistical Software Reliability/Survival
XMAXIMUM K
For parametric distribution analysis, specify the minimum and maximum X scale for the probability, survival and
hazard plots. For nonparametric distribution analysis, specify the minimum and maximum X scale for the survival
and hazard plot.
Use XMAXIMUM to specify the X-axis scale maximum.
XLABEL K
XLABEL "text"
Use XLABEL to specify an x-axis label for the graph. When you omit this subcommand, Minitab displays a default
label.
Results options
BRIEF K
For parametric, use the values in the following table to control the amount of output.
OutputValues of K
No output0
Variable information, censoring information, estimated parameters and
log-likelihood
1
K = 1 output, and characteristics of distribution and table of percentiles and survival
probabilities
2 (default)
For nonparametric, use the values in the following table to control the amount of output.
OutputValues of K
No output0
Variable information, censoring information, characteristics of variable and summary
statistics for comparing survival curves
1
K = 1 output, and Kaplan-Meier survival probabilities or actuarial table2 (default)
K = 2 output, and hazard, density (actuarial method) estimates and log-rank and
Wilcoxon statistics
3
STEP
Displays the log-likelihood at each iteration of the parameter estimation process.
Estimate parameters
START C...C
Specifies the initial values for the estimated parameters. If one column is given then the starting estimates apply
for all variables. Otherwise, a column must correspond to each variable.
ITERATION K
Changes the maximum number of iterations that Minitab will perform to reach convergence. The default value is
20. LTEST obtains maximum likelihood estimates through an iterative process. If the maximum number of iterations
is reached before convergence, the command terminates.
716
Minitab Statistical Software Reliability/Survival
Storage of fitted distributions
PPERCENTS C
Stores the percents associated with the percentiles.
PERCENTILE C...C
Stores the percentiles.
SEPERCENTILE C...C
Stores the standard error of the percentiles.
CLPERCENTILE C...C
Stores the upper and lower confidence limits of the percentiles.
Storage of estimates
PARAM C...C
Stores the estimated parameters for the distribution down the column.
SSEPARAM C...C
Stores the standard errors of the estimated parameters for the distribution down a column.
CLPARAM C...C
Stores the confidence limits for the estimated parameters for the distribution down a column.
VCPARAM M...M
Stores the variance covariance matrix for the estimated parameters.
LOGLIKELIHOOD K...K
Stores the last log-likelihood.
Subcommand
CTOLERANCE K K
Changes the convergence criteria. Both Ks must be positive numbers.
For the first K, convergence is attained relative to this criterion if from one iteration to the next the change in the
log-likelihood is less than K. The default is 0.0001.
For the second K, convergence is attained relative to this criterion if from one iteration to the next the maximum
change in the coefficients is less than K. The default is 0.0001.
717
Minitab Statistical Software Reliability/Survival
Distribution Analysis (Arbitrary Censoring)
IDIDENTIFICATION: Session command for creating probability
plots of arbitrarily-censored, failure (or survival) data
IDENTIFICATION C...C
Generates probability plots of different distributions for arbitrarily-censored, failure time data. You must specify
an even number of columns in the form of Start1, Start2 ..., End1, End 2..., and so on.
Use IDIDENTIFICATION to create up to eleven different probability plots (with distributions chosen from smallest
extreme value, Weibull, three-parameter Weibull, exponential, two-parameter exponential, normal, lognormal,
three-parameter lognormal, logistic, loglogistic, and three-parameter loglogistic) to help you determine which
of these distributions best fits your data. Usually, this is done by comparing how closely the plot points lie to the
best-fit lines—in particular, points in the tails of the distribution.
The sample data are the individual failure times. For example, you may have collected samples of failure times
under different temperatures, or under varying conditions of any combination of stress variables. The data can
be singly censored on the right, with censoring of either type I (time censoring) of type II (failure censoring). You
can also supply censor columns for multiple censored data, where a 0 denotes a censored observation and a 1
denotes a failure time.
You can have up to 50 input columns, or samples.
MeaningVariablesObservation
Exact failure time = TIMEStart = End = TIMEExact failure time
Right censored time = TIMEStart = TIME, End = *Right censored
Left censored time = TIMEStart = *, End = TIMELeft censored
Interval censored = (TIME1, TIME2)Start = TIME1, end = TIME2Interval censored
FREQUENCY C...C
Specifies the number of occurrences of a row of data. Frequency columns are useful for data where you have
large numbers of observations with common failure and censoring times.
BY C
For stacked data, C is the variable that defines the groups. Use one By variable to represent your groups.
Estimation methods
PTILES K...K
The percents K that define the additional percentiles to be estimated.
LSXY
Use LSXY to estimate parameters using least squares (failure time (X) on rank (Y)) method.
MLE
Use MLE to estimate parameters using maximum likelihood method.
718
Minitab Statistical Software Reliability/Survival
Distributions
Use the following subcommands to create distribution plots of the following distributions.
SEXTREMEVALUE
Smallest extreme value distribution.
WEIBULL
Weibull distribution.
TWEIBULL
Three-parameter Weibull distribution.
EXPONENTIAL
Exponential distribution.
TEXPONENTIAL
Two-parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal distribution.
TLNORMAL
Three-parameter lognormal distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Loglogistic distribution.
TLLOGISTIC
Three-parameter loglogistic distribution.
Graph options
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
SEPARATE
Displays each graph of different variables or By variable in a separate graph. Minitab overlays graphs, if you omit
this subcommand.
XMINIMUM K
For the endpoints of the x-axis, XMINIMUM specifies the minimum value, K, along the x-axis.
XMAXIMUM K
For the endpoints of the x-axis, XMAXIMUM specifies the maximum value, K, along the x-axis.
719
Minitab Statistical Software Reliability/Survival
IDOVIEW: Session command for creating a layout of distribution
plots
IDOVIEW C...C
IDOVIEW generates a layout of distribution plots for data for up to 50 samples of individual failure times. For
example, you may have collected samples of failure times under different temperatures, or under varying conditions
of any combination of stress variables. Arbitrarily-censored data includes exact failures and a varied censoring
scheme, including right-, left-, and interval-censored data. Enter your data in table form, using a Start column
and End column.
MeaningVariablesObservation
Exact failure time = TIMEStart = End = TIMEExact failure time
Right censored time = TIMEStart = TIME, End = *Right censored
Left censored time = TIMEStart = *, End = TIMELeft censored
Interval censored = (TIME1, TIME2)Start = TIME1, end = TIME2Interval censored
If you choose a parametric analysis, Minitab displays four different ways of describing the distribution of failure
time data in each sample—a probability density function plot, a probability plot, a survival plot, and a hazard plot.
If you choose a nonparametric analysis, Minitab displays a survival plot for the Turnbull method and a survival
plot and a hazard plot for the actuarial method.
FREQUENCY C...C
Specifies the number of occurrences of a row of data. Frequency columns are useful for data where you have
large numbers of observations with common failure and censoring times.
BY C
For stacked data, C is the variable that defines the groups. Use one By variable to represent your groups.
Parametric estimation methods
LSXY
Use LSXY to estimate parameters using least squares (failure time (X) on rank (Y)) method.
MLE
Use MLE to estimate parameters using maximum likelihood method.
Nonparametric estimation methods
TURNBULL
Displays a Turnbull survival plot.
ACTURIAL
Displays an actuarial survival plot and hazard plot.
Distributions
Use the following subcommands to create distribution plots of the following distributions.
720
Minitab Statistical Software Reliability/Survival
SEXTREMEVALUE
Smallest extreme value distribution.
WEIBULL
Weibull distribution.
TWEIBULL
Three-parameter Weibull distribution.
EXPONENTIAL
Exponential distribution.
TEXPONENTIAL
Two-parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal distribution.
TLNORMAL
Three-parameter lognormal distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Loglogistic distribution.
TLLOGISTIC
Three-parameter loglogistic distribution.
Graph options
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
SEPARATE
Displays each graph of different variables or By variable in a separate graph. Minitab overlays graphs, if you omit
this subcommand.
XMINIMUM K
For the endpoints of the x-axis, XMINIMUM specifies the minimum value, K, along the x-axis.
XMAXIMUM K
For the endpoints of the x-axis, XMAXIMUM specifies the maximum value, K, along the x-axis.
721
Minitab Statistical Software Reliability/Survival
LTABLE: Session command for fitting a distribution to
arbitrarily-censored data
LTABLE C...C
LTABLE fits a smallest extreme value, Weibull, three-parameter Weibull, exponential, two-parameter exponential,
normal, lognormal, three-parameter lognormal, logistic, loglogistic, or three-parameter loglogistic distribution
to your data. From the distribution you chose, estimate percentiles, survival probabilities, cumulative failure
probabilities, evaluate the appropriateness of the chosen distribution, make survival, cumulative failure, hazard
and probability plots, etc. Your data may be right, left, or interval censored, in addition to exact failure times. You
may have multiple failure modes. In situations when no distribution will fit your data, Minitab provides
nonparametric estimates of survival probabilities, hazard function, etc.
The failure times must be in a start-end syntax where the first K/2 columns represent start times and the remaining
columns represent end times, where K is the number of columns on the command line. Therefore, LTABLE will
perform K/2 analyses. Each analysis provides identical results to the results you would get if you ran each set of
variables separately.
MeaningVariablesObservation
Exact failure time = TIMEStart = End = TIMEExact failure time
Right censored time = TIMEStart = TIME, End = *Right censored
Left censored time = TIMEStart = *, End = TIMELeft censored
Interval censored = (TIME1, TIME2)Start = TIME1, end = TIME2Interval censored
NOPARAMETRIC
When no distribution fits your data, Minitab provides nonparametric estimates of survival probabilities, hazard
function, and so on.
Nonparametric estimation methods are Kaplan-Meier and Actuarial methods.
FREQUENCY C...C
Specifies the number of occurrences of a row of data. Frequency columns are useful for data where you have
large numbers of observations with common failure and censoring times.
BY C
For stacked data, C is the variable that defines the groups. Use one By variable to represent your groups.
Distributions
Use these subcommands to analyze data assuming one of these distributions.
SEXTREMEVALUE
Smallest extreme value distribution.
WEIBULL
Weibull distribution.
TWEIBULL
Weibull distribution.
EXPONENTIAL
Exponential distribution.
722
Minitab Statistical Software Reliability/Survival
TEXPONENTIAL
2[parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Lognormal (base e) distribution.
TLNORMAL
Lognormal (base e) distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
Failure modes
FMODE C...C
Estimates overall system reliability and component reliability when multiple causes of failure, identified in columns,
C...C, are present.
KEEP K...K
KEEP "text"
Specifies which failure modes to include in the analyses.
There may be times when you are only interested in analyzing some of the possible failure modes. For
example, you may wish to analyze the overall system reliability with only 1 of the 3 possible failure modes.
Use K to specify the number representing the failure modes you want to keep in the analysis.
Use text in double quotes representing the name of the failure modes you want to keep in the analysis.
ELIMINATE K...K
ELIMINATE "text"
Specifies which failure modes to exclude from the analyses.
There may be times when you are only interested in analyzing some of the possible failure modes. For
example, you may wish to analyze the overall system reliability with only 2 of the 3 possible failure modes.
Use K to specify the number representing the failure modes you want to eliminate from the analysis.
Use text in double quotes representing the name of the failure modes you want to eliminate from the
analysis.
MIDPOINT
When you calculate right-censored observations for other failure modes when data are interval censored,
use MIDPOINT for the midpoint of the interval.
RPOINT
When you calculate right-censored observations for other failure modes when data are interval censored,
use RPOINT for the right endpoint of the interval.
723
Minitab Statistical Software Reliability/Survival
CDISTRIBUTION K...K "text"
CDISTRIBUTION "text" "text"
Specifies which failure modes to change the distribution of, and which distribution to use. For example, to
change the distribution of failure mode A to exponential, type "A" "EXPONENTIAL".
Change the distribution of a failure mode from the assumed overall distribution when a particular failure
mode is well modeled by a specific distribution. For example, you specify LTEST; WEIBULL, for the overall
system, but change the distribution for failure mode 1 to be lognormal and for failure mode 2 to be normal.
Choose from the distributions described above.
Use K to specify the number representing the failure modes you want to change the distribution for
analysis, then type the distribution in double quotes (for example, "EXPONENTIAL").
Use text in double quotes representing the name of the failure modes you want to change the distribution
for analysis, then type the distribution in double quotes (for example, "EXPONENTIAL").
RINDANALYSES
Displays results for individual failure modes, according to the options specified by BRIEF.
SINDANALYSES
Stores results for individual failure modes.
Parametric estimation methods
Choose either the LSXY or MLE parametric estimation method.
LSXY
Use LSXY to estimate parameters using least squares (failure time (X) on rank (Y)) method.
MLE
Use MLE to estimate parameters using maximum likelihood method.
COMSHAPE
Use COMSHAPE to assume common shape parameter.
COMSCALE
Use COMSCALE to assume common scale parameter.
TIMES K...K
TIMES C
Calculate the survival probabilities or cumulative failure probabilities for times K...K or C.
ECFPROBABILITY
Choose to estimate cumulative failure probabilities instead of survival probabilities.
STIME
Stores the times associated with the survival probabilities or cumulative failure probabilities.
SURVPROBABILITY C...C
Stores the survival probability for T. Where T is given on the TIME subcommand.
CLSURVPROBABILITY C...C
Stores the upper and lower confidence limits of the survival probability.
724
Minitab Statistical Software Reliability/Survival
CFPROBABILITY C...C
Stores the cumulative failure probability for T. Where T is given on the TIME subcommand.
CLCFPROBABILITY C...C
Stores the upper and lower confidence limits of the cumulative failure probability.
PTILES K...K
PTILES C
The percents K which define the additional percentiles to be estimated.
You can enter individual percents (0 < P < 100) or a column of percents.
Bayes analysis
Choose to set the shape (SETSHAPE) or scale (SETSCALE) parameters depending on your distribution.
For the Weibull distribution, estimate the scale parameter while keeping the shape parameter fixed. The number
of arguments must be 1 or equal to the number of variables. If there is 1 argument then all distributions will have
the same shape parameter.
For all distributions except the Weibull distribution, estimate the location parameter while keeping the scale
parameter fixed. The number of arguments must be 1 or equal to the number of variables. If there is 1 argument
then all distributions will have the same scale parameter.
SETSHAPE K...K
Sets the value for the shape parameter of the Weibull distribution for up to 50 response variables. Enter a list of
values, K...K, for the shape that is equal in length to the number of variables.
SETSCALE K...K
Sets the value for the scale parameter for up to 50 response variables. Enter a list of values, K...K, for the scale that
is equal in length to the number of variables.
SETTHRESHOLD K...K
Sets the value for the threshold parameter for up to 50 response variables. Enter a list of values, K...K, for the
threshold that is equal in length to the number of variables.
For all distributions with threshold parameters (three-parameter Weibull, two-parameter exponential,
three-parameter lognormal, and three-parameter loglogistic) you can fix the threshold parameter.
The threshold parameter you set must be < the minimum data value.
Nonparametric estimation methods
Use TURNBULL or ACTUARIAL as the nonparametric estimation method.
TURNBULL
Use the Turnbull method for nonparametric estimates.
ACTUARIAL
Use the actuarial method for nonparametric estimates.
ECFPROBABILITY
Choose to estimate cumulative failure probabilities instead of survival probabilities.
725
Minitab Statistical Software Reliability/Survival
STIME C
Stores the times associated with the nonparametric survival probabilities or cumulative failure probabilities.
SURVPROBABILITY C...C
Stores the nonparametric survival probability for T. Where T is given on the TIME subcommand.
SESURVPROBABILITY C...C
Stores the standard error of the nonparametric survival probability.
CLSURVPROBABILITY C...C
Stores the upper and lower confidence limits of the nonparametric survival probability.
CFPROBABILITY C...C
Stores the nonparametric cumulative failure probability for T. Where T is given on the TIME subcommand.
SECFPROBABILITY C...C
Stores the standard error of the nonparametric cumulative failure probability.
CLCFPROBABILITY C...C
Stores the upper and lower confidence limits of the nonparametric cumulative failure probability.
HAZARD C...C
Stores hazard estimates.
HTIME C...C
Stores times associated with hazard estimates.
Confidence intervals
CONFIDENCE [K]
Specifies the percent confidence, K, for your confidence intervals.
LOWCI
Calculates one-sided, lower confidence intervals for parameter estimates and percentiles.
UPCI
Calculates one-sided, upper confidence intervals for parameter estimates and percentiles.
TWOCI
Calculates two-sided confidence intervals for parameter estimates and percentiles.
Parameter tests
TVSS K
Tests whether the shape (Weibull) or scale (other distributions) is equal to K (K > 0).
TVSL K
Tests whether the scale (Weibull or exponential) or location (other distributions) is equal to K (K > 0).
TVTHRESHOLD K
Tests whether the threshold (three-parameter Weibull, two-parameter exponential, three-parameter lognormal,
and three-parameter loglogistic) is equal to K (K>0).
726
Minitab Statistical Software Reliability/Survival
TESS
Tests for equal shape (Weibull) or scale (other distributions).
TESL
Tests for equal scale (Weibull or exponential) or location (other distributions).
TETHRESHOLD
Tests for equal threshold (three-parameter Weibull, two-parameter exponential, three-parameter lognormal, and
three-parameter loglogistic).
Graph options
CI
Displays confidence intervals on probability and survival plots.
SPLOT
Displays a parametric or nonparametric survival plot. The nonparametric survival plot is a step function, while the
parametric survival plot is a smooth curve.
CFPLOT
Displays a parametric or nonparametric cumulative failure plot. The nonparametric cumulative failure plot is a
step function, while the parametric cumulative failure plot is a smooth curve.
HPLOT
Displays a parametric or nonparametric hazard plot. The nonparametric hazard plot is a step function, while the
parametric hazard plot is a smooth curve.
PANEL
Use PANEL and SEPARATE to perform hypothesis tests on the distribution parameters.
PANEL displays each graph of different variables or By variable in a separate panel of the graph.
SEPARATE
Use PANEL and SEPARATE to perform hypothesis tests on the distribution parameters.
SEPARATE displays each graph of different variables or By variable in a separate graph.
XMINIMUM K
For parametric distribution analysis, specify the minimum and maximum X scale for the probability, survival and
hazard plots. For nonparametric distribution analysis, specify the minimum and maximum X scale for the survival
and hazard plot.
Use XMINIMUM to specify the X-axis scale minimum.
XMAXIMUM K
For parametric distribution analysis, specify the minimum and maximum X scale for the probability, survival and
hazard plots. For nonparametric distribution analysis, specify the minimum and maximum X scale for the survival
and hazard plot.
Use XMAXIMUM to specify the X-axis scale maximum.
727
Minitab Statistical Software Reliability/Survival
XLABEL K
XLABEL "text"
Use XLABEL to specify an x-axis label for the graph. When you omit this subcommand, Minitab displays a default
label.
Results options
BRIEF K
For parametric, use the values in the following table to control the amount of output.
OutputValues of K
No output0
Variable information, censoring information, estimated parameters and
log-likelihood
1
K = 1 output, and characteristics of distribution and table of percentiles and survival
probabilities
2 (default)
For nonparametric, use the values in the following table to control the amount of output.
OutputValues of K
No output0
Variable information, censoring information, characteristics of variable and summary
statistics for comparing survival curves
1
K = 1 output, and Kaplan-Meier survival probabilities or actuarial table2 (default)
K = 2 output, and hazard, density (actuarial method) estimates and log-rank and
Wilcoxon statistics
3
STEP
Displays the log-likelihood at each iteration of the parameter estimation process.
Estimate parameters
START C...C
Specifies the initial values for the estimated parameters. If one column is given then the starting estimates apply
for all variables. Otherwise, a column must correspond to each variable.
ITERATION K
Changes the maximum number of iterations that Minitab will perform to reach convergence. The default value is
20. LTEST obtains maximum likelihood estimates through an iterative process. If the maximum number of iterations
is reached before convergence, the command terminates.
Storage of fitted distributions
PPERCENTS C
Stores the percents associated with the percentiles.
728
Minitab Statistical Software Reliability/Survival
PERCENTILE C...C
Stores the percentiles.
SEPERCENTILE C...C
Stores the standard error of the percentiles.
CLPERCENTILE C...C
Stores the upper and lower confidence limits of the percentiles.
Storage of estimates
PARAM C...C
Stores the estimated parameters for the distribution down the column.
SSEPARAM C...C
Stores the standard errors of the estimated parameters for the distribution down a column.
CLPARAM C...C
Stores the confidence limits for the estimated parameters for the distribution down a column.
VCPARAM M...M
Stores the variance covariance matrix for the estimated parameters.
LOGLIKELIHOOD K...K
Stores the last log-likelihood.
Subcommand
CTOLERANCE K K
Changes the convergence criteria. Both Ks must be positive numbers.
For the first K, convergence is attained relative to this criterion if from one iteration to the next the change in the
log-likelihood is less than K. The default is 0.0001.
For the second K, convergence is attained relative to this criterion if from one iteration to the next the maximum
change in the coefficients is less than K. The default is 0.0001.
Growth Curves
PGROWTH: Session command for performing a parametric analysis
using a parametric growth curve
PGROWTH C...C
Fits a power-law process to each set of recurrence or failure times in C.
729
Minitab Statistical Software Reliability/Survival
Use parametric growth curve (PGROWTH) to perform a parametric analysis on a repairable system. Use either a
power-law process or a homogeneous Poisson process to estimate a growth curve of the mean cost of maintaining
a system or the mean number of repairs over time.
SEND
Specifies that the response variables are interval failure or retirement times. If you use the SEND subcommand,
you must have two response columns for each group. For each pair of response columns, the requirements
are as follows:
The first response variable listed is the start time.
The second response variable listed is the end time.
BY C
For stacked data, C is the variable that defines the groups. In this case, only one variable (or a pair of variables
with the SEND subcommand) is allowed on the PGROWTH command line.
System information
SYSTEM C...C
Identifies a system within a sample when you have multiple systems.
FREQ C...C
Specifies the number of failures recorded at a failure time or interval.
Retirement
RETIREMENT C...C
Put in column C an indicator variable indicating which systems are retired. By default, the lowest numeric value
or the lowest ASCII value (text columns) is the retirement value. Retirement columns must contain no more than
two distinct values.
RVALUE K
You can specify which value is the retirement value by using the RVALUE subcommand.
TIMETRUNCATE
Specifies that the largest time for each system is the retirement time.
Estimate
By default, Minitab uses maximum likelihood estimation. Use the following subcommands to select a different estimation
method.
CMLE
Conditional maximum likelihood estimation. You cannot use CMLE with the SEND or SETSHAPE subcommands.
LSXY
Least squares estimation.
730
Minitab Statistical Software Reliability/Survival
Confidence intervals
CONFIDENCE [K]
Specifies the percent confidence, K, for your confidence intervals.
LOWCI
Calculates one-sided, lower confidence intervals for parameter estimates and percentiles.
UPCI
Calculates one-sided, upper confidence intervals for parameter estimates and percentiles.
TWOCI
Calculates two-sided confidence intervals for parameter estimates and percentiles.
Graphs
GEVENTPLOT
Plots events for all systems.
DFREQ
Displays the frequency information on the event plot.
GDUANEPLOT
Creates a Duane plot.
GTTTPLOT
Plots the total time on test.
GMCFPLOT
Plots the mean cumulative function.
GONE
By default, Minitab displays plots averaged over all systems. GONE displays one plot per system instead. This
subcommand does not apply to the event plot.
PANEL
Displays graphs of different variables or by levels on the same graph in separate panels. By default, multiple plots
are overlaid on the same graph.
SEPARATE
Displays graphs of different variables or by levels in separate graphs. By default, multiple plots are overlaid on
the same graph.
CI
Includes confidence intervals on the mean cumulative function plot, Duane plot, and TTT plot.
XMINIMUM K
Specifies the X-axis scale minimum.
XMAXIMUM K
Specifies the X-axis scale maximum.
XLABEL K
Labels the X-axis.
731
Minitab Statistical Software Reliability/Survival
Results
STEP
Displays the estimated shape, scale, and log-likelihood at each iteration of the parameter estimation process.
Options
SETSHAPE K
Specifies a known value for the shape parameter instead of estimating it from the data.
START K...K
Specifies the initial value for the shape parameter.
ITERATION K
Specifies the maximum number of iterations to use. The default number of iterations is 20.
Storage
MCF C...C
Stores the mean cumulative function.
CLMCF C...C
Stores the confidence limits for the mean cumulative function.
ROCOF C...C
Stores the rate of occurrence of failures.
CLROCOF C...C
Stores the confidence limits for the rate of occurrence of failures.
PARAMETERS C...C
Stores the estimates of the shape and scale
SSEPARAMETERS C...C
Stores the standard errors of the shape and scale.
CLPARAMETERS C...C
Stores the confidence limits for the shape and scale.
NGROWTH: Session command for performing a nonparametric
analysis using a nonparametric growth curve
NGROWTH C...C
Creates a nonparametric growth curve for repair times in C.
Use nonparametric growth curve to estimate a growth curve of the mean cost of maintaining a system or the
mean number of repairs over time without assuming a distribution.
732
Minitab Statistical Software Reliability/Survival
SEND
Specifies that the response variables are interval failure or retirement times. If you use the SEND subcommand,
you must have two response columns for each group. For each pair of response columns, the requirements
are as follows:
The first response variable listed is the start time.
The second response variable listed is the end time.
BY C
For stacked data, C is the variable that defines the groups. In this case, only one variable (or a pair of variables
with the SEND subcommand) is allowed on the PGROWTH command line.
System information
SYSTEM C...C
Identifies a system within a sample when you have multiple systems.
NSYSTEMS C...C
Specifies the number of systems entering each interval for grouped data.
Retirement
RETIREMENT C...C
Put in column C an indicator variable indicating which systems are retired. By default, the lowest numeric value
or the lowest ASCII value (text columns) is the retirement value. Retirement columns must contain no more than
two distinct values.
RVALUE K
You can specify which value is the retirement value by using the RVALUE subcommand.
TIMETRUNCATE
Specifies that the largest time for each system is the retirement time.
Cost/Frequency
COST C...C
Specifies a cost or frequency column. You can specify one of the following:
The total cost for all repairs for an event
The number of items replaced (frequency)
Graphs
GMCFPLOT
Plots the mean cumulative function.
733
Minitab Statistical Software Reliability/Survival
GDMCPLOT
Plots the mean cumulative difference function. This plot is only available when there are two or more variables
(with no SEND subcommand), two or more pairs of variables (with SEND subcommand), or a BY variable.
GEVENTPLOT
Plots events for all systems.
DCOST
Displays the cost variable information on the event plot.
PANEL
Displays graphs of different variables or by levels on the same page in separate panels. By default, multiple plots
are overlaid on the same graph page.
SEPARATE
Displays graphs of different variables or by levels on separate graph pages. By default, multiple plots are overlaid
on the same graph page.
CI
Includes confidence intervals on the mean cumulative function plot, Duane plot, and TTT plot.
XMINIMUM K
Specifies the X-axis scale minimum.
XMAXIMUM K
Specifies the X-axis scale maximum.
XLABEL K
Labelss the X-axis.
Options
CONFIDENCE [K]
Specifies the percent confidence, K, for your confidence intervals.
LOWCI
Calculates one-sided, lower confidence intervals for parameter estimates and percentiles.
UPCI
Calculates one-sided, upper confidence intervals for parameter estimates and percentiles.
TWOCI
Calculates two-sided confidence intervals for parameter estimates and percentiles.
Storage
Stores estimates related to the mean cumulative function and the mean cumulative difference function.
MCF C...C
Stores the mean cumulative function.
TMCF C...C
Stores the times for the mean cumulative function.
734
Minitab Statistical Software Reliability/Survival
SEMCF C...C
Stores the standard error of the mean cumulative function.
CLMCF C...C
Stores the confidence limits for the mean cumulative function.
DMCF C...C
Stores the difference in the mean cumulative function.
TDMCF C...C
Stores the times for the difference in the mean cumulative function.
SEDMCF C...C
Stores the standard error of difference in mean cumulative function.
CLDMCF C...C
Stores the confidence limits for difference in mean cumulative function.
Regression with Life Data
LREGRESSION: Session command for performing a regression
analysis when the error distribution is Weibull, smallest extreme
value, exponential, log-normal, normal, logistic, or log-logistic
LREGRESSION C = C...C
Use LREGRESSION to perform a regression analysis when the error distribution is Weibull, smallest extreme value,
exponential, log-normal, normal, logistic, or log-logistic. The data may be right, left or interval censored in addition
to exact failure times. The regression equation can have terms which are either continuous or discrete. The
command finds maximum likelihood estimates for the parameters using a modified Newton-Raphson technique.
Also, you can estimate percentiles, survival probabilities, cumulative failure probabilities, evaluate the
appropriateness of the chosen distribution, etc.
The left hand side of the equation specifies the response variables. If SEND is used then the first half of the columns
are the START variables while the second half of the columns are the END variables. If the SEND subcommand is
not used then each column defines a separate problem. LREGRESSION will do a separate analyses for each set of
response variables. Each analyses provide identical results as if you would have run each of the problems separately.
FREQUENCY C...C
Specifies the number of occurrences of a row of data.
FACTORS C...C
Specifies a factor in the model.
Relationships
Specifies the relationship between failure times or log failure times and the accelerating variable.
735
Minitab Statistical Software Reliability/Survival
ARRHENIUS
Arrhenius relationship.
INVTEMP
Inverse temperature relationship.
LN
Power or natural log relationship.
Distributions
Specifies the distribution failure time or log failure time.
WEIBULL
Weibull distribution.
EXPONENTIAL
Exponential distribution.
SEXTREMEVALUE
Smallest extreme value distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
NORMAL
Normal distribution.
LNORMAL
Log-normal (base e) distribution.
Censoring
CENSOR C...C
Indicates which observations are censored. The censored observations are assumed to be right censored while
the uncensored observations are considered exact failure times.
CVALUE K
By default, the lowest numeric value or the lowest ASCII value for text columns is the censoring value. You
can specify which value is the censoring value by using the CVALUE subcommand.
SEND
Specifies that the response variables are in an arbitrary censoring format. You need to enter the response variable
into a start and end column.
736
Minitab Statistical Software Reliability/Survival
Estimation
ESTIMATE [K...K]
ESTIMATE [C...C]
Estimates percentiles, survival probabilities, or cumulative failure probabilities for new predictors.
TIMES
Estimates survival or cumulative failure probabilities.
PTILES
The percents K which define the percentiles to be estimated for each new observation.
PERCENTILE
Stores the percentiles.
SEPERCENTILE
Stores the standard error of the percentiles.
CLPERCENTILE
Stores the lower and upper confidence limits for the percentiles.
ECFPROBABILITY
Choose to estimate cumulative failure probabilities instead of survival probabilities.
SURVPROBABILITY
Stores the survival probabilities.
CLSURVPROBABILITY
Stores the lower and upper confidence limits for the survival probabilities.
CFPROBABILITY
Stores the cumulative failure probabilities.
CLCFPROBABILITY
Stores the lower and upper confidence limits for the cumulative failure probabilities.
CONFIDENCE [K]
Specifies the percent confidence, K, for your confidence intervals.
LOWCI
Calculates one-sided, lower confidence intervals for parameter estimates and percentiles.
UPCI
Calculates one-sided, upper confidence intervals for parameter estimates and percentiles.
TWOCI
Calculates two-sided confidence intervals for parameter estimates and percentiles.
Graphs
RPLOT
Displays a relation plot.
737
Minitab Statistical Software Reliability/Survival
PTILES K...K
PTILES C
Displays the percents associated with the percentiles to be plotted on the relation plot.
PFAILURES
Displays failure times on the relation plot. For exact failure times, the value is plotted while for an interval
censored observations the average of the start and end value is plotted.
DVALUE K
Displays the design value K on the relation plot.
ALLCI
Adds confidence intervals on all percentiles on the relation plot.
ONECI
Adds confidence intervals on the middle percentile on the relation plot.
AFPPLOT
Displays a probability plot for each level of the accelerating variable based on the fitted model.
ONECI
Adds a confidence interval for the design value on the probability plot for each level of the accelerating variable
based on the fitted model.
ALLCI
Adds a confidence interval for all levels on the probability plot for each level of the accelerating variable based
on the fitted model.
AIPPLOT
Displays a diagnostic probability plot for each accelerating variable based on individual fits.
SPPLOT
Displays a diagnostic probability plot for the standardized residuals.
EPPLOT
Displays a diagnostic exponential probability plot for the Cox-Snell residuals.
CI
Display confidence intervals on diagnostic plots.
Results
BRIEF K
Controls the amount of output.
What Minitab displaysValue of K
Displays no output, but creates all graphs and stores all specified values.0
Displays response information, censoring information, regression table, and log-likelihood.1
Displays table of percentiles and/or cumulative probabilities, in addition to the BRIEF 1 output.2
Displays list of factor level values, tests for terms with more than 1 degree of freedom, in
addition to the output from BRIEF 1 and 2.
3
738
Minitab Statistical Software Reliability/Survival
STEP
Displays the log-likelihood at each iteration of the parameter estimation process.
Options
ITERATION K
Changes the maximum number of iterations that Minitab will perform to reach convergence. The default value is
20. Minitab's life regression command obtains maximum likelihood estimates through an iterative process. If the
maximum number of iterations is reached before convergence, the command terminates.
START
Specifies the initial values for model parameters. The column containing the initial values must have one row for
each estimated coefficient in the model. For LREGRESSION, the value in the first row is assigned to the constant,
the value in the second row is assigned to the first predictor entered on the main command line, the value in the
third row is assigned to the second predictor, etc. Finally, the last value is assigned to the scale parameter if one
exists.
You can enter one column of values or a number of columns equal to the number of response variables. There
must be one row for each degree of freedom used.
SETS K
SETS K...K
For all distributions except the exponential and Weibull distributions, you can fix the scale parameter and estimate
the regression coefficients. The number of arguments must be 1 or equal to the number of response variables. If
there is 1 argument then all distributions will have the same scale parameter.
For the Weibull distribution, you can fix the shape parameter and estimate the regression coefficients. The number
of arguments must be 1 or equal to the number of response variables. If there is 1 argument, then all distributions
will have the same shape parameter.
CTOLERANCE K K
Changes the convergence criteria. Both arguments must be positive numbers.
Convergence is attained relative to this criterion if from one iteration to the next the change in the log-likelihood
is less than the first K. The default is .0001.
Convergence is attained relative to this criterion if from one iteration to the next the maximum change in the
coefficients is less than the second K. The default is .0001.
TOLERANCE K
Forces Minitab to keep a predictor in the model which is highly correlated with another predictor. Lowering
tolerance by giving very small argument values can prevent Minitab from eliminating problematic predictor
columns from the model. K is 1 R-squared, where R-squared is the value resulting from regressing one predictor
on the remaining predictors. The default is 1E-18 and the value must be positive.
REFERENCE C K...C K
Changes the reference for factor columns where C is the factor column and K is the reference level.
Storage
RESIDUAL C...C
Stores the ordinary residuals.
739
Minitab Statistical Software Reliability/Survival
SRESIDUAL C...C
Stores the standardized residuals.
CRESIDUAL C...C
Stores the Cox-Snell residuals.
COEFFICIENT C...C
Stores the coefficients for the fitted model down a column in the order they appear in the model.
SECOEFFICIENT C...C
Stores the standard errors for the coefficients.
CLCOEFFICIENT C...C
Stores the lower and upper confidence limits for the coefficients.
VCCOEFFICIENT M...M
Stores the variance-covariance matrix of the estimated coefficients.
LOGLIKELIHOOD K...K
Stores the last value of the log-likelihood.
Cox Regression
COXREGRESSION: Session command for performing a Cox
regression analysis
COXREGRESSION
Use COXREGRESSION to describe the relationship between predictors and survival time. The analysis uses both
fixed predictors and time-dependent predictors. To use time-dependent predictors, arrange the data in the
counting process form. The regression equation can have terms which are either continuous or categorical. You
can include interaction and polynomial terms and perform stepwise selection of terms.
Key results of comparative studies that use Cox regression often report relative risks for predictors and display
graphs of the survival experience of subjects under different treatments. For example, a study on a cancer treatment
concludes that the relative risk for two groups is 4, which means that the patients in one group are cancer-free
at 4 times the rate of patients in the other group over the study period. Minitab displays relative risks for each
variable so that you can easily assess their effect on the frequency of the event.
Specify the response for a model with fixed predictors only
For a model with fixed predictors only, the analysis requires RESPONSE.
RESPONSE C
The observed time for each observation. This value is either the time until the event of interest or the censoring
time. The column must be numeric.
740
Minitab Statistical Software Reliability/Survival
ENTRYTIME C
The entry time for each observation. The column must be numeric and the same length as the column you specified
with RESPONSE. The entry times must be less than or equal to the response times. If you do not specify a column,
Minitab uses 0 for the entry time for all observations.
You usually use entry times to model left-truncated data in models with fixed predictors. Left truncation occurs
when potential subjects of a study are observed at a time after the start of the study.
CENSOR C
Indicates which observations are censored. For a censored observation, the value in the response column is the
latest time for the row even though the event did not occur.
CVALUE K
Specifies which value indicates a censored observation. By default, the lowest numeric value or the lowest
ASCII value for text columns is the censoring value.
Specify the response for a model with time-dependent predictors or recurrent events
For a model with time-dependent predictors or recurrent events, the analysis requires CPIF, RESPONSE, and ENTRYTIME.
CPIF
Indicates that the data are in a counting process form.
RESPONSE C
The end time for each interval of observation. This value is either the time until the event of interest or the censoring
time. The column must be numeric.
ENTRYTIME C
The start time for each interval of observation. The column must be numeric and the same length as the column
you specified with RESPONSE. The start time must be less than or equal to the end time for that row. If you do
not specify a column for the entry times, Minitab uses 0 for the entry time for all observations.
You usually use entry times to model left-truncated data in models with fixed predictors. A time is left-truncated
when the subject enters after time 0.
CENSOR C
Indicates which observations are censored. The end of the time interval for a censored observation indicates that
the event of interest did not occur yet. Because the counting process form allows recurrence data, censored
intervals for a subject can appear after an uncensored interval.
CVALUE K
Specifies which value indicates a censored observation. By default, the lowest numeric value or the lowest
ASCII value for text columns is the censoring value.
Model
CONTINUOUS C...C
Specifies the continuous predictors if you have any. The column(s) must be numeric or date/time and must match
the length of the response column.
CATEGORICAL C...C
Specifies the categorical predictors if you have any. The column(s) can be numeric, text, or date/time and must
match the length of the response column.
741
Minitab Statistical Software Reliability/Survival
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. You can only repeat continuous predictors in a
cross-term. Nested terms are not allowed. The model can be nonhierarchical.
STRATIFY C [C]
Fit a stratified model. Each unique combination of values in the columns that you specify defines a stratum. A
stratified model estimates a baseline hazard rate for each strata but uses the same estimates for the effects of
the predictors. You can have up to two stratification variables.
Coding categorical predictors
REFERENCE C K ... C K
Changes the default coding for the categorical predictor columns. To change the default reference factor level,
specify the factor column followed by the reference level. (You must enclose text and date/time levels in double
quotation marks.) You can assign a reference level only when you use the binary coding (1, 0) scheme.
EFFECT
Specifies the effect coding (−1, 0, +1) scheme for categorical predictors.
Standardizing the continuous predictor
Use this set of subcommands to standardize the continuous predictors in your model. If you specify both SCALE and
LOCATION Minitab performs the subtraction before the division. LEVELS is mutually exclusive with LOCATION and
SCALE.
If you do not specify LOCATION, SCALE, or LEVELS Minitab uses the preferences set in File > Options > Linear
Models > Coding of Predictors.
LOCATION [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by subtracting a constant from
each predictor. If you do not specify any arguments, the mean of each predictor column is subtracted. K specifies
to subtract a constant. If you specify arguments, the number of arguments must match the number of continuous
predictors.
SCALE [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by dividing each predictor by a
constant. If you do not specify any arguments, each predictor column is divided by the standard deviation. K
specifies to divide by a constant. If you specify arguments, the number of arguments must match the number of
continuous predictors.
LEVELS [K...K]
Specifies that the analysis is to be performed on coded continuous predictors by DOE-type coding for the specified
low and high levels K K&K K. The number of arguments must be twice the number of continuous predictors.
Options
Additional options that you can specify for the analysis.
BRESLOW
Use the Breslow method for handling ties. If you do not specify this subcommand, Minitab uses the Efron method.
742
Minitab Statistical Software Reliability/Survival
CLUSTERID[C]
Perform the analysis using the WLW robust covariance matrix for the parameter estimates. If you specify a column,
Minitab uses it to identify groups of correlated observations due to the study design. For example, in recurrent
event models where each subject can experience the event multiple times the observations within the same
subjects are correlated. If you specify a column, Minitab calculates the robust covariance to account for the
presence of clustered observations. Rows with the same value are clustered observations. If you do not specify a
column, the effect is the same as if you use a column with a different value in every row.
All the tests and confidence intervals in the analysis are based on the robust covariance matrix if you specify
CLUSTERID. The input column can be numeric, text or date/time. Missing row values do not cause the rows to
be missing in the analysis. The missing rows are grouped together when calculating the robust variance-covariance
matrix.
WALD
Use the Wald test for the ANOVA table. You can specify only one of WALD, LRT, and SCOTEST. If you do not
specify the type of test, then the analysis uses the Wald test for the ANOVA table. If you specify CLUSTERID, then
the local Wald tests in the ANOVA table use the robust variance-covariance matrix instead of the model-based
variance-covariance matrix.
LRT
Use the likelihood ratio test for the ANOVA table. If you don't specify this subcommand, Minitab uses the Wald
test. If you specify CLUSTERID, then the ANOVA table displays Wald tests because likelihood ratio tests assume
that the observations within clusters are independent.
SCOTEST
Use the score test for the ANOVA table. If you don't specify this subcommand, Minitab uses the Wald test. If there
are no tied event times, then the score test is identical to the log-rank test. If you specify CLUSTERID, then the
ANOVA table displays Wald tests because likelihood ratio tests assume that the observations within clusters are
independent.
CASEID C
Specifies a column to identify the subjects in the study. Use this subcommand only if you also specify CPIF. The
column can be numeric, text, or date/time. You can identify a subject using a case number, ID, or name. Minitab
groups missing rows together to calculate the per case diagnostics.
In a counting process input format, a single subject can have multiple rows of diagnostic statistics. If you specify
a case-identification column, Minitab provides a single diagnostic statistic per case by summing the statistics over
the multiple rows pertaining to the same case.
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
743
Minitab Statistical Software Reliability/Survival
Stepwise
FINFORMATION, STEPWISE, FORWARD, and BACKWARD perform a stepwise regression procedure to fit the model. No
arguments are needed for these subcommands. If you specify CLUSTERID, only BACKWARD uses the robust
variance-covariance matrix at each step. FORWARD always use the model-based variance-covariance matrix, even if
you specify CLUSTERID.
FINFORMATION
Specifies a stepwise model selection procedure that uses forward information criteria selection. Use AICCORRECTED
or BICRITERION to specify which information criterion to use to select the final model. If you do not specify a
criterion, Minitab uses AICCORRECTED.
The forward information criteria procedure adds the term with the lowest p-value to the model at each step. If
you do not include subcommands about hierarchy, FINFORMATION adds 1 term at a step and maintains model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
Minitab calculates the information criteria for each step.
In most cases, the procedure continues until one of the following conditions occurs:
The procedure does not find an improvement of the criterion for 8 consecutive steps.
The procedure fits the full model.
The procedure fits a model that leaves 1 degree of freedom for error.
If you specify settings for the procedure that require a hierarchical model at each step and allow only one term
to enter at a time, then the procedure continues until it either fits the full model or fits a model that leaves 1
degree of freedom for error. Minitab displays the results of the analysis for the model with the minimum value
of the selected information criterion, either the corrected Akaike's Information Criterion (AICc) or the Bayesian
Information Criterion (BIC).
AICCORRECTED
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the final model.
BICRITERION
Specifies the use of the Bayesian Information Criterion (BIC) to select the final model.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. If you
do not include subcommands about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model
hierarchy, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
FORWARD
Specifies a stepwise model selection procedure that uses forward selection. If you do not include subcommands
about hierarchy, STEPWISE and FORWARD add 1 term at a step and maintain model hierarchy, the equivalent of
the following:
HIERARCHICAL; ALLTERMS; ALWAYS; SINGLE.
BACKWARD
Specifies a stepwise model selection procedure that uses backward elimination. Removes a single term at each
step and maintains a hierarchical model, the equivalent of the following:
HIERARCHICAL; ALLTERMS; ALWAYS.
AENTER K
Specifies the alpha level at which a term is entered into the model. The default is 0.15 for STEPWISE and 0.25
for FORWARD.
744
Minitab Statistical Software Reliability/Survival
AREMOVE K
Specifies the alpha level at which a term is removed from the model. The default is 0.15 for STEPWISE and
0.10 for BACKWARD. For STEPWISE, K must be greater than or equal to K for AENTER.
ENTER termlist
Specifies the terms that are contained in the starting model for STEPWISE. The ENTER termlist must be a
subset of the TERMS termlist or in the default term list in the design.
FORCE termlist
Specifies the terms to be forced in the model. The FORCE termlist must be a subset of the TERMS termlist
or in the default term list in the design.
NOHIERARCHICAL
Specifies that the model selection procedure does not consider hierarchy.
HIERARCHICAL
Maintains a hierarchical model in stepwise regression. In a hierarchical model, if a higher-order term is
included, all lower-order terms that comprise the higher-order term also appear in the model. For example,
a model that includes the interaction term A*B*C is hierarchical if it includes the following main effects and
lower-order interactions: A, B, C, A*B, A*C, and B*C.
CATONLY
Specifies that only the categorical terms in the model have to be hierarchical.
ALLTERMS
Specifies that both categorical and continuous terms have to be hierarchical.
ATEND
Specifies that the final step of the stepwise procedure adds terms to make the model hierarchical.
ALWAYS
Specifies that the model is hierarchical at every step.
SINGLE
Specifies that only one term can enter the model at each step. So a higher-order term can enter
the model only if the terms that comprise the term are already in the model. For example, the
algorithm does not consider the addition of A*B unless A and B are already in the model.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
MULTIPLE
Specifies that multiple terms can enter the model at each step. So a higher order term can enter
the model, and the terms that comprise the term enter the model at the same time. For example,
if A*B is the most statistically significant term, A*B enters the model. At the same time, A and B
enter the model if those terms are not in the model already.
BACKWARDS does not use SINGLE or MULTIPLE because terms only exit the model.
Results
NODEFAULT
Specifies that no default tables or graphs will be displayed
745
Minitab Statistical Software Reliability/Survival
TMETHOD
Displays the method table.
TMSDETAILS
Displays the type of stepwise procedure and the alpha values to enter and/or remove a predictor from the model.
Use FULL to display the coefficients, p-values, and model summary statistics for each step of the procedure. Use
NOFULL to hide these statistics. If you do not specify FULL or NOFULL, Minitab uses the preferences set in File
> Options > Linear Models > Stepwise.
TLEVELS
Displays the table of categorical predictors and their levels.
TSTEP
Displays the log-likelihood at each iterative step of the optimization algorithm.
TCENSORING
Displays the table showing the number of uncensored and censored values. If the analysis is stratified, there is a
row for each stratum plus a row for totals.
TEQUATION
Displays the regression equation table. Minitab will display up to 50 equations. If you want to see a single equation,
rather than a separate equation for each factor level combination, use SINGLE. To see the separate equations,
use SEPARATE. If you do not specify SINGLE or SEPARATE, Minitab uses the preferences set in File > Options
> Linear Models > Display of Results.
TANOVA
Displays the ANOVA table.
TSUMMARY
Displays the model summary table.
TGOODNESS
Displays the goodness-of-fit tests table. The table includes the likelihood ratio, Wald, and score testing methods.
If you specify CLUSTERID, then the likelihood ratio test results are missing values because the method requires
independence of observation within clusters.
TCOEFFICIENTS
Displays the table of coefficients. Use FULL to display the full set of coefficients for categorical predictors. Use
NOFULL to show only the linearly independent coefficients. If you do not specify FULL or NOFULL, Minitab uses
the preferences set in File > Options > Linear Models > Display of Results.
If you specify CLUSTERID, then the statistics are based on the robust variance-covariance matrix.
TRRISK
Displays the relative risks table. Minitab displays a separate table for continuous and categorical predictors.
INCREMENT K...K
Specify the unit of change for the continuous predictors. The number and order of arguments must match
the arguments you specify with CONTINUOUS. If you do not specify INCREMENT, the unit of change is 1.
TPHTEST
Displays the tests of proportional hazards table. The table contains tests of linear associations between the scaled
Schoenfeld residuals and some function, g(t), of the event times. In practice, the selected function g(t) are the log
function, the Kaplan-Meier's survival function, the rank function, or the identity function. You can select these
functions with the following subcommands:
746
Minitab Statistical Software Reliability/Survival
LOG
Use the natural log function, g(t) = ln (t), to transform the event times for the tests of proportional hazards.
KMESTIMATES
Use the Kaplan-Meier's survival function to transform the event times for the tests of proportional hazards.
The survival estimates are based on the response time.
RANK
Use the rank function, g(t) = Rank (t), to transform the event times for the tests of proportional hazards. The
rank function is based on the ranks of the event times. Tied values are assigned their average ranks.
IDENTITY
Use the original units for the tests of proportional hazards. Minitab uses this option if you do not specify a
function.
TSURVIVAL
Displays the survival function table. Minitab uses the mean of each predictor for continuous predictors and the
reference levels for categorical predictors. You cannot specify this subcommand if you also specify CPIF.
LOG
Calculate the confidence intervals based on a log transformation of the survival function. This is the default
setting.
CLOGLOG
Calculate the confidence intervals based on the complementary log-log transformation of the survival function.
TEXPAND
Displays the expanded version of tables.
Graphs
GSURVIVAL
Displays the survival plot. By default, Minitab uses the mean of each predictor for continuous predictors and the
reference levels for categorical predictors. GSURVIVAL has two optional subcommands to specify new predictor
values for the survival plot. You cannot specify this subcommand if you also specify CPIF. The subcommands
PANEL, OVERLAY, and SEPARATE only affect the graph if the model is stratified.
CPREDICTOR C...C
Specify a column of predictor values that Minitab uses for the survival function. The number and type of
arguments must match the variables in the model. Specify columns with continuous predictors first, then
specify columns with categorical predictors. For a categorical predictor, a new value must be one of the levels
of the categorical predictor.
KPREDICTORS K...K
Specify individual predictor values that Minitab uses for the survival function. Specify continuous predictors
first, then specify categorical predictors. You can repeat this subcommand. If you specify a missing value for
a continuous predictor, Minitab uses the mean of that predictors. If you specify a missing value for a categorical
predictor, Minitab uses the reference level. If you enter a missing value as a numeric value, enclose it in single
quotes. You can enclose text and date/time values in single or double quotes.
PANEL
Displays the survival plots associated with each stratum in a separate panel of the same graph. This is the
default setting.
747
Minitab Statistical Software Reliability/Survival
OVERLAY
Overlay the survival plots associated with each stratum on the same graph.
SEPARATE
Displays the survival plots associated with each stratum in a separate graph in the output pane.
GDEVIANCE
Displays a graph of the deviance residuals versus the risk scores. The graph measures the effect of a given subject
on the model. You can also use it to detect outliers.
GANDERSEN
Displays the Andersen plot for the stratification variables. Use this graph to check whether the proportional hazards
assumption is satisfied for the stratification variables. If the assumption holds, the curves should be straight lines
through the origin. If the variables do not need to be in the model, the curves should roughly follow the 45° line.
Minitab only displays this plot if the model is stratified.
GARJAS C...C
Display the Arjas plots for the variables that you specify. Use to check for a missing predictor and whether the
proportional hazards assumption holds for a predictor. You must specify at least one column. The column can be
any data type but must have the same number of rows as the column you specify with RESPONSE. You must
categorize a continuous variable before you use it in an Arjas plot.
GVARIABLE C...C
Display graphs of the martingale residuals versus the variables that you specify. Use to assess whether you should
add a predictor to the model, or whether you should use a different functional form for an existing predictor. You
must specify at least one column. The column must be numeric or date/time data and must have the same number
of rows as the column you specify with RESPONSE.
Storage
COEFFICIENT [C]
Stores the coefficients for the fitted model in a column in the order they appear in the model.
SECOEFFICIENT [C]
Stores the standard errors for the coefficients.
SCOVARIANCES M
Stores the variance-covariance matrix of the estimated coefficients.
SCORRELATION M
Stores the correlation matrix of the estimated coefficients.
STST [C]
Stores the test statistics for the coefficients.
SPVALUES [C]
Stores the p-values for the coefficients.
XMATRIX M
Stores the design matrix for the regression model.
MARRESIDUALS [C]
Stores the martingale residuals. If the data is in a counting process format and you specify a case ID variable, then
Minitab stores per subject residuals by summing the per observation residuals over the rows pertaining to the
748
Minitab Statistical Software Reliability/Survival
same subject. If you do not specify a case ID variable then Minitab stores per observation residuals which are not
necessarily per subject residuals.
DEVRESIDUALS [C]
Stores the deviance residuals. If you specify a smaller number of columns, then you get a subset of the parameters.
If the data is in a counting process format and you specify a CASEID variable, then Minitab stores per subject
deviance residuals. If you do not specify a CASEID variable then Minitab stores per observation deviance residuals
which are not necessarily per subject deviance residuals.
SCHRESIDUALS [C...C]
Stores the Schoenfeld residuals. Minitab stores residuals in a column for each parameter in the model. If the data
is in a counting process format and you specify a CASEID variable, then Minitab stores per subject residuals by
summing the per observation residuals over the rows pertaining to the same subject. If you do not specify a
CASEID variable then Minitab stores per observation residuals which are not necessarily per subject residuals.
WSCHRESIDUALS [C...C]
Stores the weighted Schoenfeld residuals. Minitab stores residuals in a column for each parameter in the model.
If the data is in a counting process format and you specify a CASEID variable, then Minitab stores per subject
residuals by summing the per observation residuals over the rows pertaining to the same subject. If you do not
specify a CASEID variable then Minitab stores per observation residuals which are not necessarily per subject
residuals.
SCRESIDUALS [C...C]
Stores the score residuals. Minitab stores residuals in a column for each parameter in the model. If the data is in
a counting process format and you specify a CASEID variable, then Minitab stores per subject residuals by summing
the per observation residuals over the rows pertaining to the same subject. If you do not specify a CASEID variable
then Minitab stores per observation residuals which are not necessarily per subject residuals.
DFBETAS [C...C]
Stores the DFBetas, also known as scaled score residuals. Minitab stores residuals in a column for each parameter
in the model. If the data is in a counting process format and you specify a CASEID variable, then Minitab stores
per subject DFBetas by summing the per observation DFBetas over the rows pertaining to the same subject. If
you do not specify a CASEID variable then Minitab stores per observation DFBetas which are not necessarily per
subject DFBetas.
LOGLIKELIHOOD [C]
Stores the first and the last value of the log-likelihood.
STETIME [C]
Stores the transformed event times associated with the proportional hazard test. Only specify this sucommand if
you also specify TPHTEST.
Algorithm options
TOLERANCE K
Specifies the tolerance level for collinearity and constant check. By default, K = 4 * 2.22e–012.
ITERATIONS K
Specifies the maximum number of iterations. By default, K = 25.
CTOLERANCE K K
Specifies the convergence tolerances used in the Newton-Raphson algorithm for maximizing the log-likelihood.
The value you enter for the first K is for the convergence of log-likelihood values. The value you enter for the
second K is for the convergence of the estimates. The default for both is 0.0001.
749
Minitab Statistical Software Reliability/Survival
Probit Analysis
PROBIT: Session command for performing probit analysis
PROBIT C [C] = C [C]
Analyzes the relationship between a binary response in C and a single stimulus and optional factor in C C using
probit analysis.
Use probit analysis when you want to estimate percentiles, survival probabilities, and cumulative failure probabilities
for the lifetime distribution of a system at some stress, and draw probability plots. When you enter a factor and
choose a Weibull, lognormal, or loglogistic distribution, you can also compare the potency of the stress under
different conditions.
Minitab calculates the model coefficients using a modified Newton-Raphson algorithm. The left-hand side of the
equation specifies the response variable. Enter one column if using a response/frequency format and two columns
if using success/trial, success/failure or failure/trial format. On the right-hand side of the equation, enter a stress
variable and optionally a factor variable.
FREQUENCY C
Specifies multiple occurrences of the same row of data when your data are in response/frequency format.
ST
The format of the response is a column of events (successes) and a column of trials.
SF
The format of the response is a column of events (successes) and a column of failures.
FT
The format of the response is a column of non-events (failures) and a column of trials.
FACTOR C
Specifies a factor in the model.
Distributions
Specifies the tolerance distribution.
WEIBULL
The Weibull distribution.
SEXTREMEVALUE
The smallest extreme value distribution.
LOGISTIC
The logistic distribution.
LLOGISTIC
The loglogistic distribution.
NORMAL
The normal distribution.
750
Minitab Statistical Software Reliability/Survival
LNORMAL
The lognormal distribution.
Estimation
PTILES K...K
PTILES C
Specifies the additional percentiles to be estimated.
You can enter individual percents (0 < P < 100) or a column of percents.
STRESS K...K
STRESS C
Calculates the survival probability for stresses in K or C.
ECFPROBABILITY
Estimates cumulative failure probabilities instead of survival probabilities.
HOSMER K
Specifies the number of groups for the Hosmer-Lemeshow goodness-of-fit test.
NAPPROXIMATION
Specifies a normal approximation confidence interval instead of the default Fiducial confidence intervals.
CONFIDENCE [K]
Specifies the percent confidence, K, for your confidence intervals.
LOWCI
Calculates one-sided, lower confidence intervals for parameter estimates and percentiles.
UPCI
Calculates one-sided, upper confidence intervals for parameter estimates and percentiles.
TWOCI
Calculates two-sided confidence intervals for parameter estimates and percentiles.
Graphs
PPLOT
Displays a probability plot that describes the fitted model.
SPLOT
Displays a survival plot that describes the fitted model.
CFPLOT
Displays a cumulative failure plot that describes the fitted model.
CI
Specifies to include confidence intervals on the probability, survival, and cumulative failure plots.
751
Minitab Statistical Software Reliability/Survival
PPEARSON
Displays a plot of the Pearson residuals versus event probability.
PDEVIANCE
Displays a plot of the deviance residuals versus event probability.
PANEL
Displays graphs of different variables or by levels in separate panels on the same graph.
SEPARATE
Displays graphs of different variables or by levels on separate graphs.
Options
ITERATION K
Changes the maximum number of iterations that Minitab will perform to reach convergence. The default value is
20. Minitab's Probit analysis command obtains maximum likelihood estimates through an iterative process. If the
maximum number of iterations is reached before convergence, the command terminates.
START C
Specifies the initial values for model coefficients. The column containing the initial values must have one row for
each estimated coefficient in the model. For Probit Analysis, the value in the first row is assigned to the constant,
the value in the second row is assigned to the first predictor entered on the main command line, the value in the
third row is assigned to the second predictor, and so on.
SETC K
Sets the natural response value to K.
OPTC
If you specify OPTC, then K is the starting value for the natural response. If you do not specify OPTC, then
the natural response is set to K and not estimated from the data
REFERENCE C K, ..., C K
Changes the default coding for a response variable and/or factor. Enter the column followed by the reference
value.
CTOLERANCE K K
Changes the convergence criteria. Both arguments must be positive numbers.
Convergence is attained relative to this criterion if from one iteration to the next the change in the log-likelihood
is less than the first K. The default is .0001.
Convergence is attained relative to this criterion if from one iteration to the next the maximum change in the
coefficients is less than the second K. The default is .0001.
Results
BRIEF K
Controls the amount of output.
What output Minitab displaysValue of K
Minitab displays no output, but displays all requested graphs and performs all requested storage.0
752
Minitab Statistical Software Reliability/Survival
What output Minitab displaysValue of K
Displays response information, regression table, test for equal slopes, log-likelihood, multiple
DF test and 2 goodness-of-fit tests.
1
Displays estimated distribution parameters, table of percentiles and survival probabilities, in
addition to the BRIEF 1 output.
2
Displays characteristic of distribution and Hosmer-Lemeshow goodness-of-fit test, in addition
to the output from BRIEF 1 and 2.
3
STEP
Displays the log-likelihood at each iteration of the parameter estimation process.
Storage of residuals and percentile information
PRESIDUAL C
Stores the Pearson residuals.
DRESIDUAL C
Stores the deviance residuals.
PPERCENT C
Stores the percents associated with the percentiles.
PERCENTILE C
Stores the percentiles.
SEPERCENTILE C
Stores the standard error of the percentiles.
CLPERCENTILE C
Stores the lower and upper confidence limits for the percentiles.
Storage of information for the survival or cumulative failure probabilities
The following subcommands store information related to the survival or cumulative failure probabilities. You can use
these subcommands only if the STRESS subcommand is given.
SSTRESS C
Stores the stress values associated with the survival or cumulative failure probabilities.
SURVPROBABILITY C
Stores the survival probabilities.
CLSURVPROBABILITY C
Stores the upper and lower confidence limits of the cumulative failure probabilities.
CFPROBABILITY C
Stores the cumulative failure probabilities.
CLCFPROBABILITY C
Stores the upper and lower confidence limits of the cumulative failure probabilities.
753
Minitab Statistical Software Reliability/Survival
Storage of information for the estimated equation
EPROBABILITY C
Stores the event probabilities.
COEFFICIENT C
Stores the coefficients for the fitted model down a column in the order they appear in the model.
SECOEFFICIENT C
Stores the standard errors of the coefficients down a column in the order that they appear in the model.
NATRESPONSE K
Stores the natural response rate.
SENATRESPONSE K
Stores the standard error of the natural response.
VCCOEFFICIENT M
Stores the variance-covariance matrix of the estimated parameters.
LOGLIKELIHOOD K
Stores the log-likelihood from the last iteration.
Warranty Analysis
TWARRANTY: Session command for pre-processing warranty data
TWARRANTY C...C
Pre-processes the warranty data in columns C...C to interval censored data. If you enter shipment values in a
column, the first argument corresponds to this shipment column, and subsequent arguments refer to columns
of failures or returns, input in chronological order. Alternatively, if you enter shipment values in the first row of
each return/failure column, arguments correspond to these columns, input in chronological order.
After pre-processing your warranty data with this command, you can complete your warranty analysis with the
Warranty Prediction command. TWARRANTY accepts warranty data in two formats: you can either enter the
numbers of items shipped in a single column alongside the triangular matrix of return/failure counts, or you can
enter the numbers of items shipped in a row above the triangular matrix containing the return/failure counts.
SHPROW
Indicates that you entered shipment values in the first row of each failure/return column. Without this
subcommand, Minitab assumes the shipment values reside in a separate column.
STWDATA C C C
Stores the transformed warranty data in columns C, C, and C. The first column stores the start times, the
second column stores the end times, and the last column stores the frequencies. These columns, containing
interval censored data, are the input columns for the Warranty Prediction command.
AFTER
Appends the transformed warranty data into three empty columns after the last column used in the current
worksheet. This subcommand s not supported in local macros.
754
Minitab Statistical Software Reliability/Survival
WPREDICTIONS: Session command for performing warranty
predictions
WPREDICTIONS C C
Performs warranty predictions on your interval censored data in C C. The first argument is the "start time" and
the second argument is the "end time".
WPREDICTIONS uses information about current warranty claims to predict the number of claims in the future.
Input data must be interval censored; use TWARRANTY command to convert warranty data from the popular
triangular matrix format to interval censored format.
FREQUENCY C
Specifies the number of occurrences of a row of the interval censored data. The length of the argument must
equal the length of the argument for WPREDICTIONS.
Distributions
Specifies the distribution that the expected failure times are assumed to follow.
SEXTREMEVALUE
Smallest extreme value distribution.
WEIBULL
Weibull distribution.
TWEIBULL
Three-parameter Weibull distribution.
EXPONENTIAL
Exponential distribution.
TEXPONENTIAL
Two-parameter exponential distribution.
NORMAL
Normal distribution.
LNORMAL
Log-normal distribution.
TLNORMAL
Three-parameter log-normal distribution.
LOGISTIC
Logistic distribution.
LLOGISTIC
Log-logistic distribution.
TLLOGISTIC
Three-parameter log-logistic distribution.
755
Minitab Statistical Software Reliability/Survival
Estimation methods
LSXY
Estimates model parameters using the least squares estimation method.
MLE
Estimates models parameters using the maximum likelihood estimation method.
ESTIMATES C
Specifies estimated parameters (historical estimates or estimates obtained from parametric distribution analysis).
Prediction options
PREDICT K
Predicts the number of failures in future time periods 1 to K.
PRODUCTION K...K
PRODUCTION C
Specifies the projected number of new units to be produced during the future time periods for which you want
to predict failures. If you enter one constant, it applies to all future time periods. If you enter multiple constants
or a column, values will correspond respectively to the future time periods. The number of constants, or the
number of values in the column, must equal the argument for the PREDICT subcommand.
WLENGTH K
Specifies the length of the warranty in K units of time. The time units must be the same as the time units of the
data itself.
COST K
Specifies the average cost K associated with a failure.
LOWCI
Specifies a one-sided lower confidence bound for the predicted number of failures based on a Poisson
approximation.
UPCI
Specifies a one-sided upper confidence bound for the predicted number of failures based on a Poisson
approximation.
TWOCI
Specifies a two-sided confidence interval for the predicted number of failures based on a Poisson approximation.
Graph options
GPFPLOT
Plots the predicted failures against their future time periods.
GPCPLOT
Plots the predicted cost of failures against their future time periods.
GCI
Displays Poisson confidence intervals on the predicted failures plot.
756
Minitab Statistical Software Reliability/Survival
Storage options
SPFAILURES C
Stores predicted future failures.
SPCOST C
Stores predicted future costs of failures.
SCLFAILURES C
Stores lower and upper confidence limits for the predicted failures in C and C.
SCLCOST C C
Stores lower and upper confidence limits for the predicted costs in C and C.
757
Minitab Statistical Software Reliability/Survival
Predictive Analytics
CART Regression
RTREE: Session command for creating a regression tree
RTREE
Creates an optimal regression tree and a set of close-to-optimal regression trees. This analysis also provides
residual plots, an important variables chart, and other diagnostic measures so that you can assess the validity of
your regression model.
The response variable column must be continuous and must contain at least 2 distinct numeric values.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable or the weights column.
RESPONSE C
Enter a column that contains 2 or more distinct values of a continuous response. C must be numeric.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Validation
Use one of the following subcommands to specify the validation method.
CVTEST
TEST
NTEST
If no validation subcommand is issued, then Minitab uses the following defaults, depending on the number of rows:
The default when the number of rows 5000
CVTEST 10;
RANDOMIZE 12345;
The default when the number of rows > 5000
TEST 0.3;
RANDOMIZE 12345;
758
Minitab Statistical Software Predictive Analytics
CVTEST K
Use K-fold cross-validation as a test method. Specify K number of folds.
K must be an integer between 2 and the sample size; 2 K 1000.
RANDOMIZE K
Specify the base number for randomly splitting the training data set into K subsets for cross-validation. K
sets the starting point for Minitab's random number generator.
K must be positive integer. Use 12345 to get the same results as Minitab's defaults.
CVTEST C
Use K-fold cross-validation as a test method. Enter C to specify the rows for each fold.
C can be numeric or text and must be the same length as the response column.
TEST K
Specify a proportion of rows for the test set. K is the proportion of the data to use for the test set. K must be
between 0 and 1.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be positive integer. Use 12345 to get the same results as Minitab's defaults.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
NTEST
No model validation.
Use SSAMPLE C to store a column that shows the assignments for each row in the validation. When CVTEST is used:
The storage column, Sample_Id, stores the fold identification in C.
C contains values 1, 2, ..., K.
When TEST is used:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the two values.
Options
Use one of the following subcommands to specify the node splitting method.
LSE: Use the Least Squared Errors method to split a node. This is the default method.
MAXRSQ: Use maximum R
2
from test set to select the optimal tree.
STERROR K: Use within K standard error of the maximum R
2
to select the optimal tree.
LAD: Use the Least Absolute Deviation method to split a node.
MINMAD: Use minimum relative mean absolute deviation (MAD) from test set to select the optimal tree.
STERROR K: Use within K standard error of minimum MAD to select the optimal tree.
If you do not specify the node splitting method, then the analysis uses LSE and STERROR 1.
The following subcommands are available to control tree growth due to sample size or node complexity.
759
Minitab Statistical Software Predictive Analytics
NOSPLIT K: Do not split a node if the node size is less than K. K=10 is the default.
NOTERMINAL K: Do not create a terminal node that is smaller than K. K=3 is the default.
MAXTDEPTH K: Set maximum tree depth to the Kth layer.
SURROGATE K
Specify K surrogates to consider when a specific predictor that splits a node has missing values.
K must be an integer between 0 and the number of predictors 1, for example:
K = 0: Specifies no consideration of surrogate variables.
K = Number of total predictors 1: Specifies to consider all predictors other than the splitter variable.
If this subcommand is not issued, K=10 is the default value.
WEIGHT C
Specify the case weights in C. The column length must be the same length as the target column length.
Values must be 0. Assigning a weight of 0 or missing excludes the row from the analysis.
MPENALTY K
Specify a penalty value for a predictor with missing values.
0.0 K 2.0, for example:
K = 0: Specifies no penalty.
K = 2: Specifies highest penalty.
.
CPENALTY K
Specify a penalty value for categorical predictors that have many values.
0.0 K 5.0, for example:
K = 0: Specifies no penalty.
K = 5: Specifies highest penalty.
Graphs
GTDIAG
Displays the optimal tree diagram.
GRSQ
Displays the R
2
vs number of terminal nodes graph when LSE is issued. If LAD is issued, GRSQ displays relative
MAD vs number of terminal nodes graph.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables.
0: Displays all predictors.
760
Minitab Statistical Software Predictive Analytics
GFIT
Displays fits vs actual response values plot.
RTYPE K
Specifies the type of residual to plot. When K =
1: Displays regular residuals.
2: Displays percent residuals.
GRBOX
Displays boxplot of the residuals. If the analysis uses a validation method, the graph has separate boxplots for
the training data set and the test data set.
SORT
Sorts terminal nodes on the x-axis in mean squared error (MSE) or mean absolute deviation (MAD) ascending
order. Otherwise, the terminal nodes are in order by identification number.
GERROR
Displays mean squared error (MSE) or mean absolute deviation (MAD) vs terminal node id plot. Y axis = MSE if
LSE is issued; otherwise Y axis = MAD
GBOX
Displays boxplot of response values by terminal node.
GRESIDUAL
Displays residual vs terminal node id plot.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes the model validation method, the node splitting method, and other
information about the analysis.
TRESPONSE
Displays the Response information table, which includes descriptive statistics about the response variable.
TSUMMARY
Displays the Model summary table, which includes the number of predictors, the number of important predictors,
the number of nodes, the R
2
statistic, and other information about the model.
TPERROR K
Displays percent of error statistics due to largest residuals. K represents the percent of largest residuals being
displayed.
0 < K 100. K = 20 is the default, which means the table includes statistics for groups that contain up to the
largest 20% of the residuals. The table always includes K%. Up to 20%, the table includes 1%, 2%, 2.5%, 3%, 4%,
5%, 7.5%, 10%, and 15%. After 20%, the table includes multiples of 10%.
TNTYPE K
Determines the types of nodes to display in the tables when you issue TCRITERIA. The type of node depends on
the value of K:
761
Minitab Statistical Software Predictive Analytics
1: Displays the best terminal nodes (lowest values of MSE or MAD).
2: Displays the worst terminal nodes (highest values of MSE or MAD).
3: Displays the best and worst terminal nodes.
TRSTAT K
Displays response fits and error statistics for K terminal nodes. The nodes are the nodes with the best fit values
unless you specify a different type of node with TNTYPE.
TCRITERIA K
Displays the criteria for classifying subjects into K terminal nodes. The nodes are the nodes with the highest rates
of correct classifications unless you specify a different type of node with TNTYPE.
For example, with the subcommands TNTYPE 2; TRSTAT 4; TCRITERIA 3; Minitab displays the 4 worst nodes in the fits
and errors table and the criteria for classifying the subjects in the 3 worst nodes.
Storage
SRTREES K
Stores the optimal tree as well as additional candidate trees that are smaller than the optimal tree, the optimal
tree, and up to K larger than optimal trees.
SFIT C
Stores the fitted response for each record in C.
SRESID C
Stores the residual for each record in C.
SPRESID C
Stores the percent residual for each record in C.
SSTDEV C
Stores the standard deviation for each record in C.
SMSE C
Stores the mean squared error for each record in C. If the analysis uses k-fold cross-validation, then the stored
value is for the terminal node when the record is in the training data set.
SMAD C
Stores the mean absolute deviation for each record in C. If the analysis uses k-fold cross-validation, then the
stored value is for the terminal node when the record is in the training data set.
SMAPE C
Stores the mean absolute percent error for each record in C. If the analysis uses k-fold cross-validation, then the
stored value is for the terminal node when the record is in the training data set.
STNID C
Stores the ID number of the terminal node for each row. The terminal node is also called a cluster.
IERTREE: Session command for selecting an alternative regression
tree
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
762
Minitab Statistical Software Predictive Analytics
IERTREE K K
Selects a different tree from the optimal one inside a tree object generated by the RTREE command.
The first argument, K, is a positive integer, that represents the regression tree object ID. The first regression tree
that you create in a project has the object ID 1. The second regression tree that you create in a project with the
RTREE command has the object ID 2. Alternative trees are always made from an optimal tree, so alternative trees
do not have a tree object ID.
The second argument, K, is an integer that indexes a specific tree within the tree object. K values may be negative
or positive values, depending on whether the alternative tree is smaller than or larger than the optimal tree. The
tree object name uses:
0: Represents the optimal tree.
Negative integers: Represents trees that are smaller than the optimal tree. For example, K = -4 would store
the tree that is 4 smaller than the optimal.
Positive integers: Represents trees that are larger than the optimal tree. For example, K = 2 would store the
tree that is 2 larger than the optimal.
The tables and graphs for the new tree are the same as for the original tree. The new tables and graphs are in a
new output tab. The same columns that the original analysis stored are also stored for the new tree. For example,
if the original analysis stored the terminal node IDs in TNODEID[0] and you select an alternative tree that is 4 trees
smaller than the optimal tree, then the new analysis stores the terminal node IDs in the column TNODEID[-4].
RTPREDICT: Session command for predicting responses for new
observations for a regression tree
RTPREDICT K K [K]
Predicts the response values for new observations with the tree that K and K indicate.
The first argument, K, is the identification number of a tree. This K is always a positive integer. The first tree that
you create in a project is identified as 1, the second is identified as 2, and so on. The number for a tree remains
the same even if you delete the output for another tree from the Navigator. For example, if you delete the output
for the first tree, the second tree that you made remains tree 2.
The second argument, K, is an integer that indexes a specific tree within the tree object. K values may be negative
or positive values, depending on whether the alternative tree is smaller or larger than the optimal tree. The second
K must match one of the additional trees stored by the RTREE command.
In the tree object:
0 represents the optimal tree.
Negative integers represent trees that are smaller than the optimal tree. For example, K = –4 stores the tree
that is 4 smaller than the optimal.
Positive integers represent trees that are larger than the optimal tree. For example, K = 2 stores the tree that
is 2 larger than the optimal.
The third argument, K, allows you to optionally specify which output tab contains the prediction results. K is a
positive integer from 1...N. K increases every time another tree with that same pruning increments. If you do not
specify this argument, Minitab appends the prediction results to the last pruning.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the tree object.
763
Minitab Statistical Software Predictive Analytics
If a predictor is categorical, the values in C must match the values in the tree object.
The order of the predictors follows a strict format.
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand from
the RTREE command.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from the RTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The RTREE command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
tree.
If a predictor is categorical, the corresponding value for K must match the values in the tree object.
The order of the values follows a strict format:
1. Enter values for continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from the RTREE command.
2. Enter values for categorical predictors second. Use the order of the predictors from the CATEGORICAL
subcommand from the RTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The RTREE command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the values in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
764
Minitab Statistical Software Predictive Analytics
Results
TPREDICTION
Displays the prediction table.
Storage
STNID C
Stores the terminal node (cluster) ID for each new observation.
SPCLASS C
Stores the predicted response values.
CART Classification
CTREE: Session command for creating a classification tree
CTREE
Creates an optimal classification tree and a set of close-to-optimal classification trees. This analysis also provides
an important variables chart, gain and lift charts, and other diagnostic measures so that you can assess the validity
of your classification model.
The response variable column must be categorical. The values can be text or numeric.
If the response column has only 2 distinct values (binary response), you can specify which value is the reference
event with EVENT. If you do not specify the event or if the response has more than 2 values (multinomial response),
then the reference event depends on whether the column contains numbers or text. When the values are numbers,
the highest value is the reference event. When the values are text, the last value alphabetically is the event. For
example, if you enter the response variable as success and failure, success is the event.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable or the weights column.
RESPONSE C
Enter a column that contains 2 or more distinct values of a categorical response. C can be text or numeric.
EVENT K
Specifies the event value for a binary response. K must be one of the two response values.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
765
Minitab Statistical Software Predictive Analytics
Prior/Cost
Use one of the following subcommands to set the prior probabilities. If no subcommand from this set is issued, EPRIOR
is the default.
EPRIOR: Sets equal prior probabilities for all response levels.
FPRIOR: Sets the prior probability for the jth response class to be the sample proportion of the class from both
training and test data sets.
PRIOR K...K: Specifies prior probabilities for all J response levels. The number of Ks must match the number of
distinct response values. All Ks must be between 0 and 1, and their sum must equal 1.
COST K K K K K K...K K K
Specify costs for misclassification. Without this subcommand, equal costs of 1 are assumed.
Suppose the response has two levels, 1 and 2, and the syntax is COST 2 1 2.45 1 2 1.37
The cost for assigning level 2 to an actual response level 1 is 2.45.
The cost for assigning level 1 to an actual response level 2 is 1.37.
Note The order of the two cost sets does not matter. Also, you can specify the cost of some sets and not other sets. Minitab assumes
the cost for unspecified sets is 1.
For a response with J levels, the total possible number of cost sets is J x (J - 1). You can specify a subset of the
sets. The order of the three number sets does not matter, as long as the first two values in each set make a distinct
pair, and the third value K is greater than 0.
Validation
Use one of the following subcommands to specify the validation method.
CVTEST
TEST
NTEST
If no validation subcommand is issued, then Minitab uses the following defaults, depending on the number of rows:
The default when the number of rows 5000
CVTEST 10;
RANDOMIZE 12345;
The default when the number of rows > 5000
TEST 0.3;
RANDOMIZE 12345;
CVTEST K
Use K-fold cross-validation as a test method. Specify K number of folds.
K must be an integer between 2 and the sample size; 2 K 1000.
RANDOMIZE K
Specify the base number for randomly splitting the training data set into K subsets for cross-validation. K
sets the starting point for Minitab's random number generator.
K must be positive integer. Use 12345 to get the same results as Minitab's defaults.
766
Minitab Statistical Software Predictive Analytics
CVTEST C
Use K-fold cross-validation as a test method. Enter C to specify the rows for each fold.
C can be numeric or text and must be the same length as the response column.
TEST K
Specify a proportion of rows for the test set. K is the proportion of the data to use for the test set. K must be
between 0 and 1.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be positive integer. Use 12345 to get the same results as Minitab's defaults.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
NTEST
No model validation.
Use SSAMPLE C to store a column that shows the assignments for each row in the validation. When CVTEST is used:
The storage column, Sample_Id, stores the fold identification in C.
C contains values 1, 2, ..., K.
When TEST is used:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the two values.
Options
Use one of the following subcommands to specify the node splitting method.
GINI: Use the Gini method to split a node. This is the default method.
ENTROPY: Use the Entropy method to split a node.
TWOING: Use the Twoing method to split a node.
CPROB: Use the class probability method to split a node.
The following subcommands are available to select an optimal tree.
MINCOST: Use minimum cost to select the optimal tree.
STERROR K : Use within K standard error of minimum cost to select the optimal tree.
If you do not specify the node splitting method, then the analysis uses GINI and STERROR 1.
The following subcommands are available to control tree growth due to sample size or node complexity.
NOSPLIT K: Do not split a node if the node size is less than K. K=10 is the default.
NOTERMINAL K: Do not create a terminal node that is smaller than K. K=3 is the default.
MAXTDEPTH K: Set maximum tree depth to the Kth layer.
SURROGATE K
Specify K surrogates to consider when a specific predictor that splits a node has missing values.
767
Minitab Statistical Software Predictive Analytics
K must be an integer between 0 and the number of predictors 1, for example:
K = 0: Specifies no consideration of surrogate variables.
K = Number of total predictors 1: Specifies to consider all predictors other than the splitter variable.
If this subcommand is not issued, K=10 is the default value.
WEIGHT C
Specify the case weights in C. The column length must be the same length as the target column length.
Values must be 0. Assigning a weight of 0 or missing excludes the row from the analysis.
MPENALTY K
Specify a penalty value for a predictor with missing values.
0.0 K 2.0, for example:
K = 0: Specifies no penalty.
K = 2: Specifies highest penalty.
.
CPENALTY K
Specify a penalty value for categorical predictors that have many values.
0.0 K 5.0, for example:
K = 0: Specifies no penalty.
K = 5: Specifies highest penalty.
Graphs
GTDIAG
Displays the optimal tree diagram.
GCOST
Displays the relative cost vs. number of terminal nodes plot.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables.
0: Displays all predictors.
GROC
Displays the ROC curve.
GGAIN
Displays the gain chart.
GLIFT K
Displays the lift chart.
The type of chart depends on the value of K. When K =
768
Minitab Statistical Software Predictive Analytics
1: Displays the cumulative lift chart.
2: Displays the non-cumulative lift chart.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes the model validation method, the node splitting method, and other
information about the analysis.
TRESPONSE
Displays the Response information table, which includes class information, count information, prior probabilities,
and other information about the response variable.
TSUMMARY
Displays the Model summary table, which includes the number of predictors, the number of important predictors,
the number of nodes, misclassification costs, and other information about the model.
TCONFUSION
Displays the Confusion matrix to compare performance measurements of the classification models.
For a binary response, issue the following commands after TCONFUSION to indicate which measurements to
show.
TPOSITIVE
Displays true positive rate.
FPOSITIVE
Displays false positive rate.
TNEGATIVE
Displays true negative rate.
FNEGATIVE
Displays false negative rate.
TMISSCLASS
Displays the Misclassification matrix.
TNTYPE K
Determines the types of nodes to display in the tables when you issue TEFFECTIVE and TCRITERIA. The type of
node depends on the value of K:
1: Displays the best terminal nodes. The best nodes have the highest event probability (binary) or highest class
probability (multinomial) values.
2: Displays the worst terminal nodes. The worst nodes have the lowest event probability (binary) or lowest
class probability (multinomial) values.
3: Displays the best and worst terminal nodes.
769
Minitab Statistical Software Predictive Analytics
TEFFECTIVE K
Displays the effectiveness of the classification table for K terminal nodes. The K terminal nodes have the highest
rates of correct classifications unless you specify a different type of node with TNTYPE.
TCRITERIA K
Displays the criteria for classifying subjects into K terminal nodes. The K terminal nodes have the highest rates of
correct classifications unless you specify a different type of node with TNTYPE.
For example, with the subcommands TNTYPE 2; TEFFECTIVE 4; TCRITERIA 3; Minitab displays the 4 worst nodes in the
classification table and the criteria for classifying the subjects in the 3 worst nodes.
Storage
SCTREES K
Stores the optimal tree as well as additional candidate trees that are smaller than the optimal tree, the optimal
tree, and up to K larger than optimal trees.
SEPROB C C or C...C
Stores the probability of each class in the response variable. Specify as many columns as the response variable
has classes.
SPCLASS C
Stores the predicted class for each record in the tree.
STNID C
Stores the ID number of the terminal node for each row. The terminal node is also called a cluster.
SODDS C
For a binary response variable, stores the odds for each record in the tree.
IECTREE: Session command for selecting an alternative classification
tree
IECTREE K K
Selects a different tree from the optimal one inside a tree object generated by the CTREE command.
The first argument, K, is a positive integer, that represents the classification tree object ID. The first classification
tree that you create in a project has the object ID 1. The second classification tree that you create in a project with
the CTREE command has the object ID 2. Alternative trees are always made from an optimal tree, so alternative
trees do not have a tree object ID.
The second argument, K, is an integer that indexes a specific tree within the tree object. K values may be negative
or positive values, depending on whether the alternative tree is smaller than or larger than the optimal tree. The
tree object name uses:
0: Represents the optimal tree.
Negative integers: Represents trees that are smaller than the optimal tree. For example, K = -4 would store
the tree that is 4 smaller than the optimal.
Positive integers: Represents trees that are larger than the optimal tree. For example, K = 2 would store the
tree that is 2 larger than the optimal.
The tables and graphs for the new tree are the same as for the original tree. The new tables and graphs are in a
new output tab. The same columns that the original analysis stored are also stored for the new tree. For example,
770
Minitab Statistical Software Predictive Analytics
if the original analysis stored the terminal node IDs in TNODEID[0] and you select an alternative tree that is 4 trees
smaller than the optimal tree, then the new analysis stores the terminal node IDs in the column TNODEID[-4].
CTPREDICT: Session command for predicting responses for new
observations for a classification tree
CTPREDICT K K [K]
Predicts the response values for new observations with the optimal tree.
The first argument, K, is the identification number of a tree. This K is always a positive integer. The first tree that
you create in a project is identified as 1, the second is identified as 2, and so on. The number for a tree remains
the same even if you delete the output for another tree from the Navigator. For example, if you delete the output
for the first tree, the second tree that you made remains tree 2.
The second argument, K, is an integer that indexes a specific tree within the tree object. K values may be negative
or positive values, depending on whether the alternative tree is smaller or larger than the optimal tree. The second
K must match one of the additional trees stored by CTREE.
In the tree object:
0 represents the optimal tree.
Negative integers represent trees that are smaller than the optimal tree. For example, K = –4 stores the tree
that is 4 smaller than the optimal.
Positive integers represent trees that are larger than the optimal tree. For example, K = 2 stores the tree that
is 2 larger than the optimal.
The third argument, K, allows you to optionally specify which output tab contains the prediction results. K is a
positive integer from 1...N. K increases every time another tree with that same pruning increments. If you do not
specify this argument, Minitab appends the prediction results to the last pruning.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the tree object.
If a predictor is categorical, the values in C must match the values in the tree object.
The order of the predictors follows a strict format.
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand from
the CTREE command.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from the CTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The CTREE command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
771
Minitab Statistical Software Predictive Analytics
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
tree.
If a predictor is categorical, the corresponding value for K must match the values in the tree object.
The order of the values follows a strict format:
1. Enter values for continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from the CTREE command.
2. Enter values for categorical predictors second. Use the order of the predictors from the CATEGORICAL
subcommand from the CTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The CTREE command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the values in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Results
TPREDICTION
Displays the prediction table.
Storage
STNID C
Stores the terminal node (cluster) ID for each new observation.
SEPROB C C or C...C
For a binary response variable, this subcommand stores the probability of the even in the first column and stores
the probability of the non-event in the second column.
For a multinomial response, this subcommand stores each probability of the response level in a separate column.
Enter the same number of columns as the response variable has levels.
772
Minitab Statistical Software Predictive Analytics
SPCLASS C
Stores the predicted class for each record in the column that you specify.
TreeNet Regression
BRTREE: Session command for creating a gradient boosted
regression tree
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
BRTREE
Creates an optimal gradient boosted regression tree and a set of close-to-optimal gradient boosted regression
trees. This analysis also provides residual plots, an important variables chart, and other diagnostic measures so
that you can assess the validity of your regression model.
Use the BOTTOM subcommand to perform automatic predictor elimination. The removal of the least important
predictors lets you focus on the predictors that are vital to a good model so that you can more easily interpret
the model and specify values that optimize your processes. The algorithm removes the least important predictors
automatically, shows you results that let you compare models with different numbers of predictors, and produces
results for the set of predictors with the maximum R
2
value.
The response variable column must be continuous and must contain at least 2 distinct numeric values.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable or the weights column.
RESPONSE C
Enter a column that contains 2 or more distinct values of a continuous response. C must be numeric.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Interaction
Use one of the following subcommands to set the predictor interaction options. If no subcommand from this set is
issued, AINTERACT is the default. Minitab ignores NINTERACT and SINTERACT when you use BOTTOM or TOP
from the Predictor Elimination subcommands.
AINTERACT
Allow all predictor interactions when growing the sequence of trees.
773
Minitab Statistical Software Predictive Analytics
NINTERACT
Do not allow predictor interactions when growing the sequence of trees. Minitab uses only the additive model.
SINTERACT K C...C
Allow two or more selected predictor interactions up to K
th
order when growing the sequence of trees.
K is a positive number greater than 1. A large K, such as K = 5, may be similar to the results with AINTERACT.
Predictor Elimination
Use one of the following subcommands to set the predictor elimination options. After you perform use predictor
elimination, you can use the BRTMODEL command to produce results for any of the models in the Predictor Elimination
table. When you use predictor elimination, Minitab ignores NINTERACT and SINTERACT from the Interaction
subcommands.
BOTTOM
Specify to eliminate the least important predictors from the model first.
Use the following subsubcommands to specify details about the predictor elimination. These subsubcommands
have to come after BOTTOM or TOP in the session commands that you specify.
PCOUNT K
Specify how many predictors with positive importance values to eliminate at each step. In addition to the K
predictors that you specify, the algorithm eliminates any predictors with 0 importance at each step. Without
this subsubcommand, the algorithm eliminates 1 predictor with positive importance at each step. If you
specify a value greater than or equal to the number of predictors, the algorithm eliminates all but 1 predictor.
NSTEP K
Specify the maximum number of elimination steps. Without this subsubcommand or if K is more than the
number of predictors, the algorithm continues until the number of predictors is less than or equal to the
argument for PCOUNT.
CORE C...C
Specify predictors to retain in the model until the elimination of all other predictors, irrespective of importance
scores. Columns that you specify have to be columns that follow the CONTINUOUS or CATEGORICAL
subcommands.
BOTH
Display a Predictor Elimination table that includes R
2
values for both the training set and the test set. The
default model results are still of the model with the highest test R
2
value. The training results are usually
more ideal than the actual results for new data. The training results are for reference only.
TOP
Specify to eliminate the most important predictors from the model first. The TOP subcommand has the same
subsubcommands as the BOTTOM subcommand.
Validation
Use one of the following subcommands to specify the validation method.
CVTEST
TEST
NTEST
If no validation subcommand is issued, then Minitab uses the following defaults, depending on the number of rows:
774
Minitab Statistical Software Predictive Analytics
The default when the number of rows 500
CVTEST 5; when the subcommands do not include TOP or BOTTOM
CVTEST 3; when the subcommands include TOP or BOTTOM
The default when the number of rows > 500
TEST 0.3;
RANDOMIZE 12345;
CVTEST K
Use K-fold cross-validation as a test method. Specify K number of folds.
K must be an integer between 2 and the sample size; 2 K 100.
CVTEST C
Use K-fold cross-validation as a test method. Enter C to specify the rows for each fold.
C is used to define the rows for each fold. The column must contain at least 2 distinct values. The column can be
numeric or text and must be the same length as the response column.
TEST K
Specify a proportion of rows for the test set. K is the proportion of the data to use for the test set. K must be
between 0 and 1.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be a positive integer. Use 12345 to get the same results as Minitab's defaults.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
NTEST
No model validation.
Use SSAMPLE C to store a column that shows the assignments for each row in the validation. When CVTEST is used:
The storage column, Sample_Id, stores the fold identification in C.
C contains values 1, 2, ..., K.
When TEST is used:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the two values.
Options
Use one of the following subcommands to specify the best fit method used in the analysis.
LSE: Use the Least Squared Errors method to find the best fits. This is the default method.
LAD: Use the Least Absolute Deviation method to find the best fits.
HUBER K: Use the Huber loss to find the best fits. K is the switching value from squared loss to absolute loss in
the hybrid Huber loss function. K must be between 0 and 1. K = 0.9 is the default value.
775
Minitab Statistical Software Predictive Analytics
NTREE K
Set the number of trees to build. K must be a positive integer less than 5000. K = 300 is the default value.
Choose either MAXNODE or MAXTDEPTH. If neither of the following subcommands are issued, then the analysis
uses MAXNODE 6.
MAXNODE K
Sets the maximum terminal nodes per tree. K must be a positive integer between 2 and 2000.
MAXTDEPTH K
Sets the maximum tree depth to the K
th
layer. K must be a positive integer between 2 and 1000. MAXTDEPTH
tends to give balanced trees.
NOTERMINAL K
Do not create terminal nodes smaller than K. K must be a positive integer greater than or equal to 3; K = 3 is the
default value.
LRATE K
Specify the learning rate of the boosting procedure to protect from overfitting. K must be from 0.0001 to 1.
K = 0.01 is the default if the number of cases in your training data is 1000 or less. For data sets with more than
1000 cases, the default learning rate is is max[0.01, 0.1 * min(1.0, N/10000)]. For example, when the data set has
9000 responses, then the learning rate = 0.09.
SUBSAMPLE K
Specify the fraction of subsampling to use at each iteration to build a tree to protect from overfitting. K must be
between 0 and 1; K = 0.5 is the default.
NPRED K
Specify the number of predictors randomly selected to come up with each node splitting rule in a tree. K must
be an integer between 0 and 100; all predictor variables are used by default. When K =
0: The number of predictors used becomes SQRT(total number of predictors) rounded down to the nearest
integer.
100: All predictor variables are used.
0 < K < 100: The number of predictor variables used becomes (total number of predictors) x (K / 100) rounded
down to the nearest integer. If (total number of predictors) x (K / 100) < 1, the number of predictors used
becomes 1.
BRANDOMIZE K
Specify the base number to randomly generate subsamples to build a tree. K must be a positive integer. K also
controls every randomly selected subset of the m total predictors to generate the splitting rule for an internal
node, if applicable.
MPENALTY K
Specify a penalty value for a predictor with missing values.
0.0 K 2.0, for example:
K = 0: Specifies no penalty (default).
K = 2: Specifies highest penalty.
.
CPENALTY K
Specify a penalty value for categorical predictors that have many values.
0.0 K 5.0, for example:
776
Minitab Statistical Software Predictive Analytics
K = 0: Specifies no penalty (default).
K = 5: Specifies highest penalty.
WEIGHT C
Specifies the weights in column C. Values in C must be 0, but rows with 0 values are unused in the analysis.
Length of C must be the same as the response column length.
Graphs
GRSQ
Displays the R
2
vs number of trees graph if LSE or HUBER loss is used. If LAD is used, GRSQ displays the mean
absolute deviation (MAD) vs number of trees graph.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables.
0: Displays all predictors.
GFIT
Displays the fits vs actual response values plot.
GRBOX
Displays the boxplot of the residuals. If the analysis uses a validation method, the graph has separate boxplots
for the training data set and the test data set.
RTYPE K
Specifies the type of residual to plot. When K =
1: Displays regular residuals.
2: Displays percent residuals.
GOPART K K
Displays one predictor partial dependence plots for the top K important predictors.
The first K must be a positive integer less than the total number of predictors. K indicates the number of important
predictors.
The second K must be either 1 or 2. When K =
1: Center the y–values before plotting (default).
2: Do not center the y–values before plotting.
GTPART K K
Displays two predictor partial dependance plots for the top K important variables.
The first K must be a positive integer less than the total number of predictors. K indicates the number of important
variables.
The second K must be either 1 or 2. When K =
1: Center the y–values before plotting (default).
777
Minitab Statistical Software Predictive Analytics
2: Do not center the y–values before plotting.
Use the following subcommands to specify the types of plots to display. If neither subcommand is specified, the
3D surface plot is displayed.
SURFACE : Displays a 3D surface plot.
GCONTOUR : Displays a contour plot.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes the model validation method, the criterion for selecting the optimal
number of trees, and other information about the analysis.
TRESPONSE
Displays the Response information table, which includes descriptive statistics about the response variable.
TSUMMARY
Displays the Model summary table, which includes the number of predictors, the number of important predictors,
the number of trees grown, the R
2
statistic, and other information about the model.
TINTERACT K
Displays the 2-way interaction strength tables. K must be 0, 1, or 2. When K =
0: Displays the % of total squared error explained by a 2-way interaction.
1: Displays the % of squared error due to specific predictor pairs.
2: Displays both the % of total squared error and the % of squared error.
Only the top 5 predictors are displayed in the tables.
TPERROR K
Displays percent of error statistics due to largest residuals. K represents the percent of largest residuals being
displayed.
0 < K 100. K = 20 is the default, which means the table includes statistics for groups that contain up to the
largest 20% of the residuals. The table always includes K%. Up to 20%, the table includes 1%, 2%, 2.5%, 3%, 4%,
5%, 7.5%, 10%, and 15%. After 20%, the table includes multiples of 10%.
Storage
SBRTREE
Stores the boosted regression tree object for prediction.
SFIT C
Stores the fitted response for each record in C.
SRESID C
Stores the residual for each record in C.
778
Minitab Statistical Software Predictive Analytics
SPRESID C
Stores the percent residual for each record in C.
BRTMODEL: Session command for Hyperparameter Tuning and
for selecting an alternative TreeNet
®
Regression model from
Discover Key Predictors
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
BRTMODEL K
After you create a TreeNet
®
Regression model with BRTREE, BRTMODEL completes one of two follow-up analyses.
With the PEMODEL subcommand, BRTMODEL produces results for a model from among the models from the
predictor elimination algorithm.
With one or more of the LRATE, SUBSAMPLE, MAXNODE, MAXTDEPTH, NTREE, NPRED, and FULLCOMB
subcommands, BRTMODEL tunes the hyperparameters for a TreeNet Regression model to find the combination
that produces the best model.
K is a positive integer that represents a TreeNet
®
Regression object ID. The first TreeNet
®
Regression that you
create in a project has the object ID 1. The second TreeNet
®
Regression model that you create with the BRTREE
command has the object ID 2, and so on. You can use BRTMODEL with the PEMODEL subcommand only for
instances of BRTREE that use the TOP subcommand, which indicates that the TreeNet
®
Regression model used
the predictor elimination algorithm to exclude the least important predictors. You can use BRTMODEL with the
subcommands for hyperparameter tuning with any TreeNet
®
Regression model. The subcommands for predictor
elimination and for hyperparameter tuning are mutually exclusive.
Minitab recreates the same tables and graphs for the new model as for the original object ID that you specify.
The tables and graphs for the new model are in a new output tab. The same columns that the original analysis
stored are also stored for the new model. The storage for the new model is in a new column. For example, if the
original analysis stored the fitted values in a column titled "Fit," then the new analysis also titles an empty column
"Fit_1" and stores the fitted values.
For purposes of using a command like BRTMODEL or BRPREDICT, the TreeNet
®
Regression object ID that comes
from the BRTMODEL command is the next TreeNet
®
Regression object ID. For example, if you run BRTREE, the
results from that model are the first TreeNet
®
Regression object ID: 1. If you then use BRTMODEL to select a
different model from the results, that model is the second TreeNet
®
Regression object ID: 2. The ARTMODEL
command with the TN subcommand also creates a TreeNet
®
Regression object ID.
Predictor elimination
PEMODEL K
Produces TreeNet Regression results for a model from the predictor elimination steps. Select K from the numbers
in the Model column of the predictor elimination table to produce results for the model in that row.
Hyperparameter tuning
When you use any of the hyperparameter tuning subcommands, Minitab produces a table that compares models with
the hyperparameters that you specify. Minitab also produces the full results for the TreeNet
®
model with the best
value of the accuracy criterion, such as the highest R
2
value.
779
Minitab Statistical Software Predictive Analytics
If you do not use one of the subcommands, then the value for the hyperparameter comes from the model that
BRTMODEL specifies.
If you specify more than one subcommand with parameters, then the models in the comparison table depend on
whether you enter the FULLCOMB subcommand.
If you enter FULLCOMB, then the algorithm evaluates every combination of the hyperparameters.
If you do not enter the FULLCOMB subcommand, then the algorithm evaluates the hyperparameters from the
subcommands in this order:
1. LRATE
2. SUBSAMPLE
3. MAXNODE or MAXTDEPTH
For a subcommand that the algorithm has not evaluated, the algorithm uses the first value to evaluate earlier
subcommands. For a subcommand that the algorithm has evaluated, the algorithm uses the best value.
For example, suppose that the algorithm receives the following subcommands:
LRATE 0.001 0.01 0.1;
SUBSAMPLE 0.4 0.5 0.7;
MAXNODE 4 6.
1. The algorithm sets the subsample proportion to 0.4 and the maximum number of terminal nodes to 4. Then, the
algorithm evaluates the learning rates in order from least to greatest: 0.001, 0.01, 0.1.
2. Suppose the algorithm identifies 0.01 as the best learning rate. Then the algorithm sets the learning rate to 0.01
and the maximum number of terminal nodes to 4. Then, the algorithm evaluates the subsample proportions of 0.4,
0.5, and 0.7.
3. Suppose that the algorithm identifies 0.5 as the best subsample proportion. Then the algorithm sets the learning
rate to 0.01, the subsample proportion to 0.5. Then, the algorithm evaluates the maximum numbers of nodes of 4
and 6.
4. Suppose that the algorithm identifies 6 as the best maximum number of terminal nodes. Then Minitab produces
the comparison table and the results for the model with learning rate = 0.01, subsample proportion 0.5, and
maximum number of terminal nodes 6.
LRATE K...K
Specifies up to 10 learning rates to evaluate. You can specify values from 0.0001 to 1.
SUBSAMPLE K...K
Specifies up to 10 subsample proportions to evaluate. You can specify positive values that are less than or equal
to 1.
MAXNODE K (K K)
Specifies up to 3 maximum numbers of terminal nodes to evaluate. You can specify values from 2 to 2,000. You
cannot use MAXNODE and MAXTDEPTH together.
MAXTDEPTH K (K K)
Specifies up to 3 maximum tree depths to evaluate. You can specify values from 2 to 1,000. You cannot use
MAXNODE and MAXTDEPTH together.
NTREE K
The maximum number of trees to build is not a hyperparameter to tune, but you can specify a different number
than the model that you specify with BCTMODEL has. Specify a single value from 1 to 5,000.
780
Minitab Statistical Software Predictive Analytics
NPRED K (K K)
Specifies the number of predictors randomly selected to evaluate at each node to split. K must be a positive
integer. If K is greater than the number of predictors, then K counts as being equal to the number of predictors.
FULLCOMB
Specifies that the table of models to compare includes a row for every combination of the hyperparameters that
you specify with the other subsubcommands. Otherwise, the algorithm evaluates a hyperparameter at only one
combination of the other hyperparameters.
BRPREDICT: Session command for predicting responses for new
observations for a gradient boosted regression tree model
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
BRPREDICT K
Predicts the response values for new observations with the optimal gradient boosted regression tree model.
K is the identification number of a model. This K is always a positive integer. The first model that you create in a
project is identified as 1, the second is identified as 2, and so on. The number for a model remains the same even
if you delete the output for another model from the Navigator. For example, if you delete the output for the first
model, the second model that you made remains model 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model.
If a predictor is categorical, the values in C must match the values in the model. Which predictors to enter depends
on if the predictor elimination algorithm removes any predictors from the model. For example predictor elimination
occurs if the BRTREE command includes the BOTTOM subcommand or if the BRTMODEL command includes the
PEMODEL subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict format:
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from the BRTREE command.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from the BRTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The BRTREE command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
Fewer predictors than in the original subcommands
If the model for the TreeNet
®
Regression Object ID does not include all of the predictors, then omit those
predictors.
781
Minitab Statistical Software Predictive Analytics
1. Enter continuous predictors that are in the model first. Use the order of the predictors from the
CONTINUOUS subcommand from the BRTREE command.
2. Enter categorical predictors that are in the model second. Use the order of the predictors from the
CATEGORICAL subcommand from the BRTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The BRTREE command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
The predictor elimination algorithm gave a model without C3 and C4 as predictors.
Enter the predictors in the following order:
CPREDICTORS C6 C2 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
tree.
If a predictor is categorical, the corresponding value for K must match the values in the model. Which predictors
to enter depends on if the predictor elimination algorithm removes any predictors from the model. For example
predictor elimination occurs if the BRTREE command includes the BOTTOM subcommand or if the BRTMODEL
command includes the PEMODEL subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict format:
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from BRTREE.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from BRTREE.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to
predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The BRTREE command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
782
Minitab Statistical Software Predictive Analytics
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Fewer predictors than in the original subcommands
If the model for the TreeNet
®
Regression Object ID does not include all of the predictors, then omit those
predictors.
1. Enter continuous predictors that are in the model first. Use the order of the predictors from the
CONTINUOUS subcommand from BRTREE.
2. Enter categorical predictors that are in the model second. Use the order of the predictors from the
CATEGORICAL subcommand from BRTREE.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to
predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The BRTREE command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
The predictor elimination algorithm gave a model without C3 and C4.
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 'Blue' 'Urgent' 'New'
Results
TPREDICTION
Displays the prediction table.
Storage
SFIT C
Stores the final fit of each row in the column that you specify.
783
Minitab Statistical Software Predictive Analytics
TreeNet Classification
BCTREE: Session command for creating a gradient boosted
classification tree
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
BCTREE
Creates an optimal gradient boosted classification tree and a set of close-to-optimal gradient boosted classification
trees. This analysis also provides an important variables chart, gain and lift charts, and other diagnostic measures
so that you can assess the validity of your classification model.
Use the BOTTOM subcommand to perform automatic predictor elimination. The removal of the least important
predictors lets you focus on the predictors that are vital to a good model so that you can more easily interpret
the model and specify values that optimize your processes. The algorithm removes the least important predictors
automatically, shows you results that let you compare models with different numbers of predictors, and produces
results for the set of predictors with the maximum R
2
value.
The response variable column must be categorical. The values can be text or numeric.
If the response column has only 2 distinct values (binary response), you can specify which value is the reference
event with EVENT. If you do not specify the event or if the response has more than 2 values (multinomial response),
then the reference event depends on whether the column contains numbers or text. When the values are numbers,
the highest value is the reference event. When the values are text, the last value alphabetically is the event. For
example, if you enter the response variable as success and failure, success is the event.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable or the weights column.
RESPONSE C
Enter a column that contains 2 or more distinct values of a categorical response. C can be text or numeric.
EVENT K
Specifies the event value for a binary response. K must be one of the two response values.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Class Weights
Use the following subcommand to specify the class weights.
CWEIGHT K or K K...K K
Specifies the class weights using one of two types of numeric constants.
784
Minitab Statistical Software Predictive Analytics
Single constant, K. K can be 1 or 2 only. The value 1 indicates the response classes are not weighted. The value
2 indicates the response classes should have their weights balanced to the class size. The value 2 ensures that
the sum of all the weights in each class are equal.
Pair of constants, K…K. The first K, in the pair, is the class ID. The class ID can be in the range of values 1 to M,
where M is the total number of classes in response C. The second K represents the weight for the class in the
pair. K > 0. The maximum number of pairs is M. If the weight for a class is not provided, a weight of 1 is the
default.
If you do not use this subcommand, the default weight is 1 for all classes.
Interaction
Use one of the following subcommands to set the predictor interaction options. If no subcommand from this set is
issued, AINTERACT is the default. Minitab ignores NINTERACT and SINTERACT when you use BOTTOM or TOP
from the Predictor Elimination subcommands.
AINTERACT
Allow all predictor interactions when growing the sequence of trees.
NINTERACT
Do not allow predictor interactions when growing the sequence of trees. Minitab uses only the additive model.
SINTERACT K C...C
Allow two or more selected predictor interaction up to K
th
order when growing the sequence of trees.
K is a positive number greater than 1. A large K, such as K = 5, may be similar to the results with AINTERACT.
Predictor Elimination
Use the BOTTOM or the TOP subcommand to perform predictor elimination. After you perform predictor elimination,
you can use the BCTMODEL command to produce results for any of the models in the Predictor Elimination table. When
you use predictor elimination, Minitab ignores NINTERACT and SINTERACT from the Interaction subcommands.
BOTTOM
Specify to eliminate the least important predictors from the model first.
Use the following optional subsubcommands to specify details about the predictor elimination. These
subsubcommands have to come after BOTTOM or TOP in the session commands that you specify.
PCOUNT K
Specify how many predictors with positive importance values to eliminate at each step. In addition to the K
predictors that you specify, the algorithm eliminates any predictors with 0 importance at each step. Without
this subsubcommand, the algorithm eliminates 1 predictor with positive importance at each step. If you
specify a value greater than or equal to the number of predictors, the algorithm eliminates all but 1 predictor.
NSTEP K
Specify the maximum number of elimination steps. Without this subsubcommand or if K is more than the
number of predictors, the algorithm continues until the number of predictors is less than or equal to the
argument for PCOUNT.
CORE C...C
Specify predictors to retain in the model until the elimination of all other predictors, irrespective of importance
scores. Columns that you specify have to be columns that follow the CONTINUOUS or CATEGORICAL
subcommands.
785
Minitab Statistical Software Predictive Analytics
BOTH
Display a Predictor Elimination table that includes loglikelihood values for both the training set and the test
set. The default model results are still of the model with the highest best loglikelihood value. The training
results are usually more ideal than the actual results for new data. The training results are for reference only.
TOP
Specify to eliminate the most important predictors from the model first. The TOP subcommand has the same
subsubcommands as the BOTTOM subcommand.
Validation
Use one of the following subcommands to specify the validation method.
CVTEST
TEST
NTEST
If no validation subcommand is issued, then Minitab uses the following defaults, depending on the number of rows:
The default when the number of rows 500
CVTEST 5; when the subcommands do not include TOP or BOTTOM
CVTEST 3; when the subcommands include TOP or BOTTOM
The default when the number of rows > 500
TEST 0.3;
RANDOMIZE 12345;
CVTEST K
Use K-fold cross-validation as a test method. Specify K number of folds.
K must be an integer between 2 and the sample size; 2 K 100.
CVTEST C
Use K-fold cross-validation as a test method. Enter C to specify the rows for each fold.
C is used to define the rows for each fold. The column must contain at least 2 distinct values. The column can be
numeric or text and must be the same length as the response column.
TEST K
Specify a proportion of rows for the test set. K is the proportion of the data to use for the test set. K must be
between 0 and 1.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be a positive integer. Use 12345 to get the same results as Minitab's defaults.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
786
Minitab Statistical Software Predictive Analytics
NTEST
No model validation.
Use SSAMPLE C to store a column that shows the assignments for each row in the validation. When CVTEST is used:
The storage column, Sample_Id, stores the fold identification in C.
C contains values 1, 2, ..., K.
When TEST is used:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the two values.
Options
Use one of the following subcommands to specify the number of trees for the optimal model.
ROC: Use the maximum area under the ROC curve value to select the number of trees for the optimal model. ROC
is only available with a binary response and is the default for a binary response.
MAXLKH : Use the maximum likelihood value to select the number of trees for the optimal model.
MISCLASS : Use the minimum misclassification rate to select the number of trees for the optimal model. MISCLASS
is the default for a multinomial response.
NTREE K
Set the number of trees to build. K must be a positive integer less than 5000. K = 300 is the default value.
Choose either MAXNODE or MAXTDEPTH. If neither of the following subcommands are issued, then the analysis
uses MAXNODE 6.
MAXNODE K
Sets the maximum terminal nodes per tree. K must be a positive integer between 2 and 2000.
MAXTDEPTH K
Sets the maximum tree depth to the K
th
layer. K must be a positive integer between 2 and 1000. MAXTDEPTH
tends to give balanced trees.
NOTERMINAL K
Do not create terminal nodes smaller than K. K must be a positive integer greater than or equal to 3; K = 3 is the
default value.
LRATE K
Specify the learning rate of the boosting procedure to protect from overfitting. K must be from 0.0001 to 1
K = 0.01 is the default if the number of cases in your training data is 1000 or less. For data sets with more than
1000 cases, the default learning rate is is max[0.01, 0.1 * min(1.0, N/10000)]. For example, when the data set has
9000 responses, then the learning rate = 0.09.
SUBSAMPLE K
Specify the fraction of subsampling to use at each iteration to build a tree to protect from overfitting. K must be
between 0 and 1; K = 0.5 is the default. To specify the fraction to sample from each outcome of a binary response
variable, use STSAMPLE.
STSAMPLE K K
Use STSAMPLE to specify the fraction to sample from each outcome of a binary response variable. The first K
indicates the fraction of subsampling whose response is the event, and the second K indicates the fraction of
subsampling whose response is the non-event. Define which response is the event with the EVENT subcommand.
787
Minitab Statistical Software Predictive Analytics
NPRED K
Specify the number of predictors randomly selected to come up with each node splitting rule in a tree. K must
be an integer between 0 and 100; all predictor variables are used by default. When K =
0: The number of predictors used becomes SQRT(total number of predictors) rounded down to the nearest
integer.
100: All predictor variables are used.
0 < K < 100: The number of predictor variables used becomes (total number of predictors) x (K / 100) rounded
down to the nearest integer. If (total number of predictors) x (K / 100) < 1, the number of predictors used
becomes 1.
BRANDOMIZE K
Specify the base number to randomly generate subsamples to build a tree. K must be a positive integer. K also
controls every randomly selected subset of the m total predictors to generate the splitting rule for an internal
node, if applicable.
MPENALTY K
Specify a penalty value for a predictor with missing values.
0.0 K 2.0, for example:
K = 0: Specifies no penalty.
K = 2: Specifies highest penalty.
.
CPENALTY K
Specify a penalty value for categorical predictors that have many values.
0.0 K 5.0, for example:
K = 0: Specifies no penalty.
K = 5: Specifies highest penalty.
WEIGHT C
Specifies the weights in column C. Values in C must be 0, but rows with 0 values are unused in the analysis.
Length of C must be the same as the response column length.
Graphs
GLIKELIHOOD
Displays the average negative loglikelihood vs number of trees plot if MAXLKH is used. Displays the area under
ROC curve vs number of trees plot if ROC is used and the response variable is binary. Displays the misclassification
rate vs number of trees plot if MISCLASS is used.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables.
0: Displays all predictors.
788
Minitab Statistical Software Predictive Analytics
GROC
Displays the ROC curve for training and test samples.
GGAIN
Displays the gain chart for training and test samples.
GLIFT K
Displays the lift chart for training and test samples.
The type of chart depends on the value of K. When K =
1: Displays the cumulative lift chart.
2: Displays the non-cumulative lift chart.
GBPROB
Displays the box plot of estimated event probabilities when the response variable is binary.
GOPART K K
Displays one predictor partial dependence plots for the top K important predictors.
The first K must be a positive integer less than the total number of predictors. K indicates the number of important
predictors.
The second K must be either 1 or 2. When K =
1: Center the y–values before plotting (default).
2: Do not center the y–values before plotting.
GTPART K K
Displays two predictor partial dependance plots for the top K important variables.
The first K must be a positive integer less than the total number of predictors. K indicates the number of important
variables.
The second K must be either 1 or 2. When K =
1: Center the y–values before plotting (default).
2: Do not center the y–values before plotting.
Use the following subcommands to specify the types of plots to display. If neither subcommand is specified, the
3D surface plot is displayed.
SURFACE : Displays a 3D surface plot.
GCONTOUR : Displays a contour plot.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes the model validation method, the criterion for selecting the optimal
number of trees, and other information about the analysis.
789
Minitab Statistical Software Predictive Analytics
TRESPONSE
Displays the Response information table, which includes class information, count information, and other information
about the response variable.
TSUMMARY
Displays the Model summary table, which includes the number of predictors, the number of important predictors,
the number of trees grown, misclassification rates, and other information about the model.
TINTERACT K
Displays the 2-way interaction strength tables. K must be 0, 1, or 2. When K =
0: Displays the % of total squared error explained by a 2-way interaction.
1: Displays the % of squared error due to specific predictor pairs.
2: Displays both the % of total squared error and the % of squared error.
Only the top 5 predictors are displayed in the tables.
TCONFUSION
Displays the confusion matrix table to compare performance measurements of the classification models.
TMISSCLASS
Displays the misclassification table.
CTHRESHOLD K
For a binary response, K specifies the threshold value such that if the probability of the event > K, then assign the
event level as the predicted response. Otherwise, assign the non-event level as the predicted response.
K must be between 0 and 1; K = 0.5 is the default. K = 0 indicates that the threshold equals the estimated event
probability of the data when no model is built.
Storage
SBCTREE
Stores the boosted classification tree object for prediction.
SEPROB C C or C...C
For a binary response variable, stores the probability of event in the first column C, and stores the probability of
non-event in the second column C.
For a multinomial response variable, stores each probability of response = level in columns C...C.
SPCLASS C
Stores the predicted class for each record in the tree in column C.
SODDS C
For a binary response variable, stores the odds for each record in the tree in column C.
SFIT C or C...C
For a binary response variable, stores the final fit of each row in column C.
For a multinomial response variable, stores the final fit of each row in columns C...C.
790
Minitab Statistical Software Predictive Analytics
BCTMODEL: Session command for Hyperparameter Tuing and
selecting an alternative TreeNet
®
Classification model from
Discover Key Predictors
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
BCTMODEL K
After you create a TreeNet
®
Classification model with BCTREE, BCTMODEL completes one of two follow-up
analyses.
With the PEMODEL subcommand, BCTMODEL produces results for a model from among the models from the
predictor elimination table.
With one or more of the LRATE, SUBSAMPLE, MAXNODE, MAXTDEPTH, NTREE, NPRED and FULLCOMB
subcommands, BCTMODEL tunes the hyperparameters for a TreeNet classification model to find the combination
that produces the best model.
K is a positive integer that represents a TreeNet
®
Classification object ID. The first TreeNet
®
Classification that
you create in a project has the object ID 1. The second TreeNet
®
Classification model that you create with the
BCTREE command has the object ID 2, and so on. You can use BCTMODEL with the PEMODEL subcommand only
for instances of BCTREE that use the TOP subcommand, which indicates that the TreeNet
®
Classification model
used the predictor elimination algorithm to exclude the least important predictors. You can use BCTMODEL with
the subcommands for hyperparameter tuning with any TreeNet
®
Classification model. The subcommands for
predictor elimination and for hyperparameter tuning are mutually exclusive.
Minitab recreates the same tables and graphs for the new model as for the original object ID that you specify.
The tables and graphs for the new model are in a new output tab. The same columns that the original analysis
stored are also stored for the new model. The storage for the new model is in a new column. For example, if the
original analysis stored the fitted values in a column titled "Fit," then the new analysis also titles an empty column
"Fit_1" and stores the fitted values.
For purposes of using the a command like BCTMODEL or BCPREDICT, the TreeNet
®
Classification object ID that
comes from the BCTMODEL is the next TreeNet
®
Classification object ID. For example, if you run BCTREE, the
results from that model are the first TreeNet
®
Classification object ID: 1. If you then use BCTMODEL to select a
different model from the Discover Best Model results, that model is the second TreeNet
®
Classification object ID:
2. The ACTMODEL command with the TN subcommand also creates a TreeNet
®
Regression object ID.
Predictor elimination
PEMODEL K
Produces TreeNet
®
Classification results for a model from the predictor elimination steps. Select K from the
numbers in the Model column of the predictor elimination table to produce results for the model in that row.
Hyperparameter tuning
When you use any of the hyperparameter tuning subcommands, Minitab produces a table that compares models with
the hyperparameters that you specify. Minitab also produces the full results for the TreeNet
®
model with the best
value of the accuracy criterion, such as the minimum average –loglikelihood.
If you do not use one of the subcommands, then the value for the hyperparameter comes from the model that
BCTMODEL specifies.
If you specify more than one subcommand with parameters, then the models in the comparison table depend on
whether you enter the FULLCOMB subcommand.
791
Minitab Statistical Software Predictive Analytics
If you enter FULLCOMB, then the algorithm evaluates every combination of the hyperparameters.
If you do not enter the FULLCOMB subcommand, then the algorithm evaluates the hyperparameters from the
subcommands in this order:
1. LRATE
2. SUBSAMPLE
3. MAXNODE or MAXTDEPTH
For a subcommand that the algorithm has not evaluated, the algorithm uses the smallest value to evaluate earlier
subcommands. For a subcommand that the algorithm has evaluated, the algorithm uses the best value.
For example, suppose that the algorithm receives the following subcommands:
LRATE 0.001 0.01 0.1;
SUBSAMPLE 0.4 0.5 0.7;
MAXNODE 4 6.
1. The algorithm sets the subsample proportion to 0.4 and the maximum number of terminal nodes to 4. Then, the
algorithm evaluates the learning rates in order from least to greatest: 0.001, 0.01, 0.1.
2. Suppose the algorithm identifies 0.01 as the best learning rate. Then the algorithm sets the learning rate to 0.01
and the maximum number of terminal nodes to 4. Then, the algorithm evaluates the subsample proportions of 0.4,
0.5, and 0.7.
3. Suppose that the algorithm identifies 0.5 as the best subsample proportion. Then the algorithm sets the learning
rate to 0.01, the subsample proportion to 0.5. Then, the algorithm evaluates the maximum numbers of nodes of 4
and 6.
4. Suppose that the algorithm identifies 6 as the best maximum number of terminal nodes. Then Minitab produces
the comparison table and the results for the model with learning rate = 0.01, subsample proportion 0.5, and
maximum number of terminal nodes 6.
LRATE K...K
Specifies up to 10 learning rates to evaluate. You can specify values from 0.0001 to 1.
SUBSAMPLE K...K
Specifies up to 10 subsample proportions to evaluate. You can specify positive values that are less than or equal
to 1.
MAXNODE K (K K)
Specifies up to 3 maximum numbers of terminal nodes to evaluate. You can specify values from 2 to 2,000. You
cannot use MAXNODE and MAXTDEPTH together.
MAXTDEPTH K (K K)
Specifies up to 3 maximum tree depths to evaluate. You can specify values from 2 to 1,000. You cannot use
MAXNODE and MAXTDEPTH together.
NTREE K
The maximum number of trees to build is not a hyperparameter to tune, but you can specify a different number
from model that you specify with BCTMODEL. Specify a single value from 1 to 5,000.
NPRED K (K K)
Specifies the number of predictors randomly selected to evaluate at each node to split. K must be a positive
integer. If K is greater than the number of predictors, then K counts as being equal to the number of predictors.
792
Minitab Statistical Software Predictive Analytics
FULLCOMB
Specifies that the table of models to compare includes a row for every combination of the hyperparameters that
you specify with the other subsubcommands. Otherwise, the algorithm evaluates a hyperparameter at only one
combination of the other hyperparameters.
BCPREDICT: Session command for predicting responses for new
observations with a gradient boosted classification tree model
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
BCPREDICT K
Predicts the response values for new observations with the optimal gradient boosted classification tree model.
K is the identification number of a model. This K is always a positive integer. The first model that you create in a
project is identified as 1, the second is identified as 2, and so on. The number for a model remains the same even
if you delete the output for another model from the Navigator. For example, if you delete the output for the first
model, the second model that you made remains model 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model.
If a predictor is categorical, the values in C must match the values in the model. Which predictors to enter depends
on if the predictor elimination algorithm removes any predictors from the model. For example predictor elimination
occurs if the BCTREE command includes the BOTTOM subcommand or if the BCTMODEL command includes the
PEMODEL subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict format:
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from the BCTREE command.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from the BCTREE command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The BCTREE command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
Fewer predictors than in the original subcommands
If the model for the TreeNet
®
Classification Object ID does not include all of the predictors, then omit those
predictors.
1. Enter continuous predictors that are in the model first. Use the order of the predictors from the
CONTINUOUS subcommand from the BCTREE command.
2. Enter categorical predictors that are in the model second. Use the order of the predictors from the
CATEGORICAL subcommand from the BCTREE command.
793
Minitab Statistical Software Predictive Analytics
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The BCTREE command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
The predictor elimination algorithm gave a model without C3 and C4 as predictors.
Enter the predictors in the following order:
CPREDICTORS C6 C2 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
model. KPREDICTORS can be repeated up to three times.
If a predictor is categorical, the corresponding value for K must match the values in the model. Which predictors
to enter depends on if the predictor elimination algorithm removes any predictors from the model. For example
predictor elimination occurs if the BCTREE command includes the BOTTOM subcommand or if the BCTMODEL
command includes the PEMODEL subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict format:
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from BCTREE.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from BCTREE.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to
predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The BCTREE command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Fewer predictors than in the original subcommands
If the model for the TreeNet
®
Classification Object ID does not include all of the predictors, then omit those
predictors.
794
Minitab Statistical Software Predictive Analytics
1. Enter continuous predictors that are in the model first. Use the order of the predictors from the
CONTINUOUS subcommand from BCTREE.
2. Enter categorical predictors that are in the model second. Use the order of the predictors from the
CATEGORICAL subcommand from BCTREE.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6
are continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to
predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The BCTREE command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
The predictor elimination algorithm gave a model without C3 and C4.
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 'Blue' 'Urgent' 'New'
Results
TPREDICTION
Displays the prediction table.
Storage
SEPROB C C or C...C
For a binary response variable, this subcommand stores the probability of the even in the first column and stores
the probability of the non-event in the second column.
For a multinomial response, this subcommand stores each probability of the response level in a separate column.
Enter the same number of columns as the response variable has levels.
SPCLASS C
Stores the predicted class for each record in the column that you specify.
SFIT C or C...C
Stores the final fit of each row in column C for a binary response variable.
Stores the final fit of each row in columns C...C for a multinomial response variable.
795
Minitab Statistical Software Predictive Analytics
Random Forests Regression
RRFOREST: Session command for creating a random forest of
regression trees
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
RRFOREST
Creates a random forest of regression trees using bootstrap samples from the original data. Based on the results,
one can gain insights into the relationship between a continuous response and the important predictors out of
many candidate predictors, and predict response values for new observations with great accuracy. This analysis
also provides residual plots, an important variables chart, and other diagnostic measures so that you can assess
the validity of your regression model.
The response variable column must be continuous and must contain at least 2 distinct numeric values.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable.
RESPONSE C
Enter a column that contains 2 or more distinct values of a continuous response. C must be numeric.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Validation
Use one of the following subcommands to specify the validation method.
OOB
TEST
If no validation subcommand is issued, then Minitab uses OOB.
OOB
Use out-of-bag data for validation. RRFOREST uses bootstrap sampling for every tree. Every record in a bootstrap
sample is randomly selected with replacement from the original data set. Out of the total observations of the
original data set, some records will be left out from every bootstrap sample. The left-out rows from a bootstrap
sample make an out-of-bag data set.
TEST K
Specify a proportion of rows for the test set if you only enter a constant. K is the proportion of the data to use
for the test set. K must be between 0 and 1.
796
Minitab Statistical Software Predictive Analytics
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be positive integer. Use 12345 to get the same results as Minitab's defaults.
SSAMPLE C
Store a column that shows the assignments for each row in the validation. The storage column, Sample_Id,
stores the training and test sample assignments in C. C is a binary text column that contains Training and
Test as the two values.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
Options
NTREE K (K)
Set K bootstrap samples to grow K trees. The first constant specifies the number of bootstrap samples and the
number of trees produced by the analysis. You must enter a value between 3 and 3000.
The second optional constant sets the bootstrap sample size. You must enter a value greater than or equal to 5.
If you don't enter a value or if you enter a value that is greater than the training data size, Minitab uses a sample
size equal to the training data size.
If you don't specify NTREE, Minitab selects 300 bootstrap samples with a sample size equal to the training data
size.
NPRED K
Specify the number of predictors randomly selected to come up with each node splitting rule in a tree. K must
be an integer between -1 and 100. When K =
-1: The number of predictors used becomes SQRT(total number of predictors) rounded down to the nearest
integer.
0: All predictor variables are used.
0 < K < 100: The number of predictor variables used becomes (total number of predictors) x (K / 100) rounded
down to the nearest integer. If (total number of predictors) x (K / 100) < 1, the number of predictors used
becomes 1.
If you don't specify NPRED, K = -1, which uses SQRT(total number of predictors), is the default.
BRANDOMIZE K
Specify the base number to randomly generate the bootstrap samples. K must be a positive integer. K also controls
every randomly selected subset of the m total predictors to generate the splitting rule for an internal node, if
applicable.
NOSPLIT K
Do not split a node if the node size is less than K. K=2 is the default.
MPENALTY K
Specify a penalty value for a predictor with missing values. The default value is K = 0 if you do not specify this
subcommand.
0.0 K 2.0, for example:
797
Minitab Statistical Software Predictive Analytics
K = 0: Specifies no penalty.
K = 2: Specifies highest penalty.
CPENALTY K
Specify a penalty value for categorical predictors that have many values. The default value is K = 0 if you do not
specify this subcommand.
0.0 K 5.0, for example:
K = 0: Specifies no penalty.
K = 5: Specifies highest penalty.
Graphs
GRSQ
Displays the R
2
vs number of trees plot.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables.
0: Displays all predictors.
GFIT
Displays fits vs actual response values plot.
GRBOX
Displays boxplot of the residuals.
RTYPE K
Specifies the type of residual to plot. When K =
1: Displays regular residuals.
2: Displays percent residuals.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes information about model validation, number of bootstrap samples,
and other information about the analysis.
TRESPONSE
Displays the Response information table, which includes descriptive statistics about the response variable.
798
Minitab Statistical Software Predictive Analytics
TSUMMARY
Displays the Model summary table, which includes the statistics that describe the model. Includes the number of
predictors, important predictors, and goodness-of-fit information about the model.
TPERROR K
Displays percent of error statistics due to largest residuals. K represents the percent of largest residuals being
displayed.
0 < K 100. K = 20 is the default, which means the table includes statistics for groups that contain up to the
largest 20% of the residuals. The table always includes K%. Up to 20%, the table includes 1%, 2%, 2.5%, 3%, 4%,
5%, 7.5%, 10%, and 15%. After 20%, the table includes multiples of 10%.
Storage
SRRTREE K
Stores the model object for prediction. You cannot predict from the model unless you store the model object. K
specifies the number of trees for prediction. The default value for K is 300.
SFIT C
Stores the fitted response for each record in C.
SRESID C
Stores the residual for each record in C.
SPRESID C
Stores the percent residual for each record in C.
RRPREDICT: Session command for predicting responses for new
observations for a random forest regression model
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
RRPREDICT K
Predicts the response values for new observations with the optimal model.
K is the identification number of a model object. This K is always a positive integer. The first model that you create
in a project is identified as 1, the second is identified as 2, and so on. The number for a model remains the same
even if you delete the output for another model from the Navigator. For example, if you delete the output for the
first model, the second model that you made remains model 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model. If a predictor is categorical, the values in C must match the values in the model.
The order of the predictors follows a strict format.
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand from
RRFOREST.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from RRFOREST.
799
Minitab Statistical Software Predictive Analytics
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The RRFOREST command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
model. KPREDICTORS can be repeated up to three times.
If a predictor is categorical, the corresponding value for K must match the values in the model.
The order of the values follows a strict format:
1. Enter values for continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from the RRFOREST command.
2. Enter values for categorical predictors second. Use the order of the predictors from the CATEGORICAL
subcommand from the RRFOREST command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The RRFOREST command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the values in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Results
TPREDICTION
Displays the prediction table.
800
Minitab Statistical Software Predictive Analytics
Storage
SFIT C
Stores the fit of each row in the column that you specify.
Random Forests Classification
RCFOREST: Session command for creating a random forest of
classification trees
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
RCFOREST
Creates a random forest of classification trees using bootstrap samples from the original data. This analysis also
provides an important variables chart, gain and lift charts, and other diagnostic measures so that you can assess
the validity of your classification model.
The response variable column must be categorical. The values can be text or numeric.
If the response column has only 2 distinct values (binary response), you can specify which value is the reference
event with EVENT. If you do not specify the event or if the response has more than 2 values (multinomial response),
then the reference event depends on whether the column contains numbers or text. When the values are numbers,
the highest value is the reference event. When the values are text, the value order of the column is used to define
the event class for the binary case and the order of displaying classes for the multinomial case. For example, if
you enter the response variable as success and failure, success is the event.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable.
RESPONSE C
Enter a column that contains 2 or more distinct values of a categorical response. C can be text or numeric.
EVENT K
Specifies the event value for a binary response. K must be one of the two response values.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Class Weights
Use the following subcommand to specify the class weights.
801
Minitab Statistical Software Predictive Analytics
CWEIGHT K or K K...K K
Specifies the class weights using one of two types of numeric constants.
Single constant, K. K can be 1 or 2 only. The value 1 indicates the response classes are not weighted. The value
2 indicates the response classes are weighted to ensure an equal sample size across all classes.
Pair of constants, K…K. The first K, in the pair, is the class ID. The class ID can be in the range of values 1 to M,
where M is the total number of classes in response C. The second K represents the weight for the class in the
pair. K > 0. The maximum number of pairs is M. If the weight for a class is not provided, a weight of 1 is the
default.
If you do not use this subcommand, the default weight is 1 for all classes.
Validation
Use one of the following subcommands to specify the validation method.
OOB
TEST
If no validation subcommand is issued, then Minitab uses OOB.
OOB
Use out-of-bag data for validation. RCFOREST uses bootstrap sampling for every tree. Every record in a bootstrap
sample is randomly selected with replacement from the original data set. Out of the total observations of the
original data set, some records will be left out from every bootstrap sample. The left-out rows from a bootstrap
sample make an out-of-bag data set.
TEST K
Specify a proportion of rows for the test set if you only enter a constant. K is the proportion of the data to use
for the test set. K must be between 0 and 1.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be positive integer. Use 12345 to get the same results as Minitab's defaults.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
SSAMPLE C
Store a column that shows the assignments for each row in the validation. The storage column, Sample_Id,
stores the training and test sample assignments in C. C is a binary text column that contains Training and
Test as the two values.
Options
NTREE K (K)
Set K bootstrap samples to grow K trees. The first constant specifies the number of bootstrap samples and the
number of trees produced by the analysis. You must enter a value between 3 and 3000.
802
Minitab Statistical Software Predictive Analytics
The second optional constant sets the bootstrap sample size. You must enter a value greater than or equal to 5.
If you don't enter a value or if you enter a value that is greater than the training data size, Minitab uses a sample
size equal to the training data size.
If you don't specify NTREE, Minitab selects 300 bootstrap samples with a sample size equal to the training data
size.
NPRED K
Specify the number of predictors randomly selected to come up with each node splitting rule in a tree. K must
be an integer between -1 and 100. When K =
-1: The number of predictors used becomes SQRT(total number of predictors) rounded down to the nearest
integer.
0: All predictor variables are used.
0 < K < 100: The number of predictor variables used becomes (total number of predictors) x (K / 100) rounded
down to the nearest integer. If (total number of predictors) x (K / 100) < 1, the number of predictors used
becomes 1.
If you don't specify NPRED, K = -1, which uses SQRT(total number of predictors), is the default.
BRANDOMIZE K
Specify the base number to randomly generate the bootstrap samples. K must be a positive integer. K also controls
every randomly selected subset of the m total predictors to generate the splitting rule for an internal node, if
applicable.
NOSPLIT K
Do not split a node if the node size is less than K. K=2 is the default.
MPENALTY K
Specify a penalty value for a predictor with missing values. The default value is K = 0 if you do not specify this
subcommand.
0.0 K 2.0, for example:
K = 0: Specifies no penalty.
K = 2: Specifies highest penalty.
CPENALTY K
Specify a penalty value for categorical predictors that have many values. The default value is K = 0 if you do not
specify this subcommand.
0.0 K 5.0, for example:
K = 0: Specifies no penalty.
K = 5: Specifies highest penalty.
Graphs
GMISCLASSIFICATION
Displays the misclassification rate vs number of trees plot.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
803
Minitab Statistical Software Predictive Analytics
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables.
0: Displays all predictors.
GINI
Specifies the Gini method to calculate the relative importance scores for predictors.
PERMUTE
Specifies the permutation method to calculate the relative importance scores for predictors.
If you don't specify either GINI or PERMUTE, Minitab uses PERMUTE when the number of observations is less
than or equal to 5000. When the number of observations is greater than 5000, Minitab uses GINI.
GROC
Displays the ROC curve.
GGAIN
Displays the gain chart.
GLIFT K
Displays the lift chart.
The type of chart depends on the value of K. When K =
1: Displays the cumulative lift chart.
2: Displays the non-cumulative lift chart.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes information about model validation, number of bootstrap samples,
and other information about the analysis.
TRESPONSE
Displays the Response table, which includes class information, count information, and other information about
the responses.
TSUMMARY
Displays the Summary table, which includes the statistics that describe the model. Includes the number of predictors,
important predictors, misclassification rate, and goodness-of-fit information about the model.
TCONFUSION
Displays the confusion matrix table to compare performance measurements of the classification model.
TMISSCLASS
Displays the misclassification table.
804
Minitab Statistical Software Predictive Analytics
Storage
SCTREE
Stores the model object for prediction. You cannot predict from the model unless you store the model object.
SEPROB C C or C...C
For a binary response variable, stores the probability of event in the first column C, and the probability of non-event
in the second column C.
For a multinomial response variable with K levels, stores each probability of response = level in columns C...C
respectively.
SPCLASS C
Stores the predicted class for each record in the training data set in column C.
SODDS C
For a binary response variable, stores the odds for each record in the training data set in column C.
RCPREDICT: Session command for predicting responses for new
observations with a random classification forest model
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
RCPREDICT K
Predicts the response values for new observations with the optimal model.
K is the identification number of a model object. This K is always a positive integer. The first model that you create
in a project is identified as 1, the second is identified as 2, and so on. The number for a model remains the same
even if you delete the output for another model from the Navigator. For example, if you delete the output for the
first model, the second model that you made remains model 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model. If a predictor is categorical, the values in C must match the values in the model.
The order of the predictors follows a strict format.
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand from
RCFOREST.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand
from RCFOREST.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The RCFOREST command used the following
subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
805
Minitab Statistical Software Predictive Analytics
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
model. KPREDICTORS can be repeated up to three times.
If a predictor is categorical, the corresponding value for K must match the values in the model.
The order of the values follows a strict format:
1. Enter values for continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand
from the RCFOREST command.
2. Enter values for categorical predictors second. Use the order of the predictors from the CATEGORICAL
subcommand from the RCFOREST command.
For example, suppose you fit a tree using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The RCFOREST command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the values in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Results
TPREDICTION
Displays the prediction table.
Storage
SEPROB C C or C...C
For a binary response variable, this subcommand stores the probability of the event class for each new record in
the first column and stores the probability of the non-event class in the second column.
For a multinomial response, this subcommand stores each probability of the response level in a separate column.
Enter the same number of columns as the number of distinct levels in the response column.
SPCLASS C
Stores the predicted class for each record in the column that you specify.
806
Minitab Statistical Software Predictive Analytics
MARS Regression
MARS: Session command for creating a multi-adaptive regression
spline model
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
MARS
Creates a MARS regression model with an optimal number of basis functions and a set of other models with
different numbers of basis functions. This analysis also provides an important variables chart. For additive models,
this analysis also provides one-predictor, partial dependence plots that provide deeper information about the
effects of the predictors.
The response variable column must be continuous and must contain at least 2 distinct numeric values.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric
values. Categorical predictors can have numeric or text values. You must use at least one of the predictor
subcommands, either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing
values from the response variable or the weights column.
RESPONSE C
Enter a column that contains 2 or more distinct values of a continuous response. C must be numeric.
CONTINUOUS C...C
Specifies the continuous predictors are in columns C...C. The columns must be numeric and must have the same
number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors are in columns C...C. The columns can be numeric or text and must have the
same number of rows as the response column.
Interaction
Use one of the following subcommands to set the predictor interaction options. If no subcommand from this set is
issued, NINTERACT is the default.
NINTERACT
Do not allow predictor interactions in the model. Minitab uses only the additive model.
SINTERACT K [C...C]
Allow predictor interactions up to the K
th
order when building the model. Optionally, specify 2 or more columns
that are arguments for CONTINUOUS and CATEGORICAL to allow only interactions among the variables that you
specify.
K is a positive number. K = 1 is equivalent to the use of the NINTERACT subcommand. The maximum value of K
is 4.
Validation
Use one of the following subcommands to specify the validation method.
CVTEST
807
Minitab Statistical Software Predictive Analytics
TEST
NTEST
If no validation subcommand is issued, then Minitab uses the following defaults, depending on the number of rows:
The default when the number of rows 500
CVTEST 5
RANDOMIZE 12345;
The default when the number of rows > 500
TEST 0.3;
RANDOMIZE 12345;
CVTEST K
Use K-fold cross-validation as a test method. Specify K number of folds.
K must be an integer of at least 2. The maximum value of K is the sample size or 100, whichever is smaller.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into folds. K sets the starting point for
Minitab's random number generator.
K must be a positive integer. Use 12345 to get the same results as Minitab's defaults.
SSAMPLE C
Store a column that shows the assignments for each row in the validation. The storage column, Sample_Id,
stores the fold identification in C. The column contains the values 1, 2, …, K where K is the number of folds.
CVTEST C
Use K-fold cross-validation as a test method. Enter C to specify the rows for each fold.
C is used to define the rows for each fold. The column must contain at least 2 distinct values. The column can be
numeric or text and must be the same length as the response column.
TEST K
Specify a proportion of rows for the test set. K is the proportion of the data to use for the test set. K must be
between 0 and 1.
RANDOMIZE K
Specify the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for Minitab's random number generator.
K must be a positive integer. Use 12345 to get the same results as Minitab's defaults.
SSAMPLE C
Store a column that shows the assignments for each row in the validation. The storage column, Sample_Id,
stores the training and test sample assignments in C. The storage column is a binary text column that contains
Training and Test as the two values.
TEST C K
Use specific rows for the test set. Enter C to specify which rows are in the test set. C is an ID column that must
contain only 2 values. The value that you specify with K indicates that the row is in the test set. The other value
is for rows that are not in the test set.
NTEST
No model validation.
808
Minitab Statistical Software Predictive Analytics
Options
Use one of the following subcommands to specify the best fit method used in the analysis.
MAXRSQ: Use the maximum R-squared to select the optimal number of basis functions. This is the default method.
MAD: Use the minimum mean absolute deviation to select the optimal number of basis functions.
BFUNCTIONS K
Set the maximum number of basis functions to evaluate in the construction of the model. K must be a positive
integer of 200 or less. K = 30 is the default value.
MINOBS K
Specifies to use an algorithm to determine the minumum number of data points between changes in the basis
functions or specifies the minumum number.
K = 0
The analysis uses sample size and model complexity to automatically select a value.
1 K N
A value of 1 indicates that consecutive data points are eligible to be points where the basis function changes.
The value of 1 allows the most rapid changes in the model predictions. Use larger values to create smoother,
potentially less locally-accurate models to explore more general relationships. N is the number of rows in
the column for the response variable. Values larger than the sample size result in an error.
MPENALTY K
Specify a penalty value for a predictor with missing values.
0.0 K 2.0, for example:
K = 0: Specifies no penalty (default).
K = 2: Specifies highest penalty.
CPENALTY K
Specify a penalty value for categorical predictors that have many values.
0.0 K 5.0, for example:
K = 0: Specifies no penalty (default).
K = 5: Specifies highest penalty.
NTRANSFORM C...C
Specifies predictors that have only a linear effect in the model. Another way to describe this effect is that every
predictor has only 1 basis function with a knot at the minimum value of the predictor. For example, suppose a
predictor in an additive model has multiple basis functions to model curvature. The partial dependence plot that
results for a predictor with 3 basis functions has the following form:
809
Minitab Statistical Software Predictive Analytics
Without a transformation for the predictor, the predictor has only 1 basis function. The partial dependence plot
that results from 1 basis function is a straight line:
WEIGHT C
Specifies the weights in column C. Values in C must be 0, but rows with 0 values are unused in the analysis.
Length of C must be the same as the response column length.
Graphs
GRSQ
Displays the R
2
vs number of basis functions graph if MAXRSQ is used. If MAD is used, GRSQ displays mean absolute
deviation (MAD) vs number of basis functions graph.
GIMPORTANCE K
Displays the variable importance chart.
The number of variables on the chart depends on the value of K. When K =
100: Displays all important variables (default).
0 < K 100: Displays a percentage of important variables. For example, GIMPORTANCE 50 displays 50% of
the important predictors.
0: Displays all predictors.
GFIT
Displays the fits vs actual response values plot.
810
Minitab Statistical Software Predictive Analytics
GRBOX
Displays the boxplot of the residuals. If the analysis uses a validation method, the graph has separate boxplots
for the training data set and the test data set.
RTYPE K
Specifies the type of residual to plot. When K =
1: Displays regular residuals.
2: Displays percent residuals.
GPLOT2D
Displays one-predictor, partial dependence plots for additive models. The number of plots is the same as the
number of variables in the final model. The analysis ignores this subcommand when the analysis includes
SINTERACT.
Results
NODEFAULT
Suppresses the display of default tables and graphs.
TMETHOD
Displays the Method table, which includes the model validation method, the criterion for selecting the optimal
number of basis functions, and other information about the analysis.
TRESPONSE
Displays the Response information table, which includes descriptive statistics about the response variable.
TSUMMARY
Displays the Model summary table, which includes the number of predictors, the number of important predictors,
the maximum number of basis functions to evaluate, the R
2
statistic, and other information about the model.
TEQUATION
Displays the model equation. The equation has a coefficient for each basis function.
TPERROR K
Displays the percent of error statistics due to the largest residuals. K represents the percent of the largest residuals
being displayed.
0 < K 100. K = 20 is the default, which means the table includes statistics for groups that contain up to the
largest 20% of the residuals. The table always includes K%. Up to 20%, the table includes 1%, 2%, 2.5%, 3%, 4%,
5%, 7.5%, 10%, and 15%. After 20%, the table includes multiples of 10%.
Storage
SMARS
Stores the model object to use in subsequent analyses. If you do not store the model, then you cannot perform
analyses like prediction or the selection of an alternative model,
SFIT C
Stores the fitted response for each record in C.
811
Minitab Statistical Software Predictive Analytics
SRESID C
Stores the residual for each record in C.
SPRESID C
Stores the percent residual for each record in C.
SAMARS
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
SAMARS K K
Produce results for a model with a specific number of basis functions from the search for the optimal MARS
®
model.
The first argument, K, is the identification number of a model. This K is always a positive integer. The first MARS
®
model that you create in a project is identified as 1, the second is identified as 2, and so on.
Note The number for a model remains the same even if you delete the output for another model from the Navigator. For example,
if you delete the output for the first model, the second MARS
®
model that you made remains model 2.
The second argument, K, is an integer that indexes a specific model within the model object. K values are 1 more
than the number of basis functions in the model. For example, 1 represents the model with 0 basis functions. With
0 basis functions, the model is the mean of the response variable. An alternative model with 9 basis functions has
an index of 10.
The tables and graphs for the new model are the same as for the original model. The new tables and graphs are
in a new output tab. The same columns that the original analysis stored are also stored for the new model. For
example, if the original analysis stored the fits and you select an alternative tree with 9 basis functions, then the
new analysis stores the fits in the column Fit[10].
MSPREDICT
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
MSPREDICT K
Predicts the response values for new observations with the optimal MARS
®
model.
K is the identification number of a model. This K is always a positive integer. The first MARS
®
model that you
create in a project is identified as 1, the second is identified as 2, and so on.
Note The number for a model remains the same even if you delete the output for another model from the Navigator. For example,
if you delete the output for the first model, the second MARS
®
model that you made remains model 2.
Specify the values to predict with either CPREDICTORS or KPREDICTORS.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model. If a predictor is categorical, the values in C must match the values in the model. The columns can
have any number of values as long as the lengths are equal.
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
model. If a predictor is categorical, the corresponding value for K must match the values in the model. Use
KPREDICTORS from 1 to 3 times with a single instance of the main command.
812
Minitab Statistical Software Predictive Analytics
Argument order of CPREDICTORS and KPREDICTORS
The order of the predictors for the subcommands follows a strict format.
1. Enter continuous predictors first. Use the order of the predictors from the CONTINUOUS subcommand from MARS.
2. Enter categorical predictors second. Use the order of the predictors from the CATEGORICAL subcommand from
MARS.
For example, suppose you fit a model using a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are
continuous and predictors C4, C5, C7, and C8 are categorical. The model used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
CPREDICTORS
To use CPREDICTORS, enter the predictors with the same order as the subcommands from the model:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
KPREDICTORS
To use KPREDICTORS, enter specific predictor values. For example, the following table gives values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
To use KPREDICTORS, enter the values using the same order as the subcommands from the model:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Results
TPREDICTION
Displays the prediction table.
Storage
SFIT C
Stores the fit of each row in the column that you specify.
813
Minitab Statistical Software Predictive Analytics
Discover Best Model (Continuous Response)
ATREGRESS: Session command for discovering the best model
type for a continuous response
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
ATREGRESS
Compares the performance of common types of models from Minitab commands: REGRESS, RTREE, BRTREE,
RRFOREST and MARS. All 5 commands model a continuous response with many categorical and continuous
predictor variables.
The response variable column must be continuous and must contain at least 2 distinct numeric values.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric values.
Categorical predictors can have numeric or text values. You must use at least one of the predictor subcommands,
either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing values
in the response variable. For a multiple regression model, Minitab also excludes observations with missing values in a
predictor variable.
RESPONSE C
Enter a column that contains 2 or more distinct values of a continuous response. C must be numeric.
CONTINUOUS C...C
Specifies the continuous predictors that are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors that are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Validation options
TEST K
Performs validation with a test set. Minitab Statistical Software randomly selects the rows for the test set. K is the
fraction of the data in the test set.
RANDOMIZE K
Specifies the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for the random number generator.
K must be a positive integer. Use 12345 to get the same results as the default setting.
CVTEST K
Performs k-fold cross validation for the multiple regression model, the TreeNet
®
model, the MARS
®
model, and
the CART
®
model. The validation of the Random Forests
®
model uses the out-of-bag statistics.
Minitab Statistical Software randomly selects the data for the folds. K is the number of folds.
SSAMPLE C
With CVTEST:
814
Minitab Statistical Software Predictive Analytics
The storage column stores the fold identification in C.
C contains values 1, 2, ..., K.
With TEST:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the 2 values.
Criteria
Use one of the following subcommands to specify the criterion that determines the best model.
LSE: Use the Least Squared Errors method. This is the default method. Use the HUBER subsubcommand to use the
Huber loss function for the TreeNet model.
HUBER K: Use the Huber method. K is the switching value from squared loss to absolute loss in the hybrid
Huber loss function. K must be from 0.01 to 0.99. K = 0.9 is the default value.
LAD: Use the Least Absolute Deviation method.
These commands also determine the optimal pruning of the tree for CART
®
models and the criterion to use to determine
the optimal number of trees for the TreeNet
®
model. If you do not specify any subcommands about the criteria, then
the analysis uses the Least Squared Errors method.
Options for multiple regression models
For a multiple regression model, you can specify which terms are in the model and a procedure for term selection.
Specification of more than one of the subcommands STEPWISE, FVALIDATION, and NONE stops the analysis.
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. Only continuous predictors can be repeated. Nested
terms are not allowed. The model can be nonhierarchical. If you do not specify this subcommand, then the analysis
uses all linear terms and all terms of order 2. For examples, go to How to specify the model for GLM on page 1167.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. The
term that enters the model has the lowest p-value below 0.15. If no terms can enter the model, the term with the
highest p-value greater than 0.15 exits the model. The procedure adds or removes 1 term at a step. The procedure
ignores model hierarchy.
FVALIDATION
Uses forward selection to select the terms for the final model. The selection of the final model uses the criterion
from the forward selection calculations. At each step, Minitab Statistical Software adds the term with the smallest
p-value to the model. The procedure ignores model hierarchy. At the end of each step, Minitab Statistical Software
calculates the validation version of the criterion. At the end of the forward selection procedure, the model with
the best value of the criterion is the final model.
When you use CVTEST, the procedure repeats forward selection on each fold. The procedure evaluates all the
folds at each step and identifies the step with the best overall k-fold value of the criterion. The last part of the
procedure is to perform forward selection on the full dataset. The procedure continues until it either fits the full
model or until it fits a model that leaves 1 degree of freedom for error. At the end of the forward selection
procedure, the model with the best value of the criterion is the final model.
NONE
Uses the model from the TERMS subcommand without any selection procedure. If you do not specify the TERMS
subcommand, the NONE subcommand specifies the use of all linear terms and all terms of order 2.
815
Minitab Statistical Software Predictive Analytics
Options for CART
®
models
Use either MINERROR or STERROR to define how the procedure identifies the optimal pruning of the tree for the
CART
®
model. These two subcommands are mutually exclusive. If you do not specify MINERROR or STERROR, the
analysis uses STERROR 1.
MINERROR
Uses the tree with the maximum R
2
or the minimum mean absolute deviation as the optimal tree, depending on
the criteria for choosing the best model.
STERROR K
Uses the smallest tree that has a value of the optimality criterion within K standard errors of the best value of the
optimality criterion to select the optimal pruning of the tree.
RNOSPLIT K
Do not split a node that is smaller than K. K=10 is the default.
NOTERMINAL K
Do not create a terminal node that is smaller than K. K=3 is the default.
Options for TreeNet
®
and Random Forests
®
models
NTREE K K
The first K is the number of trees to build for the TreeNet
®
model (gradient boosted regression tree). Enter a value
from 1 to 5,000. The second K is the number of bootstrap samples and the number of trees to build for the Random
Forests
®
model. Enter a value from 3 to 3,000.
If you do not specify NTREE, Minitab uses 300 for each value of K.
NPRED K K
Specifies the number of predictors randomly selected to evaluate at each node to split. The first K is for TreeNet
®
models. The second K is for Random Forests
®
models. K must be an integer between 0 and 100. The following
list describes what the subcommand does with different values of K.
0: Use the square root of the total number of predictors, rounded down to the nearest integer.
100: Use all predictors.
0 < K < 100: Use this percentage of the total number of predictors, rounded down to the nearest integer. If
(total number of predictors) x (K / 100) < 1, the number of predictors is 1.
If you do not specify NPRED, then TreeNet
®
models use all predictors (K = 100) and Random Forests
®
models use
the square root of the number of predictors (K = 0).
BRANDOMIZE K
Specifies the base number to randomly generate subsamples to build a tree. K must be a positive integer. K also
controls every randomly selected subset of the m total predictors to generate the splitting rule for an internal
node, if applicable.
Options for TreeNet
®
models
LRATE K...K
Specifies up to 10 learning rates to evaluate. The learning rate of the boosting procedure protects from overfitting.
K must be from 0.0001 to 1.
816
Minitab Statistical Software Predictive Analytics
If you do not specify the LRATE subcommand, then the analysis usually tunes the hyperparameters with 3 values
of K: 0.001, 0.1, and max(0.01, 0.1 * min(1.0, N/10000)), where N = number of rows in the response column. If
max(0.01, 0.1 * min(1.0, N/10000)) = 0.001 or 0.1, then the analysis tunes the hyperparameters with 0.001, 0.01
and 0.1.
SUBSAMPLE K...K
Specify up to 10 fractions of subsampling. Each iteration selects a different subset of data to construct that tree.
Subsampling protects from overfitting. K must be greater than 0 and less than or equal to 1. The default values
are 0.5 and 0.7.
For the TreeNet
®
models, choose either MAXNODE or MAXTDEPTH. If you do not specify either MAXNODE or MAXTDEPTH,
then the analysis uses MAXNODE 6.
MAXNODE K (K K)
Specifies up to 3 numbers of maximum terminal nodes per tree. K must be a positive integer between 2 and 2000.
MAXTDEPTH K (K K)
Specifies up to 3 numbers of maximum tree depths to the K
th
layer. K must be a positive integer between 2 and
1000. MAXTDEPTH tends to give balanced trees.
Options for Random Forests
®
models
BSIZE K
Sets the bootstrap sample size. You must enter a value of K greater than or equal to 5. If you don't enter the
BSIZE subcommand or if you enter a value that is greater than the training data size, then Minitab uses a sample
size equal to the training data size.
NOSPLIT K (K K)
Does not split a node that is smaller than K. Specifies up to 3 integers greater than or equal to 2. Each integer
produces a distinct Random Forests
®
model. If you do not specify the NOSPLIT subcommand, then the analysis
uses K = 5. If you specify a K larger than the maximum value for the data, then the analysis uses the maximum
value.
Options for MARS
®
models
BFUNCTIONS K
Specifes the number of basis functions to evaluate, 1 K 200 . If you do not specify this subcommand, then
the analysis uses K = 30.
MINOBS K
Specifies to use an algorithm to determine the minumum number of data points between changes in the basis
functions or specifies the minumum number.
K = 0
The analysis uses sample size and model complexity to automatically select a value.
1 K N
A value of 1 indicates that consecutive data points are eligible to be points where the basis function changes.
The value of 1 allows the most rapid changes in the model predictions. Use larger values to create smoother,
potentially less locally-accurate models to explore more general relationships. N is the number of rows in
the column for the response variable. Values larger than the sample size result in an error.
817
Minitab Statistical Software Predictive Analytics
Use one of the following subcommands to set the predictor interaction options. If no subcommand from this set is
issued, NINTERACT is the default. To evaluate a MARS
®
model with higher-order interactions, fit the model with the
MARS command.
NINTERACT
Do not allow predictor interactions when the analysis evaluates the basis functions. Minitab uses only the additive
model.
SINTERACT 2
Allow second-order interactions when the analysis evaluates the basis functions.
Storage
SMODEL
Stores the model object to use in subsequent analyses. If you do not store the model, then you cannot perform
analyses like prediction, selection of an alternative model, or the addition of partial dependence plots.
SFIT C
Stores the fitted response for each record in C.
SRESID C
Stores the residual for each record in C.
ARTMODEL: Session command for selecting an alternative model
from Discover Best Model (Continuous Response)
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
ARTMODEL K
Produces results for alternative models after ATREGRESS identifies the best model.
K is a positive integer that represents a Discover Best Model (Continuous Response) object ID. The first model
from Discover Best Model (Continuous Response) that you create in a project has the object ID 1. The second
model from Discover Best Model (Continuous Response) that you create with the command has the object ID
2, and so on.
The tables and graphs for the new model are displayed in a new output tab. The same columns that the original
analysis stored are also stored for the new model. The storage for the new model is in a new column. For example,
if the original analysis stored the fitted values in a column titled "Fit," then the new analysis names an empty
column "Fit_1" and stores the fitted values in that column.
The type of object ID that ARTMODEL creates is the same as the type of model in the results. The type of object
ID determines which command to use to predict from a model. For TreeNet
®
models, you can also add partial
dependence plots. Use the following commands to do further analysis on each type of model.
CommandAnalysisType
MRPREDICTPredict the response for new dataMultiple regression
RTPREDICTPredict the response for new dataCART
®
RRPREDICTPredict the response for new dataRandom Forests
®
BRPREDICTPredict the response for new dataTreeNet
®
818
Minitab Statistical Software Predictive Analytics
CommandAnalysisType
MSPREDICTPredict the response for new dataMARS
®
For purposes of using a command such as MRPREDICT or BRPREDICT, the object ID that comes from the
ARTMODEL command is the next object ID of that type. For example, if ARTMODEL creates the first CART
®
regression
model in the Minitab project, then the first CART
®
regression model has the object ID 1. If you then use RTREE
to create a different CART
®
regression model, then that model has the object ID 2.
Results for an existing model
To produce the results for the multiple regression model, do not enter any subcommands. Use the appropriate
subcommand to produce the results for a TreeNet
®
model, a Random Forests
®
model, a MARS
®
model, or a CART
®
model.
TN K
Produces results for the TreeNet
®
model that K specifies. K is the value in the Model column of the Optimization
of Hyperparameters table that shows the different TreeNet
®
models. If this table is not in the results, then the ID
is 1.
RF K
Produces results for the Random Forests
®
model that K specifies. K is the value in the Model column of the
Optimization of Hyperparameters table that shows the different Random Forests
®
models. If this table is not in
the results, then the ID is 1.
MARS K
Produces results for the MARS
®
model that K specifies. K values are 1 more than the number of basis functions
in the model. For example, 1 represents the model with 0 basis functions. With 0 basis functions, the model is the
mean of the response variable. An alternative model with 9 basis functions has an index of 10.
CART
Produces results for the best CART
®
model from the search for the best type of model.
Results for a new model
To produce results for a TreeNet
®
model, a Random Forests
®
model, or a MARS
®
model, specify which type of model
to create and then specify all the hyperparameters for the model. For TreeNet
®
models and Random Forests
®
models,
you can enter multiple values of the hyperparameters. If you enter multiple values for more than 1 hyperparameter,
then the procedure evaluates all of the possible combinations of the hyperparameters and produces full results for
the best model.
TN
Produces results for the TreeNet
®
model that you specify with the subsubcommands.
LRATE K...K
Specifies up to 10 learning rates to evaluate. You can specify values from 0.0001 to 1.
SUBSAMPLE K...K
Specifies up to 10 subsample proportions to evaluate. You can specify positive values that are less than or
equal to 1.
MAXNODE K (K K)
Specifies up to 3 maximum numbers of terminal nodes to evaluate. You can specify values from 2 to 2,000.
You cannot use MAXNODE and MAXTDEPTH together.
819
Minitab Statistical Software Predictive Analytics
MAXTDEPTH K (K K)
Specifies up to 3 maximum tree depths to evaluate. You can specify values from 2 to 1,000. You cannot use
MAXNODE and MAXTDEPTH together.
NTREE K
Specifies the maximum number of trees to build. Specify a single value from 1 to 5,000.
NPRED K (K K)
Specifies the number of predictors randomly selected to evaluate at each node to split. K must be a positive
integer. If K is greater than the number of predictors, then K counts as being equal to the number of predictors.
RF
Produces results for the Random Forests
®
model that you specify with the subsubcommands. If you specify more
than one argument for NPRED or NOSPLIT, the procedure evaluates all of the possible combinations of the
hyperparameters and produces full results for the best model.
NTREE K
Specifies K bootstrap samples to grow K trees. You must enter a value between 3 and 3000.
NPRED K (K K)
Specifies the number of predictors randomly selected to evaluate at each node to split. K must be a positive
integer. If K is greater than the number of predictors, then K counts as being equal to the number of predictors.
NOSPLIT K (K K)
Do not split a node if the node size is less than K.
BSIZE K
Specifies the bootstrap sample size. You must enter a value greater than or equal to 5. If you don't enter the
BSIZE subsubcommand or if you enter a value that is greater than the training data size, Minitab uses a
sample size equal to the training data size. This subsubcommand is optional.
MARS
Produces results for the MARS
®
model that you specify with the subsubcommands. Use NINTERACT or SINTERACT
2 to specify the predictor interaction options. To explore higher order interactions or to control interactions more
discretely, use the MARS command to fit a new model.
BFUNCTIONS K
Set the maximum number of basis functions to evaluate in the construction of the model. K must be a positive
integer of 200 or less. K = 30 is the default value.
MINOBS K
Specifies to use an algorithm to determine the minumum number of data points between changes in the
basis functions or specifies the minumum number.
K = 0
The analysis uses sample size and model complexity to automatically select a value.
1 K N
A value of 1 indicates that consecutive data points are eligible to be points where the basis function
changes. The value of 1 allows the most rapid changes in the model predictions. Use larger values to
create smoother, potentially less locally-accurate models to explore more general relationships. N is the
number of rows in the column for the response variable. Values larger than the sample size result in an
error.
820
Minitab Statistical Software Predictive Analytics
NINTERACT
Do not allow predictor interactions in the model. Minitab uses only the additive model.
SINTERACT 2
Allow predictor interactions up to the 2
nd
order when building the model.
ARTPREDICT: Session command to predict from a model in the
results of Discover Best Model (Continuous Response)
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
ARTPREDICT K
Predicts the response values for new observations with the model that Discover Best Model (Continuous
Response) saves.
K is the identification number of a model that the ATREGRESS command saves. This K is always a positive integer.
The first model from the ATREGRESS command that you create in a project is identified as 1, the second is
identified as 2, and so on. The number for a model remains the same even if you delete the output for another
model from the Navigator. For example, if you delete the output for the first model, the second model that you
made remains model 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model.
If a predictor is categorical, the values in C must match the values in the model. Which predictors to enter depends
on whether the model uses all of the predictors from the original analysis. CART
®
, MARS
®
, Random Forests
®
, and
TreeNet
®
models always use all of the predictors from the original subcommands for the analysis. A multiple
regression model that uses a selection procedure can have fewer predictors than in the original subcommands
for the analysis.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
the ATREGRESS command.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
the ATREGRESS command.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
Fewer predictors than in the original subcommands
If the results contain a multiple regression model that eliminates some predictors, then omit the eliminated
predictors.
821
Minitab Statistical Software Predictive Analytics
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from the ATREGRESS command.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from the ATREGRESS command.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATREGRESS command, the predictor selection procedure returns a model without C3 and
C4 as predictors. Then, you can run the prediction command with the CPREDICTORS subcommand.
Enter the predictors in the following order:
CPREDICTORS C6 C2 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
tree.
If a predictor is categorical, the corresponding value for K must match the values in the model. Which predictors
to enter depends on whether the model uses all of the predictors from the original analysis. CART
®
, MARS
®
,
Random Forests
®
, and TreeNet
®
models always use all of the predictors from the original subcommands for the
analysis. A multiple regression model that uses a selection procedure can have fewer predictors than in the original
subcommands for the analysis.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
ATREGRESS.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
ATREGRESS.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
822
Minitab Statistical Software Predictive Analytics
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Fewer predictors than in the original subcommands
If the results contain a multiple regression model that eliminates some predictors, then omit the eliminated
predictors.
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from ATREGRESS.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from ATREGRESS.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATREGRESS command, the predictor selection procedure returns a model without C3 and
C4 as predictors. Then, you can run the prediction command with the KPREDICTORS subcommand.
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 'Blue' 'Urgent' 'New'
Storage and results for all types of models
The table is available when you use CPREDICTORS or KPREDICTORS. Storage is available only when you use
CPREDICTORS.
TPREDICTION
Displays the prediction table.
SFIT C
Stores the predicted responses in C.
823
Minitab Statistical Software Predictive Analytics
Additional storage and results for multiple regression models
The table is available when you use CPREDICTORS or KPREDICTORS. Storage is available only when you use
CPREDICTORS.
TEQUATION
Displays the model equation. The results provide a separate equation for each level of each categorical predictor.
If you have only categorical variables, the results show a single equation.
SSEFIT C
Stores the standard error of the predicted responses in C.
SCLIMITS C C
Stores the lower and upper confidence limits of the predicted responses in C and C.
SPLIMITS C C
Stores the lower and upper prediction limits of the predicted responses in C and C.
Additional storage for CART
®
models
Storage is available only when you use CPREDICTORS.
STNID C
Stores the terminal node (cluster) ID for each new observation.
MRPREDICT: Session command to predict from a multiple
regression model that was an alternative model from Discover
Best Model (Continuous Response)
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
MRPREDICT K
Predicts response values for new observations from the multiple regression model object ID that K identifies. The
ARTMODEL command with no subcommands creates a multiple regression model object.
This K is always a positive integer. The first multiple regression model object that you create in a project is identified
as 1, the second object is identified as 2, and so on. The number for a model remains the same even if you delete
the output for another model from the Navigator. For example, if you delete the output for the first model object,
the second model object that you made remains model object 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model. If a predictor is categorical, the values in C must match the values in the model. Which predictors
to enter depends on if a selection algorithm removes any predictors from the model. Predictor selection does
not occur when the ATREGRESS command includes the NONE subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
the ATREGRESS command.
824
Minitab Statistical Software Predictive Analytics
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
the ATREGRESS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
Fewer predictors than in the original subcommands
If the model does not include all of the predictors, then omit the eliminated predictors.
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from the ATREGRESS command.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from the ATREGRESS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATREGRESS command, the predictor selection algorithm gave a model without C3 and
C4 as predictors. Then, you can run the prediction command with the CPREDICTORS subcommand.
Enter the predictors in the following order:
CPREDICTORS C6 C2 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
model. KPREDICTORS can be repeated up to three times.
If a predictor is categorical, the corresponding value for K must match the values in the model. Which predictors
to enter depends on if a selection algorithm removes any predictors from the model. Predictor selection does
not occur when the ATREGRESS command includes the NONE subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
the ATREGRESS command.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
the ATREGRESS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
following table gives the values to predict:
825
Minitab Statistical Software Predictive Analytics
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Fewer predictors than in the original subcommands
If the model does not include all of the predictors, then omit the eliminated predictors.
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from the ATREGRESS command.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from the ATREGRESS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATREGRESS command to create a model. The
following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATREGRESS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATREGRESS command, the predictor selection algorithm gave a model without C3 and
C4 as predictors. Then, you can run the prediction command with the KPREDICTORS subcommand.
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 'Blue' 'Urgent' 'New'
826
Minitab Statistical Software Predictive Analytics
Results
Displays a variety of tables in the output.
TEQUATION
Displays the model equation. The results provide a separate equation for each level of each categorical predictor.
If you have only categorical variables, the results show a single equation.
TPREDICTION
Displays the prediction table.
Storage
Stores information related to the predicted responses when you use the CPREDICT subcommand.
SFIT C
Stores the predicted responses in C.
SSEFIT C
Stores the standard error of the predicted responses in C.
SCLIMITS C C
Stores the lower and upper confidence limits of the predicted responses in C and C.
SPLIMITS C C
Stores the lower and upper prediction limits of the predicted responses in C and C.
Discover Best Model (Binary Response)
ATCLASS: Session command for discovering the best model type
for a binary response
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
ATCLASS
Compares the performance of 4 common types of models from Minitab commands: GZLM, CTREE, BCTREE, and
RCFOREST. The models all use a binary response with many categorical and continuous predictor variables.
The response variable column must contain two distinct values that are text or numbers.
The predictors can be continuous predictors or categorical predictors. Continuous predictors must have numeric values.
Categorical predictors can have numeric or text values. You must use at least one of the predictor subcommands,
either CONTINUOUS or CATEGORICAL.
All columns in the analysis must have the same number of rows. Minitab excludes all observations with missing values
in the response variable. For a binary logistic regression model, Minitab also excludes observations with missing values
in a predictor variable.
RESPONSE C
Enter a column that contains 2 distinct values of a categorical response. C can be text or numeric.
827
Minitab Statistical Software Predictive Analytics
EVENT K
Specifies the event value for a binary response. K must be 1 of the 2 response values. Enclose a text value of
K in quotation marks.
CONTINUOUS C...C
Specifies the continuous predictors that are in columns C...C. The columns must be numeric and must have the
same number of rows as the response column.
CATEGORICAL C...C
Specifies the categorical predictors that are in columns C...C. The columns can be numeric or text and must have
the same number of rows as the response column.
Validation options
TEST K
Performs validation with a test set. Minitab Statistical Software randomly selects the rows for the test set. K is the
fraction of the data in the test set.
RANDOMIZE K
Specifies the base number for randomly splitting the entire data set into training and test sets. K sets the
starting point for the random number generator.
K must be a positive integer. Use 12345 to get the same results as the default setting.
CVTEST K
Performs k-fold cross validation for the binary logistic regression model, the TreeNet
®
model, and the CART
®
model. The validation of the Random Forests
®
model uses the out-of-bag statistics.
Minitab Statistical Software randomly selects the data for the folds. K is the number of folds.
SSAMPLE C
With CVTEST:
The storage column stores the fold identification in C.
C contains values 1, 2, ..., K.
With TEST:
The storage column, Sample_Id, stores the training and test sample assignments in C.
C is a binary text column that contains Training and Test as the 2 values.
Criteria
Use one of the following subcommands to specify the criterion that determines the best model.
MAXLKH: Use the maximum likelihood.
ROC: Use the maximum area under the ROC curve.
MISCLASS: Use the minimum misclassification rate.
These commands also determine the optimal pruning of the tree for CART
®
models and the criterion to use to determine
the optimal number of trees for the TreeNet
®
model. If you do not specify any subcommands about the criteria, then
the analysis uses the Maximum Likelihood method.
828
Minitab Statistical Software Predictive Analytics
Options for binary logistic regression models
For a binary logistic regression model, you can specify which terms are in the model and a procedure for term selection.
Specification of more than one of the subcommands STEPWISE, FVALIDATION, and NONE stops the analysis.
TERMS termlist
Specifies the model terms. Terms must be legal cross-terms. Only continuous predictors can be repeated. Nested
terms are not allowed. The model can be nonhierarchical. If you do not specify this subcommand, then the analysis
uses all linear terms and all terms of order 2. For examples, go to How to specify the model for ATCLASS, GZLM,
OLOGISTIC and NLOGISTIC on page 1165.
STEPWISE
Specifies a stepwise model selection procedure that uses both forward selection and backward elimination. The
term that enters the model has the lowest p-value below 0.15. If no terms can enter the model, the term with the
highest p-value greater than 0.15 exits the model. The procedure adds or removes 1 term at a step. The procedure
ignores model hierarchy.
FVALIDATION
Uses forward selection to select the terms for the final model. The selection of the final model uses the criterion
from the forward selection calculations. When you use FVALIDATION, you must also use TEST. At each step,
Minitab Statistical Software adds the term with the smallest p-value to the model. The procedure ignores model
hierarchy. At the end of each step, Minitab Statistical Software calculates the validation version of the criterion.
At the end of the forward selection procedure, the model with the best value of the criterion is the final model.
The procedure continues until it either fits the full model or until it fits a model that leaves 1 degree of freedom
for error.
NONE
Uses the model from the TERMS subcommand without any selection procedure. If you do not specify the TERMS
subcommand, the NONE subcommand specifies the use of all linear terms and all terms of order 2.
Options for binary logistic regression models and
TreeNet
®
models
CTHRESHOLD K
For a binary response, K specifies the threshold value such that if the probability of the event > K, then assign the
event level as the predicted response. Otherwise, assign the non-event level as the predicted response.
K must be between 0 and 1; K = 0.5 is the default. K = 0 indicates that the threshold equals the estimated event
probability of the data when no model is built.
Options for CART
®
models
Use one of the following subcommands to specify the node splitting method.
GINI: Use the Gini method. This is the default method.
ENTROPY: Use the Entropy method.
The following subcommands are available to select the optimal pruning of the tree.
MINCOST: Use minimum cost to select the optimal pruning of the tree.
STERROR K : Use within K standard errors of the minimum cost to select the optimal pruning of the tree.
If you do not specify the node splitting method, then the analysis uses GINI and STERROR 1.
The following subcommands are available to control tree growth due to sample size or node complexity.
CNOSPLIT K: Do not split a node that is smaller than K. K=10 is the default.
829
Minitab Statistical Software Predictive Analytics
NOTERMINAL K: Do not create a terminal node that is smaller than K. K=3 is the default.
Options for TreeNet
®
and Random Forests
®
models
NTREE K K
The first K is the number of trees to build for the TreeNet
®
model (gradient boosted regression tree). Enter a value
from 1 to 5,000. The second K is the number of bootstrap samples and the number of trees to build for the Random
Forests
®
model. Enter a value from 3 to 3,000.
If you do not specify NTREE, Minitab uses 300 for each value of K.
NPRED K K
Specifies the number of predictors randomly selected to evaluate at each node to split. The first K is for TreeNet
®
models. The second K is for Random Forests
®
models. K must be an integer between 0 and 100. The following
list describes what the subcommand does with different values of K.
0: Use the square root of the total number of predictors, rounded down to the nearest integer.
100: Use all predictors.
0 < K < 100: Use this percentage of the total number of predictors, rounded down to the nearest integer. If
(total number of predictors) x (K / 100) < 1, the number of predictors is 1.
If you do not specify NPRED, then TreeNet
®
models use all predictors (K = 100) and Random Forests
®
models use
the square root of the number of predictors (K = 0).
BRANDOMIZE K
Specifies the base number to randomly generate subsamples to build a tree. K must be a positive integer. K also
controls every randomly selected subset of the m total predictors to generate the splitting rule for an internal
node, if applicable.
Options for TreeNet
®
models
LRATE K...K
Specifies up to 10 learning rates to evaluate. The learning rate of the boosting procedure protects from overfitting.
K must be from 0.0001 to 1.
If you do not specify the LRATE subcommand, then the analysis usually tunes the hyperparameters with 3 values
of K: 0.001, 0.1, and max(0.01, 0.1 * min(1.0, N/10000)), where N = number of rows in the response column. If
max(0.01, 0.1 * min(1.0, N/10000)) = 0.001 or 0.1, then the analysis tunes the hyperparameters with 0.001, 0.01
and 0.1.
SUBSAMPLE K...K
Specify up to 10 fractions of subsampling. At each iteration, the procedure selects a different subset that contains
this fraction of the data to construct a tree. Subsampling protects from overfitting. K must be greater than 0 and
less than or equal to 1. The default values are 0.5 and 0.7.
For the TreeNet
®
models, choose either MAXNODE or MAXTDEPTH. If you do not specify either MAXNODE or MAXTDEPTH,
then the analysis uses MAXNODE 6.
MAXNODE K (K K)
Specifies up to 3 numbers of maximum terminal nodes per tree. K must be a positive integer between 2 and 2000.
MAXTDEPTH K (K K)
Specifies up to 3 numbers of maximum tree depths to the K
th
layer. K must be a positive integer between 2 and
1000. MAXTDEPTH tends to give balanced trees.
830
Minitab Statistical Software Predictive Analytics
Options for Random Forests
®
models
BSIZE K
Sets the bootstrap sample size. You must enter a value of K greater than or equal to 5. If you don't enter the
BSIZE subcommand or if you enter a value that is greater than the training data size, then Minitab uses a sample
size equal to the training data size.
NOSPLIT K (K K)
Does not split a node that is smaller than K. Specifies up to 3 integers greater than or equal to 2. Each integer
produces a distinct Random Forests
®
model. If you do not specify the NOSPLIT subcommand, then the analysis
uses K = 2. If you specify a K larger than the maximum value for the data, then the analysis uses the maximum
value.
Storage
SMODEL
Stores the model object to use in subsequent analyses. You can predict, select an alternative model, or add more
partial dependence plots only if you store the model object.
SFIT C
Stores the fitted event probability for each record in C. These fitted values are for TreeNet
®
models and binary
logistic regression models. These fitted values are not for CART
®
models or Random Forests
®
models.
SPCLASS C
Stores the predicted class for each record in C.
SEPROB C C
Stores the probability of the event and the probability of the nonevent.
ACTMODEL: Session command for selecting an alternative model
from Discover Best Model (Binary Response)
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
ACTMODEL K
After the analysis identifies the best model with ATCLASS, ACTMODEL produces results for alternative models.
With none of the subcommands that specify a model type, the analysis produces results for the best binary
logistic model from the search.
With the CART subcommand, the analysis produces results for the best CART
®
model from the search for the
best model.
With the TN subcommand and an object ID that identifies the model, the analysis produces results for the
best TreeNet
®
model from the search for the best model.
With the RF subcommand and an object ID that identifies the model, the analysis produces results for the
best Random Forests
®
model from the search for the best model.
With the TN subcommand or the RF subcommand in addition to the subsubcommands that specify details
about the model type, ACTMODEL explores additional models.
K is a positive integer that represents a Discover Best Model (Binary Response) object ID. The first Discover
Best Model (Binary Response) that you create in a project has the object ID 1. The second Discover Best Model
(Binary Response) that you create with the command has the object ID 2, and so on.
831
Minitab Statistical Software Predictive Analytics
The tables and graphs for the new model are displayed in a new output tab. The same columns that the original
analysis stored are also stored for the new model. The storage for the new model is in a new column. For example,
if the original analysis stored the fitted values in a column titled "Fit," then the new analysis names an empty
column "Fit_1" and stores the fitted values in that column.
The type of object ID that ACTMODEL creates is the same as the type of model in the results. The type of object
ID determines which command to use to predict from a model. For TreeNet
®
models, you can also add partial
dependence plots. Use the following commands to do further analysis on each type of model.
CommandAnalysisType
LRPREDICTPredict the response for new dataBinary logistic regression
CTPREDICTPredict the response for new dataCART
®
RCPREDICTPredict the response for new dataRandom Forests
®
BCPREDICTPredict the response for new dataTreeNet
®
BCGOPARTAdd one-predictor partial dependence plots
BCGTPARTAdd two-predictor partial dependence plots
For purposes of using a command such as LRPREDICT or BCPREDICT, the object ID that comes from the
ACTMODEL command is the next object ID of that type. For example, if ACTMODEL creates the first CART
®
classification model in the Minitab project, then that CART
®
Classification model has the object ID 1. If you then
use CTREE to create a different CART
®
classification model, then that model has the object ID 2.
Results for an existing model
To produce the results for the binary logistic regression model, do not enter any subcommands. Use the appropriate
subcommand to produce the results for a TreeNet
®
model, a Random Forests
®
model, or a CART
®
model.
TN K
Produces results for the TreeNet
®
model that K specifies. K is the value in the Model column of the Optimization
of Hyperparameters table that shows the different TreeNet
®
models. If this table is not in the results, then the ID
is 1.
RF K
Produces results for the Random Forests
®
model that K specifies. K is the value in the Model column of the
Optimization of Hyperparameters table that shows the different Random Forests
®
models. If this table is not in
the results, then the ID is 1.
CART
Produces results for the best CART
®
model from the search for the best type of model.
Results for a new model
To produce results for a TreeNet
®
model or a Random Forests
®
model, specify which type of model to create and then
specify all the hyperparameters for the model. If you enter multiple values for more than 1 hyperparameter, then the
procedure evaluates all of the possible combinations of the hyperparameters and produces full results for the best
model.
TN
Produces results for the TreeNet
®
model that you specify with the subsubcommands.
832
Minitab Statistical Software Predictive Analytics
LRATE K...K
Specifies up to 10 learning rates to evaluate. You can specify values from 0.0001 to 1.
SUBSAMPLE K...K
Specifies up to 10 subsample proportions to evaluate. You can specify positive values that are less than or
equal to 1.
MAXNODE K (K K)
Specifies up to 3 maximum numbers of terminal nodes to evaluate. You can specify values from 2 to 2,000.
You cannot use MAXNODE and MAXTDEPTH together.
MAXTDEPTH K (K K)
Specifies up to 3 maximum tree depths to evaluate. You can specify values from 2 to 1,000. You cannot use
MAXNODE and MAXTDEPTH together.
NTREE K
Specifies the maximum number of trees to build. Specify a single value from 1 to 5,000.
NPRED K (K K)
Specifies the number of predictors randomly selected to evaluate at each node to split. K must be a positive
integer. If K is greater than the number of predictors, then K counts as being equal to the number of predictors.
RF
Produces results for the Random Forests
®
model that you specify with the subsubcommands. If you specify more
than one argument for NPRED or NOSPLIT, the procedure evaluates all of the possible combinations of the
hyperparameters and produces full results for the best model.
NTREE K
Specifies K bootstrap samples to grow K trees. You must enter a value between 3 and 3000.
NPRED K (K K)
Specifies the number of predictors randomly selected to evaluate at each node to split. K must be a positive
integer. If K is greater than the number of predictors, then K counts as being equal to the number of predictors.
NOSPLIT K (K K)
Do not split a node if the node size is less than K.
BSIZE K
Specifies the bootstrap sample size. You must enter a value greater than or equal to 5. If you don't enter the
BSIZE subsubcommand or if you enter a value that is greater than the training data size, Minitab uses a
sample size equal to the training data size. This subsubcommand is optional.
ACTPREDICT: Session command to predict from a model in the
results of Discover Best Model (Binary Response)
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
ACTPREDICT K
Predicts the response values for new observations with the model that Discover Best Model (Binary Response)
saves.
K is the identification number of a model that the ATCLASS command saves. This K is always a positive integer.
The first model from the ATCLASS command that you create in a project is identified as 1, the second is identified
833
Minitab Statistical Software Predictive Analytics
as 2, and so on. The number for a model remains the same even if you delete the output for another model from
the Navigator. For example, if you delete the output for the first model, the second model that you made remains
model 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model.
If a predictor is categorical, the values in C must match the values in the model. Which predictors to enter depends
on whether the model uses all of the predictors from the original analysis. CART
®
, Random Forests
®
, and TreeNet
®
models always use all of the predictors from the original subcommands for the analysis. A binary logistic regression
model that uses a selection procedure can have fewer predictors than in the original subcommands for the analysis.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
the ATCLASS command.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
the ATCLASS command.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The
ATCLASS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
Fewer predictors than in the original subcommands
If the results contain a binary logistic regression model that eliminates some predictors, then omit the
eliminated predictors.
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from the ATCLASS command.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from the ATCLASS command.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The
ATCLASS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATCLASS command, the predictor selection procedure gave a model without C3 and C4
as predictors. Then, you can run the prediction command with the CPREDICTORS subcommand.
Enter the predictors in the following order:
CPREDICTORS C6 C2 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
tree.
834
Minitab Statistical Software Predictive Analytics
If a predictor is categorical, the corresponding value for K must match the values in the model. Which predictors
to enter depends on whether the model uses all of the predictors from the original analysis. CART
®
, Random
Forests
®
, and TreeNet
®
models always use all of the predictors from the original subcommands for the analysis.
A binary logistic regression model that uses a selection procedure can have fewer predictors than in the original
subcommands for the analysis.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
ATCLASS.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
ATCLASS.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The
following table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATCLASS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Fewer predictors than in the original subcommands
If the results contain a binary logistic regression model that eliminates some predictors, then omit the
eliminated predictors.
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from ATCLASS.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from ATCLASS.
For example, suppose you have a worksheet with predictors in C2-C8. Predictors C2, C3, and C6 are continuous
and predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The
following table gives the values to predict:
ValuePredictor
12.1C2
100C3
835
Minitab Statistical Software Predictive Analytics
ValuePredictor
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATCLASS command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATCLASS command, the predictor elimination algorithm gave a model without C3 and
C4. Then, you can run the prediction command with the KPREDICTORS subcommand.
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 'Blue' 'Urgent' 'New'
Storage and results for all types of models
The table is available when you use CPREDICTORS or KPREDICTORS. Storage is available only when you use
CPREDICTORS.
TPREDICTION
Displays the prediction table.
SEPROB C C
Stores the predicted event and non-event probabilities in C and C.
SPCLASS C
Stores the predicted class in C.
Additional storage and results for binary logistic regression models
The table is available when you use CPREDICTORS or KPREDICTORS. Storage is available only when you use
CPREDICTORS.
TEQUATION
Displays the model equation. The results provide a separate equation for each level of each categorical predictor.
If you have only categorical variables, the results show a single equation.
SFIT C
Stores the predicted event probability in C.
Additional storage for TreeNet
®
models
Storage is available only when you use CPREDICTORS.
SFIT C
Stores the predicted event probability in C.
836
Minitab Statistical Software Predictive Analytics
Additional storage for CART
®
models
Storage is available only when you use CPREDICTORS.
STNID C
Stores the terminal node (cluster) ID for each new observation.
LRPREDICT: Session command to predict from a binary logistic
regression model with Discover Best Model (Binary Response)
Note This command is available with the Predictive Analytics Module. Click here for more information about how to activate the module.
LRPREDICT K
Predicts response values for new observations from the binary logistic regression model object ID that K identifies.
The ACTMODEL command with no subcommands creates a binary logistic regression model object.
This K is always a positive integer. The first binary logistic regression model object that you create in a project is
identified as 1, the second object is identified as 2, and so on. The number for a model remains the same even if
you delete the output for another model from the Navigator. For example, if you delete the output for the first
model object, the second model object that you made remains model object 2.
CPREDICTORS C...C
Specifies the predictor values in columns C...C. The number of columns must equal the number of predictors used
in the model. If a predictor is categorical, the values in C must match the values in the model. Which predictors
to enter depends on if a selection algorithm removes any predictors from the model. Predictor selection does
not occur when the ATCLASS command includes the NONE subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
the ATCLASS command.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
the ATCLASS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The ATCLASS
command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
CPREDICTORS C6 C2 C3 C4 C5 C7 C8
Fewer predictors than in the original subcommands
If the model does not include all of the predictors, then omit the eliminated predictors.
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from the ATCLASS command.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from the ATREGRESS command.
837
Minitab Statistical Software Predictive Analytics
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The ATCLASS
command uses the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATCLASS command, the predictor selection algorithm gave a model without C3 and C4
as predictors. Then, you can run the prediction command with the CPREDICTORS subcommand.
Enter the predictors in the following order:
CPREDICTORS C6 C2 C5 C7 C8
KPREDICTORS K...K
Specifies the predictor values in K...K. The number of constants must equal the number of predictors used in the
model. KPREDICTORS can be repeated up to three times.
If a predictor is categorical, the corresponding value for K must match the values in the model. Which predictors
to enter depends on if a selection algorithm removes any predictors from the model. Predictor selection does
not occur when the ATCLASS command includes the NONE subcommand.
All predictors from the original subcommands
The order of the predictors follows a strict sequence:
1. Enter continuous predictors. Use the order of the predictors from the CONTINUOUS subcommand from
the ATCLASS command.
2. Enter categorical predictors. Use the order of the predictors from the CATEGORICAL subcommand from
the ATCLASS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The following
table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATCLASS command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 100 'A' 'Blue' 'Urgent' 'New'
Fewer predictors than in the original subcommands
If the model does not include all of the predictors, then omit the eliminated predictors.
838
Minitab Statistical Software Predictive Analytics
1. Enter continuous predictors that are in the model. Use the order of the predictors from the CONTINUOUS
subcommand from the ATCLASS command.
2. Enter categorical predictors that are in the model. Use the order of the predictors from the CATEGORICAL
subcommand from the ATCLASS command.
For example, suppose the worksheet has predictors in C2-C8. Predictors C2, C3, and C6 are continuous and
predictors C4, C5, C7, and C8 are categorical. You use the ATCLASS command to create a model. The following
table gives the values to predict:
ValuePredictor
12.1C2
100C3
AC4
BlueC5
-45.3C6
UrgentC7
NewC8
The ATCLASS command used the following subcommands:
CONTINUOUS C6 C2 C3
CATEGORICAL C4 C5 C7 C8
When you run the ATCLASS command, the predictor selection algorithm gave a model without C3 and C4
as predictors. Then, you can run the prediction command with the KPREDICTORS subcommand.
Enter the predictors in the following order:
KPREDICTORS -45.3 12.1 'Blue' 'Urgent' 'New'
Results
Displays a variety of tables in the output.
TEQUATION
Displays the model equation. The results provide a separate equation for each level of each categorical predictor.
If you have only categorical variables, the results show a single equation.
TPREDICTION
Displays the prediction table.
Storage
Stores information related to the predicted responses when you use the CPREDICT subcommand.
SEPROB C C
Stores the predicted event and non-event probabilities in C and C.
SPCLASS C
Stores the predicted class in C.
839
Minitab Statistical Software Predictive Analytics
SFIT C
Stores the predicted event probability in C.
840
Minitab Statistical Software Predictive Analytics
Multivariate Analysis
PCA: Session command for performing principal
components analysis
PCA C...C
Performs principal component analysis (PCA).
PCA is a data reduction technique that is used to identify a small set of variables that account for a large proportion
of the total variance in the original variables. Components can be calculated from the correlation matrix (the
default) or the covariance matrix. Output consists of the eigenvalues (that is, the variances of the principal
components), the proportion and cumulative proportion of the total variance explained by each principal
component, and the coefficients for each principal component.
COVARIANCE
Calculates the principal components using the covariance matrix. The default is the correlation matrix.
NCOMP K
If there are p variables on the PCA line, then the default is to calculate all p principal components. But if p is
large, you may want just the first few. NCOMP says how many components to calculate.
Even if you use NCOMP, Minitab still prints all p eigenvalues.
COEFFICIENTS C...C
Stores the coefficients of the principal components in the columns. The number of columns given on
COEFFICIENTS must be less than or equal to the number of principal components calculated.
SCORES C...C
Stores the principal components scores in the columns. The number of columns on SCORES must be less
than or equal to the number of principal components calculated.
EIGEN C
Stores the eigenvalues in one column. The eigenvalues are stored in numerical order from largest to smallest.
DISTANCE C
Stores the Mahalanobis distance for the data points in one column.
GSCREE
Displays a Scree plot (also called eigenvalue profile plot). Minitab plots the eigenvalue associated with a
principal component versus the number of the component.
GSCORE
Plots the scores for the second principal component (y-axis) versus the scores for the first principal component
(x-axis). To create plots for other components, store the scores with the SCORES subcommand and use the
PLOT on page 947 command.
GLOADING
Plots of the loadings for the second principal component (y-axis) versus the loadings for the first principal
component (x-axis). A line is drawn from each loading to the (0, 0) point.
841
Minitab Statistical Software Multivariate Analysis
GBIPLOT
Displays a biplot, a combined score and loadings plot, for the first two components.
GOUTLIER
Plots the Mahalanobis distance for each data point. This distance is the difference between the multivariate
space's centroid and the data point. Use this plot to identify outliers in a multivariate space because it takes
into account the different scales between variables and the correlations among them.
FACTOR: Session command for performing a factor
analysis
FACTOR [C...C]
Performs factor analysis. Initial factor extraction may be done using principal components (default) or maximum
likelihood. Input can be the data, a correlation or covariance matrix, or the loadings from a previous analysis.
You can rotate the initial solution using varimax, quartimax, equamax, or orthomax.
Displayed output consists of the loadings (factor pattern), communalities, and the coefficients for the factor scores.
You can store the loadings, factor score coefficients, factor scores, and residual matrix.
Extraction
NFACTORS K
Extracts K factors.
NFAC is required if you specify ML for the initial extraction. If you do not use NFACTORS with principal components,
Minitab sets NFACTORS equal to the number of variables in the data set.
If, with ML, you specify a value of K that is too large, the solution will not be unique. Minitab will print a message
in this case. Specifically, if there are p variables on FACTOR, then there are p(p - 1)/2 parameters in the correlation
matrix and pK parameters in the factor model fit by ML. If K > (p 1)/2 then the number of parameters in the
factor model is greater than the number in the correlation matrix. The solution is not unique. Rotation will not
help in this case.
ML
Uses maximum likelihood for the initial solution. The default is to use principal components. If you use ML, you
must specify the number of factors you want with NFACTORS.
Rotation
FACTOR provides four orthogonal rotations. VMAX specifies a varimax rotation, QMAX a quartimax rotation, EMAX
an equamax rotation, and OMAX an orthomax rotation with gamma = K.
The first three rotations are actually special cases of OMAX with the appropriate choice for gamma; gamma = 1 is
varimax, gamma = 0 is quartimax, and gamma = NFACTORS/2 is equamax.
VMAX
Specifies varimax rotation.
842
Minitab Statistical Software Multivariate Analysis
QMAX
Specifies quartimax rotation.
EMAX
Specifies equamax rotation.
OMAX K
Specifies orthomax rotation with K gamma.
Options
CORRELATION [M]
Factors the correlation matrix. This is the default. Use COVARIANCE to factor the covariance matrix.
If you specify a stored correlation matrix on CORRELATION, Minitab calculates the loadings and coefficients from
the stored matrix. In this case, any data specified on FACTOR is ignored, and thus scores can not be calculated.
COVARIANCE [M]
Factors the covariance matrix. The default is to factor the correlation matrix. See CORRELATION.
If you specify a stored covariance matrix on COVARIANCE, Minitab calculates the loadings and coefficients from
the stored matrix. In this case, any data specified on FACTOR is ignored, and thus scores can not be calculated.
COVARIANCE cannot be used with ML.
PRIORS C
FACTOR uses these in the algorithm for ML, as the initial values for the communalities. C should contain one value
for each variable.
The default is to use the squared multiple correlations of each variable with all the other variables. Suppose R is
the correlation matrix of the variables. Suppose rii is the i
th
diagonal element of R**–1 then initial value of the i
th
communality is (1-1/rii).
MAXITERATIONS K
Specifies the maximum number of iterations for ML. The default is 20.
CONVERGENCE K
Specifies the criterion for convergence in ML. The ML algorithm converges when the uniquenesses do not change
very much. The value of K is the size of the smallest change. By default, K is 0.005.
INLOADINGS C...C
Uses specified columns as loadings.
INLOADINGS allows you to try different rotations without having to recalculate the initial solution each time. It is
particularly useful if you use ML for the initial solution, since this can take a long time to calculate. If you want
the rotated loadings and rotation matrix only, you do not have to specify the data on FACTOR. If you want the
coefficients, factor scores, or residual matrix, then you must specify the data.
You can also use INLOADINGS to predict factor scores for new data from previously calculated loadings, stored
with the subcommand LOADINGS. Specify the new data on FACTOR and the calculated loadings on INLOADINGS.
843
Minitab Statistical Software Multivariate Analysis
Graphs
GSCREE
Displays a Scree plot, also called an eigenvalue profile plot. Minitab plots the eigenvalue associated with a factor
versus the number of the factor.
GSCORE
Plots the scores for the second factor (y-axis) versus the scores for the first factor (x-axis). To create plots for other
factors, store the scores with the SCORES subcommand and use the PLOT on page 947 command. (Note: Scores
must be calculated from raw data. Therefore, you must not specify a matrix with either the CORRELATION or
COVARIANCE subcommands if you want to generate this graph.)
GLOADING
Plots of the loadings for the second factor (y-axis) versus the loadings for the first factor (x-axis). A line is drawn
from each loading to the (0, 0) point.
To create simple loading plots for other factors, store the loadings with the LOADINGS subcommand and use the
PLOT on page 947 command. If you want to connect the loading point to the zero point, add a zero to the bottom
of each column of loadings in the worksheet, then add lines connecting the loading points to the zero point with
the graph editor.
GBIPLOT
Displays a biplot, a combined score and loadings plot, for the first two factors.
Storage
EIGEN C M
Stores the eigenvalues and eigenvectors of the matrix that was factored, either the correlation or covariance
matrix.
EIGEN can be used only when the initial extraction is done using principal components. The eigenvalues are stored
in C, in numerical order starting with the largest, and the eigenvectors in M, one vector per column of M, in the
same order as the eigenvalues. You can then PLOT the eigenvalues to see a scree plot.
LOADINGS C...C
Stores the loadings in C...C. There must be one C for each factor. These can later be input with the subcommand
INLOADINGS. They can also be plotted with PLOT. If a rotation was specified, the loadings for the rotated solution
are stored.
COEFFICIENTS C...C
Stores the factor score coefficients in C...C. There must be one C for each factor. These can then be plotted with
PLOT. If a rotation was specified, the coefficients for the rotated solution are stored.
SCORES C...C
Stores the factor scores in C...C. There must be one C for each factor. These can then be plotted with PLOT. If a
rotation was specified, the scores for the rotated solution are stored. To use SCORES, you must specify data as
input on the FACTOR command line, and you must not specify a matrix with either the CORRELATION or
COVARIANCE subcommands.
Minitab calculates the factor scores from the original variables and the factor score coefficients. First the variables
are centered by subtracting means. Then to get the scores corresponding to factor i, the centered variables are
multiplied by the factor score coefficients corresponding to factor i. These are some times called standard scores.
844
Minitab Statistical Software Multivariate Analysis
RESIDUAL M
Stores the residual matrix. If the matrix, A, was factored, the residual matrix is (A LL' ), where L is the matrix of
loadings (after rotation if a rotation was done). Note that the residual matrix for the initial and rotated solutions
are the same.
ROTMAT M
Stores the matrix used to rotate the initial loadings. If L is the matrix of initial loadings, then LM is the matrix of
rotated loadings.
Results
SORT K
Displays the loadings in sorted order.
All variables that have their highest absolute loadings on factor 1 are printed first, ordered from largest to smallest,
then all variables that have their highest absolute loadings on factor 2 are printed, ordered from largest to smallest,
and so on. This may make variables listed below any given factor appear unsorted. If K is specified then all loadings
less than K are printed as 0.0.
SORT does not affect any storage commands.
BRIEF K
Controls the amount of printed output. BRIEF can be used as a main command as well as a subcommand. It then
effects all commands that are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output but performs all specified storage.0
Minitab displays loadings (and sorted loadings if requested) for final solution.1
In addition to the K = 1 output, Minitab displays factor score coefficients.2
In addition to K = 2 output, Minitab displays information on the iterations when you use the
ML subcommand.
3
CLUOBS: Session command for clustering
observations
CLUOBS C...C
CLUOBS M
Performs agglomerative hierarchical clustering of observations when data are in columns (C...C) or on a distance
matrix (M). The purpose of clustering observations is to help you classify observations into groups, when the
groups are initially unknown.
Agglomerative clustering of observations begins with all observations separate, each forming its own cluster. In
the first step, the two observations closest together are joined. In the next step, either a third observation joins
the first two, or two other observations join together into a different cluster. Each step results in one less cluster
than the step before until, at the end, all cases are combined in one cluster. Once two observations are combined
845
Minitab Statistical Software Multivariate Analysis
in a cluster, they may join with other observations, but they will always remain together. Minitab decides which
clusters are closest together depending on how you define distance and which linking method you choose.
With CLUOBS you may enter either columns or a matrix as input arguments. Enter columns if you want to analyze
raw data, the observations recorded for each variable. Enter a matrix if you have stored the distance matrix in M.
The entry in row i and column j of distance matrix M is the distance between observations i and j.
Using subcommands, you can specify how to measure distance between observations, how to link observations
together to form clusters, and what the final partition (final grouping of clusters) will be.
This command does not allow missing values.
Linkage method
These subcommands specify how Minitab determines which clusters are closest together, and thus which ones to
combine. Use just one of them.
The linkage method you choose determines how the distance between two clusters is defined.
SINGLE
Specifies single linkage method.
AVERAGE
Specifies average linkage method.
COMPLETE
Specifies complete linkage method.
MCQUITTY
Specifies McQuitty linkage method.
CENTROID
Specifies centroid linkage method.
MEDIAN
Specifies median linkage method.
WARD
Specifies Ward linkage method.
Distance measure
If you do not supply a distance matrix, Minitab's first step is to calculate an N x N distance matrix, D, where N is the
number of observations. Enter one of these subcommands to indicate which distance measure to use if you do not
want to use the default, which is Euclidean. Specify just one. Do not use these subcommands if you list M as the
argument with CLUOBS.
It is generally recommended that if you are using average, centroid, median, or Ward linkage, then you should use
either squared Euclidean or squared Pearson distance. Euclidean is the standard mathematical measure of distance,
Manhattan allows outliers to be down-weighted, and Pearson is a standardizing method.
EUCLIDEAN (default)
Specifies Euclidean distance measure.
846
Minitab Statistical Software Multivariate Analysis
SQEUCLIDEAN
Specifies squared Euclidean distance measure.
PEARSON
Specifies Pearson distance measure.
SQPEARSON
Specifies squared Pearson distance measure.
MANHATTAN
Specifies Manhattan distance measure.
Standardize
STANDARDIZE
Standardizes all variables (columns listed with CLUOBS) before the distance matrix is calculated. Specifically, it
replaces a variable x with (x x) / standard deviation (x). Standardizing puts all variables on a common scale, so
that one variable does not disproportionately influence the distance measure. If variables are in different units,
standardizing them is a good practice.
Dendrogram
NUMBER K
Use NUMBER or CUT to specify the final partition. Use only one of these subcommands. If you do not use either
of these subcommands, Minitab will continue clustering until all observations are combined into one cluster.
NUMBER says to cut the dendrogram so there are K clusters.
The output will contain information for the final partition. Distances printed here are always Euclidean distances.
If STANDARDIZE is used, final partition characteristics are calculated using the standardized variables. Note: Final
partition information cannot be calculated if the input is a distance matrix.
CUT K
Use NUMBER or CUT to specify the final partition. Use only one of these subcommands. If you do not use either
of these subcommands, Minitab will continue clustering until all observations are combined into one cluster.
CUT says to cut the dendrogram at similarity level K.
The output will contain information for the final partition. Distances printed here are always Euclidean distances.
If STANDARDIZE is used, final partition characteristics are calculated using the standardized variables. Note: Final
partition information cannot be calculated if the input is a distance matrix.
DENDOGRAM
Produces a dendrogram or tree diagram, showing the amalgamation steps. For some data sets, average, centroid,
median and Ward's methods do not produce a hierarchical dendrogram. That is, the amalgamation distances do
not always increase with each step. In the dendrogram, such a step will produce a join that goes downward rather
than upward.
DENDROGRAM has several subcommands of its own that allow you to customize the dendrogram.
TITLE "text"
Use TITLE to specify a title for the dendrogram.
847
Minitab Statistical Software Multivariate Analysis
CASE
Use CASE to specify case labels. The column of case labels must be the same length as the data column.
GSAVE "file"
GSAVE on page 38 allows you to save the dendrogram in a graph format. The default is a (PNG) file.
YSIMILARITY
Use YSIMILARITY or YDISTANCE to use either the similarity or distance on the y-axis.
YDISTANCE
Use YSIMILARITY or YDISTANCE to use either the similarity or distance on the y-axis.
PERPAGE K
Use PERPAGE to display K number of observations per graph. If you do not use PERPAGE, the dendrogram
is displayed in a single graph.
Storage
DMATRIX M
Saves the N x N distance matrix, D, in M. M can be used in subsequent CLUOBS commands.
MEMBERSHIP C
Saves cluster membership for each observation in column C, provided either CUT or NUMBER was given. You can
use C as a categorical variable in other Minitab commands, for example in DISCRIMINANT on page 852 or PLOT
on page 947.
DISTANCE C...C
Saves the distance between each observation and each cluster centroid, provided either CUT or NUMBER was
given. The number of columns on DISTANCE must equal the number of clusters in the final partition. These
distances are always Euclidean distances.
Results
BRIEF K
Controls the amount of output. K is an integer from 0 to 2. The larger the value of K, the more output. K = 2 is
the default. BRIEF can also be used as a main command. It then effects all commands that are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output but performs all specified storage.0
Minitab displays the amalgamation steps and displays the dendrogram if you asked
for it.
1
Minitab displays the K = 1 output, plus information on the final partition if either CUT
or NUMBER is used.
2 (default)
848
Minitab Statistical Software Multivariate Analysis
CLUVARS: Session command for clustering variables
CLUVARS C...C
CLUVARS M
Performs agglomerative hierarchical clustering of variables. Input can be the data stored in columns C...C or a
distance matrix stored in M.
The distance metric, the linkage type, and the final partition can be specified by subcommands.
Performs agglomerative hierarchical clustering of variables. Clustering of variables can help you classify variables
into groups, when the groups are initially not known.
Agglomerative clustering of variables begins with all variables separate, each forming its own cluster. In the first
step, the two variables closest together are joined. In the next step, either a third variable joins the first two, or
two other variables join together into a different cluster. Each step results in one less cluster than the step before
until, at the end, all variables are combined in one cluster. Once two variables are combined in a cluster, they may
join with other variables, but they will always remain together. Minitab decides which clusters are closest together
depending on how you define distance and which linking method you choose.
With CLUVARS you may enter either columns or a matrix as input arguments. Enter columns if you want to analyze
raw data, the observations recorded for each variable. Enter a matrix if you have stored the distance matrix in M.
The entry in row i and column j of M is the distance between variables i and j.
Using subcommands, you can specify how to measure distance between variables, how to link variables together
to form clusters, and what the final partition (final grouping of variables) will be.
CLUVARS does not allow missing values.
Linkage method
These subcommands specify how Minitab determines which clusters are closest together, and thus which ones to
combine. Use just one of them.
The linkage method you choose determines how the distance between two clusters is defined.
SINGLE
Specifies single linkage method.
AVERAGE
Specifies average linkage method.
COMPLETE
Specifies complete linkage method.
MCQUITTY
Specifies McQuitty linkage method.
CENTROID
Specifies centroid linkage method.
MEDIAN
Specifies median linkage method.
WARD
Specifies Ward linkage method.
849
Minitab Statistical Software Multivariate Analysis
Distance measure
These subcommands specify how to measure distance between clusters. Use one of these subcommands if the input
to CLUVARS is columns (do not use if the input is a distance matrix). Specify only one. The default is CORRELATION.
If you did not supply a distance matrix, Minitab's calculates a P x P distance matrix using either the correlation or
absolute correlation distance measure.
CORRELATION (default)
Specifies correlation to measure distance.
ABSCORRELATION
Specifies absolute correlation to measure distance.
Dendrogram
NUMBER K
Use NUMBER or CUT to specify the final partition. Use only one of these subcommands. If you do not use either
of these subcommands, Minitab will continue clustering until all observations are combined into one cluster.
NUMBER says to cut the dendrogram so there are K clusters.
The output will contain information for the final partition. Distances printed here are always Euclidean distances.
If STANDARDIZE is used, final partition characteristics are calculated using the standardized variables. Note: Final
partition information cannot be calculated if the input is a distance matrix.
CUT K
Use NUMBER or CUT to specify the final partition. Use only one of these subcommands. If you do not use either
of these subcommands, Minitab will continue clustering until all observations are combined into one cluster.
CUT says to cut the dendrogram at similarity level K.
The output will contain information for the final partition. Distances printed here are always Euclidean distances.
If STANDARDIZE is used, final partition characteristics are calculated using the standardized variables. Note: Final
partition information cannot be calculated if the input is a distance matrix.
DENDOGRAM
Produces a dendrogram or tree diagram, showing the amalgamation steps. For some data sets, average, centroid,
median and Ward's methods do not produce a hierarchical dendrogram. That is, the amalgamation distances do
not always increase with each step. In the dendrogram, such a step will produce a join that goes downward rather
than upward.
DENDROGRAM has several subcommands of its own that allow you to customize the dendrogram.
TITLE "text"
Use TITLE to specify a title for the dendrogram.
GSAVE "file"
GSAVE on page 38 allows you to save the dendrogram in a graph format. The default is a (PNG) file.
YSIMILARITY
Use YSIMILARITY or YDISTANCE to use either the similarity or distance on the y-axis.
YDISTANCE
Use YSIMILARITY or YDISTANCE to use either the similarity or distance on the y-axis.
850
Minitab Statistical Software Multivariate Analysis
PERPAGE K
Use PERPAGE to display K number of observations per graph. If you do not use PERPAGE, the dendrogram
is displayed in a single graph.
Storage
DMATRIX M
Saves the N x N distance matrix, D, in M. M can be used in subsequent CLUOBS commands.
Results
BRIEF K
Controls the amount of output. K is an integer from 0 to 2. The larger the value of K, the more output. K = 2 is
the default. BRIEF can also be used as a main command. It then effects all commands that are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output but performs all specified storage.0
Minitab displays the amalgamation steps and displays the dendrogram if you asked
for it.
1
Minitab displays the K = 1 output, plus information on the final partition if either CUT
or NUMBER is used.
2 (default)
KMEANS: Session command for non-hierarchical
clustering of observations
KMEANS C...C
Performs K-means non-hierarchical clustering of observations according to MacQueen's algorithm.
Like CLUOBS on page 845, the purpose of K-means clustering is to classify observations into groups when the
groups are initially unknown. KMEANS begins with a grouping of observations into a pre-defined number of
clusters. Minitab evaluates each observation, moving it into the cluster whose centroid it is closest to, using
Euclidean distance. When a cluster changes, by losing or gaining an observation, Minitab recalculates the cluster
centroid. This process is repeated until no more observations can be moved into a different cluster, that is, until
all observations are in the cluster whose centroid they are closest to.
In CLUOBS, which is a hierarchical procedure, once two observations are joined in a cluster, they can never be
separated. In K-means clustering, which is not hierarchical, there is no such constraint. KMEANS uses Euclidean
distances to measure distance between observations and clusters.
With KMEANS, list the columns containing the data. You must use either the NUMBER or INITIAL subcommand.
KMEANS does not allow missing values.
851
Minitab Statistical Software Multivariate Analysis
STANDARDIZE
This subcommand standardizes all variables (columns listed with KMEANS) before any calculations are done.
Standardizing puts all variables on a common scale, so that one variable does not disproportionately influence
the distance measure. If variables are in different units, it is a good idea to standardize them.
If STANDARDIZE is used, the final cluster centroids and cluster characteristics are printed in the standardized
variable space.
MEMBERSHIP C
Stores final cluster membership for each observation in C. You can use C as a categorical variable in other
Minitab commands, for example in DISCRIMINANT on page 852 or PLOT on page 947.
DISTANCE C...C
Saves the distance between each observation and each cluster centroid. DISTANCE must list the same number
of columns as the number of clusters requested with NUMBER or INITIAL. These are Euclidean distances.
BRIEF K
Controls the amount of output. BRIEF 0 suppresses all output, but does all requested storage. BRIEF 2, the
default, displays all output. BRIEF can be used as a main command as well as a subcommand.
Initial partition for the KMEANS algorithm
You must use one of these subcommands to specify the initial partition for the KMEANS algorithm.
The final partition will depend to some extent on the initial partition that Minitab uses. You can use INITIAL to try
different initial partitions.
NUMBER K
NUMBER specifies how many clusters to form. The first K observations are taken as initial cluster centroids. Each
observation is assigned to the cluster whose centroid it is closest to. Minitab recalculates the cluster centroids
each time a cluster gains or loses an observation.
For example, NUMBER 3 says to use the first three observations as the initial cluster centroids, and to go through
the K-means process resulting in a final partition of three clusters.
INITIAL C
INITIAL specifies the initial partition. C must be the same length as the input columns and contain positive,
consecutive integers or zeros (it should not contain all zeros). Initially, each observation is assigned to the cluster
identified by the corresponding value in C. Observations corresponding to a value of zero in C are initially
unassigned. The number of distinct positive integers in C equals the number of clusters in the final partition.
DISCRIMINANT: Session command for performing
discriminant analysis
DISCRIMINANT C, C...C
Performs linear and quadratic discriminant analysis for classifying observations into two or more groups based
on the specified predictors, with groups in C and predictors in C...C.
852
Minitab Statistical Software Multivariate Analysis
In linear discriminant analysis, all groups are assumed to have the same covariance matrix. Quadratic discrimination
does not make this assumption. Its properties, however, are not as well understood.
The column of group codes may be numeric or text, and may contain any values. The codes do not need to be
in any special order. When the group column is text, the first entry (row 1) is level 1, the next entry that is different
is level 2, and so on.
Output includes the classification matrix (sometimes called the confusion matrix), the squared distance between
group centers, the linear discriminant function (unless you requested quadratic discrimination), means, standard
deviations, covariance matrices, and a summary of how each observation was classified. You can use cross-validation
to examine the goodness of classification.
QUADRATIC
Requests quadratic discrimination. The default is linear. QUADRATIC cannot be used with LDF.
PRIORS K...K
Specifies prior probabilities. There should be one value for each group. The first probability will be assigned
to the group with the smallest code, the second to the group with the second smallest code, etc. If the
probabilities do not sum to one, Minitab normalizes them.
XVAL
Performs discrimination using cross-validation. This procedure omits the first observation from the data set,
develops a classification function using the remaining observations, then classifies the omitted observation.
Next, it returns the first observation to the data set, omits the second observation, and repeats the same
process. XVAL continues in this manner with all observations in the data set.
XVAL prints the classification matrix using cross-validation, and a summary of how each observation was
classified. Using XVAL increases computation time by approximately a factor of four.
XVAL is one technique used to compensate for an optimistic apparent error rate (AER). AER is (number of
misclassified observations in the data set)/(total number of observations in the data set). AER tends to be
optimistic because the data being classified are the same data used to build the classification function.
Another technique to calculate a more realistic error rate is to split your data set into two parts. Use one part
as a training set on which to build the discriminant function, and the other part as a validation set on which
to evaluate the function (use the PREDICT subcommand).
LDF C...C
Stores the coefficients from the linear discriminant function, using one column for each group. The constant
is stored at the top of the column. LDF cannot be used with QUADRATIC.
FITS C [C]
Stores the fitted values. The fitted value for an observation is the group into which it is classified. The optional
second column can be used to store the fitted values from cross-validation (provided you have used the
subcommand XVAL).
PREDICT E...E
Specifies the predicted group membership for new observations in E...E. A summary table is displayed. The
number of columns or constants must be equal to the number of predictors.
If you execute DISCRIMINANT from the menu, only one PREDICT subcommand is allowed.
BRIEF K
Controls the amount of printed output. BRIEF can be used as a main command as well as a subcommand,
but is not available if you execute DISCRIMINANT from the menu.
853
Minitab Statistical Software Multivariate Analysis
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the classification matrix.1
In addition to the K = 1 output, Minitab displays the distance between all pairs of group
centers (i.e., group means), the linear discriminant function, and a summary of misclassified
observations.
2 (default)
In addition to K = 2 output, Minitab displays the means, standard deviations, and
covariance matrices (for each group and pooled).
3
In addition to K = 3 output, Minitab displays a summary of how all observations were
classified. Minitab marks misclassified observations with two asterisks.
4
ITEMANALYSIS: Session command for performing
item analysis
ITEMANALYSIS C...C
Calculates Cronbach's alpha and basic statistics for items or variables in C...C.
Use item analysis to assess whether the items in a survey or test are measuring the same construct. You must
have two or more numeric columns. Typically, the data will be a score of some type, such as test scores or
Likert-scale responses. Each column must be of equal length. Any row with a missing value is not included when
calculating the output.
Options
STANDARDIZE
Standardizes the data before calculating the Cronbach's alpha and the omitted item statistics. Standardizing puts
all variables on a common scale, so that one or a few variables do not disproportionately influence the results.
Graphs
GMATRIX
Plots a matrix plot that contains a scatterplot of every unique combination of items in the analysis.
Results
RCORRELATION
Displays the correlation matrix.
RCOVARIANCE
Displays the covariance matrix.
RSUMMARY
Displays the summary statistics of item and the total.
854
Minitab Statistical Software Multivariate Analysis
RALPHA
Displays Cronbach's alpha.
ROMIT
Displays adjusted statistics by omitting items one at a time. Displayed statistics includes, mean, standard deviation,
correlation between the omitted item and the total of remaining items, multiple correlation when the omitted
item is regressed on the remaining items, and Cronbach's alpha.
CA: Session command for performing simple
correspondence analysis
CA C...C
Simple correspondence analysis helps you explore relationships in a two-way contingency table, that is, a table
of frequencies based on two categorical variables. You can also use simple correspondence analysis to analyze
three-way and four-way contingency tables. See the RCROSS and CCROSS subcommands for details.
Input data
CONTINGENCY
Specifies the arguments listed on the main command line as columns of a contingency table. When you do not
use CONTINGENCY, Minitab assumes the input columns are categorical variables. All values in the contingency
columns must be positive integers or zero.
RNAMES C
Specifies row names for the contingency table.
The name column must be a text column whose length matches the number of rows or columns in the contingency
table. CA displays the first 8 characters of the names in tables, but displays the full name on graphs.
CNAMES C
Specifies column names for the contingency table.
The name column must be a text column whose length matches the number of rows or columns in the contingency
table. CA prints the first 8 characters of the names in tables, but prints the full name on graphs.
NCOMPONENTS K
Specifies the number of components to calculate. The minimum number of components is one. The maximum
number of components for a contingency table with r rows and c columns is the smaller of (r-1) or (c-1). This is
equivalent to the dimension of the subspace onto which you project the profiles. The default number of components
is 2.
Combine
Cross two variable columns to form the rows and/or columns of the contingency table allowing you to use simple
correspondence analysis to analyze three and four-way contingency tables.
Both RCROSS and CCROSS require that you enter your data as categorical variables rather than a contingency table.
If you use just RCROSS or just CCROSS, you must specify 3 columns on the main command line. If you use both RCROSS
and CCROSS, you must specify 4 columns on the main command line.
855
Minitab Statistical Software Multivariate Analysis
RCROSS crosses the categories in the first two input columns to form the rows of the contingency table. For example,
if the first variable is Sex (with 2 levels, male and female) and the second variable is Age (with 3 levels, young, middle
aged, old), then there will be 2 x 3 = 6 rows, ordered as follows:
males / young
males / middle aged
males / old
females / young
females / middle aged
females / old
CCROSS crosses the categories in the last two input columns to form the columns of the contingency table.
RCROSS
Crosses the first two variables to form the rows.
CCROSS
Crosses the last two variables to form the columns.
Supplementary data
RSUPPLEMENTARY AND CSUPPLEMENTARY specify supplementary data for the analysis. CA does not use the
supplementary points in calculating the components (i.e., to determine the reduced dimensions), but displays table
information on supplementary points. To include supplementary points in the plots, use the SUPPLEMENTARY
subcommand. Use RSUPPLEMENTARY to specify supplementary rows. List one column for each supplementary row.
There is just one form for the supplementary data—each worksheet column is one row of the contingency table. If
there are c columns in the contingency table, there will be c entries in each worksheet column. Use CSUPPLEMENTARY
to specify supplementary columns. List one worksheet column for each supplementary column. There is just one form
for the supplementary data—each worksheet column is one column of the contingency table. If there are r rows in the
contingency table, there will be r entries in each worksheet column.
SRNAMES and SCNAMES give names for the supplementary rows and supplementary columns of the contingency
table, respectively. The specified name column must be a text column whose length matches the number of
supplementary rows or supplementary columns in the contingency table. CA prints the first eight characters of the
names in tables, but prints the full name on graphs.
RSUPPLEMENTARY C...C
Specifies row supplementary data.
CSUPPLEMENTARY C...C
Specifies column supplementary data.
SRNAMES C
Specifies names for the supplementary rows.
SCNAMES C
Specifies names for the supplementary columns.
856
Minitab Statistical Software Multivariate Analysis
Results
CTABLE
CTABLE displays the contingency table. The entry in row i and column j of the contingency table is the frequency
for that cell. The total in row i is the sum of the frequencies in row i. The total in column j is the sum of the
frequencies in column j.
RPROFILES
RPROFILES displays a table of row profiles and row masses.
CPROFILES
CPROFILES displays a table of column profiles and column masses.
EXPECTEDS
EXPECTEDS displays a table of the expected frequency in each cell of the contingency table.
DIFFERENCES
DIFFERENCES displays a table of the observed minus the expected frequency in each cell of the contingency table.
CHISQUARE
CHISQUARE displays a table of the χ
2
value in each cell of the contingency table.
INERTIAS
INERTIAS displays a table of the relative inertia in each cell of the contingency table.
Graphs
RPLOT
RPLOT displays a plot that shows the row principal coordinates. Row points are plotted with red circles: solid red
circles for regular points, and open red circles for supplementary points.
CPLOT
CPLOT displays a plot that shows the column principal coordinates. Column points are plotted with blue squares:
solid blue squares for regular points, and open blue squares for supplementary points.
SPLOT
Displays a symmetric plot that shows both row and column coordinates overlaid in a joint display. CA plots points
that represent rows with red circles: solid red circles for regular points, and open red circles for supplementary
points. CA plots points that represent columns with blue squares: solid blue squares for regular points, and open
blue squares for supplementary points.
ARPLOT
ARPLOT displays an asymmetric row plot.
ACPLOT
ACPLOT displays an asymmetric column plot. Points that represent rows are plotted with red circles.
AXES K K, ..., K K
Specifies the axis pairs for each requested plot. You may list between 1 and 15 pairs. The axes you list must be
axes in the subspace you defined on NCOMPONENTS. For example, if you specified NCOMPONENTS 4 then you
can only use axes 1, 2, 3, and 4.
The first axis in a pair will be the Y or vertical axis of the plot; the second axis will be the X or horizontal axis of
the plot. For example, AXES 2 1 3 1 plots component 2 versus component 1, and component 3 versus component
1.
857
Minitab Statistical Software Multivariate Analysis
SUPPLEMENTARY
Includes supplementary points on all plots. CA plots points that represent rows with red circles: solid red circles
for regular points, and open red circles for supplementary points. CA plots points that represent columns with
blue squares: solid blue squares for regular points, and open blue squares for supplementary points.
Asymmetric row plot and asymmetric column plot
ARPLOT displays an asymmetric row plot. ACPLOT displays an asymmetric column plot. Points that represent rows are
plotted with red circles. CA plots points that represent rows with red circles: solid red circles for regular points, and
open red circles for supplementary points. CA plots points that represent columns with blue squares: solid blue squares
for regular points, and open blue squares for supplementary points.
A disadvantage of asymmetric plots is that the profiles of interest are often bunched in the middle of the graph. A
symmetric plot of both rows and columns spreads out both profiles. However, you must be careful interpreting the
symmetric plot because this plot overlays two different mappings.
ARPLOT
ARPLOT displays an asymmetric row plot.
An asymmetric row plot shows both the coordinates of the row profiles projected onto the low dimensional
subspace (these are the coordinates that the subcommand RPCOORDINATES stores), and the coordinates of the
column vertices projected onto the low dimensional subspace (these are the coordinates that the subcommand
CSCOORDINATES stores). The vertex corresponding to column j is the point in row space with a 1 in position j
and 0's elsewhere, i.e., it is the row profile which is totally concentrated in one column group.
ACPLOT
ACPLOT displays an asymmetric column plot. Points that represent rows are plotted with red circles.
An asymmetric column plot shows both the coordinates of the column profiles projected onto the low dimensional
subspace (these are the coordinates that the CPCOORDINATES subcommand stores), and the coordinates of the
row vertices projected onto the low dimensional subspace (these are the coordinates that the RSCOORDINATES
subcommand stores). The vertex corresponding to row i is the point in column space with a 1 in position i and
0's elsewhere, i.e., it is the column profile which is totally concentrated in one row group.
Storage
RPCOORDINATES C...C
RPCOORDINATES stores the row principal coordinates. CA stores the coordinate for the first component in the
first column, the coordinate for the second component in the second column, etc. If there are supplementary
points, their coordinates are stored at the ends of the columns.
The principal coordinate for row profile i and component (axis) k is the coordinate of the projection of row profile
i onto axis k. These are the points that are plotted when you ask for a row plot (RPLOT).
The row standardized coordinates for component k are the principal coordinates for component k divided by the
square root of the k
th
inertia.
RSCOORDINATES C...C
RSCOORDINATES stores the row standardized coordinates. CA stores the coordinate for the first component in
the first column, the coordinate for the second component in the second column, etc. If there are supplementary
points, their coordinates are stored at the ends of the columns.
The principal coordinate for row profile i and component (axis) k is the coordinate of the projection of row profile
i onto axis k. These are the points that are plotted when you ask for a row plot (RPLOT).
858
Minitab Statistical Software Multivariate Analysis
The row standardized coordinates for component k are the principal coordinates for component k divided by the
square root of the k
th
inertia.
CPCOORDINATES C...C
CPCOORDINATES stores the column principal coordinates. The coordinate for the first component is stored in
the first column, the coordinate for the second component in the second column, etc. If there are supplementary
points, their coordinates are stored at the ends of the columns.
The principal coordinate for column profile j and component (axis) k is the coordinate of the projection of column
profile j onto axis k. These are the points that are plotted when you ask for a column plot (CPLOT).
The column standardized coordinates for component k are the column principal coordinates for component k
divided by the square root of the k
th
inertia.
CSCOORDINATES C...C
CSCOORDINATES stores the column standardized coordinates. The coordinate for the first component is stored
in the first column, the coordinate for the second component in the second column, etc. If there are supplementary
points, their coordinates are stored at the ends of the columns.
The principal coordinate for column profile j and component (axis) k is the coordinate of the projection of column
profile j onto axis k. These are the points that are plotted when you ask for a column plot (CPLOT).
The column standardized coordinates for component k are the column principal coordinates for component k
divided by the square root of the k
th
inertia.
SVTB C...C
Stores the contingency table. List one worksheet column for each column of the contingency table. SVTB does
not save supplementary rows and columns.
MCA: Session command for performing a multiple
correspondence analysis
MCA C...C
Multiple correspondence analysis extends simple correspondence analysis to the case of three or more categorical
variables.
There are two forms for the input columns listed on the main command line: categorical or indicator variables. If
you input the data as indicator variables, you do need to use the INDICATOR subcommand. This command does
not accept data with missing values. Remove any cases with missing data before you use this command.
Input data
INDICATORS
Specifies the input data as indicator variables (also called a disjunctive matrix). List one worksheet column for
each level of each categorical variable. The entries in all columns must be the integers 0 and 1. All columns must
be the same length and may not contain missing values.
859
Minitab Statistical Software Multivariate Analysis
CNAMES C
Gives the category names. The name column must be a text column whose length matches the number of
categories on all categorical variables.
For example, suppose there are 3 categorical variables: Sex (male, female), Hair color (blond, brown, black), and
Age (under 20, from 20 to 50, over 50), and no supplementary variables. You would assign 2 + 3 + 3 = 8 category
names, and the CNAMES column would contain 8 rows.
MCA only uses the first 8 characters of the names in displayed tables, but uses all characters on graphs.
NCOMPONENTS K
Specifies the number of components to calculate. The default number of components is 2.
Supplementary data
CSUPPLEMENTARY C...C
Specifies supplementary data for the analysis. MCA does not use the supplementary points in calculating the
components (i.e., to determine the reduced dimensions), but prints table information on supplementary points.
To include supplementary points in the plots, use the SUPPLEMENTARY subcommand.
Specify supplementary data using the same form, either categorical variables or indicator variables, as you did
for the data specified on the main command line.
SCNAMES C
Specifies names for the supplementary data. The name column must be a text column whose length matches the
number of categories for all supplementary variables. Only the first 8 characters of the names will be used in
printed tables; all characters will be used on graphs. If you do not enter names here, the rows will be named
Supcol1, Supcol2, and so on.
Results
ITABLE
Displays the indicator table. There is one indicator variable (column of the worksheet) for each level (category) of
each categorical variable. An observation (row) has a 1 in columns that correspond to levels that are true for this
observation and a 0 otherwise. An indicator table (also called a disjunctive matrix) has one column for each level
(category) of each categorical variable.
BURT
Displays the Burt table. A Burt matrix is a symmetric matrix which has one column and one row for each level
(category) of each categorical variable. The entry in row i and column j is the number of observations that have
the level corresponding to row i and also the level corresponding to column j.
Graphs
AXES K K, ..., K K
Specifies the axis pairs for the column plot. You may list between 1 and 15 pairs. The axes you list must be axes
in the subspace you defined on NCOMPONENTS. For example, if you specified NCOMPONENTS 4, then you can
use only axes 1, 2, 3, and 4.
The first axis in a pair will be the Y or vertical axis of the plot; the second axis will be the X or horizontal axis of
the plot. For example, AXES 2 1 3 1 plots component 2 versus component 1, and component 3 versus component
1.
860
Minitab Statistical Software Multivariate Analysis
SUPPLEMENTARY
Includes supplementary points in the column plot. MCA plots regular points as solid blue squares and supplementary
points as open blue squares.
CPLOT
Displays a plot that shows the column coordinates. Column points are plotted with blue squares - solid squares
for regular points, and open squares for supplementary points. To include supplementary points in the column
plot, use the SUPPLEMENTARY subcommand.
Storage
COORDINATES C...C
Stores the column coordinates. MCA stores the coordinate for the first component in the first listed column, the
coordinate for the second component in the second listed column, and so on. If there are supplementary points,
their coordinates are stored at the ends of the columns.
861
Minitab Statistical Software Multivariate Analysis
Time Series Analysis
AAMODEL: Session command for the selection of
an alternative model from Forecast with Best
ARIMA Model
AAMODEL K K
After the analysis identifies the best model with ATARIMA, AAMODEL produces results for alternative models. You
can use AAMODEl only when the ATARIMA command used the SMODEL subcommand to create the object ID and
model ID.
The first K is a positive integer that represents a Forecast with Best ARIMA Model object ID. The first Forecast
with Best ARIMA Model that you create in a project has the object ID 1. The second Forecast with Best ARIMA
Model that you create with the command has the object ID 2, and so on.
The second K represents the model ID. The value of the second K is an integer from 2 to 30. The model ID refers
to the model with that row number in the Model Selection table. The Model Selection table is for the object ID
that you specify with the first K.
The analysis displays the tables and graphs in a new output tab. The same columns that the original analysis
stored are also stored for the new model. The storage for the new model is in a new column. For example, if the
original analysis stored the fitted values in a column titled "Fit," then the new analysis names an empty column
"Fit_1" and stores the fitted values in that column.
ACF: Session command for calculating
autocorrelation
ACF C
Calculates and plots the autocorrelations of a time series.
ACF generates a high-resolution autocorrelation function, including confidence limits for the correlations, in a
graph. You can store the autocorrelations, associated Ljung-Box Q statistics, and t-statistics for up to the first 75
lags.
If you do not specify the number of lags with LAGS, then Minitab uses a default number of lags:
n / 4 for a series with less than or equal to 240 observations
+ 45 for a series with more than 240 observations, where n is the number of observations in the series
LAGS K
Specifies the number of lags to display in the ACF plot. If you omit LAGS, then Minitab uses a default number
of lags. This is n / 4 for a series that has less than or equal to 240 observations, or + 45 for a series that
has more than 240 observations, where n is the number of observations in the series.
862
Minitab Statistical Software Time Series Analysis
SACF C
Stores the autocorrelations.
TSTATS C
Stores the t-statistics.
LBQSTATS C
Stores the Ljung-Box Q statistics.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
ADF: Session command for conducting an
augmented Dickey-Fuller test
ADF C
ADF performs an augmented Dickey-Fuller test on time series data to determine whether differencing a series
makes the mean of the data stationary. Usually, you use the augmented Dickey-Fuller test to determine the
nonseasonal differencing order when you analyze your time series data with an ARIMA model.
MAXLAG K
Specifies the maximum lag order to evaluate when fitting the regression model to calculate the test statistic.
K must be an integer in the interval [0, floor(n/2)-3] where n is the row count of the column for ADF, omitting
any missing values from the beginning or end of the data. The default value if you do not specify this
subcommand is min{floor(n/2 - 3), floor[ 12 * (n/100)^(1/4)]}.
AUTOLAG K K
Specifies the criterion to use to select the lag order in the regression model. The default value if you do not
specify this command is 1. The analysis evaluates the regression model with the maximum lag order first,
then removes one lag at a time, beginning with the highest lag order.
CriterionK
The analysis uses all lag orders less than or equal to the maximum lag order to fit the regression
model.
0
The selected lag order in the regression model minimizes the Akaike Information Criterion (AIC).1
The selected lag order in the regression model minimizes the Bayesian Information Criterion
(BIC).
2
When the t-statistic for the highest lag order is significant, the analysis selects that order for
the regression model.
3
ATERMS K
Specifies additional terms other than the lag terms to include in the regression model. The default value if
you do not specify this command is 1 so that the mean of the series is non-zero when the series is stationary.
863
Minitab Statistical Software Time Series Analysis
Additional termsK
Include no additional terms in the model so that the mean of the series is 0 if the series is
stationary.
0
Include a constant term in the model.1
Include a constant term and a linear term in the model.2
Include a constant term, a linear term, and a quadratic term in the model.3
SLEVEL K
Specifies the significance level for the test. K must be in the interval (0.000001, 0.999999). The default value
if you do not specify this subcommand is 0.05.
If the significance level is 0.01, 0.05, or 0.10 then the recommendation of the analysis depends on a comparison
of the test statistic and the critical value. If the test statistic is less than or equal to the critical value, reject
the null hypothesis that the data are non-stationary. Rejection of the null hypothesis leads to the
recommendation that differencing is unnecessary.
If the significance level is any other value, then the recommendation of the analysis depends on a comparison
of the p-value to the significance level. If the p-value is less than or equal to the significance level, reject the
null hypothesis that the data are non-stationary. Rejection of the null hypothesis leads to the recommendation
that differencing is unnecessary.
TMETHOD
Displays the method table.
TTEST
Displays table of the results of the augmented Dickey-Fuller test.
GPLOT
Displays a time series plot, Autocorrelation Function (ACF) plot, and Partial Autocorrelation Function (PACF)
plot of the original time series data.
GDPLOT
Displays a time series plot, Autocorrelation Function (ACF) plot, and Partial Autocorrelation Function (PACF)
plot of the differenced time series data.
ARIMA: Session command for modeling time series
behavior and generating forecasts
ARIMA K K K K K K K C [C [C [C]]]
The ARIMA command fits nonseasonal and seasonal models to a time series.
The seven Ks specify the model, using the usual notation: (pdq ) x (PDQ) S
Thus, the first K = p, the second K = d, the third K = q. If you have a nonseasonal model, that's all you need. If
you have a seasonal model, then use the remaining four Ks to specify P, D, Q, and S.
The first column is for the data. The three optional columns are for storage. If you specify one column, then Minitab
stores the residuals. If you specify two columns, then Minitab also stores the predicted values. If you specify a
third column, then Minitab also stores the estimated parameters, in the same order they are displayed on the
output.
864
Minitab Statistical Software Time Series Analysis
The maximum order of each term, p, q, P, Q, is 5. The maximum number of parameters is 10. The maximum back
order is 100. That is, if the model is expanded out, then the highest exponent for the back-shift operator must be
< 100. At least one of the parameters p, q, P, Q must be non-zero. There must be at least 3 (nonmissing) values
left after differencing.
The BRIEF subcommand can be used to control the amount of output that is produced.
CONSTANT
CONSTANT specifies to include a constant term in the model. If d = 0 and D = 0 (or is not used), this is the
default.
NOCONSTANT
NOCONSTANT specifies to not include the constant term in the model. If d > 0 or D > 0, this is the default.
STARTING C
Specifies starting values (initial values) for the parameters. The values are entered in the order that the
parameters appear on the output: ARs (autoregressive parameters), seasonal ARs, MAs (moving average
parameters), seasonal MAs, and constant. The starting value for the constant is optional.
If you do not use START, Minitab uses 0.1 for all the parameters except the constant. This usually works well.
ARIMA performs up to 25 iterations to fit a given model. If you require more than 25 iterations to get a good
fit, store the estimated parameters. Then use them as STARTING values for a second fit. This can be repeated
as often as desired.
FORECAST [K] K [C [C C]]
Allows you to forecast observations starting at the specified origin and going up to K leads ahead. You can
specify up to 150 leads. If you do not specify the origin, then the origin is the end of the series and the
forecasts are for the future. Store the forecasts in C and specify the storage columns C C for the lower and
upper confidence limits.
Suppose that you have yearly data from 1980 to 2018. The subcommand FORECAST 5 forecasts the next 5
years, 2019 to 2023. The subcommand FORECAST 31 5 forecasts from the 31st observation, 2010, for the
next 5 years, 2011 to 2015.
Storing forecasts and confidence limits allows a variety of plots.
GSERIES
Displays a time series plot of the series. When you use the FORECASTS subcommand, Minitab displays the
forecasts and their 95% confidence limits on the plot.
GACF
GACF displays an autocorrelation function for the standard or raw residuals.
GACF and GPACF include 95% confidence limits for the standard or raw residuals.
GPACF
GPACF displays a partial autocorrelation function for the residuals.
GACF and GPACF include 95% confidence limits for the standard or raw residuals.
GHISTOGRAM
Displays a histogram of the residuals.
865
Minitab Statistical Software Time Series Analysis
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis
(for example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE
Displays a separate graph for the residuals versus each specified column.
BRIEF K
Controls the amount of output. You can also use BRIEF as a main command. When you use BRIEF as a main
command, it affects all other commands that use BRIEF to control the amount of output.
Output that is displayedValue of K
Minitab displays no output, and does not store any statistics0
Minitab displays tables of final estimates, difference information, residual sum of
squares, and number of observations
1
Same as K = 1 output, and table of estimates for each iteration2 (default)
Same as K = 2 output, and correlation matrix3
Same as K = 3 output, and back forecasts4
ATARIMA: Session command for selecting
parameters for an ARIMA model and generating
forecasts
ATARIMA C
Evaluates specified combinations of terms in ARIMA models to identify the best model for the time series data
in column C. Candidate ARIMA models with a specified order of differencing (d) can include different orders of
autoregressive (p), and moving average terms (q). Candidate ARIMA models can also include a specified order of
seasonal differencing (D) and different orders of seasonal terms (P, Q). To evaluate non-seasonal models, use the
BMODEL subcommand. To evaluate seasonal models, use the BMODEL subcommand and the SEASON subcommand.
The analysis allows missing values at the beginning or end of the column. The analysis does not allow missing
values to separate numbers in the column.
The analysis uses a specified criterion to determine the best model for the combination of the orders of the
autoregressive and moving average terms in the search. The specifications for the analysis provide the orders of
non-seasonal and seasonal differencing. The analysis provides results for the best ARIMA model.
866
Minitab Statistical Software Time Series Analysis
BMODEL K K K K K
Specify the order of the nonseasonal terms to evaluate. The first K specifies the nonseasonal order of
differencing, d. The last 4 Ks specify the range of orders to evaluate for the autoregressive terms, p, and the
moving average terms, q.
OrderConstant
Nonseasonal differencing orderFirst K
Minimum autoregressive orderSecond K
Maximum autoregressive orderThird K
Minimum moving average orderFourth K
Maximum moving average orderFifth K
The order of differencing is 0, 1, or 2. For autoregressive and moving average orders, enter values in the
interval [0, 5]. For the pairs of constants that define the range for the autoregressive and the moving average
orders, enter a minimum order the maximum order. If the two values are equal, then all of the candidate
models use that order.
SEASON K K K K K K K
Specify the seasonal period and the order of the seasonal terms to evaluate. The first K specifies the seasonal
period. The second K specifies the seasonal differencing order. The last 4 Ks specify the range of seasonal
orders to evaluate for the autoregressive terms, P, and the moving average terms, Q.
OrderConstant
Seasonal periodFirst K
Seasonal differencing orderSecond K
Minimum seasonal autoregressive orderThird K
Maximum seasonal autoregressive orderFourth K
Minimum seasonal moving average orderFifth K
Maximum seasonal moving average orderSixth K
For the seasonal period, enter a value in the interval [2, FLOOR(N/2)]. In other words, seasonal periods are
an integer greater than 1 and less than half of the length of the series.
The order of differencing is 0, 1, or 2. For seasonal autoregressive and seasonal moving average orders, enter
values in the interval [0, 5]. For the pairs of constants that define the range for the seasonal autoregressive
and the seasonal moving average orders, enter a minimum order the maximum order. If the two values
are equal, then all of the candidate models use that order.
CONSTANT
Specifies to include a constant term in candidate models that have d + D 1 where d is the non-seasonal order
of differencing and D is the seasonal order of differencing. If the parameter estimates for a candidate model with
a constant do not converge, the analysis evaluates the model without the constant term. If you do not use this
subcommand, then the analysis fits all the candidate models without a constant term.
Requirements for model orders
For a candidate model with a constant, the analysis requires that p + q + P + Q 9. For a model without a constant,
the analysis requires that p + q + P + Q 10. These requirements mean that, for example, the ARIMA model (5, 0, 5)
with a constant is not a candidate model even if the analysis includes BMODEL 0 0 5 0 5.
867
Minitab Statistical Software Time Series Analysis
For a candidate model, the analysis requires that at least 1 of p, q, P, or Q > 0. The only exception is the ARIMA model
(0, 1, 0). You can fit the ARIMA model (0, 1, 0) with or without a constant. The ARIMA model (0, 1, 0) is also known as
the random walk model.
Criteria
The analysis uses Akaike's Corrected Information Criterion (AICc), Akaike's Information Criterion (AIC) or Bayesian
Information Criterion (BIC) to select the best model among models with the same order of differencing. If you do not
specify which criterion to use, the analysis uses AICc.
AICC
Specifies the use of the corrected Akaike's Information Criterion (AICc) to select the best model.
AIC
Specifies the use of the Akaike's Information Criterion (AIC) to select the best model.
BIC
Specifies the use of the Bayesian Information Criterion (BIC) to select the best model.
Forecasts
FORECAST [K] K
Allows you to forecast observations starting at the specified origin and going up to K leads ahead.
The optional first K specifies the origin. If you do not specify the origin, then the origin is the end of the series
and the forecasts are for the future. If you specify the origin, the index for K begins at the first non-missing value
in the series. The second K specifies the number of forecasts. You can specify up to 150 forecasts.
Suppose that you have yearly data from 1980 to 2018. The subcommand FORECAST 5 forecasts the next 5 years,
2019 to 2023. The subcommand FORECAST 31 5 forecasts from the 31st observation, 2010, for the next 5 years,
2011 to 2015.
CONFIDENCE K
Specifies a confidence level for the lower and upper probability limits of the forecasts. K is in the interval (50,
100). For example, for a 90% confidence level, enter CONFIDENCE 90. If you do not use this subsubcommand,
then the confidence level is 95.
Box-Cox
BOXCOX [K]
Performs a Box-Cox transformation with a specified lambda. K is the value of lambda and must be between −5
and +5. If you do not specify K, then Minitab finds the optimal lambda. By default, Minitab rounds the optimal
value.
LULIMITS K K
Specifies the lower and upper limits for the search for the optimal lambda. The first K is the lower limit and
must be less than the second K. Both values of K must be within [-5, 5]. The default values if you do not
specify LULIMITS are -1, 2.
868
Minitab Statistical Software Time Series Analysis
Graphs
GTSERIES [C]
Displays a time series plot of the series. When you use the FORECAST subcommand, Minitab displays the forecasts
and their 95% confidence limits on the plot. C is an optional column that gives tick labels for the X-axis. The
column C must have the same length as the column for the main command. The column with the tick labels can
have any data type. If you use the BOXCOX command, then the GTSERIES command produces plots for both the
original data and the transformed data.
GACF
Displays an autocorrelation function for the regular residuals. The plot includes confidence limits.
GPACF
Displays a partial autocorrelation function for the regular residuals. The plot includes confidence limits.
RTYPE K
Specifies the type of residual to plot with following subcommands: GHISTOGRAM, GNORMAL, GFITS, GORDER,
GFOURPACK, GVARIABLE.
Type of residualsValue of K
Regular residuals1
Standardized residuals2 (default)
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Results
NODEFAULT
Specifies that no default tables or graphs will be displayed
TMETHOD
Displays the method table.
869
Minitab Statistical Software Time Series Analysis
TSELECTION
Displays the model selection table.
TITERATION
Displays the table that shows the parameter estimates for each iteration that leads to the best model.
TBFORECAST
Displays the table of back forecasts for the best model.
TBRESIDUAL
Displays the table of back forecast residuals for the best model.
TPARAMETER
Displays the final estimates of the parameters for the best model.
TCORRELATION
Displays the correlation matrix for the estimated parameters for the best model.
TSUMMARY
Displays the model summary table for the best model.
TCHISQUARE
Displays the modified Box-Pierce (Ljung-Box) chi-square statistic for the best model.
TFORECAST
Displays the forecast table for the best model.
Storage
SMODEL
Stores IDs for the alternative models so that you can use the AAMODEL command to produce ARIMA results for
the models in rows 2 to 30 of the Model Selection table.
SFITS C
Stores the fitted values. When the analysis uses a Box-Cox transformation, these values are in the transformed
units.
SRESIDUALS C
Stores the residuals (fitted values observed values). When the analysis uses a Box-Cox transformation, these
values are in the transformed units.
SSRESIDUALS C
Stores the standardized residuals. When the analysis uses a Box-Cox transformation, these values are in the
transformed units.
SCOEF C
Stores the coefficients from the best model.
SFORECAST C
Stores the forecast values from the best model. When the analysis uses a Box-Cox transformation, these values
are in the transformed units.
870
Minitab Statistical Software Time Series Analysis
SSEFORECAST C
Stores the standard errors of the forecast values. When the analysis uses a Box-Cox transformation, these values
are in the transformed units.
SLULLIMITS C C
Stores the lower and upper probability limits for the forecast values. When the analysis uses a Box-Cox
transformation, these values are in the transformed units.
SBCSERIES C
Stores the Box-Cox transformed data when the analysis uses a Box-Cox transformation.
SOFIT C
Stores the fitted values from the best model for the original series when the analysis uses a Box-Cox transformation.
SOFORECAST C
Stores the forecast values from the best model for the original series when the analysis uses a Box-Cox
transformation.
SOLULIMITS C
Stores the lower and upper probability limits for the forecast values for the original series when the analysis uses
a Box-Cox transformation.
CCF: Session command for calculating cross
correlation between two time series
CCF [K] C C
Calculates and graphs cross correlations between two time series. If the number of lags is not specified, lags from
−( + 10) to K = +( + 10), where n = the length of the series, are calculated.
LAGS K
Specifies the number of lags to display in the CCF plot. If you omit LAGS, Minitab uses a default number of
lags. This is (K = −( + 10) to K = +( + 10)), where K is the number of lags and n = the length of the series.
SCCF C
SCCF stores the cross correlations.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
GSAVE "filename"
Saves a plot of lags by cross correlations as the text string "filename".
871
Minitab Statistical Software Time Series Analysis
DECOMP: Session command for performing
decomposition on a time series
DECOMP C K
Performs classical decomposition on a time series, using either a multiplicative or an additive model. Classical
decomposition decomposes a time series into trend, seasonal, and error components.
With DECOMP, list the column that contains the series, followed by a constant that indicates the seasonal length.
If you do not specify a model, then Minitab uses the multiplicative model.
Decomposition displays a summary table and a set of plots. The summary table includes the trend equation, the
seasonal indices, and three measures to help you determine the accuracy of the fitted values: MAPE, MAD, and
MSD.
Decomposition generates three sets of plots:
A time series plot that shows the original data, the fitted trend line, the trend plus seasonal fitted values, and
forecasts
Component analysis: A set of plots that illustrate how adjusting the series for different components affects
the results
Seasonal analysis: A set of plots that illustrate how the seasonal pattern affects the data
Model
ADDITIVE
By default, Minitab uses the multiplicative model. Use the multiplicative model when the size of the seasonal
pattern in the data depends on the level of the data. This model assumes that as the data increase, so does the
seasonal pattern. Most time series exhibit such a pattern.
The multiplicative model is: y
t
= Trend * Seasonal + Error
The additive model is: y
t
= Trend + Seasonal + Error
NOTREND
Excludes a trend component from the decomposition. You might want to do this if you have already detrended
your data with TREND on page 892. Warning: If the data contain a trend component but you omit it from the
decomposition, this can influence the estimates of the seasonal indices.
FIRST K
Specifies the seasonal period of the first data value. Enter a number to specify a starting value. For example, if
you have monthly data and the first observation is in June, then enter 6 to set the seasonal period correctly. By
default, the starting value is 1 because Minitab assumes that the first data value in the series corresponds to the
first seasonal period.
Forecasts
FORECASTS K
Use FORECASTS with an integer to indicate how many forecasts you want. Forecasts appear in red on the time
series plot.
872
Minitab Statistical Software Time Series Analysis
ORIGIN K
Use ORIGIN with a positive integer to specify a starting point for the forecasts. For example, if you specify 4
forecasts and 48 for the origin, Minitab computes forecasts for periods 49, 50, 51, and 52. If you specify FORECASTS
but no ORIGIN, Minitab generates forecasts from the end of the data. Minitab uses data up to the ORIGIN for
fitting the trend model used to generate forecasts.
X-axis scale
INDEX or I
Numbers the x-axis with a single scale from 1 to n by ones (where n is the number of observations in the column
containing the time series). INDEX is the default time scale for the x-axis. The default start value for INDEX is 1,
and integers are valid values.
START K [K...K]
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands, and they should match the order the subcommands were given.
If you do not use START, the time series graph uses the default start values for the time unit subcommands. You
must specify all time unit subcommands before you use START.
INCREMENT K
Use INCREMENT to increment the time scale.
STAMP C...C
Use the STAMP subcommand to place a date/time stamp on the x-axis. The argument must be a date/time column.
You can use at least one and at most three columns of equal length to stamp the x-axis. The values in the date/time
column are stamped on the time series graph in the same format as they appear in the date/time column. When
you use the STAMP subcommand, you cannot use the START and INCREMENT subcommands and any of the time
unit subcommands.
The optional arguments to the time unit subcommands let you change the default interval in which you measure
data. This allows you to do a time series plot with, for example, bimonthly data, or data collected four times per
minute.
For example, the following commands create a graph that shows the depth of a reservoir. Measurements of the
depth were collected on a bimonthly basis (in months 1, 3, 5, 7, 9, and 11) starting in January of 1990. The argument
for MONTH uses abbreviated notation to specify every other month from months 1 to 11 inclusive.
TSPLOT Depth;
MONTH 1:11/2;
YEAR;
START 1 1990.
Calendar values for the x-axis
Labels the x-axis with calendar values. MONTH and YEAR account for different length months and leap years. Specify
all the calendar unit subcommands before using any other subcommands in the graph.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeCalendar unit subcommand
Current day1 to a maximum of 31, depending on
the month
DAY or D
Current month1 to 12MONTH or M
873
Minitab Statistical Software Time Series Analysis
Default START valueRangeCalendar unit subcommand
Current quarter1 to 4QUARTER or Q
Current year1000 to 4000YEAR or Y
Adding an additional calendar unit subcommand to the same graph adds additional x-axes to the graph. You can use
up to three subcommands in the following combinations:
DAY
DAY; MONTH
DAY; MONTH; YEAR
MONTH
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER
QUARTER; YEAR
YEAR
Time of day values for the x-axis
Labels the x-axis with time values.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeTime unit subcommand
00 to 59SECOND or SS
00 to 59MINUTE or MM
00 to 23HOUR or HH
Adding an additional time unit subcommand to the same graph adds additional x-axes to the graph. You can use up
to three subcommands in the following combinations:
DAY; HOUR
DAY; HOUR; MINUTE
HOUR
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE
MINUTE; SECOND
SECOND
Note that you can use DAY in combination with SECOND, MINUTE, and HOUR.
874
Minitab Statistical Software Time Series Analysis
Storage
TRENDS C
TRENDS stores the trend component data. This is the trend component; it does not contain the error or seasonal
component.
DETREND C
DETREND stores the detrended data (has seasonal and error components, no trend).
SEASONALS C
SEASONALS stores the seasonal component data (has seasonal component, no error or trend).
DESEASONALS C
DESEASONALS stores the data which has had the seasonal component removed (has trend and error components,
no seasonal).
RESIDUALS C
RESIDUALS stores the residuals in a column. Also called detrended data, you can use this data to do further analysis
such as generating diagnostic plots using ACF on page 862. The detrended data equal the original data minus the
fits.
FITS C
FITS stores the fits in a column. These are the values used to plot the trend line.
FSTORE C
FSTORE stores the forecasts in a column. Use this subcommand only if you also used the FORECASTS subcommand
to generate forecasts.
Graphs
NOPLOT
Suppresses the default time series plot. If you do not use NOPLOT, Minitab displays the time series plot.
GHISTOGRAM
GHISTOGRAM displays a histogram of the residuals.
GNORMAL
GNORMAL displays a normal probability plot of the residuals.
GFITS
GFITS plots the residuals versus the fitted values.
GORDER
GORDER plots the residuals versus the order of the data. The row number for each data point is shown on the
x-axis (for example, 1 2 3 4... n).
GFOURPACK
GFOURPACK displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals
vs fitted values, and residuals vs order of the data.
GVARIABLE C...C
GVARIABLE displays a separate graph for the residuals versus each specified column.
875
Minitab Statistical Software Time Series Analysis
Results
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the summary table.1
Minitab displays the summary and results table.2
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
DES: Session command for performing double
exponential smoothing
DES C
Performs Holt double exponential smoothing for a time series.
Use double exponential smoothing to smooth out noise and to forecast data that exhibit a trend. Both the Holt
and Brown methods calculate a level component and a trend component at each period. Holt's method uses two
smoothing parameters for updating these components. Double exponential smoothing uses the level and trend
components to generate forecasts. Initial values for these components are obtained either by backcasting (if you
omit the WEIGHT subcommand), or from a linear regression on time (if you use the WEIGHT subcommand).
With DES, list the column containing the time series. The time series cannot include any missing values. If you
have missing data, see Missing values in exponential smoothing on page 1171.
The method that Minitab uses to calculate level and trend components depends on the inclusion of the WEIGHT
subcommand. See for details.
Default output consists of a time series plot which displays the data and one-period-ahead forecasts, or fitted
values. It also displays the smoothing constants used for level and trend, and three measures to help you determine
the accuracy of the fitted values: MAPE, MAD, and MSD. Alternatively, you can generate a time series plot that
displays the data and the smoothed values. Optional output includes a table containing the original series, the
smoothed data, the fitted data and the errors.
Weight
WEIGHTS K
If you omit the WEIGHT subcommand, Minitab uses optimal weights, or smoothing parameters, which are computed
by minimizing the sum of squared errors. It does this by using the equivalent ARIMA (0,2,2) model.
How you specify weights controls whether DES uses Holt's or Brown's method. Minitab uses Holt's method unless
you specify the appropriate weights to use Brown's method. (Brown's method is equivalent to an equal-root
ARIMA model. If you omit WEIGHTS, Minitab computes optimal weights, which will virtually never be the equivalent
of an equal-root ARIMA model. This is why omitting WEIGHTS results in the Holt method.)
876
Minitab Statistical Software Time Series Analysis
Without WEIGHTS, the trend and level components are initialized by backcasting. With WEIGHTS, the trend and
level components are initialized using a linear regression on time.
The first weight updates the level component. Theoretically, this can be any number between 0 and 2, but it is
normally a value between 0 and 1. The second weight updates the trend component. This can be any value
between 0 and 100, although it is normally a value between 0 and 1.
Theoretically, the second weight can be any number greater than 0 and less than ( (4/first weight) 2) to preserve
invertibility. But, because the latter value can be quite high, Minitab imposes a maximum value of 100 to ensure
a more reasonable model. If you omit the WEIGHT subcommand, Minitab uses optimal weights, or smoothing
parameters, which are computed by minimizing the sum of squared errors. It does this by using the equivalent
ARIMA (0,2,2) model.
Forecasts
FORECASTS K
Use FORECASTS with an integer to indicate how many forecasts you want. Forecasts appear in red on the time
series plot with 95% prediction interval bands.
ORIGIN K
Use ORIGIN with a positive integer to specify a starting point for the forecasts. For example, if you specify 4
forecasts and 48 for the origin, Minitab computes forecasts for periods 49, 50, 51, and 52 based on the moving
average at period 48. If you omit the ORIGIN subcommand, Minitab generates forecasts from the end of the data.
X-axis scale
INDEX or I
Numbers the x-axis with a single scale from 1 to n by ones (where n is the number of observations in the column
containing the time series). INDEX is the default time scale for the x-axis. The default start value for INDEX is 1,
and integers are valid values.
START K [K...K]
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands, and they should match the order the subcommands were given.
If you do not use START, the time series graph uses the default start values for the time unit subcommands. You
must specify all time unit subcommands before you use START.
INCREMENT K
Use INCREMENT to increment the time scale.
STAMP C...C
Use the STAMP subcommand to place a date/time stamp on the x-axis. The argument must be a date/time column.
You can use at least one and at most three columns of equal length to stamp the x-axis. The values in the date/time
column are stamped on the time series graph in the same format as they appear in the date/time column. When
you use the STAMP subcommand, you cannot use the START and INCREMENT subcommands and any of the time
unit subcommands.
The optional arguments to the time unit subcommands let you change the default interval in which you measure
data. This allows you to do a time series plot with, for example, bimonthly data, or data collected four times per
minute.
877
Minitab Statistical Software Time Series Analysis
For example, the following commands create a graph that shows the depth of a reservoir. Measurements of the
depth were collected on a bimonthly basis (in months 1, 3, 5, 7, 9, and 11) starting in January of 1990. The argument
for MONTH uses abbreviated notation to specify every other month from months 1 to 11 inclusive.
TSPLOT Depth;
MONTH 1:11/2;
YEAR;
START 1 1990.
Calendar values for the x-axis
Labels the x-axis with calendar values. MONTH and YEAR account for different length months and leap years. Specify
all the calendar unit subcommands before using any other subcommands in the graph.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeCalendar unit subcommand
Current day1 to a maximum of 31, depending on
the month
DAY or D
Current month1 to 12MONTH or M
Current quarter1 to 4QUARTER or Q
Current year1000 to 4000YEAR or Y
Adding an additional calendar unit subcommand to the same graph adds additional x-axes to the graph. You can use
up to three subcommands in the following combinations:
DAY
DAY; MONTH
DAY; MONTH; YEAR
MONTH
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER
QUARTER; YEAR
YEAR
Time of day values for the x-axis
Labels the x-axis with time values.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeTime unit subcommand
00 to 59SECOND or SS
00 to 59MINUTE or MM
00 to 23HOUR or HH
878
Minitab Statistical Software Time Series Analysis
Adding an additional time unit subcommand to the same graph adds additional x-axes to the graph. You can use up
to three subcommands in the following combinations:
DAY; HOUR
DAY; HOUR; MINUTE
HOUR
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE
MINUTE; SECOND
SECOND
Note that you can use DAY in combination with SECOND, MINUTE, and HOUR.
Storage
SMOOTHED c
SMOOTHED stores the smoothed data.
LEVEL C
LEVEL stores the level components. The level component at time T equals the smoothed value at time T, while
adding the level and trend components at time T equals the one-period-ahead forecast for time T + 1.
TREND C
TREND stores the trend components.
FITS C
FITS stores the fitted values. These are the one-period-ahead forecasts.
RESIDUALS C
RESIDUALS stores the residuals. The residual at time T is the difference between the actual data at time T and the
fitted value at time T. These residuals are used to calculate MAPE, MAD, and MSD. If you store the residuals you
can generate diagnostic plots using ACF on page 862.
FSTORE C
FSTORE stores the forecasts in a column. Use this subcommand only if you also used the FORECASTS subcommand
to generate forecasts.
UPPER C
UPPER stores the upper 95% prediction limits for the forecasts.
LOWER C
LOWER stores the lower 95% prediction limits for the forecasts.
Graphs
SMPLOT
By default, Minitab plots predicted values and actual data. SMPLOT says to plot the smoothed values (the moving
averages) and actual data.
879
Minitab Statistical Software Time Series Analysis
NOPLOT
Suppresses the default time series plot. If you do not use NOPLOT, Minitab displays the time series plot.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Results
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the summary table.1
Minitab displays the summary and results table.2
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
DIFFERENCES: Session command for calculating
differences
DIFFERENCES [K] C C
Calculates the differences between the elements of a column. Minitab subtracts from each row the element K
rows above, where K is the lag specified, and stores the differences in a new column. The first K rows of the new
column will contain the missing value symbol, *.
If C1 contains Z1, Z2, ..., Zn, then DIFFERENCES K C1 C2 puts asterisks (*) into rows 1 through K of C2, and puts
Zi Zi −k into row i, K + 1 < i < n. If K is omitted, then K = 1 is used.
880
Minitab Statistical Software Time Series Analysis
LAG: Session command for calculating the lags of a
column
LAG [K] C C
Calculates the lags of a column and stores them in a new column.
Moves the row elements of a column down K rows, where K is the lag specified, storing the result in a new column
of the same length. There will be K missing value symbols, *, at the top of the output column. The output column
has the same number of rows as the input column, so the last K values from the input column are not lagged. If
K is omitted, then K = 1 is used.
If C1 contains Z1, Z2, ..., Zn, then LAG K C1 C2 puts asterisks (*) into rows 1 through K of C2, and puts Z
i
Z
i-k
into row i, K + 1 < i < n.
MLAG: Session command to calculate lags of one
or more columns
MLAG
Calculates the lags of one or more columns. Specify either the AFTER subcommand or the NWORKSHEET
subcommand to specify to store the lags at the end of the active worksheet or in a new worksheet.
ROOT C
Specify a root column. Use multiple instances of the ROOT subcommand in the same instance of MLAG to
calculate the lags for different root columns. Use the LAGS subsubcommand after each instance of the ROOT
subcommand.
LAGS K or K ... K or K:K: Specify one or more unique values that are shorter than the length of
the root column that you specify with the ROOT subcommand. You can also use a colon to denote
consecutive numbers. For example, if you enter 5:10, the lag values are 5 6 7 8 9 10. Each lag value
results in a new column that contains the lags for that value. The name of the column is the name of the
root column with "_LagK" appended, where K is the lag of the new column. For example, if the root
column's name is "Root," and the lag value is 1, the lag column's name is "Root_Lag1." Each lag column
moves the row elements of the root column down K rows. The top of the lag column has K missing value
symbols (*). The lag column has the same number of rows as the original column, so the lag column does
not contain the last K values from the original column.
Use one of the following subcommands to specify how to store the lags. Each instance of MLAG requires one of the
following subcommands.
AFTER
Store the generated lag columns after the existing columns in the active worksheet.
NWORKSHEET
Store the generated lag columns in a new worksheet.
INROOT: Store the root column in the new worksheet before the lag columns.
881
Minitab Statistical Software Time Series Analysis
Results
TMETHOD
Displays the Method table, which includes a table of the root columns and lags, where each row corresponds to
a column that is an argument of a ROOT subcommand.
MA: Session command for calculating a moving
average
MA C K
Use moving averages to smooth out the noise in a time series and forecast future values of the series.
Minitab calculates a moving average by averaging consecutive groups of observations in a series. For example,
suppose a series begins with the numbers 4, 5, 8, 9, and 10 and you use a moving average length of 3. The first
two values of the moving average are missing. The third value of the moving average is the average of 4, 5, and
8; the fourth value is the average of 5, 8, and 9; the fifth value is the average of 8, 9, and 10; and so on.
You can use the linear moving averages method with a time series that exhibits a trend, as well as with moving
average schemes involving more than two moving averages. First, compute and store the moving average of the
original series. Then use the AVERAGES subcommand to compute and store the moving average of the previously
stored column to obtain a second moving average.
You can also perform naive forecasting. In naive forecasting, the forecast for time T+1 is the data value at time
T. There are two ways to do naive forecasting with Minitab:
Execute MA and specify a moving average length of 1.
Execute SES on page 887 and specify a moving average length of 1.
With MA, list the column containing the series, followed by a constant indicating the length of the moving average.
Default output consists of a time series plot which displays the data and one-period-ahead forecasts, or fitted
values. Alternatively, you can generate a time series plot that displays the data and the smoothed values.
The uncentered moving average at time T is the one-period-ahead forecast, or fitted value, for time T+1. If you
center the moving averages, these are adjusted accordingly when producing the fitted values.
Minitab also displays three measures to help you determine the accuracy of the fitted values: MAPE, MAD, and
MSD. Optional output includes a table containing the series, moving average values, and the fits and residuals.
If you generate forecasts, they are also listed, with corresponding lower and upper 95% prediction limits.
Centering
CENTER
If you use this subcommand, Minitab places the moving average values at the period which is in the center of the
range rather than the end of it. This is called centering the moving average, and is done to position the moving
average values at their central positions in time.
882
Minitab Statistical Software Time Series Analysis
Forecasts
FORECASTS K
Use FORECASTS with an integer to indicate how many forecasts you want. Forecasts appear in red on the time
series plot with 95% prediction interval bands.
ORIGIN K
Use ORIGIN with a positive integer to specify a starting point for the forecasts. For example, if you specify 4
forecasts and 48 for the origin, Minitab computes forecasts for periods 49, 50, 51, and 52 based on the moving
average at period 48. If you omit the ORIGIN subcommand, Minitab generates forecasts from the end of the data.
X-axis scale
INDEX or I
Numbers the x-axis with a single scale from 1 to n by ones (where n is the number of observations in the column
containing the time series). INDEX is the default time scale for the x-axis. The default start value for INDEX is 1,
and integers are valid values.
START K [K...K]
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands, and they should match the order the subcommands were given.
If you do not use START, the time series graph uses the default start values for the time unit subcommands. You
must specify all time unit subcommands before you use START.
INCREMENT K
Use INCREMENT to increment the time scale.
STAMP C...C
Use the STAMP subcommand to place a date/time stamp on the x-axis. The argument must be a date/time column.
You can use at least one and at most three columns of equal length to stamp the x-axis. The values in the date/time
column are stamped on the time series graph in the same format as they appear in the date/time column. When
you use the STAMP subcommand, you cannot use the START and INCREMENT subcommands and any of the time
unit subcommands.
The optional arguments to the time unit subcommands let you change the default interval in which you measure
data. This allows you to do a time series plot with, for example, bimonthly data, or data collected four times per
minute.
For example, the following commands create a graph that shows the depth of a reservoir. Measurements of the
depth were collected on a bimonthly basis (in months 1, 3, 5, 7, 9, and 11) starting in January of 1990. The argument
for MONTH uses abbreviated notation to specify every other month from months 1 to 11 inclusive.
TSPLOT Depth;
MONTH 1:11/2;
YEAR;
START 1 1990.
Calendar values for the x-axis
Labels the x-axis with calendar values. MONTH and YEAR account for different length months and leap years. Specify
all the calendar unit subcommands before using any other subcommands in the graph.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
883
Minitab Statistical Software Time Series Analysis
Default START valueRangeCalendar unit subcommand
Current day1 to a maximum of 31, depending on
the month
DAY or D
Current month1 to 12MONTH or M
Current quarter1 to 4QUARTER or Q
Current year1000 to 4000YEAR or Y
Adding an additional calendar unit subcommand to the same graph adds additional x-axes to the graph. You can use
up to three subcommands in the following combinations:
DAY
DAY; MONTH
DAY; MONTH; YEAR
MONTH
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER
QUARTER; YEAR
YEAR
Time of day values for the x-axis
Labels the x-axis with time values.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeTime unit subcommand
00 to 59SECOND or SS
00 to 59MINUTE or MM
00 to 23HOUR or HH
Adding an additional time unit subcommand to the same graph adds additional x-axes to the graph. You can use up
to three subcommands in the following combinations:
DAY; HOUR
DAY; HOUR; MINUTE
HOUR
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE
MINUTE; SECOND
SECOND
884
Minitab Statistical Software Time Series Analysis
Note that you can use DAY in combination with SECOND, MINUTE, and HOUR.
Storage
SMOOTHED C
Stores the smoothed data.
FITS C
Stores the fitted values. The uncentered moving average at time T is the fitted value for time T + 1.
RESIDUALS C
Stores the residuals. The residual at time T is the difference between the actual data at time T and the fitted value
at time T. These residuals are used to calculate MAPE, MAD, and MSD. If you store the residuals you can generate
diagnostic plots using ACF on page 862.
FSTORE C
Stores the forecasts in a column. Use this subcommand only if you also used the FORECASTS subcommand to
generate forecasts.
UPPER C
Stores the upper 95% prediction limits for the forecasts.
LOWER C
Stores the lower 95% prediction limits for the forecasts.
Graphs
SMPLOT
By default, Minitab plots predicted values and actual data. SMPLOT says to plot the smoothed values (the moving
averages) and actual data.
NOPLOT
Suppresses the default time series plot. If you do not use NOPLOT, Minitab displays the time series plot.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
885
Minitab Statistical Software Time Series Analysis
Results
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the summary table.1
Minitab displays the summary and results table.2
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
PACF: Session command for calculating partial
autocorrelation
PACF
Calculates and plots the partial autocorrelations of a time series.
PACF has several subcommands and generates a high-resolution partial autocorrelation function, including
confidence limits for the correlations, in a graph. You can store the partial autocorrelations and associated t-statistics
for up to the first 75 lags.
If you do not specify the number of lags with LAGS, Minitab uses a default number of lags:
n / 4 for a series with less than or equal to 240 observations
+ 45 for a series with more than 240 observations, where n is the number of observations in the series
LAGS K
Specifies the number of lags to display in the PACF plot. If you omit LAGS, Minitab uses a default number of
lags. This is n / 4 for a series with less than or equal to 240 observations or + 45 for a series with more
than 240 observations, where n is the number of observations in the series.
SPACF C
Stores the partial autocorrelations.
TSTATS C
Stores the t-statistics.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
886
Minitab Statistical Software Time Series Analysis
SES: Session command for performing single
exponential smoothing
SES C
Use single exponential smoothing to smooth out the noise in a time series and forecast future values of the series.
This method uses an exponentially weighted average of all past values of the series to calculate the smoothed
value at each period. Note: An exponentially weighted average, with weight a, is approximately equivalent to an
unweighted moving average of length (2 a)/a. If you do not specify a weight, Minitab computes an optimal
weight, or smoothing parameter, based on your data (using WEIGHT). In this case, Minitab computes the initial
smoothed value by backcasting. If you do specify a weight, Minitab uses the average of the first six observations
for the initial smoothed value.
With SES, list the column containing the time series. The time series cannot include any missing values. If you
have missing data, go to Missing values in exponential smoothing on page 1171.
You can also perform naive forecasting with SES. In naive forecasting, the forecast for time T+1 is the data value
at time T. There are two ways to do naive forecasting with Minitab:
Execute MA and specify a moving average length of 1.
Execute SES on page 887 and specify a moving average length of 1.
Default output consists of a time series plot which displays the data and one-period-ahead forecasts, or fitted
values. It also displays the smoothing constant (weight) used and three measures to help you determine the
accuracy of the fitted values: MAPE, MAD, and MSD. Alternatively, you can generate a time series plot that displays
the data and the smoothed values. Optional output includes a table containing the series, smoothed data, the
one-period-ahead forecasts (or fitted values), and the one-period-ahead errors.
Weight
WEIGHT K
Single exponential smoothing uses an exponentially weighted average of all past values of the series to calculate
the smoothed value at each period. If you omit the WEIGHT subcommand, Minitab computes and uses an optimal
weight by minimizing the sum of squared errors. If you omit the WEIGHT subcommand, the initial smoothed value
is found by backcasting.
Use WEIGHT to enter a specific weight. This must be a number between 0 and 2, although it is unusual to use a
number greater than 1. By default, the initial smoothed value is the average of the first six observations. Use
INITIAL to change the default. For more information, go to Computing weights, or smoothed values on page 1138.
INITIAL K
By default, if you use WEIGHT, Minitab uses the average of the first six observations for the initial smoothed value.
Use INITIAL to specify the initial smoothed value.
Forecasts
FORECASTS K
Use FORECASTS with an integer to indicate how many forecasts you want. Forecasts appear in red on the time
series plot with 95% prediction interval bands.
887
Minitab Statistical Software Time Series Analysis
ORIGIN K
Use ORIGIN with a positive integer to specify a starting point for the forecasts. For example, if you specify 4
forecasts and 48 for the origin, Minitab computes forecasts for periods 49, 50, 51, and 52 based on the moving
average at period 48. If you omit the ORIGIN subcommand, Minitab generates forecasts from the end of the data.
X-axis scale
INDEX or I
Numbers the x-axis with a single scale from 1 to n by ones (where n is the number of observations in the column
containing the time series). INDEX is the default time scale for the x-axis. The default start value for INDEX is 1,
and integers are valid values.
START K [K...K]
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands, and they should match the order the subcommands were given.
If you do not use START, the time series graph uses the default start values for the time unit subcommands. You
must specify all time unit subcommands before you use START.
INCREMENT K
Use INCREMENT to increment the time scale.
STAMP C...C
Use the STAMP subcommand to place a date/time stamp on the x-axis. The argument must be a date/time column.
You can use at least one and at most three columns of equal length to stamp the x-axis. The values in the date/time
column are stamped on the time series graph in the same format as they appear in the date/time column. When
you use the STAMP subcommand, you cannot use the START and INCREMENT subcommands and any of the time
unit subcommands.
The optional arguments to the time unit subcommands let you change the default interval in which you measure
data. This allows you to do a time series plot with, for example, bimonthly data, or data collected four times per
minute.
For example, the following commands create a graph that shows the depth of a reservoir. Measurements of the
depth were collected on a bimonthly basis (in months 1, 3, 5, 7, 9, and 11) starting in January of 1990. The argument
for MONTH uses abbreviated notation to specify every other month from months 1 to 11 inclusive.
TSPLOT Depth;
MONTH 1:11/2;
YEAR;
START 1 1990.
Calendar values for the x-axis
Labels the x-axis with calendar values. MONTH and YEAR account for different length months and leap years. Specify
all the calendar unit subcommands before using any other subcommands in the graph.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeCalendar unit subcommand
Current day1 to a maximum of 31, depending on
the month
DAY or D
Current month1 to 12MONTH or M
Current quarter1 to 4QUARTER or Q
888
Minitab Statistical Software Time Series Analysis
Default START valueRangeCalendar unit subcommand
Current year1000 to 4000YEAR or Y
Adding an additional calendar unit subcommand to the same graph adds additional x-axes to the graph. You can use
up to three subcommands in the following combinations:
DAY
DAY; MONTH
DAY; MONTH; YEAR
MONTH
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER
QUARTER; YEAR
YEAR
Time of day values for the x-axis
Labels the x-axis with time values.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeTime unit subcommand
00 to 59SECOND or SS
00 to 59MINUTE or MM
00 to 23HOUR or HH
Adding an additional time unit subcommand to the same graph adds additional x-axes to the graph. You can use up
to three subcommands in the following combinations:
DAY; HOUR
DAY; HOUR; MINUTE
HOUR
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE
MINUTE; SECOND
SECOND
Note that you can use DAY in combination with SECOND, MINUTE, and HOUR.
889
Minitab Statistical Software Time Series Analysis
Storage
SMOOTHED c
SMOOTHED stores the smoothed data. The smoothed value at time T is the fitted value for time T + 1.
FITS C
FITS stores the fitted values. The uncentered moving average at time T is the fitted value for time T + 1.
RESIDUALS C
RESIDUALS stores the residuals. The residual at time T is the difference between the actual data at time T and the
fitted value at time T. These residuals are used to calculate MAPE, MAD, and MSD. If you store the residuals you
can generate diagnostic plots using ACF on page 862.
FSTORE C
FSTORE stores the forecasts in a column. Use this subcommand only if you also used the FORECASTS subcommand
to generate forecasts.
UPPER C
UPPER stores the upper 95% prediction limits for the forecasts.
LOWER C
LOWER stores the lower 95% prediction limits for the forecasts.
Graphs
SMPLOT
By default, Minitab plots predicted values and actual data. SMPLOT says to plot the smoothed values (the moving
averages) and actual data.
NOPLOT
Suppresses the default time series plot. If you do not use NOPLOT, Minitab displays the time series plot.
GHISTOGRAM
GHISTOGRAM displays a histogram of the residuals.
GNORMAL
GNORMAL displays a normal probability plot of the residuals.
GFITS
GFITS plots the residuals versus the fitted values.
GORDER
GORDER plots the residuals versus the order of the data. The row number for each data point is shown on the
x-axis (for example, 1 2 3 4... n).
GFOURPACK
GFOURPACK displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals
vs fitted values, and residuals vs order of the data.
GVARIABLE C...C
GVARIABLE displays a separate graph for the residuals versus each specified column.
890
Minitab Statistical Software Time Series Analysis
Results
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the summary table.1
Minitab displays the summary and results table.2
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
TBOXCOX: Session command for performing a
Box-Cox transformation on time series data
TBOXCOX C
TBOXCOX transforms a time series to try to make the variance of the series stationary. Stationary variance is a
requirement for an ARIMA model. Use a time series plot to determine if the variance of a time series is stationary.
If the time series has a pattern in the spread of the points, then the variance is not stationary.
PERIOD K
Specifies the seasonal length in the time series. For example, if you have an annual cycle and monthly data,
enter 12 for K. K must be a positive integer within [2, floor(N/2)] where N is the row count of the column for
TBOXCOX, omitting any missing values from the beginning or end of the data. The default value if you do
not specify this subcommand is 2.
LULIMITS K K
Specifies the lower and upper limits for the search for the optimal lambda. The first K is the lower limit and
must be less than the second K. Both values of K must be within [-5, 5]. This subcommand is not valid with
LAMBDA. The default values if you do not specify LULIMITS or LAMBDA are -1, 2.
LAMBDA K
Specifies the value of λ for the Box-Cox transformation. K must be within [-5, 5]. This subcommand is not
valid with LULIMITS.
TMETHOD
Displays the method table.
GTSPLOT [C]
Displays time series plots of the original and transformed time series data. Use the optional column argument
to specify a column of labels for the x-axis of the graph. The optional column must be the same length as
the time series data. The subcommand allows missing values in the optional column.
STORE C
Stores the transformed data in C.
891
Minitab Statistical Software Time Series Analysis
TREND: Session command for performing a trend
analysis
TREND C
Use trend analysis to fit a particular type of trend line to a time series or to detrend a time series.
You may fit one of four models: linear, quadratic, growth curve, and S-curve (Pearl-Reed logistic). The default is
a linear trend model.
TREND generates a time series plot that shows the original data, the fitted trend line, and forecasts. Minitab also
displays the fitted trend equation and three measures to help you determine the accuracy of the fitted values:
MAPE, MAD, and MSD.
Model type
Use to fit a quadratic, exponential growth curve or S-curve model. If you do not enter one of these subcommands,
Minitab uses the default model, the linear trend model. Use care when interpreting the coefficients from the different
models, because they have different meanings.
QUADRATIC
Specifies the quadratic model.
GROWTH
Specifies the growth curve model.
SCURVE
Specifies the S-curve trend model.
Options
You can use these subcommands to incorporate knowledge learned from fitting the same trend model to prior data
to obtain an "improved" fit to the present data. For example, suppose you fit a trend model to data covering each
annual financial cycle. Further, suppose that the type of model chosen for this year is the same type chosen for last
year. In that case, you may want to include the information from last year's model with this year's data.
This is how it works. First, fit last year's data with TREND using the appropriate model. Note the coefficients listed in
the fitted trend equation displayed in the output. Next, fit this year's data with %TREND using the same model. Include
the PRIORS subcommand, giving the coefficients you noted earlier as arguments.
Minitab generates the default time series plot, based only on this year's data, plus a second time series plot that shows
trend lines for three models. Minitab displays the coefficients and accuracy measures for all three models.
This is how to interpret the three trend lines displayed in the second time series plot:
Trend line 1 is based on this year's data only and is the same as the trend line in the first time series plot. Minitab
calls this the "new line".
Trend line 2 is based on the coefficients listed with PRIORS. The resulting fits generate the second trend line. Minitab
calls this the "priors line".
892
Minitab Statistical Software Time Series Analysis
Trend line 3 is based on coefficients computed from a weighted average of the priors coefficients and the new
coefficients. By default, these coefficients are computed by multiplying 0.2 times the new coefficient plus 0.8 times
the prior coefficient. Minitab generates a third set of fits using these "smoothed" coefficients. Minitab calls this the
"smoothed line". This smoothed trend line incorporates prior information and new information in much the same
way that exponential smoothing works. In a sense, this smoothing of coefficients filters out some of the noise from
the model parameters estimated in successive cycles.
Use WEIGHTS to change how the smoothed coefficients are computed. By default, Minitab multiplies each new
coefficient by 0.2. To change this default, enter WEIGHTS with the value you want for each coefficient in the model.
PRIORS K K [K]
Specifies prior parameter values.
WEIGHTS K K [K]
Specifies weights of coefficients of current data for the weighted average fit.
Forecasts
FORECASTS K
Use FORECASTS with an integer to indicate how many forecasts you want. Forecasts appear in red on the time
series plot.
ORIGIN K
Use ORIGIN with a positive integer to specify a starting point for the forecasts. For example, if you specify 4
forecasts and 48 for the origin, Minitab computes forecasts for periods 49, 50, 51, and 52. If you specify FORECASTS
but no ORIGIN, Minitab generates forecasts from the end of the data. Minitab uses data up to the ORIGIN for
fitting the trend model used to generate forecasts.
X-axis scale
INDEX or I
Numbers the x-axis with a single scale from 1 to n by ones (where n is the number of observations in the column
containing the time series). INDEX is the default time scale for the x-axis. The default start value for INDEX is 1,
and integers are valid values.
START K [K...K]
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands, and they should match the order the subcommands were given.
If you do not use START, the time series graph uses the default start values for the time unit subcommands. You
must specify all time unit subcommands before you use START.
INCREMENT K
Use INCREMENT to increment the time scale.
STAMP C...C
Use the STAMP subcommand to place a date/time stamp on the x-axis. The argument must be a date/time column.
You can use at least one and at most three columns of equal length to stamp the x-axis. The values in the date/time
column are stamped on the time series graph in the same format as they appear in the date/time column. When
you use the STAMP subcommand, you cannot use the START and INCREMENT subcommands and any of the time
unit subcommands.
893
Minitab Statistical Software Time Series Analysis
The optional arguments to the time unit subcommands let you change the default interval in which you measure
data. This allows you to do a time series plot with, for example, bimonthly data, or data collected four times per
minute.
For example, the following commands create a graph that shows the depth of a reservoir. Measurements of the
depth were collected on a bimonthly basis (in months 1, 3, 5, 7, 9, and 11) starting in January of 1990. The argument
for MONTH uses abbreviated notation to specify every other month from months 1 to 11 inclusive.
TSPLOT Depth;
MONTH 1:11/2;
YEAR;
START 1 1990.
Calendar values for the x-axis
Labels the x-axis with calendar values. MONTH and YEAR account for different length months and leap years. Specify
all the calendar unit subcommands before using any other subcommands in the graph.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeCalendar unit subcommand
Current day1 to a maximum of 31, depending on
the month
DAY or D
Current month1 to 12MONTH or M
Current quarter1 to 4QUARTER or Q
Current year1000 to 4000YEAR or Y
Adding an additional calendar unit subcommand to the same graph adds additional x-axes to the graph. You can use
up to three subcommands in the following combinations:
DAY
DAY; MONTH
DAY; MONTH; YEAR
MONTH
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER
QUARTER; YEAR
YEAR
Time of day values for the x-axis
Labels the x-axis with time values.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeTime unit subcommand
00 to 59SECOND or SS
894
Minitab Statistical Software Time Series Analysis
Default START valueRangeTime unit subcommand
00 to 59MINUTE or MM
00 to 23HOUR or HH
Adding an additional time unit subcommand to the same graph adds additional x-axes to the graph. You can use up
to three subcommands in the following combinations:
DAY; HOUR
DAY; HOUR; MINUTE
HOUR
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE
MINUTE; SECOND
SECOND
Note that you can use DAY in combination with SECOND, MINUTE, and HOUR.
Storage
RESIDUALS C
RESIDUALS stores the residuals in a column. Also called detrended data, you can use this data to do further analysis
such as generating diagnostic plots using ACF on page 862. The detrended data equal the original data minus the
fits.
FITS C
FITS stores the fits in a column. These are the values used to plot the trend line.
FSTORE C
FSTORE stores the forecasts in a column. Use this subcommand only if you also used the FORECASTS subcommand
to generate forecasts.
Graphs
NOPLOT
Suppresses the default time series plot. If you do not use NOPLOT, Minitab displays the time series plot.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
895
Minitab Statistical Software Time Series Analysis
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Results
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the summary table.1
Minitab displays the summary and results table.2
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
TSWINT: Session command for performing
Holt-Winters seasonal exponential smoothing
TSWINT C K
Performs Holt-Winters seasonal exponential smoothing, using either a multiplicative or an additive model, to
smooth and forecast data which exhibit both a trend and a seasonal pattern. Minitab uses the multiplicative model
by default. Use the ADDITIVE subcommand to use an additive model.
This method employs a level component, a trend component, and a seasonal component at each period. It uses
three weights, or smoothing parameters, to update the components at each period. Initial values for the level and
trend components are obtained from a linear regression on time. Initial values for the seasonal component are
obtained from a dummy-variable regression using detrended data.
With either command list the column containing the time series followed by a constant indicating the length of
the seasonal pattern. This constant must be a positive integer greater than or equal to 2. The time series cannot
include any missing values.
Default output consists of a time series plot which displays the data and one-period-ahead forecasts, or fitted
values. It also displays the smoothing constants used for the level, trend and seasonal components, and three
measures to help you determine the accuracy of the fitted values: MAPE, MAD, and MSD. Alternatively, you can
generate a time series plot that displays the data and the smoothed values. Optional output includes a table
containing the original series, the smoothed data, the fitted values and the errors.
896
Minitab Statistical Software Time Series Analysis
Model
ADDITIVE
By default, Minitab uses the multiplicative model. Use the ADDITIVE subcommand with TSWINT to use an additive
model.
Weights
WEIGHTS K K K
Specifies the weights for the level, trend, and seasonal components. By default, all three weights, or smoothing
parameters, are set to 0.2. Since an equivalent ARIMA model exists only for a very restricted form of the Holt-Winters
model, Minitab does not compute optimal parameters for TSWINT as it does for SES on page 887 and DES on
page 876.
Use WEIGHTS to specify your own smoothing parameters. Each weight must be a number from 0 to 1.
Forecasts
FORECASTS K
Use FORECASTS with an integer to indicate how many forecasts you want. Forecasts appear in red on the time
series plot with 95% prediction interval bands.
ORIGIN K
Use ORIGIN with a positive integer to specify a starting point for the forecasts. For example, if you specify 4
forecasts and 48 for the origin, Minitab computes forecasts for periods 49, 50, 51, and 52 based on the moving
average at period 48. If you omit the ORIGIN subcommand, Minitab generates forecasts from the end of the data.
X-axis scale
INDEX or I
Numbers the x-axis with a single scale from 1 to n by ones (where n is the number of observations in the column
containing the time series). INDEX is the default time scale for the x-axis. The default start value for INDEX is 1,
and integers are valid values.
START K [K...K]
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands, and they should match the order the subcommands were given.
If you do not use START, the time series graph uses the default start values for the time unit subcommands. You
must specify all time unit subcommands before you use START.
INCREMENT K
Use INCREMENT to increment the time scale.
STAMP C...C
Use the STAMP subcommand to place a date/time stamp on the x-axis. The argument must be a date/time column.
You can use at least one and at most three columns of equal length to stamp the x-axis. The values in the date/time
column are stamped on the time series graph in the same format as they appear in the date/time column. When
you use the STAMP subcommand, you cannot use the START and INCREMENT subcommands and any of the time
unit subcommands.
897
Minitab Statistical Software Time Series Analysis
The optional arguments to the time unit subcommands let you change the default interval in which you measure
data. This allows you to do a time series plot with, for example, bimonthly data, or data collected four times per
minute.
For example, the following commands create a graph that shows the depth of a reservoir. Measurements of the
depth were collected on a bimonthly basis (in months 1, 3, 5, 7, 9, and 11) starting in January of 1990. The argument
for MONTH uses abbreviated notation to specify every other month from months 1 to 11 inclusive.
TSPLOT Depth;
MONTH 1:11/2;
YEAR;
START 1 1990.
Calendar values for the x-axis
Labels the x-axis with calendar values. MONTH and YEAR account for different length months and leap years. Specify
all the calendar unit subcommands before using any other subcommands in the graph.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeCalendar unit subcommand
Current day1 to a maximum of 31, depending on
the month
DAY or D
Current month1 to 12MONTH or M
Current quarter1 to 4QUARTER or Q
Current year1000 to 4000YEAR or Y
Adding an additional calendar unit subcommand to the same graph adds additional x-axes to the graph. You can use
up to three subcommands in the following combinations:
DAY
DAY; MONTH
DAY; MONTH; YEAR
MONTH
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER
QUARTER; YEAR
YEAR
Time of day values for the x-axis
Labels the x-axis with time values.
The following table shows the time unit subcommands, the range of values they can take, and their default start values.
Default START valueRangeTime unit subcommand
00 to 59SECOND or SS
898
Minitab Statistical Software Time Series Analysis
Default START valueRangeTime unit subcommand
00 to 59MINUTE or MM
00 to 23HOUR or HH
Adding an additional time unit subcommand to the same graph adds additional x-axes to the graph. You can use up
to three subcommands in the following combinations:
DAY; HOUR
DAY; HOUR; MINUTE
HOUR
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE
MINUTE; SECOND
SECOND
Note that you can use DAY in combination with SECOND, MINUTE, and HOUR.
Storage
SMOOTHED C
Stores the smoothed data in the specified column. The smoothed value for time T is equal to the seasonal estimate
for time T p (where p is the seasonal period) multiplied by (or added to for an additive model) the level estimate
for time T 1.
LEVEL C
Stores the level components in the specified column.
TREND C
Stores the trend components in the specified column.
SEASONAL C
Stores the seasonal components in the specified column.
RESIDUALS C
Stores the one-period-ahead forecast errors in the specified column. These residuals are used to calculate MAPE,
MAD, and MSD. If you store the residuals you can generate diagnostic plots using ACF on page 862.
FITS C
Stores the one-period-ahead forecasts in the specified column. The fitted value for time T is equal to the sum of
the level and trend estimates for time T 1, multiplied by (or added to for an additive model) the seasonal estimate
for time T p (where p is the seasonal period).
FSTORE C
Stores the forecasts in a column. Use this subcommand only if you also used the FORECASTS subcommand to
generate forecasts.
UPPER C
Stores the upper 95% prediction limits for the forecasts.
899
Minitab Statistical Software Time Series Analysis
LOWER C
Stores the lower 95% prediction limits for the forecasts.
Graphs
SMPLOT
By default, Minitab plots predicted values and actual data. SMPLOT says to plot the smoothed values (the moving
averages) and actual data.
NOPLOT
Suppresses the default time series plot. If you do not use NOPLOT, Minitab displays the time series plot.
GHISTOGRAM
Displays a histogram of the residuals.
GNORMAL
Displays a normal probability plot of the residuals.
GFITS
Plots the residuals versus the fitted values.
GORDER
Plots the residuals versus the order of the data. The row number for each data point is shown on the x-axis (for
example, 1 2 3 4... n).
GFOURPACK
Displays a layout of a histogram of the residuals, a normal probability plot of the residuals, residuals vs fitted
values, and residuals vs order of the data.
GVARIABLE C...C
Displays a separate graph for the residuals versus each specified column.
Results
BRIEF K
Controls the amount of output. BRIEF can also be used as a main command. It then effects all commands that
are controlled by BRIEF.
Output that Minitab displaysValue of K
Minitab displays no output, but performs all specified storage.0
Minitab displays the summary table.1
Minitab displays the summary and results table.2
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
900
Minitab Statistical Software Time Series Analysis
Tables
TABLE: Session command for creating one-way,
two-way, and multi-way tables using categorical
variables
TABLES C...C
Displays one-way, two-way, and multi-way tables using categorical variables in C...C. TABLES uses two types of
variables, categorical and associated. All the columns specified with TABLES must be the same length.
Categorical variables determine the cells of the table and are listed with TABLES. Categorical columns may be
numeric or text. When using four categorical columns, a two-way table of the first entry (row) and second entry
(column) is displayed for all possible combination of levels of the third and the fourth entry.
Associated variables are listed in the second set of eleven commands and determine summary statistics such as
means, standard deviation, etc for each cell.
If no subcommands are used, the table displays the count for each cell which is the number of times a combination
of row and column category occurs. If subcommands are used, then the counts are not displayed unless you
specify the COUNTS subcommand. To calculate and store additional statistics such as skewness and kurtosis, go
to STATS on page 143.
The TABLE command was developed in collaboration with James R. Allen of Allen Data Systems, Cross Plains,
Wisconsin.
FREQUENCIES C
Allows the user to enter multiple occurrences in a single row of the worksheet. Usually each row of the
worksheet corresponds to one case. The column must be of same length as the column specified in the main
command. The column elements should be integers. Any value less than one, or a missing value is treated
as 0. In textbooks, frequencies are sometimes called weights or case weights.
Statistics for categorical variables
These subcommands are for categorical variables specified in the main command.
COUNTS
Displays the counts of the total number of observations in each cell.
ROWPERCENTS
Displays the percentage each cell represents of the total observations in the row.
COLPERCENTS
Displays the percentage each cell represents of the total observations in the column.
TOTPERCENTS
Displays the percentage each cell represents of all the observations in the table.
901
Minitab Statistical Software Tables
Statistics for associated variables
These subcommands calculate statistics for each associated variable for each cell and margins (the rows and columns
of a table). The columns can be numeric or date/time and must be the same length as the columns specified in the
main command. Date/time columns are treated as numeric for all subcommands except MINIMUM and MAXIMUM.
When you use MINIMUM and MAXIMUM, date/time columns display values in date/time format.
MEANS C...C
Calculates the arithmetic mean.
MEDIANS C...C
Calculates the median.
SUMS C...C
Calculates the sum of all the observations.
MINIMUMS C...C
Displays the smallest value.
MAXIMUMS C...C
Displays the largest value.
STDEV C...C
Calculates the standard deviation.
STATS C...C
Displays the same result as using the three subcommands N, MEANS, and STDEV.
DATA C...C
Displays a list of all the data in each cell except margins. The columns can be numeric, date/time, or text.
N C...C
Displays the number of nonmissing values.
NMISS C...C
Displays the number of missing values.
PROPORTION K [K] C...C
Displays the proportion of cases equal to the specified value (or in the specified range, if two K's are given). For
example, PROP 2 5 C1 C2 gives two numbers for each cell, the proportion of cases where C1 is in the range 2 and
5, and the proportion of cases where C2 is in the range 2 and 5. You must have numeric data, and there cannot
be any missing values to use the PROPORTION subcommand.
Options
These subcommands are for categorical variables. Use only columns that appeared on the main command.
CMISSING C...C
Includes missing values in calculating marginal counts and percentages.
DMISSING C...C
Missing values are not included in calculating marginal counts and percentages. Row, column, and total percentages
are not calculated for the category 'Missing'.
902
Minitab Statistical Software Tables
Output
NOALL
NOALL suppresses the printing of marginal statistics.
ALL C...C
ALL prints marginal statistics over all levels of the specified categorical variables. The variables listed on ALL must
also be listed on the TABLE command.
LAYOUT K K
Displays compact tables for reports. LAYOUT takes 2 numeric constant arguments. Both constants must be
nonnegative integers. The second cannot be greater than 2. The sum of the two constants must be less than or
equal to the number of columns specified with the TABLE command.
For example, if you use LAYOUT K1 K2, then the level combinations of the first K1 categorical variables will define
the rows of the table, and the level combinations of the next K2 categorical variables will define the columns of
the table. Any remaining variables are used to define multiple table.
TALLY: Session command for displaying a one-way
table for each column
TALLY C...C
Displays a one-way table for each column.
If no subcommands are used, the table displays the count for each category. If subcommands are used, then
counts are not displayed unless you specify COUNTS or ALL subcommand.
The data columns can be numeric or text and can contain any values.
Statistics for categorical variables
These subcommands are for categorical variables specified in the main command.
COUNTS
Displays the number of times a category occurs (count).
PERCENTS
Displays what percentage of the whole is accounted for by each category.
CUMCOUNTS
Displays the cumulative count for each category.
CUMPERCENTS
Displays the cumulative percentage for each category.
ALL
Displays the same result as using the four commands, COUNTS, PERCENTS, CUMCOUNTS, and CUMPERCENTS.
903
Minitab Statistical Software Tables
Storage
STORE C...C
Stores output from TALLY. If you specify n columns with TALLY and request m (COUNTS, CUMCOUNTS, PERCENTS,
and CUMPERCENTS) statistics, then the number of columns you require to specify with the STORE subcommand
is n + m * n. No statistics are stored for the missing values.
The first column you list, contains the data categories, and the rest store the requested statistics in the order in
which the subcommands are given. For example, the following commands store the data categories in C2, the
percents in C3, and the counts in C4.
TALLY C1;
PERCENT;
COUNT;
STORE C2 C3 C4.
You can use the stored information to produce frequency plots, cumulative frequency plots, relative frequency
plots, and cumulative relative frequency for integer data. For example, if you had integer data in column C1, you
could produce a frequency plot with the following commands.
TALLY C1;
STORE C2 C3.
PLOT C3*C2
TCHISQUARE: Session command for performing a
chi-square goodness-of-fit test
TCHISQUARE
TCHISQUARE performs a chi-square goodness-of-fit test. If your data are the actual categories in a column,
categorical data are in raw form, specify the column. If the column contains missing data, then that row is excluded
from all calculations.
OBSERVED C
OBSERVED K...K
Use OBSERVED to specify the observed counts for each category. All values entered must be nonnegative.
The number of observed counts must be greater than one. You cannot enter missing values.
LEVELS C
LEVELS K...K
Use LEVELS with OBSERVED to specify the levels of each category. You can specify the levels in a column
or as constants. The number of values in a column or constants must equal the number of categories.
PROPORTIONS [C]
PROPORTIONS [K]...[K]
Specify the proportions to calculate the expected value for each category in a column or as constants. If you
do not use this subcommand, Minitab assumes equal proportion across categories. Missing values are not
allowed.
904
Minitab Statistical Software Tables
COUNTS C
COUNTS K...K
Specifies the historical counts to calculate the expected value for each category. You can enter historical
counts as constants or in a column. Values must be nonnegative. Missing values are not allowed.
Graph
GBAR
Displays a bar chart of the observed and expected values.
GHISQ
Use GCHISQ to display a bar chart of each category's contribution to the chi-square value.
PARETO
Use PARETO with GCHISQ to display a bar chart that orders the bars from largest to smallest of each category's
contribution to the chi-square value.
Results
RTABLE
Displays a table with observed and expected counts and the test results.
XTABS: Session command for displaying one-way,
two-way, and multi-way tables for categorical
variables
XTABS [C...C]
Displays one-way, two-way, and multi-way tables. Categorical columns may be numeric or text, or date/time, and
may contain any values. All columns must be the same length. When a categorical column is text, value order of
the column is used.
UNSTACKED C...C
Specifies that the data are arranged as a table of summarized count data in C...C.
RLEVELS C
RLEVELS allows you to specify a column of names for the categories of the row variable.
CNAME K
CNAME allows you to specify a name for the column variable.
FREQUENCIES C
Allows you to enter multiple occurrences in a single row of the worksheet. Usually each row of the worksheet
corresponds to one case. The column must be of same length as the column specified in the main command.
The column elements should be integers. Any value less than one, or a missing value is treated as 0. In
textbooks, frequencies are sometimes called weights or case weights.
905
Minitab Statistical Software Tables
Categorical statistics
Each subcommand displays a statistics for categorical variables listed with XTABS.
COUNTS
Displays the count of the total number of observations (missing and nonmissing) in each cell.
ROWPERCENTS
Displays the percentage each cell and margin represents of the total observations in the row.
COLPERCENTS
Displays the percentage each cell and margin represents of the total observations in the column.
TOTPERCENTS
Displays the percentage each cell and margin represents of all the observations in the table.
Chi-square analysis
CHISQUARE
Calculates likelihood ratio and Pearson's chi-square tests of independence between the rows and columns of a
two-way table. The output includes the test statistics, the number of degrees of freedom, the p-value of the tests
and the number of cells with expected count less than 5 (if any) for each test. If expected cell count is less than
one, no p-value is displayed. The subcommand works only when using LAYOUT 1,1. (Yates' correction for 2 x 2
tables is not used.)
EXPECTED
Displays the expected cell counts in the table.
RESIDUALS
Displays the residuals (Observed - Expected) in the table.
SRESIDUALS
Displays the standardized residuals in the table.
ARESIDUALS
Displays the adjusted residuals in the table.
XRESIDUALS
Displays each cell's contribution to the Pearson chi-square statistic.
Tests for 2x2 tables
FISHER
Displays Fisher's exact test p-value for each two-way table.
MCNEMAR
Displays McNemar's test for each two-way table. McNemar's procedure tests whether paired proportions are
different. For example, you can use McNemar's test to determine whether a training program changes the
proportion of participants who answer a question correctly.
The results include the estimated difference in proportions, a confidence interval for the difference, and the p-value
for the difference.
906
Minitab Statistical Software Tables
MHCTEST
Displays the estimates of the common odds ratio and the Mantel-Haenszel-Cochran test statistics with
corresponding p-value. This subcommand applies only when three or more variables are specified with the main
command. There is only one test rather than one per table. The first two categorical variables must have 2 levels
each.
Measure of agreement
KAPPA
Displays Cohen's Kappa statistics for rater reliability for each two-way table. This subcommand applies only when
the output is in a two-way table format.
Measures of association
These subcommands are for calculating measures of association.
VSQUARE
Displays Cramer's V-squared statistics.
PRE
Displays Proportional Reduction of Error measures of association, Goodman and Kruskal lambda and tau for each
two-way table. Two versions of each statistics is displayed, one for each choice of dependent and independent
variables.
CONCORDANT
Displays the number of concordant pairs, discordant pairs, and p-values for Goodman and Kruskal's gamma,
Somer's d, and Kendall's tau-b measures of association for each two-way table.
CORRELATION
Displays the Pearson's r and Spearman's rho rank correlation coefficients for each two-way table.
Options
Use only columns that appeared on the main command.
DMISSING C...C
Missing values are not included in calculating marginal counts and percents. Row, column, and total percents are
not calculated for the category 'Missing'.
CMISSING C...C
Includes missing values in calculating marginal counts, percents, expected counts, residuals, and chi-square tests.
Output
NOALL
NOALL suppresses the printing of marginal statistics.
ALL C...C
ALL prints marginal statistics over all levels of the specified categorical variables. The variables listed on ALL must
also be listed on the TABLE command.
907
Minitab Statistical Software Tables
LAYOUT K K
Use LAYOUT to print compact tables for reports. LAYOUT takes 2 numeric constant arguments. Both constants
must be nonnegative integers. The second cannot be greater than 2. The sum of the two constants must be less
than or equal to the number of columns specified on the TABLE command.
For example, LAYOUT K1 K2, the first K1 categorical variables will define the rows of the table, while the level
combinations of the next K2 categorical variables will define the columns of the table. Any remaining variables
are used to define multiple table.
908
Minitab Statistical Software Tables
Nonparametric Analysis
1-Sample Sign
STEST: Session command for performing a 1-sample sign test
STEST [K] C...C
Performs a 1-sample sign test separately for each column. STEST tests the null hypothesis that the population
median is equal to the hypothesized value (K). If you do not specify a hypothesized median in K, STEST compares
the sample median to 0.
Use SINTERVAL on page 909 to calculate a sign confidence interval for the median.
ALTERNATIVE K
Specifies a one-sided alternative hypothesis for the test. K takes two values, 1 and −1. If K = −1, then H1: M
< hypothesized value. If K = +1, then H1: M > hypothesized value. If this command is not used, Minitab
performs a two-sided test such that H1: M hypothesized value.
SINTERVAL: Session command for calculating a sign confidence
interval
SINTERVAL [K] C...C
Calculates a sign confidence interval, separately for each column. You can specify a confidence level on the
command line. For example, if you enter the following command, Minitab calculates 90% confidence intervals. If
you do not specify a confidence level, then SINTERVAL calculates a 95% confidence interval.
SINTERVAL 0.90 C1
Use STEST on page 909 to perform a sign test for the median.
1-Sample Wilcoxon
WTEST: Session command for performing a 1-sample Wilcoxon
test
WTEST [K] C...C
Performs a 1-sample Wilcoxon signed-rank test of the median separately for each column. If you do not specify
a hypothesized median, WTEST compares the sample median to 0.
Use WINTERVAL on page 910 to calculate a confidence interval for the median.
909
Minitab Statistical Software Nonparametric Analysis
ALTERNATIVE K
Specifies a one-sided alternative hypothesis for the test. K takes two values, +1 and −1. If K = −1, then H1:
M < hypothesized value. If K = +1, then H1: M > hypothesized value. If this command is not used, Minitab
performs a two-sided test such that H1: M hypothesized value.
WINTERVAL: Session command for calculating a Wilcoxon
confidence interval
WINTERVAL [K] C...C
WINTERVAL calculates Wilcoxon confidence interval separately for each column.
You can specify a confidence level on the command line. For example, if you enter the command, Minitab calculates
a 90% confidence interval.
WINTERVAL 0.90 C1
If you do not specify a confidence level, WINTERVAL gives a 95% confidence interval.
Use WTEST on page 909 to perform a 1-sample Wilcoxon test for the median.
MANN-WHITNEY: Session command for performing
a Mann-Whitney test
MANN-WHITNEY [K] C C
MANN-WHITNEY tests for differences between two population medians.
The two columns must be numeric and can be unequal in length. You can specify a confidence level on the
command line. The confidence level must be between 0.5 1. If you do not specify a confidence level, a default
level of 95% is used.
MANN 0.90 C1 C2
ALTERNATIVE K
Specifies a one-sided alternative hypothesis for the test. K takes two values, +1 and −1. If K = −1, then H
1
:
M
1
< M
2
, where M
1
and M
2
are the medians for population 1 and 2 respectively. If K = +1, then H
1
: M
1
>
M
2
. If this command is not used, Minitab performs a two-sided test such that H
1
: M
1
M
2
.
FRIEDMAN: Session command for performing a
Friedman test
FRIEDMAN C C C [C[C]]
Performs a Friedman test with of a randomized block experiment, in the stated order, response in C, treatment
in C, blocks in C, and optionally, you can store residuals in C and fits in C. The null hypothesis for the analysis is
that the treatment has no effect.
910
Minitab Statistical Software Nonparametric Analysis
The treatment and blocks columns can be numeric or text, and can contain any values. You must have exactly
one observation per treatment-block. Missing data are not allowed.
KRUSKAL-WALLIS: Session command for performing
a Kruskal-Wallis test
KRUSKAL-WALLIS C C
Performs a Kruskal-Wallis test with response in C and factors in C.
Performs a nonparametric analysis of the one-way analysis of variance. KRUSKAL-WALLIS tests the null hypothesis
that there are no differences among the k populations.
The factor column can be numeric or text, and can contain any value. The factors do not need to be in any special
order.
MOOD: Session command for performing a Mood's
median test
MOOD C C [C[C]]
Performs a Mood's median test with response in C, factors in C, and optionally, you can store residuals in C and
fits in C.
Performs a nonparametric analysis of a one-way layout. MOOD tests the null hypothesis that the population
medians are equal.
The factor levels can be numeric or text. The levels do not need to be in any special order.
RUNS: Session command for performing a runs test
RUNS [K] C...C
Performs a run test separately on each column. RUNS tests the null hypothesis that the data come from a random
process by using the comparison criterion K. If K is not specified, the mean of the scores is used.
You can have missing data (*) at the beginning or end of the data column or columns, but not in the middle.
911
Minitab Statistical Software Nonparametric Analysis
WALSH: Session command for calculating pairwise
averages
WALSH C C [C C]
Calculates Walsh averages for data in C and stores in a column C. Optionally, you can store the two indices which
defines the Walsh averages in columns C and C.
Calculates the Walsh average of all possible pairs of values, including each value with itself.
Let x
1
, x
2
,..., x
n
be the observations. The Walsh average, ( x
i
+ x
j
) / 2, has indices i and j. If you specify columns to
store the indices, the value of i is put in the first column and j in the second column. If you have n observations,
there will be n (n + 1) / 2 Walsh averages.
This command is useful for nonparametric tests and confidence intervals.
WDIFF: Session command for calculating pairwise
differences
WDIFF C C C [C C]
Calculates differences between all the pairs of elements from two columns C and C and store in a column C.
Optionally, you can store the two indices which defines the pairwise differences in columns C and C.
Calculates all possible differences between pairs by subtracting a value in the second column from the
corresponding value in the first column.
Let x
1
, x
2
,..., x
n
be the values in the first column, and Y
1
,Y
2
,...,Y
m
be the values in the second. WDIFF calculates all
the differences, ( x
i
y
j
). If you specify columns to store the indices, the value of i is put in the first column and j
in the second column.
These differences are useful for nonparametric tests and confidence intervals. For example, the point estimate
given by MANN-WHITNEY on page 910 can be computed as the median of the differences.
WSLOPE: Session command for calculating pairwise
slopes
WSLOPE C C C [C C]
Calculates slope between pairs of points in columns C (x-coordinate)and C (y-coordinate) and stores in a column
C. Optionally, you can store the two indices which defines the pair in columns C and C.
WSLOPE calculates the slope between every pair of points and stores the slopes in the column listed on the
command line. Each row of the y-x columns defines a point in the plane. If you specify columns to store the indices,
the two row numbers used to calculate the slope are put in the corresponding row of these two columns.
912
Minitab Statistical Software Nonparametric Analysis
If any observations are missing or if the slope cannot be defined (for example, the slope of a line parallel to the
y-axis), then the slope is computed as missing. If there are n rows in the input columns, there will be n (n 1) / 2
slopes in the output column.
913
Minitab Statistical Software Nonparametric Analysis
Equivalence Test
TOST: Session command for performing an
equivalence test
You can use an equivalence test to determine whether the means for product measurements or process measurements
are close enough to be considered equivalent.
Small differences between products are not always functionally or practically important. For example, a difference of
1 mg in a 200 mg dose of a drug is unlikely to have any practical effect. When you use an equivalence test, you specify
how large the difference must be to be considered important. Smaller differences are considered unimportant. Minitab
then tests two separate null hypotheses:
The difference is less than or equal to your lower limit for equivalence.
The difference is greater than or equal to your upper limit for equivalence.
If both null hypotheses are rejected, then the difference falls within your equivalence interval and you can claim that
the means for the products are equivalent.
This information is also conveyed graphically in an equivalence plot. If the confidence interval for the difference is
completely within your equivalence limits, then you can claim equivalence.
Minitab provides equivalence tests for the following experimental designs.
1-sample equivalence test
Compare the mean of a product or a process to a standard.
2-sample equivalence test
Compare two product means or two process means using 2 independent samples.
Equivalence test with paired data
Compare two product means or two process means when observations are paired, such as when measurements
for two treatments are taken from the same person or part.
Equivalence test for 2x2 crossover design
Compare treatment means for data that was collected in a 2x2 crossover study. 2x2 crossover studies are commonly
used to test whether individual participants experience equivalent effects on 2 different drugs.
1-sample equivalence test
TOST C K
Performs a one-sample equivalence test to determine whether the test mean (test sample in C) is equivalent to
the target value K.
TOST K K K K
Performs a one-sample equivalence test on summarized data, where each K specifies the following (in the following
order):
Sample size
Sample mean
Sample standard deviation
914
Minitab Statistical Software Equivalence Test
Target value
2-sample equivalence test
TOST C C
Performs a 2-sample equivalence test to determine whether the test mean is equivalent to the reference mean;
the first column C contains the test sample, and the second column C contains the reference sample.
TOST C C
Performs a 2-sample equivalence test with the following data layout:
Sample data are in the first column C.
Sample IDs (with exactly 2 unique values) are in the second column C.
STACKED
Specifies that the data are stacked.
[REFERENCE K}
The optional constant, REFERENCE K, specifies which sample ID value represents the reference sample.
TOST K K K K K K
Performs a 2-sample equivalence test with summarized data, where each K specifies the following (in the following
order):
Test sample: Sample size
Test sample: Mean
Test sample: Standard deviation
Reference sample: Sample size
Reference sample: Mean
Reference sample: Standard deviation
Paired equivalence test
TOST C C
Performs an equivalence test for paired data with test responses in the first column C and paired reference
responses in the second column C.
PAIRED
2x2 crossover design
TOST C C C C K
Performs an equivalence test on data from a 2x2 crossover design with data in separate columns as follows (in
the following order):
Response values for period 1 of sequence 1
Response values for period 2 of sequence 1
Response values for period 1 of sequence 2
915
Minitab Statistical Software Equivalence Test
Response values for period 2 of sequence 2
OrderValue of K
Specifies that the treatment order for sequence 1 is reference followed by test1
Specifies that the order for sequence 1 is test followed by reference2
TOST C C C K
Performs an equivalence test on data from a 2x2 crossover design with sequence ID in the first column C, data
for period 1 in the second column C, paired data for period 2 in the third column C, and the order of the treatments
for sequence 1 specified by K.
OrderValue of K
Reference followed by test1
Test followed by reference2
TLABEL K K
Specifies alternative labels for the reference and test treatments (for example, "Standard" and "Experimental")
as the first K and the second K, respectively (the default labels are "Reference" and "Test").
Equivalence limits
LLIMIT and ULIMIT specify the equivalence limits. If you specify only one limit (LLIMIT or ULIMIT), then Minitab performs
a one-sided test. If you specify RATIO or LOG, then both equivalence limits must be greater than 0.
LLIMIT K
LLIMIT specifies the lower equivalence limit as numeric value K.
ULIMIT K
ULIMIT specifies the upper equivalence limit as numeric value K.
RMEAN
RMEAN specifies that the limit represents a proportion of the reference mean or target value. For example, check
to specify the limit as 0.2 multiplied by the mean of the reference sample rather than as the fixed value of 0.2.
RMEAN cannot be used with LOG or RATIO. The reference mean or target value must be greater than 0.
Hypotheses
These subcommands specify the hypothesis for 2-sample, paired, and 2x2 crossover designs.
By default, Minitab tests whether the difference, test mean reference mean (or target value), is within the equivalence
limits.
RATIO
RATIO specifies to test whether the ratio, test mean / reference mean, is within the equivalence limits. For RATIO,
both equivalence limits must be greater than 0 and the reference mean cannot be equal to 0.
LOG
LOG specifies to test the ratio by testing the difference between the means after transforming the data by taking
the natural log of each data value. (All data values and equivalence limits must be greater than 0.)
916
Minitab Statistical Software Equivalence Test
Options
UEVARIANCE
Specifies that equal variances are not assumed when performing a two-sample equivalence test.
ALPHA K
Specifies the significance level for the test (also called alpha or α).
CIALT
Displays the (1 2α)*100 % confidence interval instead of the default (1 α)*100 % confidence interval.
Graphs
GINTERVAL
Displays the equivalence plot which includes a confidence interval for the difference or ratio.
GHISTOGRAM
For 1-sample and 2-sample designs, GHISTOGRAM displays a histogram of each sample. For paired data,
GHISTOGRAM displays a histogram of the paired differences.
GINDPLOT
For 1-sample and 2-sample designs, GINDPLOT displays an individual value plot that shows the data from each
sample. For paired data, GINDPLOT displays an individual value plot of the paired differences.
GBOXPLOT
For 1-sample and 2-sample designs, GBOXPLOT displays a boxplot that shows the data from each sample. For
paired data, GBOXPLOT displays a boxplot of the paired differences.
GPROFILE
Displays a subject profile plot for paired designs and 2x2 crossover designs. Symbols for related responses are
connected by lines to help reveal response patterns.
GPERIOD
Displays a scatterplot of period 1 responses versus period 2 responses for 2x2 crossover designs.
GMEAN
Plots the mean response for each period of each sequence in a 2x2 crossover design.
Results
TMETHOD
Displays the method table, which shows the details of the analysis, such as which sample is the test sample and
which is the reference sample.
TDSTATISTICS
Displays descriptive statistics, which includes the sample size, the mean, and the standard deviation for each
sample.
TEFFECTS
Displays the effects table for 2x2 crossover designs. Minitab tests for a carryover effect, a treatment effect, and a
period effect.
917
Minitab Statistical Software Equivalence Test
TDMEAN
If you choose a difference hypothesis, then TDMEAN displays the difference between the means and the confidence
interval for that difference. If you choose a ratio hypothesis, then TDMEAN displays the ratio of the means and
the confidence interval for that ratio.
TTEST
Displays the results of the hypothesis tests.
918
Minitab Statistical Software Equivalence Test
Power and Sample Size Analysis
FDESIGN: Session subcommand for power and
sample size for a general full factorial design
FDESIGN K K
Use FDESIGN with the POWER command to calculate power, the number of replicates, or the maximum value of
the difference between main effect means for a general full factorial design.
NLEVELS K...K
Specifies the number of levels for each factors in the model as K. K is an integer greater than or equal to 2.
TORDER K
Includes terms in the model up to order K.
FITB
Specifies that blocks is a term in the model.
REPS K...K
Specifies one or more numbers of replicates.
You must specify two of REPS, MAXDIFFERENCE, and POWER. Minitab calculates the third.
MAXDIFFERENCE K...K
Specifies the maximum difference between main effect means.
You must specify two of REPS, MAXDIFFERENCE, and POWER. Minitab calculates the third.
POWER K...K
Specifies one or more power values.
You must specify two of REPS, MAXDIFFERENCE, and POWER. Minitab calculates the third.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K
Specifies an estimate for the standard deviation.
Storage
These subcommands store information about the power and sample size calculations.
SREPLICATES C
Stores the number of replicates.
SMAXDIFFERENCE C
Stores the maximum difference between main effect means.
919
Minitab Statistical Software Power and Sample Size Analysis
SPOWER C
Stores the power values.
STOTALRUNS C
Stores the total number of runs.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus maximum difference for the specified
test conditions.
NSIZE K...K
NSIZE generates additional power curves based on specified number of replicates.
FFDESIGN: Session subcommand for power and
sample size for a 2-level factorial design
FFDESIGN
Use with the POWER command to calculate power, number of replicates, effect size, or number of center points
for a two-level full or fractional factorial design.
REPS K...K
Specifies one or more numbers of replicates.
You must specify two of REPS, MAXDIFFERENCE, and POWER. Minitab calculates the third.
EFFECT K...K
Specifies one or more alternative hypotheses as a difference in means or effect size.
POWER K...K
Specifies one or more power values.
You must specify two of REPS, MAXDIFFERENCE, and POWER. Minitab calculates the third.
CPBLOCK K...K
Specifies the number of center points per block. The default is 0.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
BLOCKS K
Specifies the number of blocks. The default is 1.
920
Minitab Statistical Software Power and Sample Size Analysis
OMIT K
Specifies the number of terms that you are going to omit from the default model.
FITC
Specifies that, if there are center points, there will be a term for center points in the model.
FITB
Specifies that, if there are blocks, there will be a term for blocks in the model.
Storage
The following subcommands store information about the power and sample size calculations.
SREPLICATES C
Stores the number of replicates.
SEFFECT C
Stores the effect sizes.
SPOWER C
Stores the power values.
SCPBLOCK C
Stores the number of center points per block.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus effect for the specified test conditions.
The following optional subsubcommands generate additional power curves on one graph to compare experimental
designs.
NSIZE K...K
Generates additional power curves based on specified number of replicates.
NCTRPT K...K
Generates additional power curves based on specified number of center points per block.
ONERATE: Session subcommand for power and
sample size for a 1-sample Poisson rate test
ONERATE
Use with the POWER command to calculate power, sample size, or comparison rate for a one-sample Poisson
rate procedure.
RNULL K
Specifies the hypothesized null rate. K must be greater than 0.
921
Minitab Statistical Software Power and Sample Size Analysis
ALPHA K
Specifies the significance level of the test. The default is 0.05.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
LENGTH K
Specifies the length of the observation period as K. The default is 1.
Power, sample size, and comparison rate
You must specify values for any two of the following subcommands. Minitab solves for the third.
POWER K...K
Specifies one or more power values.
SAMPLE K...K
Specifies one or more sample sizes.
RCOMPARE K...K
Specifies one or more comparison rates. K must be greater than 0.
Storage
SSAMPLE C
Stores the sample size.
SRCOMPARE C
Stores comparison rates.
SPOWER C
Stores power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison rate for the specified
test conditions.
NSIZE K...K
Generates additional power curves on one graph to compare sample sizes.
922
Minitab Statistical Software Power and Sample Size Analysis
ONEVARIANCE: Session command for power and
sample size for a 1 variance test
ONEVARIANCE
Use with the POWER command to calculate power, sample size, or significant ratio for a 1 variance test.
STDEV
Indicates that input and output values refer to standard deviation instead of variance, where applicable.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Power, sample size, and ratio
You must specify values for any two of the following subcommands. Minitab solves for the third.
POWER K...K
Specifies one or more power values.
SAMPLE K...K
Specifies one or more sample sizes.
RATIO K...K
Specifies one or more alternative hypotheses in terms of the ratio between the comparison variability and the
hypothesized variability.
Storage
SSAMPLE C
Stores the sample size.
SRATIO C
Stores the ratios.
SPOWER C
Stores power values.
923
Minitab Statistical Software Power and Sample Size Analysis
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison rate for the specified
test conditions.
NSIZE K...K
Generates additional power curves on one graph to compare sample sizes.
ONEWAY: Session command for power and sample
size for one-way ANOVA
ONEWAY
Use with the POWER command to calculate power, sample size, or maximum difference between means for a
one-way analysis of variance procedure with K levels.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
Power, sample size, and maximum difference
You must specify values for any two of the following subcommands. Minitab solves for the third.
POWER K...K
Specifies one or more power values.
SAMPLE K...K
Specifies one or more sample sizes.
MAXDIFFERENCE K...K
Specifies the maximum difference between means.
Storage
SSAMPLE C
Stores the sample size.
SPOWER C
Stores power values.
SMAXDIFFERENCE C
Stores maximum differences.
924
Minitab Statistical Software Power and Sample Size Analysis
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison rate for the specified
test conditions.
NSIZE K...K
Generates additional power curves on one graph to compare sample sizes.
PBDESIGN: Session subcommand for power and
sample size for Plackett-Burman design
PBDESIGN K K
Use with the POWER command to calculate power, number of replicates, effect size, or number of center points
for a Plackett-Burman design with K factor levels and K corner points.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
OMIT K
Specifies the number of main effect terms to omit from the full main effects model.
FITC
Specifies that, if there are center points, there will be a term for center points in the model.
Power, replicates, effect, and center points
You must specify values for any two of the following subcommands. Minitab solves for the third.
POWER K...K
Specifies one or more power values.
REPS K...K
Specifies one or more numbers of replicates.
EFFECT K...K
Specifies one or more alternative hypotheses as a difference in means or effect size.
CPBLOCK K...K
Specifies the number of center points. The default is 0.
Storage
SREPLICATES C
Stores the number of replicates.
925
Minitab Statistical Software Power and Sample Size Analysis
SEFFECT C
Stores the effect sizes.
SPOWER C
Stores one or more power values.
SCPBLOCK C
Stores the number of center points.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison rate for the specified
test conditions.
NSIZE K...K
Generates additional power curves on one graph to compare sample sizes.
NCTRPT K...K
Generates additional power curves based on the specified number of center points.
PONE: Session subcommand for power and sample
size for a 1 proportion test
PONE
Use with the POWER command to calculate power, sample size, or comparison proportion for a 1 proportion test.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
PNULL K
Specifies the value of the proportion under the null hypothesis.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Comparison proportions, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
926
Minitab Statistical Software Power and Sample Size Analysis
PCOMPARE K...K
Specifies one or more comparison proportions.
SAMPLE K...K
Specifies one or more sample sizes.
POWER K...K
Specifies one or more power values.
Storage
SSAMPLE C
Stores the sample sizes.
SPCOMPARE C
Stores the comparison proportions.
SPOWER C
Stores the power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
POWER: Session command for power and sample
size
POWER
Calculates power or other experimental parameters such as sample size. Each of the following subcommands
contains several subsubcommands. Click on the corresponding link for a listing of those subsubcommands.
Use Minitab's power and sample size capabilities to perform both prospective and retrospective power analysis.
Prospective power analysis
Use a prospective study before collecting data to assess the power of an experimental design while you can
do something about it. For example, you can increase the power of a design by increasing the sample size
or by taking measures to decrease the error variance.
Retrospective power analysis
Use a retrospective study after collecting data to help understand the power of the tests that you have
performed. For example, suppose you conduct an experiment and the data analysis does not reveal any
statistically significant results. You can calculate power based on the minimum difference (effect) you wish
to detect. If the power to detect this difference is low, you may want modify your experimental design to
927
Minitab Statistical Software Power and Sample Size Analysis
increase the power and continue to evaluate the same problem. However, if the power is high, you may want
to conclude that there is no meaningful difference (effect) and discontinue further experimentation.
ZONE
Calculates power, sample size, or significant difference for a 1-sample Z-test. For more information, go to
ZONE on page 940.
TONE
Calculates power, sample size, or significant difference for a 1-sample t-test. For more information, go to
TONE on page 933.
TTWO
Calculates power, sample size, or significant difference for a 2-sample t-test. For more information, go to
TTWO on page 936.
TPAIRED
Calculates power, sample size, or significant difference for a paired t-test. For more information, go to TPAIRED
on page 935.
PONE
Calculates power, sample size, or alternative proportion for a 1-sample proportion test. For more information,
go to PONE on page 926.
PTWO
Calculates power, sample size, or significant difference for a 2-sample proportion test. For more information,
go to PTWO on page 929.
ONERATE
Calculates power, sample size, or significant difference for a 1-sample Poisson rate test. For more information,
go to ONERATE on page 921.
TWORATE
Calculates power, sample size, or significant difference for a 2-sample Poisson rate test. For more information,
go to TWORATE on page 938.
ONEVARIANCE
Calculates power, sample size, or significant ratio for a one variance test. For more information, go to
ONEVARIANCE on page 923.
TWOVARIANCE
Calculates power, sample size, or significant ratio for a two variances test. For more information, go to
TWOVARIANCE on page 939.
TOST
Calculates power, sample size, or difference (or ratio) for an equivalence test. For more information, go to
TOST on page 934.
ONEWAY
Calculates power, sample size, or maximum difference between means for a one-way analysis of variance
(ANOVA) test. For more information, go to ONEWAY on page 924.
FFDESIGN
Calculates power, number of replicates, effect size, or number of center points for two-level full and fractional
factorial designs. For more information, go to FFDESIGN on page 920.
928
Minitab Statistical Software Power and Sample Size Analysis
PBDESIGN
Calculates power, number of replicates, effect size, or number of center points for a Plackett-Burman design.
For more information, go to PBDESIGN on page 925.
FDESIGN
Calculates power, number of replicates, or maximum value of difference between main effect mean for a
general full factorial design. For more information, go to FDESIGN on page 919.
PTWO: Session subcommand for power and sample
size for a 2 proportion test
PTWO
Use with the POWER command to calculate power, sample size, or comparison proportion for a 2 proportion
procedure.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
PBASELINE K
Specifies the baseline proportion as K.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Comparison proportions, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
PCOMPARE K...K
Specifies the comparison proportion.
SAMPLE K...K
Specifies one or more sample sizes. Sample sizes are per group.
POWER K...K
Specifies one or more power values.
929
Minitab Statistical Software Power and Sample Size Analysis
Storage
SSAMPLE C
Stores the sample sizes.
SPCOMPARE C
Stores the comparison proportions.
SPOWER C
Stores the power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
SSCI: Session command for estimating sample size
SSCI
Estimates the sample size needed to achieve a specific margin of error for confidence intervals for the mean,
standard deviation, variance, proportion, Poisson rate, or Poisson mean. Conversely, you can estimate the margin
of error based on sample size.
NMEAN
Use NMEAN to estimate the margin of error or sample size based on a confidence interval from a normal
distribution.
SIGMA K [K]
Use SIGMA K to specify the standard deviation planning value. Use SIGMA [K] to specify whether the
population standard deviation is known.
Population standard deviationValue of [K]
Population standard deviation is not known0
Population standard deviation is known1
NSTDEV K
Use NSTDEV to estimate the margin of error or the sample size with a standard deviation planning value K
based on a confidence interval from a normal distribution.
NVARIANCE K
Use NVARIANCE K to estimate the margin of error or the sample size with variance planning value K based
on a confidence interval from a normal distribution.
930
Minitab Statistical Software Power and Sample Size Analysis
BPROPORTION K
Use BPROPORTION to estimate the margin of error or the sample size with proportion planning value K
based on a confidence interval from a binomial distribution. K must be greater than 0 but less than 1.
PRATE K
Use PRATE to estimate the margin of error or the sample size with rate planning value K based on a confidence
interval from a Poisson distribution.
LENGTH K
Use LENGTH to specify the length of the observation. K > 0.
PMEAN K
Use PMEAN to estimate the margin or error or the sample size based on a confidence interval from a Poisson
distribution.
MERROR K...K
MERROR specifies that you want to estimate the sample size based on the margins of error K...K.
SAMPLE K...K
SAMPLE specifies that you want to estimate the margin of errors for the confidence interval based on sample
sizes K...K.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
SESTIMATE C
Stores sample size or margin of error (depending on what you are estimating) in C, one row for each estimate.
SSTI: Session command for sample size for tolerance
intervals
SSTI
Estimates the sample size or margin of error for exact parametric and nonparametric tolerance intervals.
Use to determine the sample size that is required to achieve a specific margin of error for a tolerance interval.
Conversely, you can calculate the margin of error based on sample size.
931
Minitab Statistical Software Power and Sample Size Analysis
MERROR K...K
Specifies K...K as the margins of error for which you want to calculate sample size. Each K must be less than
100 PPERCENT K. For example, if K for PPERCENT is 95, then each K for MERROR must be less than 5.
SAMPLE K...K
Specifies K...K as the sample sizes for which you want to calculate margins of error.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
PPERCENT K
Specifies K as the minimum percentage of the population that you want the tolerance interval to cover. The default
is 95.
MEPROB K
Specifies K as the margin of error probability. The following statistics define the precision of the tolerance interval:
MERROR
The margin of error measures the additional percentage of the population, beyond the desired PPERCENT,
that might be included in the interval.
MEPROB
The margin of error probability is the probability that the actual interval content exceeds PPERCENT by
MERROR or more.
Choose a value that is greater than 0 and less than or equal to 0.5. Common values for the margin of error
probability include 0.01, 0.05, and 0.1.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
Results
TMETHOD
Displays the method table which includes the confidence level, the percentage of the population in the interval,
and the margin of error probability.
TRESULTS
Displays the results table which includes the sample sizes and associated margins of error. Minitab displays the
results for both the normal and nonparametric methods. The results for the nonparametric method include the
achieved confidence and the achieved error probability.
932
Minitab Statistical Software Power and Sample Size Analysis
TONE: Session command for power and sample size
for a 1-sample t-test
TONE
Use with the POWER command to calculate power, sample size, or significant difference for a 1-sample t-test. For
a paired t procedure, proceed as if conducting a 1-sample t-test on the distribution of differences.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Difference, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
DIFFERENCE K...K
Specifies one or more alternative hypotheses in terms of the difference from the null hypothesis mean.
SAMPLE K...K
Specifies one or more sample sizes.
POWER K...K
Specifies one or more power values.
Storage
SDIFFERENCE C
Stores the differences.
SSAMPLE C
Stores the sample sizes.
SPOWER C
Stores the power values.
933
Minitab Statistical Software Power and Sample Size Analysis
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
TOST: Session command for power and sample size
for an equivalence test
TOST K
Use with the POWER command to calculate power, sample size, or difference (or ratio) for one of the following
equivalence tests.
Equivalence test designValue of K
Paired design0
1-sample design1
2-sample design2
2x2 crossover design2, with the CROSSOVER subcommand
CROSSOVER
Use for a 2x2 crossover design.
RATIO
By default, Minitab performs calculation for the test of the difference. To perform calculations for the test of
the ratio by taking the log transformation of the data, use RATIO.
SIGMA K (required)
Specifies an estimate for sigma.
ALPHA K
Specifies the significance level (also called alpha or a) of the test. The default is 0.05.
LLIMIT K
LLIMIT specifies the lower equivalence limit as numeric value K. If RATIO is used, then both equivalence limits
must be greater than 0.
ULIMIT K
ULIMIT specifies the upper equivalence limit as numeric value K. If RATIO is used, then both equivalence
limits must be greater than 0.
Difference, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
934
Minitab Statistical Software Power and Sample Size Analysis
DIFFERENCE K...K
Specifies one or more difference values. If the RATIO subsubcommand is also used, then use DIFFERENCE to
specify the ratio values rather than difference values. All values for DIFFERENCE must be within the equivalence
limits specified by LLIMIT and ULIMIT.
SAMPLE K...K
Specifies one or more sample sizes.
POWER K...K
Specifies one or more power values.
Storage
SDIFFERENCE C
Stores the differences.
SSAMPLE C
Stores the sample sizes.
SPOWER C
Stores the power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
TPAIRED: Session subcommand for power and
sample size for a paired t-test
TPAIRED
Use with the POWER command to calculate power, sample size, or significant difference for a paired t-test.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
935
Minitab Statistical Software Power and Sample Size Analysis
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Difference, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
DIFFERENCE K...K
Specifies one or more alternative hypotheses in terms of the difference from the null hypothesis mean.
SAMPLE K...K
Specifies one or more sample sizes.
POWER K...K
Specifies one or more power values.
Storage
SDIFFERENCE C
Stores the differences.
SSAMPLE C
Stores the sample sizes.
SPOWER C
Stores the power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
TTWO: Session subcommand for power and sample
size for a 2-sample t-test
TTWO
Use with the POWER command to calculate power, sample size, or significant difference for a 2-sample t-test.
936
Minitab Statistical Software Power and Sample Size Analysis
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Difference, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
DIFFERENCE K...K
Specifies one or more alternative hypotheses expressed in terms of the difference between the means.
SAMPLE K...K
Specifies one or more sample sizes. Sample sizes are per group.
POWER K...K
Specifies one or more power values.
Storage
SDIFFERENCE C
Stores the differences.
SSAMPLE C
Stores the sample sizes.
SPOWER C
Stores the power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
937
Minitab Statistical Software Power and Sample Size Analysis
TWORATE: Session subcommand for power and
sample size for a 2-sample Poisson rate test
TWORATE
Use with the POWER command to calculate power, sample size, or comparison rate for a 2-sample Poisson rate
test.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
RBASELINE K
Specifies the baseline rate as K. K must be greater than 0.
LENGTH K
Specifies the length of the observation period as K. The default is 1.
Comparison rate, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
RCOMPARE K...K
Specifies one or more comparison rates. K must be greater than 0.
SAMPLE K...K
Specifies one or more sample sizes.
POWER K...K
Specifies one or more power values.
Storage
SCOMPARE C
Stores the comparison rates.
SSAMPLE C
Stores the sample sizes.
SPOWER C
Stores the power values.
938
Minitab Statistical Software Power and Sample Size Analysis
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
TWOVARIANCE: Session subcommand for power
and sample size for a 2 variances test
TWOVARIANCE
Use with the POWER command to calculate power, sample size, or significant ratio for a 2 variances test.
STDEV
Indicates that input and output values refer to standard deviation instead of variance, where applicable.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Type of test
Specifies which test to use to calculate the power and sample size results.
LEVENE
Use Levene's test when data are from a continuous, but not necessarily normal, distribution.
FTEST K...K
Use the F-test only when data are from a normal distribution.
BONETT K
You can also use Bonett's test when data are from a continuous, but not necessarily normal, distribution. However,
the power calculations for Bonett's test are very sensitive to kurtosis, so you must enter a good estimate of the
kurtosis value for your data. Enter the true common kurtosis of the parent populations as K. Do not enter the
"excess kurtosis". (Excess kurtosis = kurtosis 3.)
939
Minitab Statistical Software Power and Sample Size Analysis
Power, sample size, and ratio
You must specify values for any two of the following subcommands. Minitab solves for the third.
POWER K...K
Specifies one or more power values.
SAMPLE K...K
Specifies one or more sample sizes.
RATIO K...K
Specifies the ratio between comparison and baseline variability.
Storage
SSAMPLE C
Stores the sample size.
SRATIO C
Stores the ratios.
SPOWER C
Stores power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison rate for the specified
test conditions.
NSIZE K...K
Generates additional power curves on one graph to compare sample sizes.
ZONE: Session subcommand for power and sample
size for a 1-sample Z-test
ZONE
Use with the POWER command to calculate power, sample size, or significant difference for a 1-sample Z-test.
ALPHA K
Specifies the significance level of the test. The default is 0.05.
SIGMA K (required)
Specifies an estimate for sigma.
ALTERNATIVE K
Enter K to specify the direction of the alternative hypothesis.
940
Minitab Statistical Software Power and Sample Size Analysis
Format of the alternative hypothesisValue of K
Less than–1
Not equal to0 (default)
Greater than1
Difference, sample size, and power
You must specify values for any two of the following subcommands. Minitab solves for the third.
DIFFERENCE K...K
Specifies one or more alternative hypotheses in terms of the difference from the null hypothesis mean.
SAMPLE K...K
Specifies one or more sample sizes.
POWER K...K
Specifies one or more power values.
Storage
SDIFFERENCE C
Stores the differences.
SSAMPLE C
Stores the sample sizes.
SPOWER C
Stores the power values.
Graphs
GPCURVE
Displays power curves. Power curves plot every combination of power versus comparison proportion for the
specified test conditions.
NSIZE K...K
Generates additional power curves based on specified sample sizes.
941
Minitab Statistical Software Power and Sample Size Analysis
Graphs
CHART: Session command for creating a bar chart
CHART C...C
CHART F(C...C)
CHART F(C...C) * C
CHART (C...C) * C
Use to compare categories of data. Each bar can represent a count for a category, a function of a category, or
summary values from a table.
The following commands create two bar charts: counts of flaws and counts of grade.
CHART 'Flaws' 'Grade'.
The following commands create two bar charts: the mean of mileage for each quality category and the mean of
PSI for each quality category.
CHART MEAN('Mileage' 'PSI')*'Quality'.
The following commands create a bar chart of the amount of money lost for each flaw.
CHART 'Losses'*'Flaws';
SUMMARIZED.
Chart
STACK
Specifies how to display categories when you have multiple grouping levels. K refers to the stack order based on
a column's value order.
Stack orderValue of K
Stacks the first variable on the bottom and the remaining variables in ascending order.1
Stacks the first group on the top and the remaining in groups descending order.2
SUMMARIZED
Denotes that data are summarized. That is, one numeric or date/time value describes each category.
Scale
CUMULATIVE
Use a cumulative y-scale. Thus, the height of the third bar, for example, is the sum of the observations in the first
three categories. The subcommand SLEVEL designates on which scale level both PERCENT and CUMULATIVE
operate.
INCREASING and DECREASING are performed before CUMULATIVE and PERCENT.
942
Minitab Statistical Software Graphs
INCREASING
Present the groups in the chart in increasing order based on the y-axis values.
INCREASING and DECREASING are performed before CUMULATIVE and PERCENT.
INCREASING and DECREASING do not affect the ordering within clusters, stacks, or cluster/stack combinations;
they instead move entire clusters, stacks, or cluster/stack combinations into order by the sum of the values in
each outermost scale level category.
DECREASING
Present the groups in the chart in decreasing order based on the y-axis values.
INCREASING and DECREASING are performed before CUMULATIVE and PERCENT.
INCREASING and DECREASING do not affect the ordering within clusters, stacks, or cluster/stack combinations;
they instead move entire clusters, stacks, or cluster/stack combinations into order by the sum of the values in
each outermost scale level category.
PERCENT
Use a percent scale on the y-axis so that all bars at the designated level total 100%. The subcommand SLEVEL
designates within which scale level both PERCENT and CUMULATIVE operate.
INCREASING and DECREASING are performed before CUMULATIVE and PERCENT.
SLEVEL [K]
Designates the scale level within which both PERCENT and CUMULATIVE operate.
Scale levelValue of K
All the data0 (default)
Within groups of the outermost scale (must have 2 or more levels)1
Within groups of the second from the outermost scale level (must have 3 or more
levels)
2
Within groups of the third from the outermost scale level (must have 4 levels)3
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
GAPWIDTH and COFFSET: Session subcommands for the space between clusters and items in a cluster on page 1028
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
943
Minitab Statistical Software Graphs
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Data view
BAR: Session subcommand for representing data values with bars on page 1003
CONNECT: Session subcommand for connecting points with lines on page 1012
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
944
Minitab Statistical Software Graphs
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
TABLE and NOTABLE: Session subcommand for controlling the table within the figure region on page 1085
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
HMAP: Session command for creating a heatmap
HMAP [C...C]
Displays a heatmap for each column C. The column can be text or numeric and must be the same length. If the
column is a text column, the only functions you can use are PEQUAL, N, and NMISSING. Missing values are ignored
in calculations except when the function is N or NMISSING. If you do not specify any columns, Minitab uses the
number of nonmissing rows to define the gradient.
You must specify a function and at least one of RVARIABLE or CVARIABLE.
RVARIABLE C...C
Specify the categorical variables that appear on the rows. The columns can be text or numeric and must be the
same length as the column you specify with HMAP. You can enter up to five columns. The order of the levels of
the categorical variables in the heatmap follow the value order. Missing values appear as another categorical
level.
CVARIABLE C...C
Specify the categorical variables that appear on the columns. The columns can be text or numeric and must be
the same length as the column you specify with HMAP. You can enter up to five columns. The order of the levels
of the categorical variables in the heatmap follow the value order. Missing values appear as another categorical
level.
Functions
MEAN
The heatmap uses means to summarize the contents of the cell. Requires a numeric column for HMAP.
SUM
The heatmap uses sums to summarize the contents of the cell. Requires a numeric column for HMAP.
MEDIAN
The heatmap uses medians to summarize the contents of the cell. Requires a numeric column for HMAP.
945
Minitab Statistical Software Graphs
PERCENTILE K
The heatmap uses percentiles to summarize the contents of the cell. K must be a numeric value between 0 and
100. Requires a numeric column for HMAP.
STDEV
The heatmap uses standard deviations to summarize the contents of the cell. Requires a numeric column for
HMAP.
MINIMUM
The heatmap uses minimums to summarize the contents of the cell. Requires a numeric column for HMAP.
MAXIMUM
The heatmap uses maximums to summarize the contents of the cell. Requires a numeric column for HMAP.
PBETWEEN K1 K2
The heatmap uses the percent of observations between K1 and K2 to summarize the contents of the cell. K1 and
K2 must be numeric values where K1 is less than or equal to K2. The observation is included in the percentage if
it is equal to K1 or K2. Requires a numeric column for HMAP.
PEQUAL K...K
The heatmap uses the percent of observations equal to any of K....K to summarize the contents of the cell. K can
be text or numeric, but the values you enter for K must be the same type of data as the column you specified
with HMAP.
N
The heatmap uses the number of non-missing cells to summarize the contents of the cell.
NMISSING
The heatmap uses the number of missing cells to summarize the contents of the cell.
Options
GRADIENT
Select the color scale for the rectangles. By default, Minitab uses DIVERGING with no arguments if you do not
specify GRADIENT.
DIVERGING[K]
Minitab colors rectangles with high values red and rectangles with low values blue. If you specify K, then the
gradient is symmetric around K.
SEQUENTIAL[K]
If K = -1, Minitab colors rectangles with low values dark blue and rectangles with high values light blue and
light gray. This option could be used to highlight rectangles with low defect rates or to minimize cost. If K =
1, Minitab colors rectangles with high values dark blue and rectangles with low values light blue and light
gray. This option could be used to highlight rectangles with more productivity or to maximize revenue.
MULTIPLE C...C
Creates separate graphs for each group created by the grouping columns C...C. The grouping columns can be
numeric or text, but must be the same length as the columns that you specify with HMAP. Minitab treats missing
values as a separate group.
INDEPENDENT
Creates separate plots for each group created by the individual columns specified with MULTIPLE independent
of the other columns. For example, suppose you specify two columns with MULTIPLE. The first column
946
Minitab Statistical Software Graphs
contains the gender, either male or female, and the other contains the marriage status, either married or
single. If you specify INDEPENDENT, Minitab creates a graph for each group created by the columns
individually:
Male
Female
Single
Married
If you do not specify INDEPENDENT, Minitab creates a graph for each group created by all the columns:
Male and Single
Male and Married
Female and Single
Female and Married
SAME 3
When you specify multiple columns with HMAP, use this subcommand to use the same gradient scale for each
heatmap created for the different columns.
PLOT: Session command for creating a scatterplot
Scatterplots illustrate the relationship between two variables by plotting one against the other on the y- and x-axes.
You can also use PLOT with a date/time variable to create a time series plot, including time series plots with irregular
intervals (which cannot be handled by TSPLOT).
PLOT with no subcommands displays symbols. Use SYMBOL if you want symbols to be displayed with CONNECT,
PROJECT, AREA, LOWESS, or REGRESS.
Scatterplots that are displayedCommand language
One graph of Revenue by Year
PLOT Revenue*Year
Two graphs: Revenue by Year and Expense by Year
PLOT Revenue*Year Expense* Year
Two graphs: Revenue by Year and Expense by Year
PLOT (Revenue Expense)*Year
Four graphs: Revenue by Quarter, Revenue by Year, Expense by
Quarter, and Expense by Year
PLOT (Revenue Expense)*(Quarter
Year)
One graph of Sales and Advertis by Year with different symbols
representing Sales and Advertis
PLOT (Sales Advertis)*Year;
OVERLAY.
PLOT C * C
Creates a scatterplot of y (1st column) by x (2nd column).
PLOT C * C ... C * C
Creates multiple scatterplots.
947
Minitab Statistical Software Graphs
Scale
XYSAME
Specifies the same scale for the x- and y-axes.
If XYSAME is used, the MIN and MAX subcommands to SCALE on page 1076 are ignored.
XYMIN K
Use the optional XYMIN subcommand to specify the minimum for the scales.
XYMAX K
Use the optional XYMAX subcommand to specify maximum for the scales.
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999
CONNECT: Session subcommand for connecting points with lines on page 1012
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
LOWESS: Session subcommand for fitting a LOWESS smoother to a scatterplot, a matrix plot, a histogram, or a time
series plot on page 1049
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
REGRESS: Session subcommand for fitting a regression line to data on a graph on page 1075
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
948
Minitab Statistical Software Graphs
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
NPLOT: Session command for creating a binned
scatterplot
Use to investigate the relationship between a pair of continuous variables when the data set contains many observations.
NPLOT C*C C*C...C*C
Displays a scatterplot for each pair of numeric columns. The columns for each pair of columns must have the
same number of rows.
BINNED
Specify a binned scatterplot.
949
Minitab Statistical Software Graphs
MEAN C
Specify a column that defines the color of a bin by the mean of C for the observations in the bin. If you do
not specify MEAN, Minitab defines the color of a bin by the number of observations in the bin.
Options
SCALE K
Specify either the x scale (K=1) or the y scale (K=2).
LOGSK
Perform a log transformation of the scale specified with SCALE. Enter a value in K to specify the base of the
logarithm used to transform the scale. You must enter a numeric value between 2 and 10. A logarithmic scale
linearizes logarithmic relationships by changing the axis, so that the same distance represents different
changes in value across the scale.
MULTIPLE C...C
Creates separate plots for each group created by the grouping columns C...C. The grouping columns can be
numeric or text, but must be the same length as the columns that you specify with NPLOT. Minitab treats missing
values as a separate group.
INDEPENDENT
Creates separate plots for each group created by the individual columns specified with MULTIPLE independent
of the other columns. For example, suppose you specify two columns with MULTIPLE. The first column
contains the gender, either male or female, and the other contains the marriage status, either married or
single. If you specify INDEPENDENT, Minitab creates a plot for each group created by the columns individually:
Male
Female
Single
Married
If you do not specify INDEPENDENT, Minitab creates a plot for each group created by all the columns:
Male and Single
Male and Married
Female and Single
Female and Married
GRADIENT
Select the color scale for the bins. By default, Minitab uses DIVERGING with no arguments if you do not specify
GRADIENT. You can only specify GRADIENT and its subcommands when you also specify BINNED.
DIVERGING[K]
Minitab colors bins with high values red and bins with low values blue. If you specify K then the gradient is
symmetric around K.
SEQUENTIAL[K]
If K = -1 Minitab colors bins with low values dark blue and bins with high values light blue and light gray.
This option could be used to highlight bins with low defect rates or to minimize cost. If K = 1 Minitab colors
bins with high values dark blue and bins with low values light blue and light gray. This option could be used
to highlight bins with more productivity or to maximize revenue.
950
Minitab Statistical Software Graphs
SAME K [K] [K]
Use the same scale on each graph. Specify multiple arguments to set more than one scale the same.
To use the same x-scale, set K = 1.
To use the same y-scale, set K = 2.
To use the same color gradient scale on a binned scatterplot for different pairs of x y-variables, set K =
3. For the same pair of x y-variables, the gradient scale will always be the same.
GCORRELATION: Session command for creating a
correlogram
GCORRELATION C...C
Displays a correlogram for columns C...C. You must enter at least two columns and all columns must have the
same number of rows. The columns must be numeric. Minitab calculates the Pearson correlation coefficient for
each pair of columns.
Options
MULTIPLE C...C
Creates separate plots for each group created by the grouping columns C...C. The grouping columns can be
numeric or text, but must be the same length as the columns that you specify with GCORRELATION. Minitab treats
missing values as a separate group.
INDEPENDENT
Creates separate plots for each group created by the individual columns specified with MULTIPLE independent
of the other columns. For example, suppose you specify two columns with MULTIPLE. The first column
contains the gender, either male or female, and the other contains the marriage status, either married or
single. If you specify INDEPENDENT, Minitab creates a graph for each group created by the columns individually
Male
Female
Single
Married
If you do not specify INDEPENDENT, Minitab creates a graph for each group created by all the columns:
Male and Single
Male and Married
Female and Single
Female and Married
GRADIENT
Select the color scale for the rectangles. If you do not specify GRADIENT, the gradient type depends on the
calculation of the Pearson correlation coefficients.
If the coefficients are positive and negative, the gradient type is DIVERGING.
951
Minitab Statistical Software Graphs
If the coefficients are all positive, the gradient type is SEQUENTIAL 1.
If the coefficients are all negative, the gradient type is SEQUENTIAL -1.
DIVERGING
Minitab colors rectangles with high values red and rectangles with low values blue. The gradient is symmetric
around 0.
SEQUENTIAL[K]
If K = -1, Minitab colors rectangles with low values dark blue and rectangles with high values light blue and
light gray. If K = 1, Minitab colors rectangles with high values dark blue and rectangles with low values light
blue and light gray.
MATRIXPLOT: Session command for creating a
matrix of plots
A matrix plot is a two-dimensional array of individual plots that provides an efficient way to see meaningful relationships
among a number of variables at once.
MATRIXPLOT C...C
Displays a matrix of plots. The list of variables defines both the row (y) variables and column (x) variables in the
plot matrix. You can use 2 to 20 numeric or date/time columns of equal length.
The following command language displays a 3x3 matrix plot.
MATRIXPLOT 'Weight' 'Head.L' 'Head.W'.
MATRIXPLOT (C...C) * (C...C)
Displays a graph of each y versus each x (draftsman plot or casement display). The variables before the * define
the row (y) variables, and the variables after the * define the column (x) variables of the matrix. You can have 1–20
numeric or date/time columns of equal length for both y and x.
The following command language displays a matrix plot of each y (Pulse1 and Pulse2) versus each x (Height,
Weight, and Activity).
MATRIXPLOT ('Pulse1' 'Pulse2')*('Height' 'Weight' 'Activity').
Matrix labels
The following subcommands specify where to display labels, and apply only to the matrix of plots form of MATRIXPLOT.
DIAGONAL (default)
Labels the variables in the diagonal.
BOUNDARY
Labels the variables on the outside of the frame.
Graphs
Specifies the graphs to display.
952
Minitab Statistical Software Graphs
FULL (default)
Displays all graphs.
LL
Displays graphs in the lower left triangle.
UR
Displays graphs in the upper right triangle. The default sides for tick and axis lines and labels shift to the upper
and right sides, respectively.
Alternating sides for tick marks
NOALTERNATE
Turn off the default method of alternating sides for tick display.
By default, Minitab places the ticks of adjacent panels on alternating sides of the graph. Invoking NOALTERNATE
places ticks on the same side of adjacent panels.
Margin size
MARGIN K
Specify the margin size separating all panels.
By default, margins for a matrix plot are 0. You can enter a value from 0 to 0.25. The maximum valid value depends
on how many panels there are. If you use a margin argument that is too large, Minitab will use the largest possible
value.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
953
Minitab Statistical Software Graphs
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999
CONNECT: Session subcommand for connecting points with lines on page 1012
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
LOWESS: Session subcommand for fitting a LOWESS smoother to a scatterplot, a matrix plot, a histogram, or a time
series plot on page 1049
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
REGRESS: Session subcommand for fitting a regression line to data on a graph on page 1075
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Multiple graphs
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
954
Minitab Statistical Software Graphs
BUBBLEPLOT: Session command for creating a
bubble plot
BUBBLEPLOT C * C
Use a bubble plot to explore the relationships among three variables on a single plot. Like a scatterplot, a bubble
plot plots a y-variable versus an x-variable. However, the symbols (also called bubbles) on the bubble plot vary
in size. The area of each bubble represents the value of a third variable.
You need three columns of equal length, in numeric or date/time format. You can also use up to three columns
of categorical data for grouping and up to two columns of categorical data for paneling.
Minitab does not plot an observation in the following cases:
An x-value, y-value, or bubble size value is missing.
The value in BSIZE C is less than or equal to zero.
BSIZE C
Specifies the size of the bubbles.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
BSYMBOL [C...C]
Specifies up to three columns of categorical variables for grouping. Minitab displays all groups on the same graph.
COLOR K...K
COLOR C
Specifies the color for the bubble groups, which is a number from Numbers for colors to use in session
commands on page 1172. Enter one K for each group or store the symbol colors in C.
BSCALE K
Specifies to make K the maximum bubble size. The bubble that represents the largest value in column BSIZE
C is displayed at size K. The area of the remaining bubbles is scaled proportionally. K must be greater than
0 and less than or equal to 100. The default is 20.
NOSCALE
Specifies to interpret the values in BSIZE C as Minitab symbol sizes. The maximum Minitab symbol size is
100.
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
955
Minitab Statistical Software Graphs
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
Multiple graphs
PANEL: Session subcommand for paneling graphs on page 1061
Data options
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
956
Minitab Statistical Software Graphs
MARGPLOT: Session command for creating a
marginal plot
MARGPLOT C * C
Displays a marginal plot of y * x.
Use to display a scatterplot with separate marginal plots of the x- and y-variables. You can choose to have
histograms, boxplots, or dotplots as the marginal plots.
The data must be two numeric or date/time columns of equal length.
MARGIN K
Specifies the variables for which to create marginal plots. If you do not use MARGIN, both x and y are used
(the default).
Variables that the plot is created forValue of K
x-variables only1
y-variables only2
OPTION K
Specifies the type of marginal plot to display:
Type of marginal plotValue of K
Histograms1 (default)
Boxplots2
Dotplots3
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
HLABEL: Session subcommand for labeling histogram bars on a marginal plot with y-axis values on page 1030
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
957
Minitab Statistical Software Graphs
Data view
BAR: Session subcommand for representing data values with bars on page 1003
DOT: Session subcommand for displaying a symbol for each data value on page 1021
IQRBOX: Session subcommand for displaying an interquartile range box on a boxplot on page 1041
OUTLIER: Session subcommand for displaying a symbol for each outlier on a boxplot on page 1060
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graphs, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
HISTOGRAM: Session command for creating a
histogram
HISTOGRAM C...C
Displays a separate histogram for each column.
HISTOGRAM divides sample values into many intervals called bins. Bars represent the number of observations
falling within each bin (its frequency). Observations that fall exactly on an interval boundary are included in the
interval to the right (or left, if the last bin).
958
Minitab Statistical Software Graphs
HISTOGRAM with no subcommands displays bars. Use BAR if you want bars to be displayed with SYMBOL, PROJECT,
AREA, or DISTRIBUTION.
Y-scale type
CUMULATIVE
Specifies a cumulative scale for the y-axis. When CUMULATIVE is used with a frequency scale, for example, the
height of the third bar represents the total number of observations in the first three intervals. You can also use
CUMULATIVE with PERCENT to get a cumulative percent scale. CUMULATIVE may not be used with DENSITY.
DENSITY
Specifies a density scale for the y-axis in which the area of a bar is equal to the proportion of observations that
fall within that bin. The height of each bar is calculated as:
A density scale is useful for viewing probability density functions.
PERCENT
Specifies a percent scale for the y-axis in which the height of a bar represents the percentage of observations that
fall within that bin.
YFREQUENCY
Specifies a frequency scale for the y-axis in which the height of a bar represents the number of observations that
fall within that bin.
If you use more than one of DENSITY, PERCENT, and YFREQUENCY for the same graph, only the last one is used.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
CUTPOINT, MIDPOINT, and NINTERVAL: Session subcommands for specifying cutpoints and midpoints on page
1014
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
959
Minitab Statistical Software Graphs
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999
BAR: Session subcommand for representing data values with bars on page 1003
DISTRIBUTION: Session command for fitting a distribution on page 1018 You must use HPARAM with DISTRIBUTION.
LOWESS: Session subcommand for fitting a LOWESS smoother to a scatterplot, a matrix plot, a histogram, or a time
series plot on page 1049
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
960
Minitab Statistical Software Graphs
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
TABLE and NOTABLE: Session subcommand for controlling the table within the figure region on page 1085
DOTPLOT: Session command for creating a dotplot
Use to assess and compare distributions by plotting the values along a number line.
The x-axis for a dotplot is divided into many small intervals, or bins. Data values falling within each bin are represented
by dots.
If possible, Minitab displays a dot for each observation. If there is insufficient space, a dot represents multiple
observations with a footnote indicating the maximum number of observations represented by the dots.
The data must be numeric or date/time. The categorical grouping data can be numeric, date/time, or text.
DOTPLOT C...C
Displays a separate graph for each C.
The following command language displays two dotplots: one of Sales and one of Advertis.
DOTPLOT 'Sales' 'Advertis'.
DOTPLOT (C...C) * C
Displays a separate graph for each C on the left, with a dotplot for each category of the C on the right.
The following command language displays a dotplot of yearly sales.
DOTPLOT 'Sales'*'Year'.
Dotplot options
STACK K
Specifies how to display categories when you have multiple grouping levels. K refers to the stack order based on
a column's value order.
How categories are displayedValue of K
Stacks the first variable on the bottom and the remaining variables in ascending
order
1 (default)
Stacks the first group on the top and the remaining variables in descending order2
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
961
Minitab Statistical Software Graphs
CUTPOINT, MIDPOINT, and NINTERVAL: Session subcommands for specifying cutpoints and midpoints on page
1014
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODOTFOOTNOTE: Session subcommand for suppressing footnotes on a dotplot on page 1057
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
DOT: Session subcommand for displaying a symbol for each data value on page 1021
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
962
Minitab Statistical Software Graphs
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
STEM-AND-LEAF: Session command for creating a
stem-and-leaf plot
STEM-AND-LEAF C...C
Displays a separate stem-and-leaf plot for each C. Provides a display that is similar to a histogram, but uses the
actual numbers to create the display.
BY C
Produces a separate display for each value in C. All displays for one column are put on the same scale. C
must contain integers from –10,000 to +10,000 or the missing value code (*).
TRIM
Trims all values beyond the inner fences, and shows them on special lines labeled LO and HI. TRIM and BY
cannot be used together.
INCREMENT K
Controls scaling. K is the distance between two lines of the display (that is, the distance between the smallest
possible number on one line and the smallest possible number on the next).
PPLOT: Session command for creating a probability
plot
PPLOT C...C
Displays a separate probability plot for each column. Minitab calculates the fitted cumulative distribution function
(CDF) and associated confidence intervals based on parameters estimated from your data, or on historical
parameters if you provide them using HPARAMETERS. Parameter estimates or historical parameters are displayed
963
Minitab Statistical Software Graphs
in an output table along with an Anderson-Darling (AD) goodness-of-fit statistic and associated p-value, and the
number of observations.
Note To change the method used to calculate the plot points, choose File > Options > Individual Graphs > Probability Plots.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
PTILES: Session subcommand for specifying the location of the percentile lines on a graph on page 1066
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
PERCENT
PERCENT specifies a percent scale for the y-axis.
PROBABILITY
PROBABILITY specifies a probability scale for the y-axis.
SCORES
SCORES specifies that the inverse cumulative probability from the standardized version of the chosen distribution
be plotted on the y-axis.
UATHRESHOLD
UATHRESHOLD specifies that the x-axis will not be adjusted for the threshold parameter.
Distributions
NORMAL
Fits a normal distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates the
mean and standard deviation from the data.
LNORMAL
Fits a lognormal distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates
the mean and standard deviation from the data.
TLNORMAL
Fits a 3-parameter lognormal distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab
estimates the mean and standard deviation from the data.
GAMMA
Fits a gamma distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates the
mean and standard deviation from the data.
TGAMMA
Fits a 3-parameter gamma distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab
estimates the mean and standard deviation from the data.
964
Minitab Statistical Software Graphs
EXPONENTIAL
Fits a exponential distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates
the mean and standard deviation from the data.
TEXPONENTIAL
Fits a 2-parameter exponential distribution. If you don't use HPARAMETERS to specify historical parameters,
Minitab estimates the mean and standard deviation from the data.
SEXTREMEVALUE
Fits a smallest extreme value distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab
estimates the mean and standard deviation from the data.
WEIBULL
Fits a Weibull distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates the
mean and standard deviation from the data.
TWEIBULL
Fits a 3-parameter Weibull distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab
estimates the mean and standard deviation from the data.
LEXTREMEVALUE
Fits a largest extreme value distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab
estimates the mean and standard deviation from the data.
LOGISTIC
Fits a logistic distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates the
mean and standard deviation from the data.
LLOGISTIC
Fits a loglogistic distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab estimates
the mean and standard deviation from the data.
TLLOGISTIC
Fits a 3-parameter loglogistic distribution. If you don't use HPARAMETERS to specify historical parameters, Minitab
estimates the mean and standard deviation from the data.
Data view
FITD: Session command for fitting a distribution to the data on a probability plot on page 1024
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
HPARAMETERS
Specifies the distribution parameters. If you want Minitab to estimate all parameters, do not use HPARAMETERS.
Parameter arguments are given in the order shown in the table below. For each parameter that you want Minitab
to estimate, enter ' * ' for K. For example:
To have Minitab estimate the mean for a normal distribution, enter ' * ' for the mean and a value for the
standard deviation.
NORMAL;
HPARAMETERS '*' 7.
To have Minitab estimate the scale for a 3-parameter Weibull distribution, enter ' * ' for the scale and values
for the shape and threshold.
TWEIBULL;
HPARAMETERS 13 '*' 4.
965
Minitab Statistical Software Graphs
Use the following table to determine the necessary parameters and restrictions.
Minitab can estimateDistributionsParameters
Mean and standard deviationNORMALMean and standard
deviation
Mean, given standard deviation
Location and scaleLOGNORMALLocation and scale
Location, given scaleSEXTREME (smallest extreme value)
LEXTREME (largest extreme value)
LOGISTIC
LOGLOGISTIC
Shape and scaleGAMMAShape and scale
Scale, given shapeWeibull
MeanEXPONENTIALMean
Scale and thresholdTEXPONENTIAL (2-parameter
exponential)
Scale and threshold
Scale, given threshold
Shape, scale, and thresholdTWEIBULL (3-parameter Weibull)Shape, scale, and
threshold
Shape and scale, given thresholdTGAMMA (3-parameter gamma)
Scale and threshold, given shape
Scale, given shape and threshold
Location, scale, and thresholdTLNORMAL (3-parameter lognormal)Location, scale, and
threshold
Location and scale, given thresholdTLLOGISTIC (3-parameter loglogistic)
Location and threshold, given scale
Location, given scale and threshold
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
966
Minitab Statistical Software Graphs
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
TABLE and NOTABLE: Session subcommand for controlling the table within the figure region on page 1085
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
967
Minitab Statistical Software Graphs
ECDF: Session command for creating an empirical
CDF plot
ECDF C...C
Displays a separate empirical CDF plot for each column.
An empirical cumulative distribution function (ECDF) resembles a cumulative histogram without bins. Minitab
plots the value of each observation against the percentage of values in the sample that are less than or equal to
that value. In this respect, an ECDF is similar to a probability plot except that both axes are linear, which can make
interpreting the ECDF more intuitive.
Y-scale type
PERCENT
Specifies a percent scale for the y-axis.
PROBABILITY
Specifies a probability scale for the y-axis.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
PTILES: Session subcommand for specifying the location of the percentile lines on a graph on page 1066
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CONNECT: Session subcommand for connecting points with lines on page 1012
DISTRIBUTION: Session command for fitting a distribution on page 1018
968
Minitab Statistical Software Graphs
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
TABLE and NOTABLE: Session subcommand for controlling the table within the figure region on page 1085
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
969
Minitab Statistical Software Graphs
DPLOT: Session command for creating a probability
distribution plot
DPLOT
Creates a probability distribution plot.
Use to view and compare the shape of distribution curves and to view areas under distribution curves corresponding
to either probabilities or data values. These graphs plot probability density functions (PDF) which describe the
likelihood of each value that a variable can take on. Typically, you specify the distribution, parameter values, and,
sometimes, an area under the curve.
DISTRIBUTION
Draws the distribution and parameters as specified in its subcommand. You can have an unlimited number
of DISTRIBUTION subcommands per plot.
SHADE K
Adds a shaded region to the plot that corresponds to a probability or x-value. For more information
and subcommands of SHADE, see the following section "Shaded area".
Shaded area
SHADE K
Shade a region of a single distribution corresponding to a probability or x-value using this subcommand of
DISTRIBUTION. You can use this subcommand only once per DISTRIBUTION command. Specify the region to
shade: right tail (K=1), left tail (K=2), equal tails (K=3), or middle (K=4).
SHTYPE K
Specifies shading by probability (K=1) or x-value (K=2).
SHVALUE K [K]
Specify one or two probabilities or x-values depending upon the values specified for SHADE and SHTYPE.
If SHADE = 1–3, then one value is required.
If SHADE = 4, then two values are required.
If SHTYPE = 1, then the value or values must be between 0 and 1 (noninclusive).
TYPE K
Specifies the fill type of the shading in K, which is a number from Numbers for fill types to use in session
commands on page 1173.
COLOR K
Specifies the background color of the shading in K, which is a number from Numbers for colors to use in
session commands on page 1172.
ETYPE K
Specifies the fill edge type of the shading in K, which is a number from Numbers for line types to use in
session commands on page 1173.
970
Minitab Statistical Software Graphs
ECOLOR K
Specifies the fill edge color of the shading in K, which is a number from Numbers for colors to use in session
commands on page 1172.
ESIZE K
Specifies the fill edge size, which can be any positive number.
Distributions
CHISQUARE K
Draws a Chi-square distribution with degrees of freedom = K.
NORMAL K K
Draws a normal distribution with mean = K and standard deviation = K.
F K K
Draws an F distribution with numerator degrees of freedom = K and denominator degrees of freedom = K.
T K
Draws a t distribution with degrees of freedom = K.
UNIFORM K K
Draws a uniform distribution with lower endpoint = K and upper endpoint = K.
BETA K K
Draws a beta distribution with first shape parameter = K and second shape parameter = K.
LNORMAL K K K
Draws a lognormal distribution with location = K, scale = K, and threshold (optional) = K.
BINOMIAL K K
Draws a binomial distribution with number of trials = K and event probability = K.
GAMMA K K K
Draws a gamma distribution with shape = K, scale = K, and threshold (optional) = K.
CAUCHY K K
Draws a Cauchy distribution with location = K and scale = K.
EXPONENTIAL K K
Draws an exponential distribution with scale = K, and threshold (optional) = K.
INTEGER K K
Draws an integer distribution with minimum value = K and maximum value = K.
SEXTREME K K
Draws a smallest extreme value distribution with location = K and scale = K.
WEIBULL K K K
Draws a Weibull distribution with shape = K, scale = K, and threshold (optional) = K.
LAPLACE K K
Draws a Laplace distribution with location = K and scale = K.
971
Minitab Statistical Software Graphs
LEXTREME K K
Draws a largest extreme value distribution with location = K and scale = K.
LOGISTIC K K
Draws a logistic distribution with location = K and scale = K.
LLOGISTIC K K K
Draws a loglogistic distribution with location = K, scale = K, and threshold (optional) = K.
GEOMETRIC K
Draws a geometric distribution with event probability = K.
HYPERGEOMETRIC K K K
Draws a hypergeometric distribution with population size = K, event count = K, and sample size = K.
NEGBINOMIAL K K
Draws a negative binomial distribution with event probability = K and number of events needed = K.
POISSON K
Draws a Poisson distribution with mean = K.
TRIANGULAR K K K
Draws a triangular distribution with lower endpoint = K, mode = K, and upper endpoint = K.
DISCRETE C C
Draws a discrete distribution using values in C and probabilities in C.
NONEVENT
Models the number of non-events for the geometric and negative binomial distributions.
TOTAL
Models the number of trials for the geometric and negative binomial distributions.
Fill pattern and background fill color of the distribution bar for discrete distributions
BTYPE K
Specifies the fill pattern in K, which is a number from Numbers for fill types to use in session commands on page
1173.
BCOLOR K
Specifies the background color in K, which is a number from Numbers for colors to use in session commands on
page 1172.
Type, color, and width of the fill edge line for discrete distributions
BETYPE K
Specifies the fill edge type in K, which is a number from Numbers for line types to use in session commands on
page 1173.
BECOLOR K
Specifies the fill edge color, which is a number from Numbers for colors to use in session commands on page 1172.
972
Minitab Statistical Software Graphs
BESIZE K
Specifies the fill edge size, which can be any positive number.
Line type, color, and size for continuous distributions
LTYPE K
Specifies the line type in K, which is a number from Numbers for line types to use in session commands on page
1173.
LCOLOR K
Specifies the line color in K, which is a number from Numbers for colors to use in session commands on page 1172.
LSIZE K
Specifies the line size, which can be any number that is greater than 0.
Labels
POSITION K "K"
Specify a label to apply font, font color, font size, and label angle changes. The first K is the specific label; the
second "K" is the optional label text. The positions are ordered left-to-right and top-to-bottom.
The label attributes and positioning commands below can be used as subcommands to POSITION. If POSITION
is not used, or after executing ENDPOSITION, the attribute and positioning commands apply to all labels.
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands
on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
ENDPOSITION
End changes by label position.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
973
Minitab Statistical Software Graphs
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
SHOW K
Show (K=1) or do not show (K=0) the label specified by POSITION.
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
974
Minitab Statistical Software Graphs
Annotation
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057: NODFOOTNOTE does not work with DPLOT.
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TEXT: Session subcommand for displaying text on a graph on page 1088
TITLE: Session subcommand for adding a title to a graph on page 1089
Region
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
TABLE and NOTABLE: Session subcommand for controlling the table within the figure region on page 1085
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
BOXPLOT: Session command for creating a boxplot
Use to examine characteristics of a sample distribution. Also called box-and-whisker plots.
The data must be numeric or date/time. The categorical grouping data can be numeric, date/time, or text.
BOXPLOT C...C
Displays a separate boxplot for each C.
The following command language displays two boxplots: one of Sales and one of Advertis.
BOXPLOT 'Sales' 'Advertis'.
975
Minitab Statistical Software Graphs
BOXPLOT (C...C) * C
Displays a separate graph for each C on the left, with a box for each category of the C on the right.
The following command language displays a boxplot of yearly sales.
BOXPLOT 'Sales'*'Year'.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
GAPWIDTH and COFFSET: Session subcommands for the space between clusters and items in a cluster on page 1028
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
ILABEL: Session subcommand for labeling individual values on a boxplot or interval plot on page 1033
MEALAB: Session subcommand for labeling means on a boxplot or an interval plot on page 1051
MEDLAB: Session subcommand for labeling medians on a boxplot on page 1055
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
OLAB: Session subcommand for labeling outliers on a boxplot on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CIBOX: The session subcommand for displaying a median confidence interval box on a boxplot on page 1005
CMEAN: Session subcommand for connecting means with lines on a boxplot on page 1010
CMEDIAN: Session subcommand for connecting means with lines on a boxplot on page 1011
INDIVIDUAL: Session subcommand for displaying a symbol for each individual data value on a boxplot or an
individual value plot on page 1036
IQRBOX: Session subcommand for displaying an interquartile range box on a boxplot on page 1041
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
976
Minitab Statistical Software Graphs
MEAN: Session subcommand for displaying symbol for each mean on a boxplot, interval plot, or individual value
plot on page 1053
MEDIAN: Session subcommand for displaying a symbol for each median on a boxplot, interval plot, or individual
value plot on page 1054
OUTLIER: Session subcommand for displaying a symbol for each outlier on a boxplot on page 1060
PROPORTIONAL and NOPROPORTIONAL: Session subcommands for making the boxes on a boxplot proportional
to the square root of the number of observations in the boxes on page 1066
RBOX: Session subcommand for displaying a range box on a boxplot on page 1070
SOFFSET: Session subcommand for offsetting points from the center on page 1082
WHISKER: Session subcommand for controlling the display of whiskers on a boxplot on page 1093
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
977
Minitab Statistical Software Graphs
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
INTPLOT: Session command for creating an interval
plot
INTPLOT C...C
INTPLOT (C...C) * C
Use to plot means and confidence intervals for one or more variables. An interval plot illustrates both a measure
of central tendency and the variability of the data.
By default, Minitab displays confidence intervals, but you can change the display type to standard error bars using
the INTBAR subcommand.
The data must be numeric or date/time. The categorical grouping data can be numeric, date/time, or text.
INTPLOT C...C displays a separate interval plot for each graph variable.
INTPLOT (C...C) * C displays a separate graph for each C on the left, with an interval for each category of the C on
the right.
The following table shows a few of the possible ways to generate interval plots.
What the command language displaysCommand language
Two graphs: interval plots of Sales and of Advertis
INTPLOT 'Sales' 'Advertis'.
A graph with intervals representing yearly sales
INTPLOT 'Sales'*'Year'.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
GAPWIDTH and COFFSET: Session subcommands for the space between clusters and items in a cluster on page 1028
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
978
Minitab Statistical Software Graphs
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
ILABEL: Session subcommand for labeling individual values on a boxplot or interval plot on page 1033
INTLAB: Session subcommand for labeling interval bar endpoints on an interval plot on page 1039
MEALAB: Session subcommand for labeling means on a boxplot or an interval plot on page 1051
MEDLAB: Session subcommand for labeling medians on a boxplot on page 1055
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
BAR: Session subcommand for representing data values with bars on page 1003
CMEAN: Session subcommand for connecting means with lines on a boxplot on page 1010
CMEDIAN: Session subcommand for connecting means with lines on a boxplot on page 1011
INDIVIDUAL: Session subcommand for displaying a symbol for each individual data value on a boxplot or an
individual value plot on page 1036
INTBAR: Session subcommand for displaying a vertical line with horizontal lines at the endpoints of the confidence
interval for the mean on page 1037
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
MEAN: Session subcommand for displaying symbol for each mean on a boxplot, interval plot, or individual value
plot on page 1053
MEDIAN: Session subcommand for displaying a symbol for each median on a boxplot, interval plot, or individual
value plot on page 1054
SOFFSET: Session subcommand for offsetting points from the center on page 1082
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
979
Minitab Statistical Software Graphs
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
INDPLOT: Session command for creating an
individual value plot
INDPLOT C...C
INDPLOT (C...C) * C
Use to assess and compare sample distributions by plotting individual values for each variable or group in a
vertical column, making it easy to spot outliers and see distribution shape. By default, Minitab adds horizontal
jitter so that overlapping points are visible.
The data must be numeric or date/time. The categorical grouping data can be numeric, date/time, or text.
The table below shows a few of the possible ways to display interval plots.
INDPLOT C...C displays a separate individual value plot for each graph variable.
INDPLOT (C...C) * C displays a separate graph for each C on the left, with a column of individual values for each
category of the C on the right.
980
Minitab Statistical Software Graphs
The following table shows two of the possible ways to display individual value plots.
What the command language displaysCommand language
Two individual value plots: one of Sales and one of Advertis
INDPLOT 'Sales' 'Advertis'.
A individual value plot of yearly sales
INDPLOT 'Sales'*'Year'.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
GAPWIDTH and COFFSET: Session subcommands for the space between clusters and items in a cluster on page 1028
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38GSAVE: Session subcommand for saving a
graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
ILABEL: Session subcommand for labeling individual values on a boxplot or interval plot on page 1033
INTLAB: Session subcommand for labeling interval bar endpoints on an interval plot on page 1039
MEALAB: Session subcommand for labeling means on a boxplot or an interval plot on page 1051
MEDLAB: Session subcommand for labeling medians on a boxplot on page 1055
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
BAR: Session subcommand for representing data values with bars on page 1003
CMEAN: Session subcommand for connecting means with lines on a boxplot on page 1010
CMEDIAN: Session subcommand for connecting means with lines on a boxplot on page 1011
981
Minitab Statistical Software Graphs
INDIVIDUAL: Session subcommand for displaying a symbol for each individual data value on a boxplot or an
individual value plot on page 1036
INTBAR: Session subcommand for displaying a vertical line with horizontal lines at the endpoints of the confidence
interval for the mean on page 1037
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
MEAN: Session subcommand for displaying symbol for each mean on a boxplot, interval plot, or individual value
plot on page 1053
MEDIAN: Session subcommand for displaying a symbol for each median on a boxplot, interval plot, or individual
value plot on page 1054
SOFFSET: Session subcommand for offsetting points from the center on page 1082
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
982
Minitab Statistical Software Graphs
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LPLOT: Session command for creating a line plot
Use to compare response patterns for two or more groups. The line plot has two distinct applications: looking for
interactions in simple two-way designs and looking for consistency in response patterns of many groups. Each point
on a line plot can represent a Bar chart functions on page 1133 of a category, or summary values from a table.
LPLOT F(C) * C
GROUP C
Displays a line plot of a function of a single response.
The following command language displays a line plot of mean hole diameter ('Diameter') as produced on two
different production lines ('Line') each of which use two different drills ('Drill'). Drill type is identified through the
legend.
LPLO MEAN('Diameter')*'Line';
GROUP 'Drill'.
LPLOT F(C...C) * C
OVERLAY
Displays a line plot of a function of a multiple responses.
The following command language displays a line plot of the mean temperature ('Temp') and nutrient quotient of
flour produced on two different types of grain mill ('Mill').
LPLO MEAN('Temp''Nutrient')*'Mill';
OVERLAY.
LPLOT (C...C) * C
SUMMARIZED
Displays a line plot of tabled, multivariate data with one grouping column.
The following command language displays a line plot of the 25 chemical profiles (tabled in columns
'ChemProfile1'-'ChemProfile25') labeled by the component levels in 'Component.'
LPLO('ChemProfile1'-'ChemProfile25')*'Component';
SUMMARIZED.
Plot options
PERCENT
Use a percent scale on the y-axis.
SLEVEL 1
Use with a percent scale to display the percent within each x-category so that all points at the designated x-category
total 100%. If you do not use SLEVEL 1, the line plot displays the percent across all categories.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
983
Minitab Statistical Software Graphs
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CONNECT: Session subcommand for connecting points with lines on page 1012
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Multiple graphs
GROUP: Session subcommand for specifying categorical variables for grouping on page 1029
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
984
Minitab Statistical Software Graphs
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
PIECHART: Session command for creating a pie chart
Use to see the proportion of each data category relative to the whole data set.
PIECHART C...C
Displays a separate pie chart for each column of raw data (numeric, text, or date/time), where each row represents
the category of a single observation. Minitab creates a slice for each unique value with the area representing the
proportion of that value in the column.
PIECHART C*C...C*C
PIECHART C*C...C
Displays a pie chart of summarized data, where categories (or groups) are in the second set of columns and
summarized data (numeric or date/time data that describe the category) are in the first set of columns. Minitab
creates a pie chart for every combination of summary columns and categorical columns, using the worksheet
order of the data.
Pie chart options
DONUT
Change display to a donut.
SEMICIRCLE
Change display to a semicircle.
COMBINE K
Combines categories with individual percentages less than or equal to K% into a category named Others (when
one or more slices are at or below K%). When you use COMBINE, the Others category is always placed last, even
when you specify INCREASING or DECREASING.
INCREASING
Orders slices from smallest to largest.
DECREASING
Orders slices from largest to smallest.
985
Minitab Statistical Software Graphs
DIAMETER K
Specifies the pie chart diameter in figure units. K must be greater than 0 and less than or equal to 1.
START K
Specifies the starting angle in degrees for the slices. By default, slices start at 90° (12 o'clock) and go clockwise.
When you specify START 0, slices start at the 3 o'clock position.
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SLABEL: Session subcommand for labeling the slices on a pie chart on page 1080
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
SLICE: Session subcommand for specifying the attributes of slices on a pie chart on page 1081
Multiple graphs
PANEL: Session subcommand for paneling graphs on page 1061
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
FREQUENCY: Session subcommand for using a frequency column for a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
986
Minitab Statistical Software Graphs
Regions
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
TSPLOT: Session command for creating a time series
plot
TSPLOT C...C
Displays a separate time series plot for each column.
Use to evaluate trends in data over time. Minitab plots time series data on the y-axis versus time on the x-axis.
Minitab plots the data in worksheet order, in equally-spaced time intervals.
The data must be one or more columns of time series data (regular sequences of observations of a numeric or
date/time variable over time).
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Time scale
For information about the following subcommands, go to Time unit subcommands on page 1180.
INDEX
STAMP
SECOND
MINUTE
HOUR
DAY
987
Minitab Statistical Software Graphs
MONTH
QUARTER
YEAR
START
INCREMENT
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CONNECT: Session subcommand for connecting points with lines on page 1012
LOWESS: Session subcommand for fitting a LOWESS smoother to a scatterplot, a matrix plot, a histogram, or a time
series plot on page 1049
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
988
Minitab Statistical Software Graphs
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
PARPLOT: Session command for creating a parallel
plot
Use to compare observations or groups on multiple variables by plotting each observation on parallel coordinates.
PARPLOT C...C
Displays a parallel plot where each column (numeric), represents a separate y-scale on the plot. Every column
must have the same number of rows.
Parallel plot options
RLABEL C
Specify row labels. A line is plotted for each row with a label in the legend. RLABEL C can be specified with GROUP
C but not MEAN C.
GROUPC
Specify a column that groups the rows into categories. Minitab uses the group variable to create a legend for the
parallel plot. GROUP C can be specified with RLABEL C but not MEAN C.
MEANC
Specify a column that groups the rows into categories. Minitab plots the mean for each group for each variable.
Unique labels appear in legend. If MEAN C is specified then RLABEL C and GROUP C cannot be specified.
SORT
Sort the Y variables in descending order based on the variation between points plotted for each variable. If you
specify STANDARD, the scale is sorted by the standard deviation of each variable. If you specify SHARED, the scale
is sorted by the kurtosis of each variable. You cannot use this option when you specify MINMAX.
989
Minitab Statistical Software Graphs
SCALE 2
Indicates the y scales. MINMAX, STANDARD, and SHARED are subcommands of SCALE 2.
MINMAX
Use to plot each variable with a unique y-scale. The minimum and maximum values on each scale are parallel for
all of the columns. A row that contains all of the minimum or maximum values for each variable will be a horizontal
line. You cannot use MINMAX with STANDARD or SHARED.
STANDARD
Use to plot each variable with a unique y-scale. The minimum and maximum values for each column are converted
to the transformed standard deviation units, and the scales are based on these values. You cannot use STANDARD
with MINMAX or SHARED.
SHARED
Use to plot a single y-scale for every variable. The minimum and maximum values for the scale are the overall
minimum and maximum values from all the data that you entered. You cannot use SHARED with STANDARD or
MINMAX.
MULTIPLE C...C
Creates separate graphs for each group created by the grouping columns C...C. The grouping columns can be
numeric or text, but must be the same length as the columns that you specify with PARPLOT. Minitab treats
missing values as a separate group.
INDEPENDENT
Creates separate plots for each group created by the individual columns specified with MULTIPLE independent
of the other columns. For example, suppose you specify two columns with MULTIPLE. The first column
contains the gender, either male or female, and the other contains the marriage status, either married or
single. If you specify INDEPENDENT, Minitab creates a graph for each group created by the columns
individually:
Male
Female
Single
Married
If you do not specify INDEPENDENT, Minitab creates a graph for each group created by all the columns:
Male and Single
Male and Married
Female and Single
Female and Married
ARGRAPH: Session command for creating an area
graph
ARGRAPH C...C
Use to evaluate trends in data over time by plotting series of sequential observations. An area graph stacks areas
for each time series, illustrating the proportion each series contributes to the sum.
990
Minitab Statistical Software Graphs
You need one or more columns of time series data (regular sequences of observations of a numeric or date/time
variable over time) of equal length.
ORDER
Stacks areas by the degree of variation, with the area having the smallest standard deviation on the bottom.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TSHOW: Session subcommand for specifying the level of tick labels that are displayed on page 1091
Time scale
Time unit subcommands on page 1180
Labels
DATLAB: Session command for labeling data values on page 1016
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NOSEPSUBTITLE: Session subcommand for subtitles on separate graphs on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999
Multiple graphs
PANEL: Session subcommand for paneling graphs on page 1061
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
GAPS: Session subcommand for displaying a gap in time on a graph on page 1027
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
991
Minitab Statistical Software Graphs
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
CONTOURPLOT: Session command for creating a
contour plot
In a contour plot, values for the x- and y-variables are represented on the x- and y-axes, respectively. Values for a third
variable, z, are estimated and represented by contour lines and/or shaded regions. A contour plot is like a topographical
map in which x-, y-, and z-values are plotted instead of longitude, latitude, and altitude.
Note You can create mesh data for CONTOURPLOT with MESH on page 84.
CONTOURPLOT C * C * C
Displays a contour plot of z (1
st
column) as a function of y (2
nd
column) and x (3
rd
column).
CONTOURPLOT (C...C) * C * C
Displays contour plots for each z as a function of the same y and x.
992
Minitab Statistical Software Graphs
Contour options
APOLYNOMIAL
Specifies the Akima's polynomial method to estimate the z-values for irregular data (data not on a rectangular
grid). If x-y data are sampled on a rectangular grid, APOLYNOMIAL is ignored. APOLYNOMIAL and DISTANCE are
mutually exclusive. The last one entered will be used.
BOUNDARY K
BOUNDARY sets the z-estimate for points far from your x-y data.
DISTANCE
Specifies the Distance method to estimate the z-values for irregular data (data not on a rectangular grid). If data
are sampled on a rectangular grid, DISTANCE is ignored. APOLYNOMIAL and DISTANCE are mutually exclusive.
The last one entered will be used.
NOSTANDARDIZE
Specifies not to standardize x- and y-data before interpolation. Use if your data are not measured on different
scales.
POWER K
POWER specifies the amount of local variation smoothing. K is an integer greater than 0 and less than or
equal to 12. The closer to 0, the closer the fits are to the overall mean. The farther from 0, the more weight
is placed on local variation.
LEVELS K...K
LEVELS C
Specifies from 2 to 11 z-values for the contour lines. If you specify LEVELS more than once, CONTOURPLOT uses
only the last occurrence.
NLEVELS K
Specifies the number of contour lines as an integer from 2 to 11. If you specify NLEVELS more than once,
CONTOURPLOT uses only the last occurrence.
NMESH
Specifies the number of mesh values in the x- or y-direction. For example, NMESH 1 20 specifies 20 mesh positions
in the x-direction and NMESH 2 30 specifies 30 positions in the y-direction.
By default, Minitab uses the mesh defined by your data if they are regular, or a 15 by 15 mesh for irregular data.
(Data with a regular shape form a grid with evenly spaced intervals. Data with an irregular shape are not located
on evenly spaced intervals.)
If you specify NMESH more than once for x or y, CONTOURPLOT uses only the last occurrence.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
993
Minitab Statistical Software Graphs
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999
CONNECT: Session subcommand for connecting points with lines on page 1012
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Data options
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
994
Minitab Statistical Software Graphs
PLTX: Session command for creating a 3D scatterplot
Use to evaluate relationships between three variables at once by plotting data on three axes: z, y, and x.
PLTX with no subcommands displays symbols. Use SYMBOL if you want symbols to be displayed with PROJECT.
PLTX C * C * C
Displays a three-dimensional scatterplot of z (1st column) by y (2nd column) by x (3rd column).
PLTX (C...C) * C * C
Displays a separate three-dimensional scatterplot for each z by the same y and x.
Regions
DATA [K K K K]
DATA for PLTX has limited functionality compared to DATA for other commands. DATA specifies the position of
the box in terms of the x-minimum, x-maximum, y-minimum, and y-maximum as values from 0 to 1. Subcommands
of DATA are ignored for PLTX.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
JITTER and NOJITTER: Session subcommands for randomly offsetting data points to reveal overlapping points on
page 1043
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
3D orientation
VASPECT: Session subcommand for specifying the aspect ratio of the data box on page 1091
VBOX: Session subcommand for specifying the display of the box that surrounds the data on a graph on page 1092
VFIELD: Session subcommand for specifying the dimensions of the field of view in object units on page 1092
995
Minitab Statistical Software Graphs
VPOSITION: Session subcommand for specifying the view position as a ratio on page 1092
VUP: Session subcommand for specifying which direction is up in relation to the data box on page 1092
Data options
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
DATA: Session subcommand for controlling the data region within the figure region on page 1015
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
SURFACEPLOT: Session command for creating a
surface plot
Use to evaluate relationships between three variables at one time by plotting data on three axes: z, y, and x. Like a
three-dimensional scatterplot, a three-dimensional surface plot has three axes. In addition, SURFACEPLOT uses
interpolation to produce a continuous surface (surface plot) or grid (wireframe plot) of z-values that fits your data. For
information on a three-dimensional scatterplot, go to PLTX on page 995.
SURFACEPLOT with no subcommands displays a fitted surface. Use SFIT if you want a fitted surface or wireframe to
be displayed with PROJECT or SYMBOL.
Note You can create mesh data for SURFACEPLOT with MESH on page 84.
SURFACEPLOT C * C * C
Displays a three-dimensional surface plot of z (1
st
column) by y (2
nd
column) by x (3
rd
column).
996
Minitab Statistical Software Graphs
SURFACEPLOT (C...C) * C * C
Displays a separate surface plot for each z by the same y and x.
SURFACEPLOT C * C * C
WIREFRAME
Displays a three-dimensional wireframe plot of z (1
st
column) by y (2
nd
column) by x (3
rd
column).
SURFACEPLOT (C...C) * C * C
WIREFRAME
Displays a separate wireframe plot for each z by the same y and x.
Surface options
APOLYNOMIAL
Specifies the Akima's polynomial method to estimate the z-values for irregular data (data not on a rectangular
grid). If x-y data are sampled on a rectangular grid, APOLYNOMIAL is ignored. APOLYNOMIAL and DISTANCE are
mutually exclusive. The last one entered will be used.
BOUNDARY K
BOUNDARY sets the z-estimate for points far from your x-y data.
DISTANCE
Specifies the Distance method to estimate the z-values for irregular data (data not on a rectangular grid). If data
are sampled on a rectangular grid, DISTANCE is ignored. APOLYNOMIAL and DISTANCE are mutually exclusive.
The last one entered will be used.
NOSTANDARDIZE
Specifies not to standardize x- and y-data before interpolation. Use if your data are not measured on different
scales.
POWER K
POWER specifies the amount of local variation smoothing. K is an integer greater than 0 and less than or
equal to 12. The closer to 0, the closer the fits are to the overall mean. The farther from 0, the more weight
is placed on local variation.
LBRIGHT K
Specifies the brightness (as an integer from 0 to 100) of the lights illuminating the surface. LBRIGHT has no effect
when WIREFRAME is used.
LIGHT K K K K
The first argument for LIGHT specifies the number of the light (1, 2, or 3). The remaining arguments specify the
position of the light in x-, y-, and z-coordinates. For example LIGHT 1 0 0 1 specifies that light 1 is to be centered
on the x- and y-axes, one unit above the surface in the positive z-direction. LIGHT has no effect when WIREFRAME
is used.
COLOR K
COLOR specifies the color of the light as an integer. To find the integer for a color, go to Numbers for colors
to use in session commands on page 1172.
VISIBILITY K
VISIBILITY specifies whether the light is on (0) or off (1).
997
Minitab Statistical Software Graphs
NMESH
Specifies the number of mesh values in the x- or y-direction. For example, NMESH 1 20 specifies 20 mesh positions
in the x-direction and NMESH 2 30 specifies 30 positions in the y-direction.
By default, Minitab uses the mesh defined by your data if they are regular, or a 15 by 15 mesh for irregular data.
(Data with a regular shape form a grid with evenly spaced intervals. Data with an irregular shape are not located
on evenly spaced intervals.)
If you specify NMESH more than once for x or y, SURFACEPLOT uses only the last occurrence.
WIREFRAME
Specifies a wireframe display.
Scale
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
PROJECT: Session subcommand for extending projection lines from each point to the x-axis on page 1064
SFIT: Session subcommand for specifying the attributes of the surface on a 3D surface plot on page 1079
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
3D orientation
VASPECT: Session subcommand for specifying the aspect ratio of the data box on page 1091
VBOX: Session subcommand for specifying the display of the box that surrounds the data on a graph on page 1092
VFIELD: Session subcommand for specifying the dimensions of the field of view in object units on page 1092
VPOSITION: Session subcommand for specifying the view position as a ratio on page 1092
VUP: Session subcommand for specifying which direction is up in relation to the data box on page 1092
Data options
INCLUDE and EXCLUDE: Session subcommands for including or excluding rows on a graph on page 1036
998
Minitab Statistical Software Graphs
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graph Options
AREA: The session subcommand for shading the area below the
data values to the base
AREA [C...C]
Shades the area below the data values to the base (scatterplot, matrix plot, histogram, or area graph) or the areas
between contours (contour plot), where C...C can specify up to 3 grouping variables.
For grouping variables specified on the main command line:
You can use up to three grouping columns.
Grouping variables are not allowed with CONTOURPLOT and ARGRAPH.
The AREA arguments are grouping variables. In the following example, C2 is the grouping column, and, for
each unique value in C2, Minitab assigns different area attributes.
PLOT C1*C2;
AREA C2.
For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the
SYMBOL and COLOR subcommands for PLOT on page 1183 for more information.
DIRECTION K
Specifies the direction the area extends away from the data values. DIRECTION is not available with
HISTOGRAM.
999
Minitab Statistical Software Graphs
DirectionValue of K
Horizontally to the base1
Vertically to the base2 (default)
Area edge line
Specifies the type, color, and width of the area edge line.
ETYPE K...K
ETYPE C
ETYPE specifies the line type in K, which is a number from Numbers for line types to use in session commands on
page 1173. Enter one K for each area or store the line types in C.
ETYPE does not apply for CONTOURPLOT.
ECOLOR K...K
ECOLOR C
ECOLOR specifies the line color in K, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each area or store the line colors in C.
ECOLOR does not apply for CONTOURPLOT.
ESIZE K...K
ESIZE C
ESIZE specifies the line width, which can be any positive number. Enter one K for each area or store the line sizes
in C.
ESIZE does not apply for CONTOURPLOT.
Area
Specifies the fill pattern and background fill color of the area.
TYPE K...K
TYPE C
TYPE specifies the fill pattern in K, which is a number from Numbers for fill types to use in session commands on
page 1173. Enter one K for each area or store the fill types in C.
COLOR K...K
COLOR C
COLOR specifies the background color in K, which is a number from Numbers for colors to use in session commands
on page 1172. Enter one K for each area or store the fill colors in C.
Color ramp for the levels of a contour plot
Specifies the color ramp to be used for the levels of a contour plot.
1000
Minitab Statistical Software Graphs
RAMP K [K]
RAMP specifies a one-color ramp or a two-color ramp. Use one argument for a one-color ramp and two arguments
for a two-color ramp for example. The constant arguments, K, refer to the ramp (1=red, 2=green, 3=blue, 4=gray).
The first argument is used for the high values, and the second is used for the low values. One-color ramps, available
only with contour plots with five contour levels or less, use light shades to represent the low values and dark
shades to represent the high values.
SPECTRUM
SPECTRUM specifies the spectrum color ramp, which mimics the spectrum with red representing the low values
and blue representing the high values.
Data point connect lines
STRAIGHT (default)
STRAIGHT connects data points with straight lines.
STEP [K]
The following table shows how STEP connects data points. STEPS is not available with CONTOURPLOT, ARGRAPH,
or HISTOGRAM.
How STEP connects data pointsValue of K
Makes steps with each data point at the left of a step level.–1
Puts each point in the middle of the step level.0 (default)
Makes steps with each point at the right of the step level.1
AXLABEL: Session subcommand for customizing graph axis labels
AXLABEL K "string"
AXLABEL K C
Generates customized axis labels. You can also modify axis lines and labels using graph editing, which may be
easier than using AXLABEL.
Specifies the axis to be affected and its label.
AxisValue of K
X-axis1
Y-axis2
Z-axis on a 3D graph3
You can enter a custom axis label in quotation marks or specify a column that contains only the axis label that
you want to use.
MODEL K
Specifies the graph that will accept the axis label subcommand. Use this subcommand only when you create
multiple graphs with a single command. Allows you to apply its related subcommand and subsubcommands
to a specific graph. The argument refers to the order in which the graphs are created. MODEL 1 affects the
first graph created, MODEL 2 the second, and so on.
1001
Minitab Statistical Software Graphs
SECSCALE
Specifies that the scale is a secondary scale. Invoking this subsubcommand associates its related subcommand
with the secondary scale.
ADISPLAY K [K...K]
Specifies the side and display of the axis label.
How the axis label is displayedValue of K
Hides the axis label0
Displays the axis label on the low side1
Displays the axis label on the high side2
LSHOW K
Shows or hides axis labels on a multi-level axis. By default, axis labels for all levels are shown. When you use
LSHOW, only specified levels are shown. A K value of 1 refers to the first or outermost variable level, 2 to the
second, and so on.
LABEL [K] "string"
Use LABEL in two settings: with matrix plots and with multi-level scales, such as those on nested boxplots.
With matrix plots, use LABEL K "string". The first argument specifies the variable number that will take the
custom label that follows it in quotes. The first variable listed in the MATRIXPLOT command is referenced by
1, the second by 2, and so on.
With multi-level axes, use LABEL "string" with the subsubcommand ALEVEL K.
ALEVEL K
With multi-level axes, use LABEL "string" with the subsubcommand ALEVEL K. The argument to ALEVEL
specifies the variable level that takes the custom label that follows the LABEL command in quotes. A K
value of 1 refers to the first or outermost label, 2 to the second, and so on.
TFONT "font"
TFONT specifies the font and uses the font name as an argument.
TCOLOR K
TCOLOR specifies the color of the text in K, which is a number from Numbers for colors to use in session
commands on page 1172.
TSIZE K
Use TSIZE or PSIZE to specify the size of the text. TSIZE takes values in Minitab units.
PSIZE K
Use TSIZE or PSIZE to specify the size of the text. PSIZE takes point units.
ANGLE K
ANGLE rotates the text K degrees in a counterclockwise direction around the reference point on the axis.
OFFSET K K
Moves the text from the default rotation of 0 0. OFFSET 0 0 gives you axis labels directly on the axis line,
centered at the midpoint. The first argument is the x-direction offset (−1 is to the left of the point and 1 is
to the right). The second argument is the y-direction offset (−1 is below the point and 1 is above). Both are
in figure units.
1002
Minitab Statistical Software Graphs
BOLD
Specifies that the axis labels are in bold.
ITALIC
Specifies that the axis labels are in italics.
UNDERLINE
Specifies that the axis labels are underlined.
NOBOLD
Specifies that the axis labels are not in bold.
NOITALIC
Specifies that the axis labels are not in italics.
NOUNDERLINE
Specifies that the axis labels are not underlined.
BAR: Session subcommand for representing data values with bars
BAR [C...C]
Displays a bar for each data value. If you use other data displays with a graph that has BAR as a default, such as
histogram, you must issue the BAR subcommand.
For grouping variables specified on the main command line:
Histograms can use up to three grouping columns.
Bar chart, interval plot, and individual value plot can use up to four grouping columns.
For interval plot and individual value plot, grouping columns must be categorical variables that are included
on the main graph command line, or with the GROUP subcommand. In the following example, C2 is the
grouping column, and, for each unique value in C2, Minitab assigns different bar attributes.
INTPLOT C1*C2;
BAR C2.
For bar chart, grouping columns must be categorical variables that are GROUP, STACK, or, CLUSTER variables.
In the following example, C3 is the grouping column, and, for each unique value in C3, Minitab assigns
different bar attributes.
CHART C1;
GROUP C2 C3;
BAR C3.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN K...K
VASSIGN C
For overlaid bar charts, interval plots, and individual value plots, assigns different attributes (color, fill type)
to the bars representing each graph variable and displays a legend. (CHART, INTPLOT, and INDPLOT only)
1003
Minitab Statistical Software Graphs
BASE K...K
BASE C
Specifies the base position for each bar. (For more information, go to Base position for project lines, area,
and bar on page 1134.) Bars extend from the data value to the base. The default base is the minimum data
value for the y-scale.
Enter one K for each base or store the bases in C. If one value is specified it applies to all points.
You can draw a base line by using REFERENCE on page 1073.
Bar edge line
Specifies the type, color, and width of the bar edge line.
ETYPE K...K
ETYPE C
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each bar or store the line types in C.
ECOLOR K...K
ECOLOR C
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
ESIZE K...K
ESIZE C
ESIZE specifies the line width, which can be any positive number. Enter one K for each bar or store the line sizes
in C.
Fill pattern and background fill color
Specifies the fill pattern and background fill color of the bar.
TYPE K...K
TYPE C
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173. Enter one K for each bar or store the fill types in C.
COLOR K...K
COLOR C
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172. Enter one K for each bar or store the fill colors in C.
Positions where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, see Using the POSITION
and MODEL subcommands on page 1185.
1004
Minitab Statistical Software Graphs
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
CIBOX: The session subcommand for displaying a median
confidence interval box on a boxplot
CIBOX [C...C]
Displays a median confidence interval box on a boxplot. The box endpoints correspond to the values of a confidence
interval for the median based on the sign test.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main BOXPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different box attributes.
BOXPLOT C1*C2;
MEAN C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN K...K
VASSIGN C
For overlaid boxplots, assigns different attributes (color, fill type) to the median confidence interval boxes
representing each graph variable and displays a legend.
Fill pattern and background fill color of the box
Specifies the fill pattern and background fill color of the box.
TYPE K...K
TYPE C
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173. Enter one K for each bar or store the fill types in C.
COLOR K...K
COLOR C
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172. Enter one K for each bar or store the fill colors in C.
1005
Minitab Statistical Software Graphs
Type, color, and width of box edge line
ETYPE K...K
ETYPE C
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each bar or store the line types in C.
ECOLOR K...K
ECOLOR C
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
ESIZE K...K
ESIZE C
ESIZE specifies the line width, which can be any positive number. Enter one K for each bar or store the line sizes
in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
CLIMITS: Session command for specifying attributes for control
limit lines
CLIMITS
Specifies attributes for the upper and lower control limit lines and their labels on a control chart.
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number that is specified in Numbers for line types to use in session
commands on page 1173 list. Enter one K for line or store the line types in C.
1006
Minitab Statistical Software Graphs
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number that is specified in Numbers for colors to use in session commands
on page 1172 list. Enter one K for each line or store the line colors in C.
SIZE K...K
SIZE C
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line sizes
in C.
Label attributes
LSHOW K
Specifies whether to display the label.
LabelValue of K
Do not display the label.0
Display the label.1 (default)
POSITION K
Specifies a particular control limit label. For example, POSITION 3 refers to the upper control limit of the 3
rd
stage. The lower control limit position depends on the number of stages. For example, if there are 4 stages, then
1–4 refers to upper control limits and 5–8 refers to lower control limits. Use any of the subcommands, TFONT
through ANGLE, to modify the label, then issue ENDPOSITION.
ENDPOSITION
Specifies the end of the POSITION subcommand language.
TFONT "font name"
TFONT specifies the text font. Enclose the font name "K" in double quotation marks.
TCOLOR K
TCOLOR specifies the label color and uses integer arguments that are specified in Numbers for colors to use in
session commands on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
1007
Minitab Statistical Software Graphs
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Label positioning
OFFSET K K
Moves the label. The first argument specifies how far to move the label horizontally (in figure units). The second
argument specifies how far to move the title vertically. The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 specifies horizontal text.
CLINE: Session command for specifying attributes for a center line
CLINE
Specify attributes for the center line on a control chart. The CLINE attributes apply to all center lines on a chart.
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number that is specified in Numbers for line types to use in session
commands on page 1173 list. Enter one K for line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number that is specified in Numbers for colors to use in session commands
on page 1172 list. Enter one K for each line or store the line colors in C.
SIZE K...K
SIZE C
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line sizes
in C.
Label attributes
LSHOW K
Specifies whether to display the label.
1008
Minitab Statistical Software Graphs
LabelValue of K
Do not display the label.0
Display the label.1 (default)
TFONT "font name"
TFONT specifies the text font. Enclose the font name "K" in double quotation marks.
TCOLOR K
TCOLOR specifies the label color and uses integer arguments that are specified in Numbers for colors to use in
session commands on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Label positioning
OFFSET K K
Moves the label. The first argument specifies how far to move the label horizontally (in figure units). The second
argument specifies how far to move the title vertically. The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 specifies horizontal text.
1009
Minitab Statistical Software Graphs
CMEAN: Session subcommand for connecting means with lines
on a boxplot
CMEAN
Connects means with lines on a boxplot, interval plot, or individual value plot. Mean lines are visible only if you
have categorical variables in the boxplot.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main graph command line, or with
the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique value
in C2, Minitab assigns different line attributes.
BOXPLOT C1*C2;
CMEAN C2.
When used without grouping variables, connects the means of the boxes from left to right.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN K...K
VASSIGN C
For overlaid graphs, connects mean symbols representing the same graph variable and displays a legend.
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
SIZE K
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line sizes
in C.
Lines that connect means
STRAIGHT (default)
Connects means with straight lines.
STEP K
Connects points with stepwise lines of the following possible justifications.
1010
Minitab Statistical Software Graphs
Steps and justificationValue of K
Steps with each point at the left of a step level−1
Steps centered between the points0 (default)
Steps with each point at the right of the step level1
CMEDIAN: Session subcommand for connecting means with lines
on a boxplot
CMEDIAN [C...C]
Connects medians with lines on a boxplot, interval plot, or individual value plot. Median lines are only visible if
you have categorical variables in the boxplot.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main graph command line, or with
the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique value
in C2, Minitab assigns different line attributes.
BOXPLOT C1*C2;
CMEDIAN C2.
When used without grouping variables, connects the means of the boxes from left to right.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN K...K
VASSIGN C
For overlaid graphs, connects median symbols representing the same graph variable and displays a legend.
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
SIZE K
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line sizes
in C.
1011
Minitab Statistical Software Graphs
Lines that connect means
STRAIGHT (default)
Connects medians with straight lines.
STEP K
Connects points with stepwise lines of the following possible justifications.
Steps and justificationValue of K
Steps with each point at the left of a step level−1
Steps centered between the points0 (default)
Steps with each point at the right of the step level1
CONNECT: Session subcommand for connecting points with lines
CONNECT [C...C]
Connects points with lines, and turns off default bars, boxes, or symbols. CONNECT also restores connect lines
when another data display command turns them off (so you can display for example, CONNECT and SYMBOL).
For grouping variables specified on the main command line:
Can use up to three grouping columns.
Bar chart can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main CHART command line, or with
the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique value
in C2, Minitab assigns different line attributes.
CHART C1;
CONNECT C2.
Grouping variables are not allowed with CONTOURPLOT and CONNECT.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid bar charts, connects symbols representing the same graph variable and displays a legend.
ORDER K
Specifies the order in which points are connected. You have the following three choices:
Order in which points are connectedValue of K
Worksheet order (the order of occurrence in the worksheet)0
X-order (from smallest to largest horizontally)1 (default)
Y-order (from smallest to largest vertically)2
You cannot use ORDER 0 and STEP together.
Used only with PLOT and MATRIXPLOT.
1012
Minitab Statistical Software Graphs
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
SIZE K
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line sizes
in C.
Labels
NOLABEL
Does not show labels.
LABEL
Shows labels.
TYPE K...K
TYPE C
TYPE specifies the fill type, which is a number from Numbers for line types to use in session commands on page
1173.
COLOR K...K
COLOR C
COLOR specifies the background color for fill, which is a number from Numbers for colors to use in session
commands on page 1172.
ETYPE K
ETYPE specifies the edge type for fill, which is a number from Numbers for line types to use in session commands
on page 1173.
ECOLOR K
ECOLOR specifies the edge color for fill, which is a number from Numbers for colors to use in session commands
on page 1172.
ESIZE K
ESIZE specifies the edge size for fill. The edge size can be any positive real number value.
TFONT "font name"
TFONT specifies the font name for the labels.
1013
Minitab Statistical Software Graphs
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Lines that connect data values
STRAIGHT (default)
Connects values with straight lines.
STEP K
Connects points with stepwise lines of the following possible justifications.
Steps and justificationValue of K
Steps with each point at the left of a step level−1
Steps centered between the points0 (default)
Steps with each point at the right of the step level1
CUTPOINT, MIDPOINT, and NINTERVAL: Session subcommands
for specifying cutpoints and midpoints
You can specify your own midpoints or cutpoints by putting them on the subcommand line. Specify arguments in
order, from smallest to largest. MIDPOINT requires equally spaced intervals. CUTPOINT does not.
1014
Minitab Statistical Software Graphs
CUTPOINT K...K
CUTPOINT C
Used without arguments, CUTPOINT places ticks at default cutpoint. To specify custom cutpoints, list each value
(smallest to largest), create a patterned range, or specify a column containing the values. For example, the patterned
range 10:50/5 places cutpoints at every 5 units from positions 10 to 50.
MIDPOINT K...K
MIDPOINT C
Used without arguments, MIDPOINT places ticks at default midpoint intervals. To specify custom midpoints, list
each value (smallest to largest), create a patterned range, or specify a column containing the values. For example,
the patterned range 10:50/5 places midpoints at every 5 units from positions 10 to 50.
NINTERVAL K [K]
NINTERVAL is a subsubcommand for CUTPOINT and MIDPOINT.
NINTERVAL with a single argument (between 2 and 1000, inclusive) allows you to specify a number of binning
intervals to display on the x-axis. Minitab attempts to give useful tick values to histograms or dotplots produced
with NINTERVAL. If you specify NINTERVAL with two arguments—for example, NINTERVAL 3 7—the graph has
useful tick locations and between 3 and 7 intervals. Midpoints are displayed by default when you specify NINTERVAL.
You can specify CUTPOINT or MIDPOINT without arguments and an NINTERVAL subcommand to display a graph
with a certain number (or range) of intervals and cutpoints or midpoints. With NINTERVAL, the graph does not
display first and/or last intervals that do not contain any observations.
DATA: Session subcommand for controlling the data region within
the figure region
DATA [K K K K]
Controls size and placement of the data region within the figure region, the fill type and color of the data region,
and the type, color and thickness of the edge line around the data region.
Represents the x-minimum, x-maximum, y-minimum, and y-maximum values for the data region, respectively,
and uses figure units that range from 0 to 1. When used without arguments, the data region maintains its default
size.
Fill type and color of the data region
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
1015
Minitab Statistical Software Graphs
Type, color, and width of the data region border
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number.
DATLAB: Session command for labeling data values
DATLAB [C]
Labels data values. Minitab determines the label by the main command line argument or a subcommand.
Enter a column on the main command line to use labels that are stored in a column. If no argument is given
on the main command line, Minitab labels the points with their y-axis values. The label column can be numeric,
text, or date/time. Labels can be any combination of up to 80 characters, including spaces.
If graph data match worksheet rows, as for scatterplot, Minitab matches the label column to the data column
by worksheet row number. If graph data are summaries of worksheet values, such as for histogram and bar
chart, the label column order is left-to-right on the graph. If the label column contains more values than are
needed, Minitab ignores the extra labels. If the label column contains less values than are needed, the remaining
data values are not labeled.
Use the YVALUE subcommand to label data values with their y-axis value.
Use the ROWNUM subcommand to label data values with their worksheet row number.
Use the POSITION subcommand to label an individual data value. After issuing POSITION, the font and
positioning subcommands affect only the individual label until ENDPOSITION is issued.
YVALUE
Labels each data value with its y-axis value.
ROWNUM
Labels each data value with its worksheet row number. You cannot label histograms or bar charts with row
numbers.
Labeling individual data values
POSITION K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
1016
Minitab Statistical Software Graphs
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
1017
Minitab Statistical Software Graphs
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
DISTRIBUTION: Session command for fitting a distribution
DISTRIBUTION [C...C]
Fits a distribution to the data, where C...C can specify up to 3 grouping variables. When you use grouping variables,
DISTRIBUTION displays a separate distribution for each group.
Fits a distribution to a histogram and empirical cdf graph to help you determine whether the data can be adequately
modeled by the selected distribution. Minitab estimates the distribution parameters from the data unless you use
the HPARAMETERS subcommand. Use the HPARAMETERS subsubcommand to enter 1–3 historical parameters.
Minitab provides 14 distributions: normal, lognormal, three-parameter lognormal, gamma, three-parameter
gamma, exponential, two-parameter exponential, smallest extreme value, Weibull, three-parameter Weibull, largest
extreme value, logistic, loglogistic, and three-parameter loglogistic.
Histogram with a normal distribution
Histogram with a lognormal distribution
1018
Minitab Statistical Software Graphs
ECDF graph with a normal distribution
ECDF graph with a lognormal distribution
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
SIZE K
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line sizes
in C.
Distributions and parameters
NORMAL
Fits a normal distribution.
LNORMAL
Fits a lognormal distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab estimates
them from the data.
TLNORMAL
Fits a three-parameter lognormal distribution. If you do not use HPARAMETERS to specify historical parameters,
Minitab estimates them from the data.
GAMMA
Fits a gamma distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab estimates
them from the data.
1019
Minitab Statistical Software Graphs
TGAMMA
Fits a three-parameter gamma distribution. Minitab estimates the shape, scale, and threshold from the data.
EXPONENTIAL
Fits a exponential distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab estimates
them from the data.
TEXPONENTIAL
Fits a two-parameter exponential distribution. If you do not use HPARAMETERS to specify historical parameters,
Minitab estimates them from the data.
SEXTREMEVALUE
Fits a smallest extreme value distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab
estimates them from the data.
WEIBULL
Fits a Weibull distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab estimates
them from the data.
LEXTREMEVALUE
Fits a largest extreme value distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab
estimates them from the data.
LOGISTIC
Fits a logistic distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab estimates
them from the data.
LLOGISTIC
Fits a loglogistic distribution. If you do not use HPARAMETERS to specify historical parameters, Minitab estimates
them from the data.
TLLOGISITIC
Fits a three-parameter loglogistic distribution. If you do not use HPARAMETERS to specify historical parameters,
Minitab estimates them from the data.
HPARAMETERS K
HPARAMETERS K K
HPARAMETERS K K K
Specifies the distribution parameters. Parameter arguments are given in the order shown in the table below. For
each parameter that you want Minitab to estimate, enter ' *' for K. For example:
To have Minitab estimate the mean for a normal distribution, enter ' * ' for the mean and a value for the
standard deviation.
DISTRIBUTION;
NORMAL;
HPARAMETERS '*' 7.
To have Minitab estimate the scale for a 3-parameter Weibull distribution, enter ' * ' for the scale and values
for the shape and threshold.
DISTRIBUTION;
TWEIBULL;
HPARAMETERS 13 '*' 4.
If you want Minitab to estimate all parameters, do not use HPARAMETERS.
Use the following table to determine the necessary parameters and restrictions.
1020
Minitab Statistical Software Graphs
What Minitab can estimateParametersDistribution subsubcommand
Mean and standard deviationMeanNORMAL
Mean, given standard deviationStandard deviation
Location and scaleLocationLOGNORMAL
Location, given scaleScaleSEXTREME
LEXTREME
LOGISTIC
LOGLOGISTIC
Shape and scaleShapeGAMMA
Scale, given shapeScaleWEIBULL
MeanMeanEXPONENTIAL
Scale and thresholdScaleTEXPONENTIAL
Scale, given thresholdThreshold
Shape, scale, and thresholdShapeTWEIBULL
Shape and scale, given thresholdScaleTGAMMA
Scale and threshold, given shapeThreshold
Scale, given shape and threshold
Location, scale, and thresholdLocationTLNORMAL
Location and scale, given thresholdScaleTLLOGISTIC
Location and threshold, given scaleThreshold
Location, given scale and threshold
DOT: Session subcommand for displaying a symbol for each data
value
DOT [C...C]
Displays a symbol for each data value, or for multiple data values if there is insufficient room for individual symbols,
on a dotplot, where C...C can specify up to 4 grouping variables.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
1021
Minitab Statistical Software Graphs
Grouping columns must be categorical variables that are included on the main DOTPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different symbol attributes.
DOTPLOT C1*C2;
DOT C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid dotplots, assigns different attributes (color, type) to the dots representing each graph variable
and displays a legend.
Symbol type, color, and size
Specifies the symbol type, color, and size. You can enter a single K to apply to all symbols. If you use group variables,
each K applies to a single group.
TYPE K...K
TYPE C
TYPE specifies the symbol type, which is a number from Numbers to use for symbols and markers in session
commands on page 1174. Enter one K for each symbol or store the symbol types in C.
COLOR K...K
COLOR C
COLOR specifies the symbol color, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each symbol or store the symbol colors in C.
SIZE K
SIZE specifies the size of the symbol. Enter one K for each symbol or store the symbol types in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
ELLIPSE: Session subcommand for constructing an ellipse from
points on a graph
ELLIPSE K K K K [K K K K]
ELLIPSE displays an ellipse at the points specified in the subcommand.
1022
Minitab Statistical Software Graphs
You can also put an ellipse anywhere on a graph using graph editing. Using the graph editing features is often
easier, unless you want to place an ellipse in exact locations using predefined points.
An ellipse is defined by either four or eight arguments. If the ellipse is a circle, use four arguments (X Y X Y) that
represent coordinates for the lower left and upper right corners of the square that defines the circle. Use eight
arguments to represent coordinate of all four corners (lower left, lower right, upper right, upper left) of the
rectangular region that defines a non-circular ellipse.
UNIT K
To place ellipses using figure units, use the argument 0. To specify data units, use 1.
With paneled graphs (including matrix plots), you can still place ellipses using data units if you also specify
the panel with the UNIT command. UNIT 1 for example places the ellipse relative to the first panel of the
graph and reads the ELLIPSE arguments in the data units of the first panel. You can associate the placement
of annotation with data units or figure units to accommodate changes in scales or graph size. As a
subcommand to LAYOUT, ELLIPSE always uses graph units.
Fill pattern and background fill color
Specifies the fill pattern and background fill color of the box.
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
Type, color, and width of the line
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number. Enter a value that is greater than 0.
FIGURE: Session subcommand for controlling the figure region
within the graph region
FIGURE [K K K K]
Controls size and placement of the figure region within the graph region, the fill type and color of the figure
region, and the type, color and thickness of the edge line around the figure region.
The arguments represent the x-minimum, x-maximum, y-minimum, and y-maximum values for the figure region,
respectively, and use graph units which range from 0 to 1. When used without arguments, the figure region
maintains its default size.
1023
Minitab Statistical Software Graphs
Fill type and color of the figure region
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background fill color, which is a number from Numbers for colors to use in session commands
on page 1172.
Type, color, and width of the figure region border
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K.
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number.
FITD: Session command for fitting a distribution to the data on a
probability plot
FITD [C...C]
Fits a distribution to the data on a probability plot to help you determine whether the data can be adequately
modeled by the selected distribution. To specify the distribution, go to PPLOT on page 963.
Minitab provides 14 distributions: normal, lognormal, three-parameter lognormal, gamma, three-parameter
gamma, exponential, two-parameter exponential, smallest extreme value, Weibull, three-parameter Weibull, largest
extreme value, logistic, loglogistic, and three-parameter loglogistic.
Histogram with a normal distribution
Histogram with a lognormal distribution
1024
Minitab Statistical Software Graphs
ECDF graph with a normal distribution
ECDF graph with a lognormal distribution
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
NOCI
Hides the confidence interval.
Line type, color, and size
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for fill types to use in session commands on page
1173. Enter one K for each distribution fit or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each distribution fit or store the line colors in C.
SIZE K...K
SIZE C
SIZE specifies the line width, which can be any positive number. Enter one K for each distribution fit or store the
line sizes in C.
FOOTNOTE: Session subcommand for adding a footnote to a
graph
FOOTNOTE ["footnote"]
Adds a footnote to a graph, placed in the lower left corner of the figure region by default.
If you use FOOTNOTE more than one time, each additional footnote goes below the preceding footnote.
1025
Minitab Statistical Software Graphs
For LAYOUT, the footnote goes at the lower left hand corner of the page, instead of the lower left hand corner
of the figure region.
You can suppress the default footnote with the subcommand NODFOOTNOTE.
Attributes
TFONT "font name"
TFONT specifies the font name for the footnote.
TCOLOR K
TCOLOR specifies the footnote text color, which is a number from Numbers for colors to use in session commands
on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the footnote in bold font.
NOBOLD
Specifies to not display the footnote in bold font.
UNDERLINE
Specifies to underline the footnote.
NOUNDERLINE
Specifies to not underline the footnote.
ITALIC
Specifies to display the footnote in italic font.
NOITALIC
Specifies to not display the footnote in italic font.
Positioning
LEFT (default)
Puts the footnote in the left of the figure region.
CENTER
Puts the footnote in the center of the figure region.
RIGHT
Puts the footnote in the right of the figure region.
OFFSET K K
Moves a footnote away from the position specified with LEFT, CENTER or RIGHT. The first argument specifies how
far to move the footnote horizontally (in figure units). The second argument specifies the how far to move the
footnote vertically (in figure units). The default offset is 0.0 0.0.
1026
Minitab Statistical Software Graphs
FREQUENCY: Session subcommand for using a frequency column
for a graph
FREQUENCY C...C
If your worksheet is organized appropriately, you can use a frequency column when you create a graph.
You can use one frequency column for all graph variables, or a different one for each. Frequency variables are
used in the order they are entered. Be sure they match the entry order of their corresponding graph variables.
Without a frequency column
C1
Colors
Red
Blue
Blue
Red
Red
Blue
Red
With a frequency column
C2C1
FrequencyColors
4Red
3Blue
GAPS: Session subcommand for displaying a gap in time on a
graph
GAPS
Specifies a gap to be displayed for excluded data points. GAPS is used with the INCLUDE or EXCLUDE subcommand
for graphs with time scales.
GAPS is a valid subcommand, with the use of INCLUDE or EXCLUDE for the following types of graphs:
Area graphs
Time series plots
Control charts
1027
Minitab Statistical Software Graphs
GAPWIDTH and COFFSET: Session subcommands for the space
between clusters and items in a cluster
Control the spacing between and within clusters on a multi-level categorical scale.
GAPWIDTH K
Use a value from 0 to 5 to specify the space between clusters. Using 0 minimizes the gap between the clusters,
and 5 maximizes the gap.
COFFSET K
Use a value from –1 to 1 to specify the space between items in a cluster. A negative value overlap the items, using
0 places them next to one another, and 1 maximizes the space between items.
GRAPH: Session subcommand for controlling the graph region fill
and border line
GRAPH [K K]
Controls the size, the fill type, and the fill color of the graph region, and the type, the color, and the thickness of
the border line around the graph region.
The arguments represent the width and height of the graph region, respectively, and use inches. Values for
arguments must be greater than or equal to 1 and less than or equal to 30. When used without arguments, the
graph region maintains its default size.
Fill pattern and background fill color
Specifies the fill pattern and background fill color of the graph region.
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
Graph region border
Specifies the type, color, and width of the border line.
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number. Enter one K for each bar or store the line sizes
in C.
1028
Minitab Statistical Software Graphs
MGRID, NOGRID, and NOMGRID: Session subcommands for
controlling the grid on a graph
MGRID K
Generates customizable horizontal or vertical lines that extend across the graph from the major and/or minor
positions. You must customize major and minor, x-axis, y-axis and z-axis gridlines separately.
With MGRID K, the argument 1 places gridlines on minor ticks of the x-axis, 2 places them on the y-axis. Categorical
scales do not have minor ticks and do not accept minor gridlines. 3 specifies the z-axis on 3D graphs.
SECSCALE
Use to place gridlines in relation to ticks on the secondary scale of the specified axis.
NOGRID
NOMGRID
If you've set graph preferences to display major or minor gridlines by default, use NOGRID and NOMGRID to
remove gridlines on a graph-by-graph basis.
Type, color, and size of the gridlines
Specifies the type, color, and size of the gridlines that are invoked by the preceding command.
TYPE K
Specifies the line type in K, which is a number from Numbers for line types to use in session commands on page
1173.
COLOR K
COLOR specifies the line color in K, which is a number from Numbers for colors to use in session commands on
page 1172.
SIZE
Specifies the size of the gridlines.
GROUP: Session subcommand for specifying categorical variables
for grouping
GROUP C [C...C]
Use GROUP when using two or more categorical variables with a dotplot, boxplot, interval plot, individual value
plot, or bar chart.
Specify the first grouping variable with the graph command. Specify additional grouping variables as arguments
to the GROUP subcommand.
1029
Minitab Statistical Software Graphs
GSAVE: Session subcommand for saving a graph in a file
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
HLABEL: Session subcommand for labeling histogram bars on a
marginal plot with y-axis values
HLABEL
Labels histogram bars on a marginal plot with their y-axis values.
1030
Minitab Statistical Software Graphs
POSITION K "K"
Labels individual histogram bars. The first K is the row number; the second "K" is the label. The attributes
and positioning subcommands can be used as subcommands to POSITION. You can use POSITION more
than one time.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
1031
Minitab Statistical Software Graphs
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
HLINE: Session subcommand for specifying attributes for historical
stage lines
HLINE
Specify attributes for the historical stage lines on a control chart. The HLINE attributes apply to all historical stage
lines on a chart.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number that is specified in Numbers for line types to use in session
commands on page 1173 list. Enter one K for line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number that is specified in Numbers for colors to use in session
commands on page 1172 list. Enter one K for each line or store the line colors in C.
SIZE K...K
SIZE C
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line
sizes in C.
Label attributes
LSHOW K
Specifies whether to display the label.
1032
Minitab Statistical Software Graphs
LabelValue of K
Do not display the label0
Display the label1 (default)
TFONT "font name"
TFONT specifies the text font. Enclose the font name "K" in double quotation marks.
TCOLOR K
TCOLOR specifies the label color and uses integer arguments that are specified in Numbers for colors to use in
session commands on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Label positioning
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 specifies horizontal text.
ILABEL: Session subcommand for labeling individual values on a
boxplot or interval plot
ILABEL [C]
Labels individual data values on a boxplot with text stored in C.
Labels individual data values on a boxplot or interval plot. Minitab determines the label by the main command
line argument or a subcommand.
1033
Minitab Statistical Software Graphs
Enter a column on the main command line to use labels that are stored in a column. If no argument is given
on the main command line, Minitab labels the points with their y-axis values. The label column can be numeric,
text, or date/time. Labels can be any combination of up to 80 characters, including spaces.
Minitab matches the label column to the data column by worksheet row number. If the label column contains
more values than are needed, Minitab ignores the extra labels. If the label column contains less values than
are needed, the remaining data values are not labeled.
Use the YVALUE subcommand to label data values with their y-axis value.
Use the ROWNUM subcommand to label data values with their worksheet row number.
Use the POSITION subcommand to label an individual data value. After issuing POSITION, the font and
positioning subcommands affect only the individual label until ENDPOSITION is issued.
YVALUE
Labels each data value with its y-axis value.
ROWNUM
Labels each data value with its worksheet row number.
Labeling individual data values
POSITION K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
1034
Minitab Statistical Software Graphs
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
1035
Minitab Statistical Software Graphs
INCLUDE and EXCLUDE: Session subcommands for including or
excluding rows on a graph
INCLUDE
EXCLUDE
These commands are mutually exclusive: the last one issued is honored. Choose INCLUDE or EXCLUDE based on
the degree of subsetting. For example, if you want to use all but a few select rows in creating your graph, it is
more efficient to use EXCLUDE and name a small number of rows with the ROWS subsubcommand.
ROWS K...K
List all row numbers to be included or excluded with a space between each. Denote a patterned range by
K:K/K. For example, 10:50/5 denotes all values from 10 to 50 by intervals of 5.
BRUSHED
Use to specify all brushed rows for subsetting.
WHERE "expression"
Specify a condition to be met for subsetting. This condition must be in double quotation marks. For example:
If you want to subset where C1 is 2, enter WHERE "C1 = 2".
If you want C2 = a, enter WHERE "C2 = ""a""".
If you want C3 = 3/3/18, enter WHERE "C3 = DATE(""3/3/18"")".
INDIVIDUAL: Session subcommand for displaying a symbol for
each individual data value on a boxplot or an individual value plot
INDIVIDUAL [C...C]
Displays a symbol for each individual data value on a boxplot or an individual value plot.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main DOTPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different symbol attributes.
INDPLOT C1*C2;
INDIVIDUAL C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid graphs, assigns different attributes (color, type) to the symbols representing each graph variable
and displays a legend.
Symbol type, color, and size
Specifies the symbol type, color, and size. You can enter a single K to apply to all symbols. If you use group variables,
each K applies to a single group.
1036
Minitab Statistical Software Graphs
TYPE K...K
TYPE C
TYPE specifies the symbol type, which is a number from Numbers to use for symbols and markers in session
commands on page 1174. Enter one K for each symbol or store the symbol types in C.
COLOR K...K
COLOR C
COLOR specifies the symbol color, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each symbol or store the symbol colors in C.
SIZE K
SIZE specifies the size of the symbol. Enter one K for each symbol or store the symbol types in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
INTBAR: Session subcommand for displaying a vertical line with
horizontal lines at the endpoints of the confidence interval for the
mean
INTBAR
Displays a vertical line with horizontal lines at the endpoints of the confidence interval for the mean.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main graph command line, or with
the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique value
in C2, Minitab assigns different bar attributes.
INDPLOT C1*C2;
INTBAR C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid graphs, assigns a different color to the interval bar representing each graph variable and displays
a legend.
1037
Minitab Statistical Software Graphs
CIBAR [K]
Displays the confidence interval for the mean. The default is 95. Specify the confidence level K as a proportion
(e.g. 0.95) or as a percent (e.g. 95). Enter a positive number between 0 and 100. CIBAR and ERRBAR are
mutually exclusive, Minitab honors the last one entered.
ERRBAR
Displays standard error bars with K multiples of the standard error away from the mean of each subgroup.
CIBAR and ERRBAR are mutually exclusive, Minitab honors the last one entered.
SIDE
Specifies how the error bars or confidence intervals are drawn.
How the error bars or confidence intervals are drawnValue of K
Lower one-sided−1
Two-sided0
Upper one-sided1
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies line type, which is a number from Numbers for line types to use in session commands on page
1173.Enter one K for each distribution fit or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each distribution fit or store the line colors in C.
SIZE K...K
SIZE C
SIZE specifies the line width, which can be any positive number. Enter one K for each distribution fit or store the
line sizes in C.
Bonferroni confidence intervals
NOBONFERRONI (default)
NOBONFERRONI specifies that the confidence intervals are individual confidence intervals.
BONFERRONI
Specifies to use Bonferroni confidence intervals, which applies a family confidence level to the set of intervals.
1038
Minitab Statistical Software Graphs
Pooling the standard error
NOPOOL (default)
NOPOOL (default) specifies to not pool the standard error.
POOL
Pools standard error across all subgroups instead of calculating the standard error for each subgroup separately.
If you display confidence intervals instead of standard error bars, the critical value from the t-distribution is
calculated using the pooled degrees of freedom.
Positions where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, see Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
INTLAB: Session subcommand for labeling interval bar endpoints
on an interval plot
INTLAB [C]
Labels interval bar endpoints on an interval plot. Minitab determines the label by the main command line argument
or a subcommand.
Enter a column on the main command line to use labels that are stored in a column. If no argument is given
on the main command line, Minitab labels the points with their y-axis values. The label column can be numeric,
text, or date/time. Labels can be any combination of up to 80 characters, including spaces.
Minitab assigns labels from left to right across the graph. If the label column contains more values than are
needed, Minitab ignores the extra labels. If the label column contains less values than are needed, the remaining
data values are not labeled.
Use the YVALUE subcommand to label data values with their y-axis value.
Use the POSITION subcommand to label an individual data value. After issuing POSITION, the font and
positioning subcommands only affect the individual label until ENDPOSITION is issued.
YVALUE
Labels each data value with its y-axis value.
1039
Minitab Statistical Software Graphs
Labeling individual data values
POSITION K "K"... K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
1040
Minitab Statistical Software Graphs
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
IQRBOX: Session subcommand for displaying an interquartile range
box on a boxplot
IQRBOX [C...C]
Displays an interquartile range box on a boxplot with the default box bottom at the 25th percentile and default
box top at the 75th percentile.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main BOXPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different box attributes.
BOXPLOT C1*C2;
IQRBOX C2.
VASSIGN
For ovelaid boxplots, assigns different attributes (color, fill type) to the interquartile range boxes representing
each graph variable and displays a legend.
Box edge line
Specifies the type, color, and width of the box edge line.
1041
Minitab Statistical Software Graphs
ETYPE K...K
ETYPE C
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each bar or store the line types in C.
ECOLOR K...K
ECOLOR C
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
ESIZE K...K
ESIZE C
ESIZE specifies the line width, which can be any positive number. Enter one K for each bar or store the line sizes
in C.
Box fill pattern and background fill color
Specifies the fill pattern and background fill color of the box.
TYPE K...K
TYPE C
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173. Enter one K for each bar or store the fill types in C.
COLOR K...K
COLOR C
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172. Enter one K for each bar or store the fill colors in C.
Endpoints for the box
Determines the endpoints for the box. You can only use one QUARTILE, HINGE, or PERCENTILE subcommand. If you
enter more than one, Minitab only uses the last subcommand.
QUARTILE
QUARTILE places the box endpoints at the first and third quartiles.
HINGE
HINGE places the box endpoints at the lower hinge and upper hinge.
Quartiles and hinges are both measures of the middle half of the data. The hinges may be a bit closer to the
median than the quartiles are. In practice, you would not notice this difference. However, with rare data sets
(usually small in size) the quartile method can cause the whiskers to be drawn into the box.
PERCENTILE K
PERCENTILE places the box endpoints at the specified percentile. Enter a number between 0 and 50.
1042
Minitab Statistical Software Graphs
Positions where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, see Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
JITTER and NOJITTER: Session subcommands for randomly
offsetting data points to reveal overlapping points
JITTER [K K]
JITTER [K K K]
Randomly offsets data points to reveal overlapping points. The first K is the x-axis range and the second K is the
y-axis range. For 3D plots, the third K is the z-range. The proportion constants control the maximum distance
jittered. Enter a value between 0 and 1 for the x- and y-axis ranges, respectively.
BASE K
Sets the starting point for Minitab's random number generator. The generator uses this starting point until
you set a new BASE or exit Minitab. To create a graph with the same jitter, use BASE with the same starting
point K, provided the number of data values remains constant.
NOJITTER
Turns off JITTER.
LAYOUT and ENDLAYOUT: Session subcommands for specifying
where a graph appears on a page
Specify where one or more graphs appear on one page. In LAYOUT mode, subsequent graphs that you create are
displayed on a single page. After you create all the graphs you want, take Minitab out of LAYOUT mode and display
the page by using ENDLAYOUT.
By default, Minitab places each graph at the same page coordinates, one on top of the other as if you were stacking
transparencies, unless you specify different coordinates for each graph using the FIGURE subcommand.
You can annotate a page with titles, footnotes, text, symbols, lines, and polygons that are not specific to any graph,
or make text charts and drawings without any graphs on them at all.
The following commands generate a single graph page with a bar chart in the top half and a time series graph in the
bottom. The layout is titled "Sales Figures: 2015–2016."
LAYOUT;
TITLE "Sales Figures: 2015-2016".
CHART ('Sales') * 'Year';
SUMMARIZED;
BAR;
FIGURE 0 1 0.5 1.
1043
Minitab Statistical Software Graphs
TSPLOT 'Sales';
FIGURE 0 1 0 0.5.
LAYOUT
Begins a graph layout.
ENDLAYOUT
Ends a graph layout.
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Labels
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Regions
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LBRIGHT: Session subcommand for specifying the brightness of
the lights that illuminate a surface plot
LBRIGHT K
Specifies the brightness (as an integer from 0 to 100) of the lights that illuminate the surface. LBRIGHT has no
effect when WIREFRAME is used.
1044
Minitab Statistical Software Graphs
LEGEND and NOLEGEND: Session subcommands for controlling
the legend on a graph
LEGEND [K K K K]
Controls the size and placement of the legend within the figure region, the fill type and color of the legend, the
type, color and thickness of the edge line around the legend, the font characteristics of the legend text, and the
legend text displayed.
The arguments represent the x-minimum, x-maximum, y-minimum, and y-maximum values for the legend,
respectively, and use figure units which range from 0 to 1. When used without arguments, the legend maintains
its default size.
NOLEGEND
Use NOLEGEND to hide the legend.
Pattern and color of the legend background
Specifies the pattern and color of the legend background.
TYPE K
TYPE specifies the background fill pattern, which is a number from Numbers for fill types to use in session
commands on page 1173.
COLOR K
COLOR specifies the background fill color, which is a number from Numbers for colors to use in session commands
on page 1172.
Type, color, and size of the legend border
Specifies the type, color, and width of the legend border.
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number.
Font, color, size, and style of the legend body text
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
1045
Minitab Statistical Software Graphs
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
Font, color, size, and style of the legend header text
HFONT "font name"
TFONT specifies the font name for the text.
HCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
HTSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
HPSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
HBOLD
Specifies to display the text in bold font.
HNOBOLD
Specifies to not display the text in bold font.
HUNDERLINE
Specifies to underline the footnote.
HNOUNDERLINE
Specifies to not underline the text.
HITALIC
Specifies to display the text in italic font.
1046
Minitab Statistical Software Graphs
HNOITALIC
Specifies to not display the text in italic font.
Section number and section title
SECTION K
Specifies the section number.
STITLE "string"
Specify the section title.
CHEADER K "string"
Specify the header for column K.
BTEXT K K "string"
Specify the text for table row number K and column K.
STHIDE
Hide the section title.
CHHIDE
Hide the column headers.
RHIDE K...K
Hide row numbers K...K.
CHIDE K...K.
Hide table columns K...K.
LIGHT: Session subcommand for specifying the position, color,
and visibility of the lights that illuminate a surface plot
LIGHT K K K K
Specifies the position, color, and visibility of the lights illuminating the surface.
The first argument for LIGHT specifies the number of the light (1, 2, or 3). The remaining arguments specify the
position of the light in x-, y-, and z-coordinates. For example, LIGHT 1 0 0 1 specifies that light 1 is to be
centered on the x- and y-axes, one unit above the surface in the positive z-direction.
LIGHT has no effect when WIREFRAME is used.
COLOR K
COLOR specifies the color of the light in K, which is a number from Numbers for colors to use in session
commands on page 1172.
VISIBILITY K
VISIBILITY specifies whether the light is on (0) or off (1).
1047
Minitab Statistical Software Graphs
LINE: The session subcommand for constructing a line from points
on a graph
LINE K K...K K
LINE C C
Creates a line on a graph and controls attributes of the line.
You can also put lines anywhere on a graph by using graph editing. Using the graph editing is often easier, unless
you want to repeatedly produce a graph with lines in the same positions, or you want to place a line in an exact
location with predefined points. The REFERENCE on page 1073 subcommand is well suited to drawing horizontal
and vertical reference lines and their labels in the data region. Use LINE for miscellaneous annotation lines.
To specify single lines, use the x y-coordinates of the line's start point for the first pair of arguments and the x
y-coordinates of the line's end point for the second pair of arguments.
For a polyline, simply continue to add x y-coordinate pairs. For a polyline with many points, you can put x-arguments
in one column, y-arguments in another and specify both columns.
To specify an x-axis coordinate that represents categories (as with CHART) in data units, specify the categories as
axis positions 1, 2, ..., c (where c is the total number of categories) as they appear on the graph from left to right.
You can specify points between categories. For example, a point midway between the third and fourth categories
at location 44 on the y-axis would be 3.5 44.
LESTYLE K K
Specifies a starting and ending arrow style. The first argument specifies the line's starting arrow style, the
second its ending arrow style. Use 0 for no arrow, 1 for a thin arrow, 2 for medium, and 3 for thick.
UNIT K
Specifies the unit system used by LINE and allows the use of data units in placing lines.
To place lines using figure units, use the argument 0. Use 1 to specify data units.
In cases of paneled graphs (including matrix plots), you may still place lines using data units if you also specify
the panel with the UNIT command. UNIT 1 for example will place the line relative to the first panel of the
graph and will read the LINE arguments in the data units of the first panel. You may choose to associate the
placement of annotation with data units or figure units to accommodate changes in scales or graph size. As
a subcommand to LAYOUT, LINE always uses graph units.
Type, color, and size of the line
Specifies the type, color, and size of the line.
TYPE K
TYPE specifies the line type in K, which is a number from Numbers for line types to use in session commands on
page 1173.
COLOR K
COLOR specifies the line color in K, which is a number from Numbers for colors to use in session commands on
page 1172.
SIZE K
For SIZE, use a value that is greater than 0.
1048
Minitab Statistical Software Graphs
LOWESS: Session subcommand for fitting a LOWESS smoother to
a scatterplot, a matrix plot, a histogram, or a time series plot
LOWESS [C...C]
Fits a lowess smoother to the data, where C...C can specify up to 3 grouping variables. When you use grouping
variables, LOWESS generates a separately smoothed line for each group.
Fits a LOWESS smoother to a scatterplot, matrix plot, histogram, or time series plot. You can use a lowess smoother
to explore the relationship between two variables without fitting a specific model. You can use LOWESS more
than one time in a graph, each using different parameters.
Type, color, and size of the LOWESS line
Specifies the type, color, and size of the line.
TYPE K...K
TYPE C
TYPE specifies the line type in K, which is a number from Numbers for line types to use in session commands on
page 1173. Enter one K for each lowess smoother or store the line types in C.
COLOR K
COLOR C
COLOR specifies the line color in K, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each lowess smoother or store the line colors in C.
SIZE K
SIZE C
Specifies the line width, which can be any positive number. Enter one K for each lowess smoother or store the
line sizes in C.
Algorithm
F K
Specifies the fraction K of the total number of points used to calculate the fitted values at each x-value. K can be
any number from 0 to 1. The default is 0.5.
NSTEPS K
Specifies the number of iterations of smoothing used to limit the influence of outliers on the smoothed y-values.
Each step reduces the weights given to outliers in the next iteration of weighted linear regression, based on the
size of residuals in the previous lowess step. K can be any integer from 0 to 10. The default is 2. Some statisticians
suggest that two robust steps adequately smooth outlier effects for most data.
Storage
Stores the fits and residuals for the lowess line. Not available for matrix plot or when the main command is in a LAYOUT.
FITS C...C
FITS stores the fitted values (new y-values) that comprise the lowess smoother.
1049
Minitab Statistical Software Graphs
RESIDUALS C...C
RESIDUALS stores the residual values (original y-values minus the fitted values).
If you specify one graph, specify a single column, even if you use groups with LOWESS. If you specify more than
one graph, specify a residual column for each graph. The number of argument columns must be equal to the
number of response columns.
You cannot store fits or residuals for matrix plot or when the graph is in a LAYOUT.
MARKER: Session subcommand for displaying a symbol at specified
points on a graph
MARKER K K
MARKER C C
Specify the location of a marker.
MARKER displays a symbol (or marker) at the points specified in the subcommand.
You can also put markers anywhere on a graph using graph editing. Using the graph editing features is often
easier, unless you want to repeatedly produce a graph with markers in the same positions, or you want to place
markers in exact locations using predefined points.
UNIT K
Specifies the unit system used by MARKER and allows the use of data units in placing markers.
If you want to place markers using figure units, use the argument 0. Use 1 to specify data units.
With paneled graphs (including matrix plots), you can still place markers using data units if you also specify
the panel with the UNIT command. For example, UNIT 1 places the marker relative to the first panel of the
graph and reads the MARKER arguments in the data units of the first panel. You can associate the placement
of annotation with data units or figure units to accommodate changes in scales or graph size. As a
subcommand to LAYOUT, MARKER always uses graph units.
Marker type, color, and size
Specifies the marker type, color, and size.
TYPE K
TYPE specifies marker type in K, which is a number from Numbers to use for symbols and markers in session
commands on page 1174.
COLOR K
COLOR specifies the marker color, which is a number from Numbers for colors to use in session commands on
page 1172.
SIZE K
For the marker size, choose a value greater than 0 and less than or equal to 15.
1050
Minitab Statistical Software Graphs
MEALAB: Session subcommand for labeling means on a boxplot
or an interval plot
MEALAB [C]
Labels means on boxplot or interval plot. Minitab determines the label by the main command line argument or
a subcommand.
Enter a column on the main command line to use labels that are stored in a column. If no argument is given
on the main command line, Minitab labels the points with their y-axis values. The label column can be numeric,
text, or date/time. Labels can be any combination of up to 80 characters, including spaces.
Minitab assigns labels from left to right across the graph. If the label column contains more values than are
needed, Minitab ignores the extra labels. If the label column contains less values than are needed, the remaining
data values are not labeled.
Use the YVALUE subcommand to label data values with their y-axis value.
Use the POSITION subcommand to label an individual data value. After issuing POSITION, the font and
positioning subcommands only affect the individual label until ENDPOSITION is issued.
YVALUE
Labels each data value with its y-axis value.
Labeling individual data values
POSITION K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
1051
Minitab Statistical Software Graphs
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
1052
Minitab Statistical Software Graphs
MEAN: Session subcommand for displaying symbol for each mean
on a boxplot, interval plot, or individual value plot
MEAN [C...C]
Displays a symbol for each mean on a boxplot, interval plot, or individual value plot. The subcommands of MEAN
allow you to control attributes (symbol type, color, size) for symbols (or groups of symbols) that represent means
on a graph.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main BOXPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different symbol attributes.
BOXPLOT C1*C2;
MEAN C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid graphs, assigns a different color to the mean symbol that represents each graph variable and
displays a legend.
Symbol type, color, and size
Specifies the symbol type, color, and size. You can enter a single K to apply to all symbols. If you use group variables,
each K applies to a single group.
TYPE K...K
TYPE C
TYPE specifies the symbol type, which is a number from Numbers to use for symbols and markers in session
commands on page 1174. Enter one K for each symbol or store the symbol types in C.
COLOR K...K
COLOR C
COLOR specifies the symbol color, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each symbol or store the symbol colors in C.
SIZE K
SIZE specifies the size of the symbol. Enter one K for each symbol or store the symbol types in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
1053
Minitab Statistical Software Graphs
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
MEDIAN: Session subcommand for displaying a symbol for each
median on a boxplot, interval plot, or individual value plot
MEDIAN [C...C]
Displays a symbol for each median on a boxplot, interval plot, or individual value plot. The subcommands of
MEDIAN allow you to control attributes (symbol type, color, size) for symbols (or groups of symbols) that represent
medians on a graph.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main BOXPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different symbol attributes.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid graphs, assigns a different color to the median symbol that represents each graph variable and
displays a legend.
Symbol type, color, and size
Specifies the symbol type, color, and size. You can enter a single K to apply to all symbols. If you use group variables,
each K applies to a single group.
TYPE K...K
TYPE C
TYPE specifies the symbol type, which is a number from Numbers to use for symbols and markers in session
commands on page 1174. Enter one K for each symbol or store the symbol types in C.
COLOR K...K
COLOR C
COLOR specifies the symbol color, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each symbol or store the symbol colors in C.
SIZE K
SIZE specifies the size of the symbol. Enter one K for each symbol or store the symbol types in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
1054
Minitab Statistical Software Graphs
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
MEDLAB: Session subcommand for labeling medians on a boxplot
MEDLAB [C]
Labels medians on a boxplot. Minitab determines the label by the main command line argument or a subcommand.
Enter a column on the main command line to use labels that are stored in a column. If no argument is given
on the main command line, Minitab labels the points with their y-axis values. The label column can be numeric,
text, or date/time. Labels can be any combination of up to 80 characters, including spaces.
Minitab assigns labels from left to right across the graph. If the label column contains more values than are
needed, Minitab ignores the extra labels. If the label column contains less values than are needed, the remaining
data values are not labeled.
Use the YVALUE subcommand to label data values with their y-axis value.
Use the POSITION subcommand to label an individual data value. After issuing POSITION, the font and
positioning subcommands only affect the individual label until ENDPOSITION is issued.
YVALUE
Labels each data value with its y-axis value.
Labeling individual data values
POSITION K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
1055
Minitab Statistical Software Graphs
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
1056
Minitab Statistical Software Graphs
NODOTFOOTNOTE: Session subcommand for suppressing
footnotes on a dotplot
NODOTFOOTNOTE
Suppresses the default footnotes on a dotplot.
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session
subcommands for suppressing titles, subtitles, and footnotes on
a graph
NODTITLE
Suppresses default titles. NODTITLE does not work when you use LAYOUT.
NODSUBTITLE
Suppresses default subtitles.
NODFOOTNOTE
Suppresses default footnotes.
Note For an interval plot, use NOINTFOOTNOTE to suppress the footnote.
NOEMPTY and NOMISS: Session subcommands for excluding
missing data from graphs
NOEMPTY
Exclude empty values from attribute assignment rotation. Any combination of group levels that do not contain
data are not assigned attributes. By default, groups that have empty values are included in attribute assignment
rotation.
NOMISS
Exclude missing groups from the graph that is being created. If there is a group with a missing level for any group
combination, then that row is excluded from the graph. By default, groups with missing levels are included in the
graph.
NOFRAME: Session subcommand for suppressing lines and labels
on a graph
NOFRAME
Specifies to suppress axis lines and labels, tick lines and labels, reference lines and labels, and grid lines in a graph.
1057
Minitab Statistical Software Graphs
NOHLEGEND: Session subcommand for suppressing the legend
of hold values on a graph
NOHLEGEND
Use NOHLEGEND to suppress display of the legend of hold values.
NOPERFOOTNOTE: Session subcommand for suppressing My
Footnote
NOPERFOOTNOTE
Suppresses the personal footnote stamped on a graph when set up in File > Options > Graphics > Annotation
> My Footnote.
NOSEPSUBTITLE: Session subcommand for subtitles on separate
graphs
NOSEPSUBTITLE
Suppresses default subtitles on separate graphs when you make multiple graphs.
OLAB: Session subcommand for labeling outliers on a boxplot
OLAB [C]
Labels outliers on a boxplot. Minitab determines the label by the main command line argument or a subcommand.
Enter a column on the main command line to use labels that are stored in a column. If no argument is given
on the main command line, Minitab labels the points with their y-axis values. The label column can be numeric,
text, or date/time. Labels can be any combination of up to 80 characters, including spaces.
Minitab assigns labels from left to right across the graph. If the label column contains more values than are
needed, Minitab ignores the extra labels. If the label column contains less values than are needed, the remaining
data values are not labeled.
Use the YVALUE subcommand to label data values with their y-axis value.
Use the ROWNUM subcommand to label data values with their worksheet row number.
Use the POSITION subcommand to label an individual data value. After issuing POSITION, the font and
positioning subcommands only affect the individual label until ENDPOSITION is issued.
YVALUE
Labels each data value with its y-axis value.
ROWNUM
Labels each data value with its worksheet row number.
1058
Minitab Statistical Software Graphs
Labeling individual data values
POSITION K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
1059
Minitab Statistical Software Graphs
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
OUTLIER: Session subcommand for displaying a symbol for each
outlier on a boxplot
MEAN [C...C]
Displays a symbol for each outlier on a boxplot, where C...C can specify up to 4 grouping variables, and restores
outlier symbols when another data display command turns them off (for example, if you type IQRBOX, OUTLIER
is turned off).
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main BOXPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different symbol attributes.
BOXPLOT C1*C2;
OUTLIER C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid graphs, assigns a different color to the mean symbol that represents each graph variable and
displays a legend.
Symbol type, color, and size
Specifies the symbol type, color, and size. You can enter a single K to apply to all symbols. If you use group variables,
each K applies to a single group.
1060
Minitab Statistical Software Graphs
TYPE K...K
TYPE C
TYPE specifies the symbol type, which is a number from Numbers to use for symbols and markers in session
commands on page 1174. Enter one K for each symbol or store the symbol types in C.
COLOR K...K
COLOR C
COLOR specifies the symbol color, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each symbol or store the symbol colors in C.
SIZE K
SIZE specifies the size of the symbol. Enter one K for each symbol or store the symbol types in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
OVERLAY: Session subcommand for combining graphs specified
in a multiple graph command into a single graph
OVERLAY
When you create multiple graphs with the same command, use OVERLAY to specify that they display on the same
data region.
OVERLAY displays the graph variables on the same graph and assigns different attributes to each. A legend is
produced to link the different data representations to the graph variables.
When overlaying charts, dotplots, interval plots, individual value plots, or boxplots, OVERLAY causes the graph
variables to be treated as groups on a single scale level.
PANEL: Session subcommand for paneling graphs
PANEL [C...C]
PANEL is used in several ways. Use it to panel multiple graphs together, or to divide a single graph into panels
defined by a paneling variable. You can also combine these methods and panel both by graph variables and
groups.
Used without an argument, PANEL specifies the placement of multiple graphs created with a single graph command.
Arguments to PANEL are By variables that split the graph.
1061
Minitab Statistical Software Graphs
SPLIT K
Split the data of a time series plot or area graph into panels. Available only with time series plot and area
graph when a group variable is not entered in the PANEL subcommand. SPLIT separates sets of K data into
panels. This subcommand is especially useful with vary large data sets or cycling data. SPLIT is available as
a subcommand to control charts.
NOALTERNATE
By default, Minitab places the ticks of adjacent panels on alternating sides of the graph. Invoking
NOALTERNATE places ticks on the same side of adjacent panels.
Panel order
Use one of these subcommands when you have paneled both by model and by a paneling variable.
VFIRST
Use one of these subcommands when you have paneled both by model and by a paneling variable. VFIRST
arranges panels by model first. Thus, when read left to right each row displays one model with a varying paneling
variable.
VLAST
VLAST reverses this arrangement.
Row and column configuration
Specify the row and column configuration as well as the margins separating them.
RC K K
RC takes two arguments to customize the panel layout. The first specifies the number of rows in the layout, the
second specifies the number of columns.
MARGIN K
The optional MARGIN specifies the margin size separating all panels. Use a value from 0 to 0.25.
Label type, font, style, color, and size
Specify the label type, font, style, color, and size.LABEL
TYPE K [K]
Specify the degree of information to include in the panel labels. The first argument to TYPE refers to Y–X
information, the second to group information.
Degree of Y–X information to include in the panel labelsValue of the first K
No Y–X information0
Y and X information1
Y information2
X information3
Degree of group variable information to include in the panel labelsValue of the second K
No group variable information0
Group level information1
1062
Minitab Statistical Software Graphs
Degree of group variable information to include in the panel labelsValue of the second K
Group variable and level information2
TFONT "font name"
TFONT specifies the font name for the labels.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands
on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
POLYGON: Session subcommand for constructing a polygon from
points on a graph
POLYGON K K...K K
POLYGON C C
POLYGON constructs a polygon from the points specified in the subcommand. Each pair of arguments defines a
vertex of the polygon. The first argument of a pair is the x-coordinate, the second, the y-coordinate. The first and
last points connect to close the polygon.
For a polygon with many points, you can put x-arguments in one column, y-arguments in another and specify
both columns.
To specify an x-axis coordinate when the x-axis represents categories (as with CHART), specify the categories as
axis positions 1, 2, ..., c (where c is the total number of categories) as they appear on the graph from left to right.
You can specify points between categories. For example, a point midway between the third and fourth categories
at location 44 on the y-axis would be 3.5 44.
1063
Minitab Statistical Software Graphs
You can also put polygons anywhere on a graph using the graph editing features. Using the graph editing features
is often easier, unless you want to repeatedly produce a graph with polygons in the same positions, or you want
to place a polygon in an exact location using predefined points.
When POLYGON is a direct subcommand of LAYOUT on page 1043, use page units to specify the argument pairs.
UNIT K
To place polygons using figure units, use the argument 0. Use 1 to specify data units.
With paneled graphs (including matrix plots), you can still place polygons using data units if you also specify
the panel with the UNIT command. For example, UNIT 1 places the polygon relative to the first panel of the
graph and reads the POLYGON arguments in the data units of the first panel. You can associate the placement
of annotation with data units or figure units to accommodate changes in scales or graph size. As a
subcommand to LAYOUT, POLYGON always uses graph units.
Fill pattern and background fill color
Specifies the fill pattern and background fill color of the polygon.
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
Type, color, and width of the line
Specifies the type, color, and size of the polygon's edge.
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number. Enter a value that is greater than 0.
PROJECT: Session subcommand for extending projection lines
from each point to the x-axis
PROJECT [C...C]
Extends projection lines from each point down to the horizontal, or x-axis.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
1064
Minitab Statistical Software Graphs
Grouping columns must be categorical variables that are included on the main graph command line, or with
the GROUP subcommand. In the following example, C3 is the grouping column, and, for each unique value
in C3, Minitab assigns different line attributes and symbol attributes.
PLOT C1*C2;
PROJECT C3.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid graphs, assigns a different color to the mean symbol that represents each graph variable and
displays a legend.
DIRECTION
Specifies the direction the project lines extends away from the data values. DIRECTION does not apply to
HISTOGRAM.
Direction of the linesValue of K
Extends horizontally from the data values to the base (the yz-plane for 3D graphs)1
Extends from the data values to the base (the xz-plane for 3D graphs) (default for 2D
graphs)
2
Extends vertically from the data values to the base (the xy-plane for 3D graphs)3
BASE
Specifies the for the project lines. For more information, go to Base position for project lines, area, and bar
on page 1134. Project lines extend from the data value to the base. The default base is the minimum data value
for the y-scale.
Enter one K for each base or store the bases in C. If one value is specified it applies to all points.
You can draw a base line by using REFERENCE on page 1073.
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each line or store the line types in C.
SIZE K
SIZE specifies the line width. Enter one K for each line or store the line types in C.
1065
Minitab Statistical Software Graphs
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
PROPORTIONAL and NOPROPORTIONAL: Session subcommands
for making the boxes on a boxplot proportional to the square root
of the number of observations in the boxes
PROPORTIONAL
Makes the width of each box on a boxplot proportional to the square root of the number of observations in the
box.
NOPROPORTIONAL (default)
Returns the box to the standard width.
PTILES: Session subcommand for specifying the location of the
percentile lines on a graph
PTILES K [K...K]
PTILES generates reference lines on percentile scales. A percentile line runs from the percentile scale to the
distribution fit, and then to its corresponding point on the data value scale. The points on both scales are labeled.
A percentile line is placed for each argument given. Arguments are in percentiles.
DVALUE
Specifies that the argument to the previous PTILES subcommand are not percentiles, but data values.
PSHOW K
Specifies the percentile line label display.
Percentile lines that are displayedValue of K
Hide labels0
Show both labels1 (default)
Show x-scale label2
Show y-scale label3
1066
Minitab Statistical Software Graphs
MODEL K
Use only when you create multiple graphs with a single command. Allows you to apply its related subcommand
and subsubcommands to a specific graph. The argument refers to the order the graphs are created. MODEL
1 affects the first graph created, MODEL 2 the second graph, and so on.
Attributes for all labels
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
Attributes for percentile line labels
PLABEL [K]
Customize the label corresponding to the PTILE argument. Use any subcommands (TFONT through PLACEMENT)
to customize the percentile line label, then issue ENDLABEL.
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands
on page 1172.
1067
Minitab Statistical Software Graphs
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how
far to move the label horizontally (in figure units). The second argument specifies the how far to move the
label vertically (in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default
value of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve
certain angle effects.
PPOSITION K and ENPPOSITION
Specifies the panel position for customizing a particular percentile line label or information label. PPOSITION
3 would refer to the third panel.
When customizing a percentile line label, use ANGLE, OFFSET, or PLACEMENT subcommands by panel position
to modify the label then issue ENPPOSITION.
1068
Minitab Statistical Software Graphs
ENDLABEL
Specifies the end of the PLABEL command.
Attributes for information labels
ILABEL
Specifies the value (information label) calculated by Minitab given the PTILE value.
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands
on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
1069
Minitab Statistical Software Graphs
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how
far to move the label horizontally (in figure units). The second argument specifies the how far to move the
label vertically (in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default
value of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve
certain angle effects.
STRING
Specify text (in quotation marks if a supplied constant) for a particular information label, for example, "50th
percentile."
PPOSITION K and ENPPOSITION
Specifies the panel position for customizing a particular percentile line label or information label. PPOSITION
3 would refer to the third panel.
When customizing a percentile line label, use ANGLE, OFFSET, or PLACEMENT subcommands by panel position
to modify the label then issue ENPPOSITION.
GPOSITION K and ENGPOSITION
Specifies the panel position for customizing a particular information label. GPOSITION 3 would refer to
the third group. Use any subcommands (TFONT through STRING) by panel position to modify the
information label then issue ENGPOSITION.
ENDLABEL
Specifies the end of the ILABEL command.
RBOX: Session subcommand for displaying a range box on a
boxplot
RBOX [C...C]
Displays a range box on a boxplot that extends from the minimum to the maximum data value, where C...C can
specify up to 4 grouping variables.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
Grouping columns must be categorical variables that are included on the main BOXPLOT command line, or
with the GROUP subcommand. In the following example, C2 is the grouping column, and, for each unique
value in C2, Minitab assigns different box attributes.
BOXPLOT C1*C2;
RBOX C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN K...K
VASSIGN C
For overlaid boxplots, assigns different attributes (color, fill type) to the range boxes representing each graph
variable and displays a legend.
1070
Minitab Statistical Software Graphs
Fill pattern and background fill color of the box
Specifies the fill pattern and background fill color of the box.
TYPE K...K
TYPE C
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173. Enter one K for each bar or store the fill types in C.
COLOR K...K
COLOR C
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172. Enter one K for each bar or store the fill colors in C.
Type, color, and width of box edge line
ETYPE K...K
ETYPE C
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each bar or store the line types in C.
ECOLOR K...K
ECOLOR C
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each bar or store the line colors in C.
ESIZE K...K
ESIZE C
ESIZE specifies the line width, which can be any positive number. Enter one K for each bar or store the line sizes
in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
1071
Minitab Statistical Software Graphs
RECTANGLE: Session subcommand for constructing a rectangle
from points on a graph
RECTANGLE K K K K [K K K K]
RECTANGLE displays a rectangle at the points specified in the subcommand.
You can also put a rectangle anywhere on a graph using graph editing. Using the graph editing features is often
easier, unless you want to place a rectangle in exact locations using predefined points.
A rectangle is defined by either four or eight arguments. Four arguments are used to represent the lower left and
upper right coordinates (X Y X Y) when the rectangle is a square. This is sufficient for squares that are not rotated
or are rotated exactly 90 degrees. If eight parameters are entered they represent X Y coordinates (lower left, lower
right, upper right, upper left) for the four corners of the rectangle.
UNIT K
To place rectangles using figure units, use the argument 0. Use 1 to specify data units.
With paneled graphs (including matrix plots), you can still place rectangles using data units if you also specify
the panel with the UNIT command. For example, UNIT 1 places the rectangle relative to the first panel of
the graph and reads the RECTANGLE arguments in the data units of the first panel. You can associate the
placement of annotation with data units or figure units to accommodate changes in scales or graph size. As
a subcommand to LAYOUT, RECTANGLE always uses graph units.
Fill pattern and background fill color
Specifies the fill pattern and background fill color of the rectangle.
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
Type, color, and width of the line
Specifies the type, color, and size of the rectangle's edge.
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number. Enter a value that is greater than 0.
1072
Minitab Statistical Software Graphs
REFERENCE: Session subcommand for specifying the axis and
location of reference lines on a graph
REFERENCE K [K...K]
REFERENCE K C
REFERENCE generates horizontal and vertical reference lines and their labels.
The first argument specifies the axis (1 = x-axis, 2 = y-axis, 3 = z-axis) at which the REFERENCE lines start/end.
The arguments that follow give the locations of the reference lines in data units (K) or a column (C) that contains
the locations of the reference lines in data units. If you specify a scale transformation, be sure to use the new scale
units when placing reference lines. With a log transformation, reference line locations are in transformed units;
with a power transformation, transformed units.
Label attributes
SECSCALE
Places the reference line in reference to the secondary scale of the stated axis.
SIDE K
Specifies the side where the reference line label is placed.
LABEL "label"..."label"
LABEL C
Specifies custom reference line labels or a column where the labels are located.
TFONT K
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
1073
Minitab Statistical Software Graphs
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
Label positioning
MODEL K
Use MODEL only when you create multiple graphs with a single command. Allows you to apply its related
subcommand and subsubcommands to a specific graph. The argument refers to the order the graphs are created.
MODEL 1 affects the first graph created, MODEL 2 the second graph, and so on.
PPOSITION and ENPPOSITION
Specifies the panel position for customizing a particular reference line label. PPOSITION 3 would refer to the third
panel label. Use ANGLE, OFFSET, or PLACEMENT subcommands to modify the label then issue ENPPOSITION.
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
1074
Minitab Statistical Software Graphs
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each line or store the line types in C.
SIZE K
SIZE specifies the line width. Enter one K for each line or store the line types in C.
REGRESS: Session subcommand for fitting a regression line to data
on a graph
REGRESS [C...C]
Fits a regression line to the data, where C...C can specify up to 3 grouping variables. If you use grouping variables,
REGRESS generates a separately smoothed line for each group.
Use to fit a least squares regression line to a scatterplot or matrix plot. Use the regression line to examine the
relationship between the response variable (y) and the predictor variable (x). If you hover the mouse pointer over
the fitted line, Minitab displays the equation. You can use REGRESS more than once in a graph, each with a different
polynomial order.
NOCONSTANT
Omits the b
o
term (the intercept) from the equation. For example, for the default linear model, Minitab fits:
Y = β
1
X
1
+ e
RPOLY K
Specifies the order of the regression model.
Order of the regression modelValue of K
Fits a linear model1
Fits a quadratic model2
Fits a cubic model3
Line type, color, and size
Specifies the line type, color, and size.
TYPE K...K
TYPE C
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173. Enter one K for each line or store the line types in C.
COLOR K...K
COLOR C
COLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172. Enter one K for each line or store the line types in C.
1075
Minitab Statistical Software Graphs
SIZE K...K
SIZE C
SIZE specifies the line width, which can be any positive number. Enter one K for each regression fit or store the
line sizes in C.
SAME: Session subcommand for specifying that one or more axes
are the same for multiple graphs
Specify that one or more axes are the same when creating multiple graphs.
SAME 1 makes the x-scale the same for all graphs. SAME 2 makes the y-scale the same. SAME 2 for dotplot means
the same number of data values per dot. SAME 1 2 makes the x- and y-scales the same.
SAME does not work for graphs with categorical or time scales.
SCALE: Session subcommand for customizing the axes and ticks
of a graph
SCALE K
Use the argument 1 to denote the x-axis, 2 for the y-axis, 3 for the z-axis. All subcommands that follow will affect
this scale.
LDISPLAY K K K K
LDISPLAY refers to the low sides of the scales (bottom and left side). The four arguments refer to the axis
line, major ticks, major tick labels, and minor ticks, respectively. For categorical and time scales, the fourth
argument is ignored. The argument 1 displays the corresponding item, 0 hides it.
HDISPLAY K K K K
HDISPLAY refers to the high (top and right) sides. The four arguments refer to the axis line, major ticks, major
tick labels, and minor ticks, respectively. For categorical and time scales, the fourth argument is ignored. The
argument 1 displays the corresponding item, 0 hides it.
SECSCALE C...C
Displays a secondary scale when you have multiple x or y variables on the same graph. Useful when overlaying
graphs with dissimilar scales. In the following example, C1 is the primary y-variable and C3 is the secondary
y-variable. Available only with the continuous scales of overlaid scatterplots and time series plots.
PLOT C1*C2 C3*C2;
SCALE 2;
SECSCALE C3;
OVERLAY.
MIN K
Set the minimum value for the scale. For continuous scales only. This subsubcommand replaces the
subcommand MINIMUM. Not available with categorical scales.
MAX K
Set the maximum value for the scale. For continuous scales only. This subsubcommand replaces the
subcommand MAXIMUM. Not available with categorical scales.
1076
Minitab Statistical Software Graphs
Type, color, and size of the axis lines and ticks
TYPE K
TYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
SIZE K
SIZE specifies the size of the axis lines and ticks.
Continuous scale ticks
TICK K...K
TICK C
Set the positions for tick marks. You can list the positions individually, set a patterned range, or name a column
that contains the tick positions. The patterned range 10:50/5, for example, places ticks at every five units from 10
to 50. You cannot use both TICK and NMAJOR.
NMAJOR K
Set the number of major ticks. Minitab positions the ticks.
NMINOR K
Set the number of minor ticks between each pair of major ticks.
ORIENT K
Set the ticks to point out (K=1), in (K=2), or out and in (K=3). Not available with 3D graphs.
LENGTH K
Specify the length of the tick lines, from 0 to 0.05. Not available with 3D graphs.
Categorical and time scale ticks
TLEVEL K
Use TLEVEL to specify the units used to place ticks. The argument 1 refers to the outermost scale level, 2 to the
second outermost, and so on. TLEVEL is only available with time scales.
TSTART K
Use TSTART to specify the starting point on the given level when used in conjunction with TLEVEL, and on the
innermost level in all other cases. The argument 2 to refer to the month scale gives a starting point of February.
When referring to a non-time variable, the starting point is the second value on the innermost scale.
TINCREMENT K
Use TINCREMENT to specify the frequency of the ticks. The argument 2 places ticks at every other value on the
innermost level or the one set with TLEVEL.
1077
Minitab Statistical Software Graphs
Tick labels
LABEL "string"..."string"
LABEL C
Specify labels for major ticks, either by listing them individually or by naming a column that contains the labels.
For categorical and time scales you need to list a single label only once and Minitab will cycle that label.
LEVEL K
Using the subsubcommand LEVEL K applies the named labels to a particular variable level on a multi- level
scale, such as a nested boxplot. The label closest to the axis is referenced by an argument value of 1, the
second closest by 2, and so on.
TFONT "font name"
TFONT specifies the font name for the labels.
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands
on page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
ANGLE K
Specify the angle of the tick labels in degrees from the horizontal.
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
TSHOW K [K [K [K]]]
Specify the tick labels displayed, by level. The level farthest from the axis is referenced by the argument 1, the
second farthest by 2, and so on. Tick labels are shown for all levels by default.
Transformations
Transform the scale. Unless you have negative values you cannot use negative arguments.
1078
Minitab Statistical Software Graphs
LOGS K
Use LOGS K (where K is an integer from 2 to 10) to specify the base of the log transformation.
LOGE
LOGE for log base e.
POWER K
POWER K (where K is an integer from −5 to 5) to specify the degree of power.
STANDARD
Use standardized units for the y-scale. You can only use this subcommand when you specify SCALE2
Model reference
When a set of SCALE subsubcommands refer to a specific model of an overlaid graph, the commands should be bound
with MODEL K and ENDMODEL K, where K refers to the model to be modified. Within SCALE, MODEL is valid with
MIN/MAX, TICK, NMAJOR, NMINOR, and LABEL.
MODEL K
Specifies the model.
ENDMODEL K
Specifies the end of the model.
SEPARATE: Session subcommand for placing groups in separate
graphs when you use a paneling variable
SEPARATE [C...C]
When you use a paneling variable, SEPARATE places the different groups in separate graphs. Arguments to
SEPARATE are By variables that split the graph into panels with one panel for each level or level combination of
the By variable.
SFIT: Session subcommand for specifying the attributes of the
surface on a 3D surface plot
SFIT
Controls the attributes of the surface on a surface plot.
COLOR K
COLOR specifies the color of the surface in K, which is a number from Numbers for colors to use in session
commands on page 1172.
ESIZE K
ESIZE specifies the wireframe width in K, which can be any positive number.
ECOLOR K
ECOLOR specifies the color of the wireframe in K, which is a number from Numbers for colors to use in session
commands on page 1172.
1079
Minitab Statistical Software Graphs
SLABEL: Session subcommand for labeling the slices on a pie chart
SLABEL
Labels slices on a pie chart. If you do not use any subcommand, Minitab labels the slices with their category name.
Label attributes and positioning subcommands can apply to all labels (as subcommands of SLABEL) or to specified
labels (as subcommands of POSITION).
PCATEGORY
Labels pie slices with their category names.
PFREQUENCY
Labels pie slices with their frequency.
PERCENT
Labels pie slices with their percentage of the whole.
PLINE
PLINE draws a line from the label to the slice.
TYPE K
TYPE specifies the line type in K, which is a number from Numbers for line types to use in session commands
on page 1173.
COLOR K
COLOR specifies the line color in K, which is a number fromNumbers for colors to use in session commands
on page 1172.
SIZE K
SIZE specifies the line width, which can be any positive number. Enter one K for each line or store the line
sizes in C.
Labeling individual data values
POSITION K "K"
Labels individual data values. The first K is the row number; the second "K" is the label. The attributes and positioning
subcommands can be used as subcommands to POSITION. You can use POSITION more than one time.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all labels. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
Label font, color, and size
TFONT "font name"
TFONT specifies the font name for the labels.
1080
Minitab Statistical Software Graphs
TCOLOR K
TCOLOR specifies the label color, which is a number from Numbers for colors to use in session commands on
page 1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the label
BOLD
Specifies to display the label in bold font.
NOBOLD
Specifies to not display the label in bold font.
UNDERLINE
Specifies to underline the label.
NOUNDERLINE
Specifies to not underline the label.
ITALIC
Specifies to display the label in italic font.
NOITALIC
Specifies to not display the label in italic font.
Positioning
Specifies the placement of the label in relationship to the anchor position.
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
SLICE: Session subcommand for specifying the attributes of slices
on a pie chart
SLICE
Specifies the attributes of slices on a pie chart.
1081
Minitab Statistical Software Graphs
POSITION K...K
Lists the positions where subsequent subcommands apply. Any slice subcommand can be used with POSITION.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all slices.
Type and color of the slices
TYPE K
TYPE specifies the fill pattern, which is a number from Numbers for fill types to use in session commands on page
1173.
COLOR K
COLOR specifies the background color, which is a number from Numbers for colors to use in session commands
on page 1172.
Type, color, and size of the slice edge lines
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number. Enter a value that is greater than 0.
Separating the slices
EXPLODE
EXPLODE separates the slices from one another by moving them out radially from the center by LENGTH K.
LENGTH K
Enter a value between 0 and 1 for the LENGTH argument.
SOFFSET: Session subcommand for offsetting points from the
center
SOFFSET
Offsets identical points symmetrically from the center.
1082
Minitab Statistical Software Graphs
STAMP: Session subcommand for specifying columns that contain
time values for observations
STAMP C [C...C]
Specify up to three columns that contain the time values for the observations.
SUBTITLE: Session subcommand for adding a subtitle to a graph
SUBTITLE ["subtitle"]
Adds a subtitle to a graph. Using SUBTITLE with no argument displays the default subtitle. Using SUBTITLE one
time with an argument overwrites the default subtitle.
Font, color, and size of the subtitle
TFONT "font name"
TFONT specifies the text font.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the subtitle
BOLD
Specifies to display the subtitle in bold font.
NOBOLD
Specifies to not display the subtitle in bold font.
UNDERLINE
Specifies to underline the subtitle.
NOUNDERLINE
Specifies to not underline the subtitle.
ITALIC
Specifies to display the subtitle in italic font.
NOITALIC
Specifies to not display the subtitle in italic font.
1083
Minitab Statistical Software Graphs
Position of the subtitle
LEFT
Positions the subtitle on the left of the figure region.
CENTER (default)
Positions the subtitle at the center of the figure region.
RIGHT
Positions the subtitle on the right of the figure region.
OFFSET K K
Moves a subtitle away from the position specified with LEFT, CENTER or RIGHT. The first argument specifies how
far to move the subtitle horizontally (in figure units). The second argument specifies the how far to move the
subtitle vertically (in figure units). The default offset is 0.0 0.0.
SYMBOL: Session subcommand for displaying a symbol for each
data value
SYMBOL [C...C]
Displays a symbol for each data value, where C...C can specify up to 4 grouping variables for CHART and 3 for
other graphs.
For grouping variables specified on the main command line:
Can use up to four grouping columns.
CHART can use up to four grouping columns. Grouping columns must be categorical variables that are included
on the main CHART command line, or with the GROUP subcommand. In the following example, C2 is the
grouping column, and, for each unique value in C2, Minitab assigns different symbol attributes.
CHART C1;
SYMBOL C2.
Note For an overview and examples, go to Using groups in graphs on page 1182. For more information, go to Using the SYMBOL and
COLOR subcommands for PLOT on page 1183.
VASSIGN
For overlaid dotplots, assigns different attributes (color, type) to the dots representing each graph variable
and displays a legend.
Symbol type, color, and size
Specifies the symbol type, color, and size. You can enter a single K to apply to all symbols. If you use group variables,
each K applies to a single group.
TYPE K...K
TYPE C
TYPE specifies the symbol type, which is a number from Numbers to use for symbols and markers in session
commands on page 1174. Enter one K for each symbol or store the symbol types in C.
1084
Minitab Statistical Software Graphs
COLOR K...K
COLOR C
COLOR specifies the symbol color, which is a number from Numbers for colors to use in session commands on
page 1172. Enter one K for each symbol or store the symbol colors in C.
SIZE K
SIZE specifies the size of the symbol. Enter one K for each symbol or store the symbol types in C.
Position where subsequent attribute subcommands apply
POSITION K...K
Lists the positions where subsequent attribute subcommands apply. For an example, go to Using the POSITION
and MODEL subcommands on page 1185.
MODEL K
The MODEL subcommand allows you to use POSITION with paneled graphs. For an example, go to Using
the POSITION and MODEL subcommands on page 1185.
ENDPOSITION
After ENDPOSITION is executed, additional subcommands apply to all models. For an example, go to Using the
POSITION and MODEL subcommands on page 1185.
TABLE and NOTABLE: Session subcommand for controlling the
table within the figure region
TABLE
Controls the size and the placement of the table within the figure region, the fill type and color of the legend, the
type, color and thickness of the edge line around the table, the font characteristics of the table text, and the table
text that is displayed.
NOTABLE
Hides the table.
Fill pattern and background fill color of the table
Specifies the fill pattern and background fill color of the table.
TYPE K
TYPE specifies the fill pattern in K, which is a number from Numbers for fill types to use in session commands on
page 1173.
COLOR K
COLOR specifies the background color in K, which is a number from Numbers for colors to use in session commands
on page 1172.
1085
Minitab Statistical Software Graphs
Type, color, and width of the table border
ETYPE K
ETYPE specifies the line type, which is a number from Numbers for line types to use in session commands on page
1173.
ECOLOR K
ECOLOR specifies the line color, which is a number from Numbers for colors to use in session commands on page
1172.
ESIZE K
ESIZE specifies the line width, which can be any positive number.
Font, color, and size of the table text
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
Style of the table text
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
1086
Minitab Statistical Software Graphs
Font, color, and size of the header text
HFONT "font name"
HFONT specifies the font name for the text.
HCOLOR K
HCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on
page 1172.
HTSIZE K
HTSIZE specifies the size of the text in Minitab units. K can be any positive number.
HPSIZE K
HTSIZE specifies the size of the text in Minitab units. K can be any positive number.
Style of the header text
HBOLD
Specifies to display the header text in bold font.
HNOBOLD
Specifies to not display the header text in bold font.
HUNDERLINE
Specifies to underline the header text.
HNOUNDERLINE
Specifies to not underline the header text.
HITALIC
Specifies to display the header text in italic font.
HNOITALIC
Specifies to not display the header text in italic font.
Section
SECTION K
Specify the section number.
STITLE "string"
Specify the section title.
CHEADER K "string"
Specify the header for table column K.
BTEXT K K "string"
Specify the text for table row number K and column K.
STHIDE
Hide the section title.
1087
Minitab Statistical Software Graphs
CHHIDE
Hide the column headers.
RHIDE K...K
Hide table row numbers K...K.
CHIDE K...K
Hide table columns K...K.
TEXT: Session subcommand for displaying text on a graph
TEXT K K "text"
TEXT C C C
Displays a text string anywhere on a graph. Use the x coordinate as the first argument and the y coordinate as
the second argument. Enclose the text string in quotation marks.
To label the points on a graph, you can also use DATLAB on page 1016 with many graph commands.
When placing many text strings you can put x-coordinates in one column, the corresponding y-coordinates in a
second, and the corresponding text strings in a third. Use these columns in this order as arguments to TEXT.
To specify an x-axis coordinate that represents categories (as with CHART) in data units, specify the categories as
axis positions 1, 2, ..., c (where c is the total number of categories) as they appear on the graph from left to right.
You can specify points between categories. For example, a point midway between the third and fourth categories
at location 44 on the y-axis would be 3.5 44.
BOX K K K K
Specify the coordinates of the text box that will contain the text. The four arguments represent the x-minimum,
x-maximum, y-minimum, and y-maximum coordinates of the text box
UNIT K
Specifies the unit system used by TEXT and allows the use of data units in placing text on paneled graphs.
To place text using figure units, use the argument 0. Use 1 to specify data units.
With paneled graphs (including matrix plots), you can still place text using data units if you also specify the
panel with the UNIT command. For example, UNIT 1 places the text in the first panel of the graph and reads
the TEXT arguments in the data units relative to the first panel. You can associate the placement of annotation
with data units or figure units to accommodate changes in scales or graph size. As a subcommand to LAYOUT,
TEXT always uses graph units.
Attributes for the text
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
1088
Minitab Statistical Software Graphs
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
Positioning of the text
PLACEMENT K K
Specifies where the label attaches to the anchor position. The first argument specifies the horizontal placement.
The second argument specifies the vertical placement.
Horizontal placement (first K argument)Vertical placement
(second K
argument)
10−1
1
0
−1
OFFSET K K
Moves a label away from the anchor position specified with PLACEMENT. The first argument specifies how far to
move the label horizontally (in figure units). The second argument specifies the how far to move the label vertically
(in figure units). The default offset is 0.0 0.0.
ANGLE K
Rotates the text counterclockwise by K degrees. K can be any number between −360 and 360. The default value
of 0 produces horizontal text. You may need to change the POSITION and OFFSET values to achieve certain angle
effects.
TITLE: Session subcommand for adding a title to a graph
TITLE ["title"]
Adds a title to a graph.
1089
Minitab Statistical Software Graphs
You can use TITLE more than one time. Each additional title goes below the preceding title.
Using TITLE with no argument displays the default title. Using TITLE with an argument replaces the default
title.
Default titles precede additional titles.
TITLE works the same for the basic graph commands and control chart commands. You can suppress the default
title with the subcommand NODTITLE.
Attributes for the title text
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
Positioning
LEFT
Puts the title in the left of the figure region.
CENTER (default)
Puts the title in the center of the figure region.
RIGHT
Puts the title in the right of the figure region.
1090
Minitab Statistical Software Graphs
OFFSET K K
Moves a title away from the position specified with LEFT, CENTER or RIGHT. The first argument specifies how far
to move the footnote horizontally (in figure units). The second argument specifies the how far to move the footnote
vertically (in figure units). The default offset is 0.0 0.0.
TRANSPOSE and NOTRANSPOSE: Session subcommands for
transposing the x- and y-axis on a graph
TRANSPOSE
TRANSPOSE interchanges the position of the x and y-axis on a graph. Transposing does not change the variable
or name of the axis: the x-axis and y-axis remain the same whether they are horizontal or vertical. Keep this in
mind when you use graphics options that require you to specify locations or directions in terms of the axis, such
as gridlines or reference lines.
When TRANSPOSE is invoked, the data region is in effect turned on its side; the y-scale and x-scale trade places.
NOTRANSPOSE
Use to specify that a particular graph model is not to be transposed. Useful if you have specified (through
preferences) that probability plots are to be transposed by default.
TSHOW: Session subcommand for specifying the level of tick labels
that are displayed
TSHOW K [K [K [K]]]
Specify the tick labels displayed, by level. The level farthest from the axis is referenced by the argument 1, the
second farthest by 2, and so on. Tick labels are shown for all levels by default.
VASPECT: Session subcommand for specifying the aspect ratio of
the data box
VASPECT K K K
Specifies the aspect ratio of the data box in x, y, z order. Without arguments, VASPECT specifies that the ratio be
proportional to the data range in each direction.
Some common reasons for changing aspect ratios are as follows:
To make similar units be the same length on different axes. For example, suppose you have a range of 50 cm
for x and 30 cm for y, and you want one centimeter to be represented by the same length on each axis. You
can use VASPECT without arguments, or you can use VASPECT with arguments of 50 for x, 30 for y, and
whatever makes the graph look good for the z.
To make the graph a certain shape. For example, the default aspect ratio of 3:3:2 is a pleasing aspect ratio
often known as a golden triangle. By making the graph a different shape, you can also achieve effects such as
emphasizing changes in one variable (say, a variable with a large range) over another.
1091
Minitab Statistical Software Graphs
VBOX: Session subcommand for specifying the display of the box
that surrounds the data on a graph
VBOX K
Specifies the display of the box surrounding the data. VBOX does not control the display of axis lines, which are
separate from the box and displayed behind.
Display of the box facesValue of K
Hide all faces.0
Show the back faces.1 (default)
Show all the faces.2
VFIELD: Session subcommand for specifying the dimensions of the
field of view in object units
VFIELD K K
Specifies the width and height of the field of view in object units. You can best think of object units in terms of
the cube that displays three-dimensional graphs. The center of the cube is the origin (0, 0, 0) in object unit terms.
Each edge of the cube is 2 object units long. This makes the shortest distance to an edge from the center of the
cube 1 object unit. Larger values create a larger field of view and result in a smaller data box. The default is 3.75,
with values between 2.5 and 4.0 being optimal for most applications.
VPOSITION: Session subcommand for specifying the view position
as a ratio
VPOSITION K K K
Specifies the view position as a ratio in x, y, and z. The view position is the point from which you are viewing the
data box. For example, at VPOSITION 1 0 0, your angle of view is parallel with the x-axis, so that the graph
looks like a two-dimensional scatterplot of the z- and y-variables. At VPOSITION 1 1 1, you are looking down
on the data box from a position just off the corner where the x-, y-, and z-values are highest.
The default is 1.5 −3.5 1.0.
Note The VPOSITION and VUP on page 1092 vectors must not be the same and must not differ by a constant multiplier.
VUP: Session subcommand for specifying which direction is up in
relation to the data box
VUP K K K
Specifies which direction is up in relation to the data box (the view-up direction) as a ratio in x, y, and z. The default
is VUP 0 0 1, which specifies that the positive z-direction is up. For example, VUP 1 0 0 turns the data box
on its side by making the positive x-direction up, instead of the positive z-direction.
Note The VPOSITION on page 1092 and VUP vectors must not be the same and must not differ by a constant multiplier.
1092
Minitab Statistical Software Graphs
WHISKER: Session subcommand for controlling the display of
whiskers on a boxplot
WHISKER K
Controls the display of whiskers on a boxplot.
Display of whiskersValue of K
Hides the whiskers.0
Displays the whiskers.1
WTITLE: Session subcommand for specifying the title of the output
pane
WTITLE "title"
Specifies the title for the output pane.
You can use WTITLE as a subcommand with LAYOUT and all graph commands. The title you specify becomes the
title of the output pane.
1093
Minitab Statistical Software Graphs
Model-Based Commands
FACPLOT: Session command for creating a factorial
plot
FACPLOT C
Displays factorial plots for the model associated with the response variable in the specified column To create this
graph, you need to specify a model. To produce an interaction plot, you must have two or more variables.
These plots can illustrate how a response variable relates to one or more variables. You can produce two types
of factorial plots.
Use a main effects plot to compare fitted means or data means across levels of one or more variables.
Use an interactions plot to assess the effects of one variable at levels of another variable. An interactions plot
displays the fitted means for a level of a variable with the level of a second variable held constant.
Although you can use these plots to display the effects, be sure to evaluate significance by looking at the effects
in the analysis of variance table.
FACTORS C...C
Specifies the variables to display in both the main effect and interaction plots. You must specify 2 or more
variables to generate an interaction plot.
GMAIN
GMAIN displays the main effect plot.
GINT
GINT displays the interactions plot.
FULL
Use FULL to display both interaction plots for each pair of categorical variables, such as Predictor 1 by
Predictor 2 and Predictor 2 by Predictor 1. Sometimes you can identify interactions more easily when
you examine both plots.
LOWER
Use LOWER to display one version of each interaction plot.
GMODEL (default)
GMODEL display plots for only terms that are in the model and listed in FACTORS. For purposes of a main
effect plot, a variable is in the model if the model includes any terms that involve only that variable, e.g. A,
A*A, or A*A*A. For purposes of an interaction plot, the interaction of two variables is in the model if the
model includes any terms that involve both variables, e.g. A*B, A*B*B.
GALL
GALL displays plots for all terms involving variables on the FACTORS subcommand.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
1094
Minitab Statistical Software Model-Based Commands
MFFCUBE: Session command for creating a cube
plot for fitted means
MFFCUBE C
Creates a cube plot of the fitted means for the response in C.
You can draw a cube plot for a model from a 2-level factorial design. The factor columns can be numeric or text,
and can contain any values. When the factor column is text, the first entry (row 1) is level 1, the next entry that is
different is level 2. All factors must have 2 levels, and can have center points.
To draw a cube plot of the data means or a cube plot of the process variables in a mixtures design, use FFCUBE
on page 340.
FACTORS C...C
Specifies the factors to include on the cube plot in C...C. You can specify 2–8 factors.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
MMOPT: Session command for the Response
Optimizer
MMOPT C...C
You can use Minitab's Response Optimizer to identify the combination of input variable settings that jointly
optimize a single response or a set of responses. All models in the optimization must be the same type of linear
model (e.g. regression, binary logistic regression, general linear model, etc). Joint optimization must satisfy the
requirements for all the responses in the set. The overall desirability (D) is a measure of how well you have satisfied
the combined goals for all the responses. Overall desirability has a range of zero to one. One represents the ideal
case; zero indicates that one or more responses are outside their acceptable limits.
Minitab calculates an optimal solution and draws a plot. The optimal solution serves as the starting point for the
plot. This optimization plot allows you to interactively change the input variable settings to perform sensitivity
analyses and possibly improve the initial solution.
Note Although numerical optimization along with graphical analysis can provide useful information, it is not a substitute for subject
matter expertise. Be sure to use relevant background information, theoretical principles, and knowledge gained through observation
or previous experimentation when applying these methods.
For each response, you must do the following:
Select a goal.
Specify a minimum acceptable value, a maximum acceptable value, and a target value.
Specify a weight and importance level.
GOAL K...K
Specifies a goal for each response. Enter the goals in coded form, with 1 = "smaller is better", 2 = "target is
best", 3 = "larger is better". "Smaller is better" means "make this response as small as possible". "Larger is
better" means "make this response as large as possible". "Target is best" means "set this response as near
to the target value as possible". You must enter one argument (K) for each model.
1095
Minitab Statistical Software Model-Based Commands
HOLD K1 K2 [K3]
Specifies a fixed level or range of levels for variable K1. The variables are indexed based on their order in the
first model in which they appear. K2 without K3 specifies a fixed level. K2 and K3 together specify a range of
levels.
HOLD levels should be specified in uncoded units.
Default for a factor is K2 = minimum value defined by models, K3 = maximum value defined by models.
Default for a covariate in a DOE model is a fixed level at the covariate data mean. Covariates can only be
held at a constant level, not a range of levels.
UTWEIGHTS K...K
Specifies the weights for each response. You must enter one argument (K) for each model. The weight defines
the shape of the desirability function for each response. For each response, you can select a weight (from
0.1 to 10) to emphasize or de-emphasize the target. Weights place emphasis as follows:
Weights that are less than 1 (the minimum is 0.1) place less emphasis on the target.
Weights that are equal to 1 place equal importance on the target and the bounds.
Weights that are greater than 1 (the maximum is 10) place more emphasis on the target.
The shape of the function as it goes from 0 to 1, or from 1 to 0, is determined by the weights value. If the
value is 1, the shape is a straight line. If the value is less than 1, the shape is concave up. If the value is greater
than 1, the shape is concave down.
IMPORTANCE K...K
Specifies the relative importance of each response in the composite desirability function. The number of
arguments must match the number of models. These are numbers between 0.1 and 10. If all responses are
equally desirable, use the default value of 1.0 for each response. The composite desirability is then the
geometric mean of the individual desirabilities.
However, if some responses are more important than others, you can incorporate this information into the
optimal solution by setting unequal importance values.
Larger values correspond to more important responses, smaller values to less important responses. You can
also change the weights to perform sensitivity analyses on the optimal solution. For example, you may find
that the optimal solution when one response has a large weight is very different from the optimal solution
when the same response has a small weight.
START K...K
Specifies a starting point for the search algorithm by giving a coordinate for each factor. These are entered
as constants. Specifying starting points is optional. However, if you specify any starting point, you must
specify one value for each factor, and each value must be between the minimum and the maximum for that
factor, or within the range of any user defined constraints.
DSTORE C
Stores the composite desirability values calculated at the points in DSTORE.
DLEVELS E...E
DLEVELS is required if DSTORE is used. This subcommand specifies the predictor levels in column or constants
for the computation of the composite desirability stored in the DSTORE column. The number of arguments
must match the number of predictors in all of the models. For categorical factors, the levels must be legal
values of the corresponding factors.
1096
Minitab Statistical Software Model-Based Commands
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default
value of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
Minimum acceptable values, maximum acceptable values, and target values
Specifies the minimum acceptable values, the maximum acceptable values, and the target values for the responses.
You must enter one argument (K) for each model. You must use all three subcommands because they are needed to
obtain the numerically optimum solution. You must also enter a value for each response in each of these subcommands.
In other words, you need a minimum acceptable value for each response, you need a maximum acceptable value for
each response, you need a target value for each response.
If you have a "smaller is better" goal for a response, your goal is to minimize the response. Identify the some point
that can be described as the point of diminishing returns ( i.e., while I want to minimize, going beyond a certain value
makes little or no difference). If such a point exists, use it as the target value. If it does not, use a very small number,
one that is probably not achievable, as the target value. For a "smaller is better" response, the target and the minimum
acceptable value are also equal. The same can be said for a case where the goal is "larger is better", except that now
you need a value on the upper end instead of the lower end of the range. When the goal is "target is best", you probably
have upper and lower specification limits for the response, which can be used as minimum and maximum acceptable
values. If not, you may want to use upper and lower points of diminishing returns, or some other method.
MINACCEPT
Specifies the minimum acceptable values with K...K.
MAXACCEPT
Specifies the maximum acceptable values with K...K.
TARGET
Specifies the target values with K...K.
Output
OPTIPLOT
Displays the interactive optimization plot.
TPARAMETER
Displays the table of parameters that define the desirability to optimize.
TSOLUTION
Displays the table with the numerically optimal solution and the desirabilities for the responses.
THOLD
Displays the table with the hold values.
1097
Minitab Statistical Software Model-Based Commands
TSTART
Displays the table of user-specified start values for the search algorithm.
TPREDICTION
Displays the table of prediction with the confidence intervals.
NODEFAULT
Specifies that no default tables and graphs will be displayed.
MOVERCONT: Session command for creating an
overlaid contour plot
MOVERCONT C...C
Use MOVERCONT to draw a contour plot for multiple responses. All models used in the overlaid contour plot
must be the same type of linear model (for example, regression, binary logistic regression, general linear model,
etc).
Contour plots show how a response variable relates to two variables based on a model equation. In a contour
plot, the response surface is viewed as a two-dimensional plane where all points that have the same response
are connected to produce contour lines of constant responses. Contour plots are useful for establishing operating
conditions that produce desirable response values.
Applications that involve multiple responses present a different challenge than single response experiments. Since
each response is important in determining the quality of the product, you need to consider the responses
simultaneously. Optimal factor settings for one response may be far from optimal for another response. Overlaid
contour plots allow you to visually identify an area of compromise among the various responses.
To produce this graph, you need to specify a model that contains at least 2 continuous variables. By default, the
graph uses the first two continuous variables specified in the model as the x- and y-variables.
MOVERCONT uses the equation in the specified model to generate the z-values (responses) that appear in the
graphs. The values used in the equation are the values in the x- and y-variables along with the HOLD and CHOLD
values of the remaining variables.
You have the following contour plot options:
Generating a single graph and choosing the x- and y-axis variables
Specifying the values of contour levels on the graph
INUNIT K
Specifies the type of units to display the variables in the plots. Applies only to cases, such as DOE models, in
which there are coded and uncoded units. Otherwise, the subcommand is ignored.
Form of designValue of K
Coded0
Uncoded1
1098
Minitab Statistical Software Model-Based Commands
HOLD K...K
HOLD keeps the continuous variables at the settings you specify. HOLD is required if the model includes
more than two continuous variables. With HOLD, you need to specify a constant for each continuous variables
in the model.
For both HOLD and CHOLD, Minitab interprets the first value you enter as the hold value for the first variable
that you entered in the model, the second as the second, and so on.
The hold values are ignored for the variables that appear in each plot.
CHOLD K...K
CHOLD keeps the categorical variables at the settings that you specify. CHOLD is required if the model
includes any categorical variables. With CHOLD, you need to specify one of the categorical levels for each
categorical variable in the model.
For both HOLD and CHOLD, Minitab interprets the first value you enter as the hold value for the first variable
that you entered in the model, the second as the second, and so on.
The hold values are ignored for the variables that appear in each plot.
SINGLE K K
Specify a pair of variables to plot. K and K must be indices of continuous variables in the models. 1 is the first
continuous variable, even when the categorical variables are specified first.
Each of these variables must appear in a term of at least one model. They do not need to appear in the same
model.
The default plots the first two continuous variables that appear in model terms.
LEVELS K K...K K
Specifies the low and high value of the contour levels for each response in K K...K K. You must enter a pair
of values for each response.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
MSURFACE: Session command for creating a surface
plot
MSURFACE C
To produce this graph, you need to specify a model that contains at least 2 continuous variables. A surface plot
shows how a response variable (the z-variable) relates to two variables (the x- and y-variables) based on a model
equation. By default, the graph uses the first two continuous variables specified in the model as the x- and
y-variables.
MSURFACE uses the equation in the specified model to generate the z-values (responses) that appear in the
graphs. The values used in the equation are the values in the x- and y-variables along with the HOLD and CHOLD
values of the remaining variables.
You have the following contour plot options:
Generating a single graph and choosing the x- and y-axis variables
1099
Minitab Statistical Software Model-Based Commands
Generating separate graphs for every combination of variables in the model
For information on how to change a surface plot to more easily compare it to contour plot, go to A comparison
of MSURFACE and RMCONTOUR plots on page 1148.
For graphics options for MSURFACE, go to Graphics options for MSURFACE on page 1152.
INUNIT K
Specifies the type of units to display the variables in the plots. Applies only to cases, such as DOE models, in
which there are coded and uncoded units. Otherwise, the subcommand is ignored.
Form of designValue of K
Coded0
Uncoded1
HOLD K...K
HOLD keeps the continuous variables at the settings you specify. HOLD is required if the model includes
more than two continuous variables. With HOLD, you need to specify a constant for each continuous variables
in the model.
For both HOLD and CHOLD, Minitab interprets the first value you enter as the hold value for the first variable
that you entered in the model, the second as the second, and so on.
The hold values for the variables in the plot are ignored when you specify the default plot (of the first two
variables) or SINGLE. When you specify ALLPAIRS, you generate many graphs. In each ALLPAIRS graph, the
hold values are ignored for the variables that appear in the plot.
CHOLD K...K
CHOLD keeps the categorical variables at the settings that you specify. CHOLD is required if the model
includes any categorical variables. With CHOLD, you need to specify one of the categorical levels for each
categorical variable in the model.
For both HOLD and CHOLD, Minitab interprets the first value you enter as the hold value for the first variable
that you entered in the model, the second as the second, and so on.
The hold values for the variables in the plot are ignored when you specify the default plot (of the first two
variables) or SINGLE. When you specify ALLPAIRS, you generate many graphs. In each ALLPAIRS graph, the
hold values are ignored for the variables that appear in the plot.
ALLPAIRS
By default, MSURFACE uses the first two continuous variables specified in the model as x- and y-variables
and produces one graph.
When you use ALLPAIRS, MSURFACE displays a separate graph for each possible combination of (x,y) factors
with the calculated response (z). With n variables, using ALLPAIRS results in (n*(n - 1))/2 different contour
plots. When a graph of, for example, Temp as the x-variable and Pressure as the y-variable is generated, the
transposed graph (that is, Pressure as the x-variable and Temp as the y-variable) is not generated.
You cannot specify both ALLPAIRS and SINGLE.
PANEL
PANEL displays all plots in panels of one graph.
1100
Minitab Statistical Software Model-Based Commands
SEPARATE
SEPARATE displays all plots in separate graphs.
SINGLE K K
When you specify SINGLE, MSURFACE displays a single graph. The two arguments are the continuous variables
for the x- and y-axis, respectively.
LEVELS K K...K K
Specifies the low and high value of the contour levels for each response in K K...K K. You must enter a pair
of values for each response.
The graphs are generated by calculating responses (z-values) using the values in the x- and y-variables and
giving the other variables the HOLD or CHOLD values.
You cannot specify both ALLPAIRS and SINGLE.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
PREDICT: Session command for predicting response
values
PREDICT C
Predicts the response value of new observations for the model associated with the specified column.
Use a stored model to do the following:
Predict the value of the response variable (fitted values) for the combinations of variable settings that you
request.
Create a confidence interval for the mean response at these combinations.
Create a prediction interval for a single observation at these combinations (except for GZLM models).
Store the prediction information in the worksheet.
CPREDICTORS C...C
Specifies new variable values with columns.
The number and type of arguments must match the variables in the model. In DOE, new values are assumed
to be in uncoded units. For categorical variables, new values must be one of the values for the variable in
the model.
Either CPREDICTORS or KPREDICTORS is required for all models. CPREDICTORS and KPREDICTORS are
mutually exclusive.
KPREDICTORS K...K
Specifies new variable values with constants. KPREDICTORS can be repeated to add values for multiple new
observations.
1101
Minitab Statistical Software Model-Based Commands
The number and type of arguments must match the variables in the model. In DOE, new values are assumed
to be in uncoded units. For categorical variables, new values must be one of the values for the variable in
the model.
Either CPREDICTORS or KPREDICTORS is required for all models. CPREDICTORS and KPREDICTORS are
mutually exclusive.
CWEIGHT C (optional)
Use CWEIGHT when you use CPREDICTORS. CWEIGHT specifies new weight values with a column, one row
for each combination of variables. Mixed effects models assume weights of 1 in prediction, even though the
estimation of the model parameters can use weights that are different from 1.
The arguments must match the number of predictions to make.
CWEIGHT and KWEIGHT are mutually exclusive.
KWEIGHT K (optional)
Use KWEIGHT when you use KPREDICTORS. KWEIGHT specifies new weight values with constants. KWEIGHT
can be repeated to add values for multiple new observations. The number of KWEIGHT commands must
match the number of KPREDICTORS commands. Mixed effects models assume weights of 1 in prediction,
even though the estimation of the model parameters can use weights that are different from 1.
The arguments must match the number of predictions to make.
CWEIGHT and KWEIGHT are mutually exclusive.
CCOVARIATES C...C
Either CCOVARIATE or KCOVARIATE can be used for models that contain covariates. If the model contains
covariates but neither of these subcommands are issued, Minitab uses the mean of each covariate.
CCOVARIATE and KCOVARIATE are ignored if the model is not a factorial design, general linear model, or a
mixed effects model. For both subcommands, the number of arguments must match the number of covariates
in the model.
Use CCOVARIATE when you use CPREDICTORS. CCOVARIATE specifies new covariate values with columns.
The columns must be numeric.
COVARIATE and KCOVARIATE are mutually exclusive.
KCOVARIATES K...K
Either CCOVARIATE or KCOVARIATE can be used for factorial design models and general linear models that
contain covariates. If the model contains covariates but neither of these subcommands are issued, Minitab
uses the mean of each covariate. CCOVARIATE and KCOVARIATE are ignored if the model is not a factorial
design, general linear model, or a mixed effects model. For both subcommands, the number of arguments
must match the number of covariates in the model.
Use KCOVARIATES when you use KPREDICTORS. KCOVARIATE specifies new covariate values with constants.
The constants must be numeric. KCOVARIATE can be repeated to add values for multiple new observations.
The number of constants after KCOVARIATE must match the number of covariates in the model.
CCOVARIATE and KCOVARIATE are mutually exclusive.
1102
Minitab Statistical Software Model-Based Commands
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
Results
Displays a variety of tables in the output.
NODEFAULT
Specifies that no default tables or graphs are displayed.
TEQUATION
Displays the model equation.
SINGLE
If you have categorical variables or factors, you can use SINGLE to display one equation instead of separate
equations for each combination of categorical levels.
SEPARATE
Use SEPARATE to display separate equations for each level of each categorical variable. If you have only
categorical variables, the display is always a single equation.
TPREDICTION
Displays the prediction table. In 2 cases, TPREDICTION displays the prediction table for any random level
combinations defined by the random factors that are in the model:
Stability study models with batch as a random factor
Mixed effects models
TCPREDICTION
Displays the prediction table for selected levels of random factors in the model. TCPREDICTION is for 2 types of
models:
Stability study models with batch as a random factor
Mixed effects models
TMODEL
Displays the model information table for general linear models and mixed effects models.
1103
Minitab Statistical Software Model-Based Commands
Storage
Stores information related to the predicted responses. The availability and function of the storage commands are
different for mixed effects models and for stability study models that have batch as a random factor.
PFITS C
Stores the predicted responses in C. For stability study models with batch as a random factor, this subcommand
stores the predicted responses for any random batch. For mixed effects models, this subcommand stores the
predicted responses for any random level combinations defined by the random factors that are in the model.
CPFITS C
Stores the predicted responses for selected levels of a random factor in 2 cases:
Stability study models with batch as a random factor
Mixed effects models
PSEFITS C
Stores the standard error of the predicted responses in C. For stability study models with batch as a random factor,
this subcommand stores the standard error of the predicted responses for any random batch. For mixed effects
models, this subcommand stores the standard error of the predicted responses for any random level combinations
defined by the random factors that are in the model.
CPSEFITS C
Stores the standard errors of the predicted responses for selected levels of a random factor in 2 cases:
Stability study models with batch as a random factor
Mixed effects models
DFCI C
For a mixed effects model, this subcommand stores the degrees of freedom for the confidence interval for the
predicted responses at any random level combinations defined by the random factors that are in the model.
DFPI C
For a mixed effects model, this subcommand stores the degrees of freedom for the prediction interval for the
predicted responses at any random level combinations defined by the random factors that are in the model.
CDFCI C
For a mixed effects model, this subcommand stores the degrees of freedom for the confidence interval for the
predicted response at the selected levels of the random factors.
CDFPIC
For a mixed effects model, this subcommand stores the degrees of freedom for the prediction interval for the
predicted response at the selected levels of the random factors.
CLIMITS C, C
Stores the lower and upper confidence limits of the predicted responses in C and C (except for GZLM models).
For Stability Study models with batch as a random factor, this subcommand stores the confidence limits of the
predicted responses for any random batch. For mixed effects models, this subcommand stores the confidence
limits of the predicted responses for any random level combinations defined by the random factors that are in
the model.
CCLIMITS C, C
Stores the confidence limits of the predicted responses for selected levels of a random factor in C and C in 2 cases:
Stability study models with batch as a random factor
Mixed effects models
1104
Minitab Statistical Software Model-Based Commands
PLIMITS C, C
Stores the lower and upper prediction limits of the predicted responses in C and C. For Stability Study models
with batch as a random factor, this subcommand stores the prediction limits of the predicted responses for any
random batch. For mixed effects models, this subcommand stores the prediction limits of the predicted responses
for any random level combinations defined by the random factors that are in the model.
CPLIMITS C, C
Stores the prediction limits of the predicted responses for selected levels of a random factor in C and C in 2 cases:
Stability study models with batch as a random factor
Mixed effects models
BPFITS C
Stores the predicted responses using the original units for models that use the Box-Cox transformation. For
Stability Study models with batch as a random factor, this subcommand stores the predicted responses in the
original units for any random batch. Estimation for mixed effects models does not use the Box-Cox transformation,
so the subcommand has no effect.
BCPFITS C
Stores the predicted responses for selected batches using the original units for models that use the Box-Cox
transformation (Stability Study models with batch as a random factor only).
BCLIMITS C, C
Stores the confidence limits of the predicted responses using the original units for models that use the Box-Cox
transformation. For Stability Study models with batch as a random factor, this subcommand stores the confidence
limits in the original units for any random batch. Estimation for mixed effects models does not use the Box-Cox
transformation, so the subcommand has no effect.
BCCLIMITS C, C
Stores the confidence limits of the predicted responses for selected batches using the original units for models
that use the Box-Cox transformation (Stability Study models with batch as a random factor only).
BPLIMITS C, C
Stores the prediction limits using the original units for models that use the Box-Cox transformation. For Stability
Study models with batch as a random factor, this subcommand stores the prediction limits in the original units
for any random batch. Estimation for mixed effects models does not use the Box-Cox transformation, so the
subcommand has no effect.
BCPLIMITS C, C
Stores the prediction limits for selected batches using the original units for models that use the Box-Cox
transformation (Stability Study models with batch as a random factor only).
MMPREDICT: Session command to calculate
predictions from multiple models
MMPREDICT C...C
The Response Optimizer uses MMPRED to create a table of predictions for multiple models with the same settings
of the predictors. All the models must be created by the same command (for example, REGRESSION, GZLM, RSREG,
etc). Models from GZLM must be the same type, all binary or all Poisson.
Use a stored model to do the following:
1105
Minitab Statistical Software Model-Based Commands
Predict the value of the response variable (fitted values) for the combinations of variable settings that you
request.
Create a confidence interval for the mean response at these combinations (if applicable for the model type).
Create a prediction interval for a single observation at these combinations (if applicable for the model type).
To store the predictions in the worksheet, run the PREDICT command for each model.
KPREDICTORS K...K
Specifies new variable values with constants. The variables are indexed based on their order in the first model
in which they appear.
The number and type of arguments must match the variables in the model. In DOE, new values are assumed
to be in uncoded units. For categorical variables, new values must be one of the values for the variable in
the model.
KCOVARIATES K...K
KCOVARIATE can be used for factorial design models and general linear models that contain covariates. If
the model contains covariates but neither of these subcommands are issued, Minitab uses the mean of each
covariate. KCOVARIATE is ignored if the model is not a factorial design, general linear model, or a mixed
effects model. The number of arguments must match the number of covariates in the model.
KCOVARIATE specifies new covariate values with constants. The constants must be numeric. The number of
constants after KCOVARIATE must match the number of covariates in the model.
Options
CONFIDENCE K
Specifies a confidence level. For example, for a 90% confidence level, enter CONFIDENCE 90. The default value
of K is 95.
ITYPE K
Specifies the type of confidence interval.
Type of confidence intervalValue of K
Lower bound–1
Two-sided0 (default)
Upper bound1
TITLE "title"
Specifies a title for the table. If you do not specify a title, Minitab uses a default title.
1106
Minitab Statistical Software Model-Based Commands
RMCONTOUR: Session command for creating a
contour plot
RMCONTOUR C
To produce this graph, you need to specify a model that contains at least 2 continuous variables. A contour plot
shows how a response variable (the z-variable) relates to two variables (the x- and y-variables) based on a model
equation. By default, the graph uses the first two continuous variables specified in the model as the x- and
y-variables.
RMCONTOUR uses the equation in the specified model to generate the z-values (responses) that appear in the
graphs. The values used in the equation are the values in the x- and y-variables along with the HOLD and CHOLD
values of the remaining variables.
You have the following contour plot options:
Generating a single graph and choosing the x- and y-axis variables
Generating separate graphs for every combination of variables in the model
Specifying the number of contour levels on the graph
Specifying the values of contour levels on the graph
For information on how to change a surface plot to more easily compare it to contour plot, go to A comparison
of MSURFACE and RMCONTOUR plots on page 1148.
INUNIT K
Specifies the type of units to display the variables in the plots. Applies only to cases, such as DOE models, in
which there are coded and uncoded units. Otherwise, the subcommand is ignored.
Form of designValue of K
Coded0
Uncoded1
HOLD K...K
HOLD keeps the continuous variables at the settings you specify. HOLD is required if the model includes
more than two continuous variables. With HOLD, you need to specify a constant for each continuous variables
in the model.
For both HOLD and CHOLD, Minitab interprets the first value you enter as the hold value for the first variable
that you entered in the model, the second as the second, and so on.
The hold values are ignored for the variables that appear in each plot.
CHOLD K...K
CHOLD keeps the categorical variables at the settings that you specify. CHOLD is required if the model
includes any categorical variables. With CHOLD, you need to specify one of the categorical levels for each
categorical variable in the model.
For both HOLD and CHOLD, Minitab interprets the first value you enter as the hold value for the first variable
that you entered in the model, the second as the second, and so on.
The hold values are ignored for the variables that appear in each plot.
1107
Minitab Statistical Software Model-Based Commands
ALLPAIRS
By default, MSURFACE uses the first two continuous variables specified in the model as x- and y-variables
and produces one graph.
When you use ALLPAIRS, MSURFACE displays a separate graph for each possible combination of (x,y) factors
with the calculated response (z). With n variables, using ALLPAIRS results in (n*(n 1))/2 different contour
plots. When a graph of, for example, Temp as the x-variable and Pressure as the y-variable is generated, the
transposed graph (that is, Pressure as the x-variable and Temp as the y-variable) is not generated.
You cannot specify both ALLPAIRS and SINGLE.
PANEL
PANEL displays all plots in panels of one graph.
SEPARATE
SEPARATE displays all plots in separate graph.
SINGLE K K
When you specify SINGLE, MSURFACE displays a single graph. The two arguments are the continuous variables
for the x- and y-axis, respectively.
NLEVELS K
Specifies number of contour levels. K must be a positive integer from 2 to 11.
LEVELS K...K
Specifies the values of the contour levels. The number of Ks must be from 2 to 11.
TITLE "title"
Specifies a title for the graph. If you do not specify a title, Minitab uses a default title.
1108
Minitab Statistical Software Model-Based Commands
Macros Session Commands
Structure Commands
GMACRO, MACRO, and ENDMACRO: Session commands for
marking the beginning and ending of a macro
GMACRO
GMACRO must be the first line of your global macro. GMACRO specifies a global macro. GMACRO cannot be
abbreviated.
MACRO
MACRO must be in the first line of your local macro, and specifies a local macro.
ENDMACRO
ENDMACRO ends all macros and must be in the last line of your macros. ENDMACRO cannot be abbreviated.
Declaration Statements
MCONSTANT, MCOLUMN, MMATRIX, and MTYPE: Session
commands for declaring variables
All variables used in a local macro must be declared. Declaring a variable tells the local macro what type of variable
to expect from the user, or the macro, while invoking.
Declaration requirements
Declare variables that are constants with MCONSTANT, variables that are columns with MCOLUMN, and variables
that are matrices with MMATRIX. (You may also use the plural synonyms MCONSTANTS, MCOLUMNS, and
MMATRICES.) After the M- command, list all the variables that are of that type, separated by a space.
An argument, which is a variable in the template, may be given the declaration MFREE. The variable data
type—column, constant, or matrix—is determined by the type of the variable that is given when the macro is
invoked. The macro statement MTYPE allows you to determine whether a variable declared with MFREE is a column,
constant, or matrix.
You may use a declaration statement several times, but only for different variables and only between the template
and the body of the macro. Once a variable is declared, it cannot be redeclared. Variable declarations can only be
made between the template and the body of the macro.
The declaration commands (MCOLUMN, MCONSTANT, etc.) cannot be abbreviated.
The declared variable must have a legal name. For more information, go to Using Variables.
1109
Minitab Statistical Software Macros Session Commands
Example of declaring variables
For example, suppose the template is as follows:
TRIM X Xbar
TRIM is the name of the macro and X and Xbar are variables that will be passed into the macro. The macro would need
declaration statements that define whether X and Xbar are constants, columns, matrices, or "free" variables (defined
below). Let's say X is a column in the global worksheet and Xbar is a constant in the global worksheet. The user would
invoke the macro by typing, say, %TRIM C5 K1. The local macro file would have the following first few lines:
MACRO
TRIM X Xbar
MCOLUMN X
MCONSTANT Xbar
Note If you see an error that END does not follow READ or SET, a local variable could have the same name as a Minitab command. For
example:
SET col1
mini:maxi/1
END
where min and max are local variable names. Minitab interprets the second line as a command because MINI and MAXI are also Minitab
commands. It displays the error message because it thinks you are trying to execute a command without first having entered the required
END statement. You must avoid using Minitab commands for variable names if you need to use the variables in data entry.
Variable types
There are four special-purpose variables, which are each declared differently.
Subcommand
An implicit constant that has a value of either 1 (if the subcommand was invoked) or 0 (if the subcommand was
not invoked).
Text
Declared with MCONSTANT as a text constant that contains a text string.
Suffixed
Declared with MCOLUMN or MCONSTANT as a range of columns or constants.
Free
Declared with MFREE as a column, constant, or matrix whose type is undetermined until the macro is invoked.
MFREE: Session command for declaring a free variable
You may want a local macro to operate with a column, constant, or matrix—whatever the user decides to use when
he or she invokes the macro. The local macro can then take appropriate action, depending on the type of variable
used when invoking the macro. A free variable is an argument variable whose type—column, constant, or matrix—is
not determined until the macro is invoked.
Use a free variable in a macro
You must do five things in the local macro code to make free variables work:
1. List the free variable as an argument on the template. For example, here is a template for the macro TELLME that
has X as an argument: TELLME X
2. Declare the free variable with the declaration statement MFREE. For example: MFREE X
3. Declare an additional variable as a constant: MCONSTANT Vartype
1110
Minitab Statistical Software Macros Session Commands
4. Use the macro statement MTYPE to analyze the free variable and store its variable type number in the constant
declared in step. If the variable is a constant, then Vartype is set to 1; if it is a column, Vartype is set to 2; and if it
is a matrix, Vartype is set to 3. You can include an MTYPE statement anywhere within the body of a local macro.
For example, the command MTYPE X Vartype looks at the free variable X and stores its variable type (1, 2, or 3) in
the constant Vartype.
5. Write code that can respond to the variable type that was used. In the following example, the IF statements make
the macro perform different actions depending on what type of variable X is: IF Vartype = 1, NOTE X is a constant!,
ELSEIF Vartype = 2, NOTE X is a column!, ELSE, NOTE X is a matrix!, ENDIF.
Invoke macros that use free variables like any other macros.
Note There is one case when the macro processor cannot determine the type of a variable. This happens when a variable that appears on
an optional subcommand is declared as MFREE, and a user invokes the macro without using the subcommand. In this case, the macro
processor assumes the variable is a column.
Example of a simple macro that uses free variables
The following local macro, TELLME, tells the user what kind of variable was used when the variable was invoked.
MACRO
TELLME X
MFREE X
MCONSTANT Vartype
MTYPE X Vartype
IF Vartype = 1
NOTE X is a constant!
ELSEIF Vartype = 2
NOTE X is a column!
ELSE
NOTE X is a matrix!
ENDIF
ENDMACRO
You can invoke TELLME can be invoked in the following ways, which produce the following output:
Produces thisInvoked like this
X is a column!%TELLME C1
X is a constant!%TELLME K1
X is a matrix!%TELLME M1
Example of a more complex macro that uses free variables
In the following local macro, BETWEEN.MAC, the arguments LOW and HI can be either columns or constants. Enter
data in the worksheet before you run the macro so that you can specify X.1-X.N.
MACRO
BETWEEN X.1-X.N LOW HI ANS;
STRICT.
MCOLUMN X.1-X.N L H ANS
MFREE LOW HI
#
# X.1-X.N is a list of columns. LOW and HI can each be either
# a column or a constant.
#
# BETWEEN checks to see if the values in one row of X.1-X.N are
# all greater than or equal to LOW and all less than or equal
# to HI. If they are, the corresponding row of ANS is set 1.
# If not then ANS is set to 0. If the STRICT subcommand is used
# then BETWEEN checks for < and > rather than <= and >=.
#
RMINIMUM X.1-X.N L
RMAXIMUN X.1-X.N H
1111
Minitab Statistical Software Macros Session Commands
# Case where subcommand is not used
IF STRICT = 0
LET ANS = ( L >= LOW ) AND ( H <= HI )
# Case where subcommand is used
ELSE
LET ANS = ( L > LOW ) AND ( H < HI )
ENDIF
ENDMACRO
You can invoke BETWEEN in any of the following ways:
%BETWEEN C1-C3 .25 .35 C10
%BETWEEN C1-C3 C4 .35 C10
%BETWEEN C1-C3 .25 C5 C10
%BETWEEN C1-C3 C4 C5 C10
You can write a macro where a suffixed list of variables is declared as MFREE. But recall that all variables in a suffixed
list must be of one type. Thus, in any one invocation of this macro, all the variables in the list must be of the same
type. If you need to know what type of variable was passed in, use MTYPE.
DEFAULT: Session command for assigning default values to
subcommand arguments
The DEFAULT statement is an optional line that allows you to assign a default value to a stored constant that appears
on an optional subcommand. If a subcommand is not used when a user invokes the macro, the value on the DEFAULT
line is used for the subcommand argument.
You cannot use DEFAULT to assign values to arguments on the main command - only arguments that are stored
constants for a subcommand. Defaults for columns and matrices must be handled within the body of the macro.
Two rules about the syntax of DEFAULT:
The DEFAULT line must come immediately after the declaration statements, before any other commands in the
macro.
The DEFAULT command cannot be abbreviated.
Local Macro Variables
KKCAT, KKNAME, and KKSET: Session commands for using text
You can use text data in columns, in stored constants, and as text strings in all three types of macros. In addition, you
can pass a text string into a macro by enclosing the string in double quotes when invoking the macro. The passed
string can then be assigned to a constant in your macro. Constants that hold text data are useful for specifying graph
titles, file names, and names for variables that could be created in a local macro.
The following macro commands allow you to store text in a constant. They are especially useful for displaying titles
and other annotation on macro output. The following text commands are used only in the body of global and local
macros.
1112
Minitab Statistical Software Macros Session Commands
KKCAT K K K
Concatenates, or combines, the text in the first constant K with the text in the second constant K, and stores the
combined string of text in the third constant K. For example, if the constant X contained "Mr." and the text constant
Y contained "Jones", the following command KKCAT X Y Z would put the string "Mr.Jones" in constant Z.
KKNAME K C
Stores the name of column C in the constant K. For example, KKNAME K1 C1 stores the name of column C1 in
the constant K1.
KKSET K "text"
Stores the text within the double quotes in the constant K. You can also use the regular Minitab command LET
to store text in constants. However, KKSET can store several text strings in several constants at once, whereas LET
stores one text string in one constant. For example, KKSET K1 "Text1" K2 "Text2" stores the text strings
in the constant K1 and K2.
Note In older versions of Minitab, you used single quotes around the text in KKSET. You can still use single quotes, but they are not
recommended.
Example of a macro that uses text strings
The following local macro receives two strings when invoked and assigns them to constants.
MACRO
REVERSE file1 file2
#
# REVERSE reads the first 3 columns of the input file, file1.
#
MCONSTANT file1 file2
MCOLUMN X Y Z
PRINT file1 file2
#
# The FORMAT statement says that the data in file1 are text with 1 character.
# Valid rows would look like the following examples:
# a b c
# d e f
#
READ X Y Z;
FORMAT(a1, x, a1, x, a1);
FILE file1.
WRITE Z Y X;
FILE file2.
#
# REVERSE now stores the 3 columns from file1 in reverse order as the output file,
file2.
#
ENDMACRO
Example of invoking a macro that uses text strings
We could use the preceding macro to reverse the columns in the file called INPUT.DAT and store the reversed data in
the file called OUTPUT.DAT by using the following commands.
%REVERSE "INPUT" "OUTPUT"
1113
Minitab Statistical Software Macros Session Commands
DTYPE: Session command for determining the data type of a
column or a constant
DTYPE E K
Use DTYPE to determine the data type of a column or constant (E), and store the results in a constant (K).
Data typeValue returned by DTYPE
Text0
Real numbers1
Integers2
Date/time3
Empty10
DTYPE is often used with free variables (and the MFREE and MTYPE commands) in cases where the macro must
be flexible enough to respond to a variety of possible inputs.
DTYPE is very useful when parts of your macro only work on some types of data. For example, you may have a
subcommand of your local macro that lets the user specify a title for a graph; DTYPE can tell you if the user
specified a text string or a number. Or, perhaps a part of your macro requires an integer; DTYPE could tell you if
a variable was not an integer, allowing your macro to convert the real number to an integer.
Note DTYPE works only as a command. It does not work with IF or LET, for example.
Example of a macro that uses DTYPE
TELLDATA tells a user the data type of the variable that is specified when the macro is invoked.
MACRO
TELLDATA X
MFREE X
MCONSTANT Vartype
DTYPE X Vartype
IF Vartype = 0
NOTE Variable is text
ELSEIF Vartype = 1
NOTE Variable is real number
ELSEIF Vartype = 2
NOTE Variable is integer
ELSEIF Vartype = 3
NOTE Variable is date/time
#constants cannot be in date/time format
ELSEIF Vartype = 10
NOTE Variable is empty
ENDIF
ENDMACRO
1114
Minitab Statistical Software Macros Session Commands
Control Statements
IF, ELSEIF, ELSE, ENDIF: Session commands for executing code
depending on a logical condition
IF logical expression
ELSEIF logical expression
ELSE
ENDIF
Allows you to execute different blocks of code depending on a logical condition. A logical expression is any expression
from the LET command. The comparison and Boolean operators listed below are the features of LET that are most
often used in IF.
DescriptionAlternative formComparison and Boolean
operators
Equal toEQ=
Not equal toNE~=
Less thanLT<
Greater thanGT>
Less than or equal toLE<=
Greater than or equal toGE>=
AndAND&
OrOR|
NotNOT~
In most cases the logical expression evaluates to a single number. If the number is 0 (false), the block of statements
is skipped; if it is not 0 (true), the block is executed. If the logical expression evaluates to a column, then if all entries
in the column are 0, the expression is considered false, otherwise it is considered true.
You can use multiple ELSEIF statements within the IF-ENDIF block.
The following is a simple example, using a global macro. Enter data in columns C1-C3 before you run the macro.
GMACRO
SMALL
#
# Takes the data in C1-C3. Finds the column with the smallest mean
# and prints that column. If, because of ties, there is no single column
# with the smallest mean, a message is printed.
#
LET K1 = MEAN(C1)
LET K2 = MEAN(C2)
LET K3 = MEAN(C3)
IF K1 < K2 AND K1 < K3
PRINT C1
ELSEIF K2 < K1 AND K2 < K3
PRINT C2
ELSEIF K3 < K1 AND K3 < K2
PRINT C3
ELSE
NOTE Note: There are ties.
1115
Minitab Statistical Software Macros Session Commands
ENDIF
ENDMACRO
DO and ENDDO: Session commands for looping through a block
of commands
DO K
ENDDO
Allows you to loop through a block of commands. K is set equal to the first number in the list, then the block of
commands is executed. When Minitab reaches the ENDDO, K is set equal to the next number in the list and the block
is executed again. This continues until all numbers in the list are used, or until you branch out of the DO-loop with a
BREAK, GOTO, RETURN, or EXIT command.
The list of numbers can be an explicit list of any numbers or stored constants. A patterned list can be abbreviated
using a colon and slash as in SET. For example, 1:10 is the list 1, 2, 3, ... , 10, and 1:1.8 /.2 is the list 1, 1.2, 1.4, 1.6, 1.8.
Numbers can be in either increasing order or decreasing order. The following DO-loop changes the values in rows 1
through 10 and row 50 of columns C1 and C2 to the missing value code:
DO K1 = 1:10 50
LET C1(K1) = '*'
LET C2(K1) = '*'
ENDDO
The following is a local macro that calculates a moving average of length three. It shows how to loop through the
values in a column. Enter data in a column of the worksheet before you run the macro so that you can specify X.
MACRO
MOVAVE X Y
#
# Calculates the simple moving average of the data in X and
# stores the answer in Y.
#
MCONSTANT N I
MCOLUMN X Y
LET N = COUNT(X)
LET Y(1) = '*'
LET Y(2) = '*'
DO I = 3 : N
LET Y(I) = (X(I) + X(I-1) + X(I-2))/3
ENDDO
ENDMACRO
Note Instead of modifying a worksheet variable inside a DO/ENDDO loop, copying the worksheet variable to a local macro variable,
modifying the macro variable in the loop, then copying the macro variable back to the worksheet variable might be faster.
WHILE and ENDWHILE: Session commands for repeating a block
of commands depending on a logical expression
WHILE logical expression
Repeats a block of commands as long as a logical expression is true.
ENDWHILE
Marks the end of the WHILE loop.
Repeats a block of commands as long as the logical expression is true. The logical expression follows the same rules
as in the IF statement.
1116
Minitab Statistical Software Macros Session Commands
Suppose you want to find the root of the equation, y = -1 + x + x
3
. This equation has only one real root, which is
between 0 and 1. The following global macro calculates, approximately, what the root is.
GMACRO
ROOT
#
# Finds the root of a specific polynomial. The result is
# within .01 of the exact answer.
# K90-K93 are used for scratch work
#
NAME K90 'X' K91 'Y' K92 'Xlow' K93 'Ylow'
LET 'X' = 0
LET 'Y' = -1
WHILE 'Y' < 0
LET 'X' = 'X' + .01
LET 'Y' = -1 + 'X' + 'X'**3
ENDWHILE
LET 'Xlow' = 'X' - .01
LET 'Ylow' = -1 + 'Xlow' + 'Xlow'**3
PRINT 'Xlow' 'Ylow' 'X' 'Y'
ENDMACRO
The macro first initializes the two variables, X and Y, to 0 and −1. Each time through the WHILE-loop, Minitab first
checks to see that Y is still less than zero. If it is, Minitab increases X by .01 and calculates Y at this new value. When
the condition fails—that is, when Y is no longer less than zero—the macro exits the loop and goes to the first statement
after ENDWHILE. Then, the macro prints the result.
Note Instead of modifying a worksheet variable inside a WHILE / ENDWHILE loop, copying the worksheet variable to a local macro variable,
modifying the macro variable in the loop, then copying the macro variable back to the worksheet variable might be faster.
NEXT: Session command for transferring control from a loop to
the beginning of the block
Transfers control from within a DO- or WHILE-loop back to the beginning of the block. For DO, the loop variable is
then set to the next value in the list and the loop is executed again. The following is a simple example, using a global
macro.
GMACRO
FIVES
#
# Takes the column named X and changes all entries
# that are greater than 5 to 5.
# Constants K90 and K91 are used for scratch work.
#
NAME K90 'N' K91 'I'
LET 'N' = COUNT('X')
DO 'I' = 1 : 'N'
IF 'X'('I') <= 5
NEXT
ELSE
LET 'X'('I') = 5
ENDIF
ENDDO
ENDMACRO
The DO-loop goes through all the values in X. If a value is less than or equal to 5, NEXT passes control to the top of
the DO-loop and the value is left unchanged. If a value is greater than 5, the ELSEIF block is executed and that value
is set to 5.
1117
Minitab Statistical Software Macros Session Commands
BREAK: Session command for transferring control from a DO- or
WHILE-loop
Transfers control from within a DO- or WHILE-loop to the command immediately following the end of the loop. Thus
BREAK breaks out of the loop.
The following is a simple example of BREAK in a global macro. The program works on a worksheet where one of the
columns has the name X. The program goes through the values of X until it finds a missing value. It then leaves the
loop and goes to the statement following ENDDO—in this example, DELETE. Note that this program does not handle
the case when X has no missing values correctly. For an example that handles the case when X has no missing values,
go to EXIT: Session command for transferring control back to Minitab or for closing Minitab on page 1120.
GMACRO
NOMISS
#
# Takes data from the column named X. Finds the first missing
# observation. Then deletes all observations starting with the
# first missing to the end of the column.
# Constants K90 and K91 are used for scratch work
#
LET K90 = COUNT('X')
DO K91 = 1:K90
IF 'X'(K91) = '*'
BREAK
ENDIF
ENDDO
DELETE K91:K90 'X'
ENDMACRO
GOTO and MLABEL: Session commands for branching to any line
in a macro
GOTO number
MLABEL number
Allows you to branch to any line in your macro. There can be several GOTO's in one program. A GOTO is matched to
the MLABEL that has the same number. The number can be any integer from 1 to 8 digits long. It cannot be a variable.
The following example is a modification of the macro NOMISS, but uses GOTO instead of BREAK. The program works
on a worksheet where one of the columns has the name X. The program goes through the values of X until it finds a
missing value. It then leaves the loop and goes to the statement following ENDDO—in this example, DELETE. If X has
no missing values, the program prints a note.
GMACRO
NOMISS3
#
# Takes data from the column named X. Finds the first missing
# observation. Then deletes all observations starting with the
# first missing to the end of the column.
# Constants K90 and K91 are used for scratch work
#
LET k90 = COUNT('X')
DO K91 = 1:k90
IF 'X'(K91) = '*'
GOTO 5
ENDIF
IF k91 = k90
NOTE Note: there are no missing observations in X
Exit
ENDIF
1118
Minitab Statistical Software Macros Session Commands
ENDDO
MLABEL 5
DELETE K91:k90 'X'
ENDMACRO
CALL and RETURN: Session commands for passing control to
another macro
CALL template
RETURN
You can include several macros in one file, just as a program often includes several subroutines. CALL and RETURN let
you specify when to pass control to another macro and when to return to the main macro. You can include several
global macros in one file, or several local macros in one file, but you cannot mix global and local macros together in
one file.
When you invoke a macro, from interactive Minitab or from another macro, the first macro in the file is executed first.
Use the macro statements CALL and RETURN to invoke a different macro within the macro file.
Recall that the second line of a macro is the template, or the macro name. When one macro in a macro file calls another
macro in that file, use the command CALL, followed by the name on that macro's template. If it is a local macro, include
appropriate arguments and subcommands. Any macro in a macro file can CALL any other macro in the file, any number
of times.
RETURN says to leave the current macro and go back to the calling macro, to the statement just after the CALL. RETURN
is optional. If RETURN is not present in the macro that was called (the subroutine), then, after it has executed, control
is transferred back to the calling macro.
The following example is a variation on ANALYZE2.MAC. This example, ANALYZE3, uses the TSET command to ask the
user whether to print all the data. If the response is "yes", then the macro sets K80 to 1. If the answer is anything else,
then the macro sets K80 to 0. For more information, go to READ, TSET, and SET: Session command for asking users
questions and using the answers in a macro on page 1128. The OK subroutine checks the value of K80 with an IF statement.
If K80 equals 1, then the RETURN statement sends control back to the main macro. If K80 is anything else, then the
macro prints one more note. When the ENDMACRO statement is encountered in either the TOOSMALL or OK subroutine,
control is transferred back to the calling macro.
GMACRO
ANALYZE3
#
MTITLE "ANALYZE3"
NOTE Do you want all the data printed?
NOTE Type "yes" or "no" in quotation marks,
NOTE then click the Submit button.
tset c10;
file "terminal".
IF c10(1) = "yes"
LET k80 = 1
ELSE
LET k80 = 0
ENDIF
ERASE c10.
# If user types "yes" K80 = 1, if "no" K80 = 0
LET K90 = COUNT(C1)
IF K90 < 5
CALL TOOSMALL
ELSE
CALL OK
ENDIF
#
IF K80 = 1
NOTE Here are the data.
1119
Minitab Statistical Software Macros Session Commands
PRINT C1-C3
ENDIF
ENDMTITLE
ENDMACRO
#
#
GMACRO
TOOSMALL
NOTE Data set has fewer than 5 observations.
NOTE No analysis will be done.
ENDMACRO
#
#
GMACRO
OK
NAME C1 'Yield' C2 'Chem1' C3 'Chem2' C5 'Ln.Yield'
DESCRIBE C1-C3
LET C5 = LOGE('Yield')
REGRESS;
RESP c5;
CONT c2 c3;
TERMS c2 c3.
IF K80 = 1
RETURN
ENDIF
NOTE Analysis done, but no data printed by request
ENDMACRO
EXIT: Session command for transferring control back to Minitab
or for closing Minitab
EXIT
EXIT has two very different behaviors depending on whether it is used in global and local macros, or in an exec
file, as follows:
In a global or local macro, EXIT transfers control back to interactive Minitab.
In an exec file, EXIT closes Minitab.
The following example is a modification of the macro NOMISS, which correctly handles the case when X contains
no missing values. The program works on a worksheet where one of the columns has the name X. The program
goes through the values of X until it finds a missing value. It then leaves the loop and goes to the statement
following ENDDO—in this example, DELETE. If X has no missing values, the program prints a note.
GMACRO
NOMISS2
#
# Takes data from the column named X. Finds the first missing
# observation. Then deletes all observations starting with the
# first missing to the end of the column. Prints a message if
# the column has no missing values.
# Constants K90 and K91 are used for scratch work
#
LET K90 = COUNT('X')
DO K91 = 1:K90
IF 'X'(K91) = '*'
BREAK
ENDIF
IF K91 = K90
NOTE Note: There are no missing observations in X.
EXIT
ENDIF
ENDDO
DELETE K91:K90 'X'
ENDMACRO
1120
Minitab Statistical Software Macros Session Commands
PAUSE and RESUME: Session commands for pausing and resuming
a macro
PAUSE
When Minitab encounters a PAUSE in a macro, control is shifted from the macro to the keyboard. You can then
type any Minitab command. PAUSE can help you debug a macro you are developing. It can also allow you to get
input from the macro user.
If you are in PAUSE mode from within a local macro, you have access to the local worksheet and only the local
worksheet. You can also declare new local variables and use them. They will be stored at the end of the local
worksheet.
When you are in PAUSE mode, you can type any Minitab command. You cannot CALL other macros in the same
file, invoke a macro from another macro file, or use control statements.
RESUME
When you want to return control to the macro, type RESUME (or just R).
Using DOS Commands
CD: Session command for displaying or changing the current
directory
CD [filepath]
CD without a path displays the current directory. CD with a path changes the current directory to the one that
you specify.
For example, CD displays the current directory, and CD WILLIAMS\SALES91 changes the current directory to
WILLIAMS\SALES91.
Labeling Macro Output
MTITLE: Session command for adding a title above output
MTITLE "title"
Starts the MTITLE mode. This mode adds a title for any output that is produced by commands between MTITLE
and ENDMTITLE. While in MTITLE mode, you cannot save a project, open a project, open a worksheet, or open
a graph. You cannot nest MTITLE in another MTITLE command. Because you cannot nest MTITLE, you usally
do not use MTITLE in a macro that is nested in another macro.
NOTITLE
Suppresses the titles of the commands executed while in MTITLE mode.
1121
Minitab Statistical Software Macros Session Commands
ENDMTITLE
Ends the MTITLE mode. Minitab does not display any output until you specify ENDMTITLE.
TITLE: Session subcommand for adding a title to a graph
TITLE ["title"]
Adds a title to a graph.
You can use TITLE more than one time. Each additional title goes below the preceding title.
Using TITLE with no argument displays the default title. Using TITLE with an argument replaces the default
title.
Default titles precede additional titles.
TITLE works the same for the basic graph commands and control chart commands. You can suppress the default
title with the subcommand NODTITLE.
Attributes for the title text
TFONT "font name"
TFONT specifies the font name for the text.
TCOLOR K
TCOLOR specifies the text color, which is a number from Numbers for colors to use in session commands on page
1172.
TSIZE K
TSIZE specifies the size of the text in Minitab units. K can be any positive number.
PSIZE K
PSIZE specifies the size of the text in points. K can be any positive number.
BOLD
Specifies to display the text in bold font.
NOBOLD
Specifies to not display the text in bold font.
UNDERLINE
Specifies to underline the text.
NOUNDERLINE
Specifies to not underline the text.
ITALIC
Specifies to display the text in italic font.
NOITALIC
Specifies to not display the text in italic font.
1122
Minitab Statistical Software Macros Session Commands
Positioning
LEFT
Puts the title in the left of the figure region.
CENTER (default)
Puts the title in the center of the figure region.
RIGHT
Puts the title in the right of the figure region.
OFFSET K K
Moves a title away from the position specified with LEFT, CENTER or RIGHT. The first argument specifies how far
to move the footnote horizontally (in figure units). The second argument specifies the how far to move the footnote
vertically (in figure units). The default offset is 0.0 0.0.
WTITLE: Session subcommand for specifying the title of the output
pane
WTITLE "title"
Specifies the title for the output pane.
You can use WTITLE as a subcommand with LAYOUT and all graph commands. The title you specify becomes the
title of the output pane.
Debugging Tools
ECHO and NOECHO: Commands for displaying Minitab commands
from macros and execs
The ECHO and NOECHO commands control whether commands in a macro or exec are in the output. When you
develop a macro, you can use ECHO to see the commands so that you can find errors more easily.
You can submit ECHO and NOECHO before you invoke a macro. You can also place them anywhere within the body
of a macro. You can use ECHO and NOECHO several times in a macro to turn on and off the display of commands.
ECHO
In ECHO mode, only commands in the body of the macro are in the output. The commands include Minitab
commands, macro statements, and invocations of macros in other files. The commands do not include the template
and declarations. (Declarations are in local macros only.) Text that is after a # is not in the output.
NOECHO (default)
In NOECHO mode, no Minitab commands or macro statements are in the output. The output of Minitab commands
is in the output.
1123
Minitab Statistical Software Macros Session Commands
DEBUG and NODEBUG: Session commands for finding problems
in macros
DEBUG
Displays information about the macro in the output.
NODEBUG (default)
Suppresses the display of information about the macro in the output.
PAUSE and RESUME: Session commands for pausing and resuming
a macro
PAUSE
When Minitab encounters a PAUSE in a macro, control is shifted from the macro to the keyboard. You can then
type any Minitab command. PAUSE can help you debug a macro you are developing. It can also allow you to get
input from the macro user.
If you are in PAUSE mode from within a local macro, you have access to the local worksheet and only the local
worksheet. You can also declare new local variables and use them. They will be stored at the end of the local
worksheet.
When you are in PAUSE mode, you can type any Minitab command. You cannot CALL other macros in the same
file, invoke a macro from another macro file, or use control statements.
RESUME
When you want to return control to the macro, type RESUME (or just R).
Additional Local Macro Features
INFO: Session command for summarizing the current worksheet
INFO [C...C]
Summarizes the current worksheet.
If no columns are specified, INFO prints a list of all columns used with their names and counts, all stored constants,
all matrices. If there are missing observations, a count of these is also given. If a column contains text data, the
letter T is printed to the left of the column. If columns have assigned formulas, these are printed along with the
method selected for updating the calculations (manual or automatic). If you list columns, information is given on
just those columns.
WRITE: Session command for storing data in a text file
WRITE E...E
Writes data in the specified columns or constants to the screen or to a data file.
1124
Minitab Statistical Software Macros Session Commands
Because of potential conflicts with the global worksheet, the commands SAVE and RETRIEVE do not work in a
local macro. Global worksheet variables that have been passed into the macro as arguments assume any new
values given to them during the course of the macro execution. You can always save those variables after the
macro executes. But you may also want to save local worksheet variables that are not passed as arguments. You
can use WRITE to save local worksheet variables, use the WRITE command within your macro.
FILE "filename"
Specifies the file to store the data in.
Example
Suppose you have three column variables in the local worksheet named X, Y, and Z. The following command saves
those three columns in a text file named MYWORK.DAT.
WRITE X Y Z;
FILE "MYWORK".
Commands that Affect Output
BRIEF: Session command for controlling the amount of output
BRIEF K
Controls the amount of output. For example, the following table describes how BRIEF works with most commands
that create a designed experiment.
Output that is displayedValue of K
Minitab displays no output from the command, but performs all specified storage and
displays the following output: error messages, warnings, prompts, and notes; graphs;
WRITE to the screen.
0
Minitab displays a summary of the design.1
Same as K = 1 output.2 (default)
Same as K = 2 output, but Minitab also displays the design table.3
Used as a main command, BRIEF affects the amount of output produced by subsequent commands. Used as a
subcommand, BRIEF only affects output for the command it is used with.
Most commands are affected by BRIEF only when it is set to 0. However, BRIEF affects the amount of output
produced by the following commands in specific ways. Go to the individual commands for details.
ARIMA on page 864
BBDESIGN on page 342
CCDESIGN on page 343
CLUOBS on page 845
CLUVARS on page 849
DISCRIMINANT on page 852
EVDESIGN on page 365
1125
Minitab Statistical Software Macros Session Commands
FACTOR on page 842
FFDESIGN on page 279
KMEANS on page 851
LREGRESSION on page 735
LTABLE on page 722
LTEST on page 709
MIXREG on page 375
NLOGISTIC on page 216
OLOGISTIC on page 213
OPTDES on page 361
PROBIT on page 750
SCDESIGN on page 369
SLDESIGN on page 372
GSAVE: Session subcommand for saving a graph in a file
GSAVE "file_name"
GSAVE K
Saves the graph in a file.
The default file name is Minitab.PNG. You can specify a custom file name in double quotation marks ("file_name"),
or as a stored text constant (K). You can also use any of the following subcommands to save the graph in a different
graphics format.
Some graph commands—for example, HISTOGRAM C1 C2 C3—generate more than one graph. If you include
the GSAVE subcommand with such a command, Minitab saves multiple files. Minitab gives each file a different
file name. Minitab uses the first five characters of the name you specify, then appends a number (001, 002, and
so on), for up to 300 files.
JPEG
JPEG color
PNGB
PNG grayscale
PNGC
PNG color
TIFB
TIF grayscale
TIF
TIF color
1126
Minitab Statistical Software Macros Session Commands
BMPB
BMP grayscale
BMPC
BMP color
GIF
GIF
EMF
EMF
RESOLUTION K
Saves the graph at a resolution of K dots per inch.
GSCALE: Session command to determine appropriate scaling for
a graph
GSCALE K K
GSCALE is useful primarily when you are writing a macro that produces graphs, and you need to know information
before you produce the graphs to ensure that the scaling on the graphs will look right. For example, you might
want to generate two or more graphs that use the same scale, but you want to control the scale. You can use the
data stored by GSCALE to specify scaling options in subsequent graph commands.
The arguments on the main command are the minimum (the first K) and the maximum (the second K) of the data
from the columns to be graphed, combined. An easy way to get those values is to STACK all of the columns on
top of each other in a new column, then use the MIN and MAX commands to store the minimum and maximum
values.
NMINIMUM K
Specifies the minimum number of ticks to use.
NMAXIMUM K
Specifies the maximum number of ticks to use.
NTICKS K
Stores the number of ticks.
TMINIMUM K
Stores the minimum tick value.
TMAXIMUM K
Stores the maximum tick value.
TINCREMENT K
Stores the distance between ticks.
SMINIMUM K
Stores the scale minimum.
SMAXIMUM K
Stores the scale maximum.
1127
Minitab Statistical Software Macros Session Commands
NOBRUSH: Session subcommand for disabling brushing on a graph
Can be used as a subcommand of any graphics command to disable brushing on the resulting graph. Why disable
brushing? Brushing can only highlight rows of data in the global worksheet. But graphs created in local macros are
sometimes based on data in the local worksheet that have no relationship to corresponding rows of data in the global
worksheet.
Communicating with Macro Users
READ, TSET, and SET: Session command for asking users questions
and using the answers in a macro
READ, TSET and SET have a special feature that allows you to ask users questions and then use their answers in the
macro. A macro will pause for user input if you use READ, TSET or SET with the subcommand FILE with the special
filename TERMINAL. TERMINAL tells Minitab to wait for input from the keyboard.
READ, TSET and SET have other subcommands.
READ C...C
FILE "TERMINAL"
SET C
FILE "TERMINAL"
TSET C
FILE "TERMINAL"
PAUSE and RESUME: Session commands for pausing and resuming
a macro
PAUSE
When Minitab encounters a PAUSE in a macro, control is shifted from the macro to the keyboard. You can then
type any Minitab command. PAUSE can help you debug a macro you are developing. It can also allow you to get
input from the macro user.
If you are in PAUSE mode from within a local macro, you have access to the local worksheet and only the local
worksheet. You can also declare new local variables and use them. They will be stored at the end of the local
worksheet.
When you are in PAUSE mode, you can type any Minitab command. You cannot CALL other macros in the same
file, invoke a macro from another macro file, or use control statements.
RESUME
When you want to return control to the macro, type RESUME (or just R).
1128
Minitab Statistical Software Macros Session Commands
NOTE: Session command for adding comments that are displayed
in the output
NOTE
Use NOTE to annotate your macro program with comments that are displayed in the output. To annotate with
comments that are not displayed, use the comment symbol #.
Use notes to make your output more readable with spaces or to add helpful notes to yourself. Text from notes
will appear in separate output tabs unless you use the MTITLE and ENDMTITLE commands to specify a block of
output.
Put the NOTE command at the beginning of a line.
All text on that line will be ignored by the macro processor. However, text on a NOTE line (except the first five
spaces the word NOTE and a space) does display in the output when the macro is executed.
Note The NOTE cannot end with a semicolon. You can use a semicolon, but end the line with it. For example, NOTE AB;CD is acceptable,
but NOTE ABCD; is not acceptable.
You can also make your macro file more readable by adding blank lines between the lines of macro statements
and commands. The blank lines do not interfere with the execution of the macro, and will not appear in the output.
You do not have to start a blank line with the comment symbol #.
Example of using NOTE in a macro
ResultsMacro Code
Here come the data
Data
Row Yield Chem1 Chem2
1 11.28 87 1.83
2 8.44 61 25.42
3 13.19 59 28.64
...
GMACRO
SAMPLEMACRO
RAND 50 C1 C2 C3;
UNIFORM 5 10.
MTITLE "Print Columns".
NOTE Here come the data
NOTE
PRINT C1-C3.
ENDMTITLE
ENDMACRO
1. The first tab will contain Here come the data.
2. The second tab will be blank.
3. The third tab will contain the data.
Note If you don't use MTITLEand ENDMTITLE, then this example
will generate 2 tabs of output. The instance of NOTE without any text
does not generate an output tab.
Execs Commands
ECHO and NOECHO: Commands for displaying Minitab commands
from macros and execs
The ECHO and NOECHO commands control whether commands in a macro or exec are in the output. When you
develop a macro, you can use ECHO to see the commands so that you can find errors more easily.
1129
Minitab Statistical Software Macros Session Commands
You can submit ECHO and NOECHO before you invoke a macro. You can also place them anywhere within the body
of a macro. You can use ECHO and NOECHO several times in a macro to turn on and off the display of commands.
ECHO
In ECHO mode, only commands in the body of the macro are in the output. The commands include Minitab
commands, macro statements, and invocations of macros in other files. The commands do not include the template
and declarations. (Declarations are in local macros only.) Text that is after a # is not in the output.
NOECHO (default)
In NOECHO mode, no Minitab commands or macro statements are in the output. The output of Minitab commands
is in the output.
EXECUTE: Session command for running an Exec file
EXECUTE "filename" K
Note You cannot use EXECUTE in a local macro.
Runs commands that are stored in a file. These command files are called Execs.
You may specify the filename as either the name of the file in double quotes, or a stored text constant. The default
file extension for Execs is MTB. When you use EXECUTE, you do not need to type the file extension if it is .MTB.
The default file name is Minitab.MTB. If you do not specify a file name with EXECUTE, Minitab runs Minitab.MTB
if it exists.
The optional argument K lets you specify how many times to run the Exec. K can be any integer. The default value
is 1, which means that the Exec runs one time. If K > 1, the Exec runs K times. If K is < 1, the macro does not run.
For information on using K to determine whether to run an Exec, go to Using Conditional Execution
To interrupt an Exec, press Ctrl+Break. Minitab will finish the command in process before it stops the macro.
1130
Minitab Statistical Software Macros Session Commands
Supporting Concepts
Add your own function
1. Start a word processor or text editor, such as Notepad.
2. Open the file USERFUNC.MAC. The file is in the Macros folder of your main Minitab folder.
3. Back up the file by saving it as a different name, such as USERFUNC.BAK. Save the file as plain text (ASCII file).
4. In USERFUNC.MAC, add your own function by following the instructions at the top of the file. In the macro you
will assign your function a number between 1 and 1000.
5. Save USERFUNC.MAC as a plain text file.
Adding comments to a macro
You can add comments to a macro that are displayed or not displayed.
Add comments that are displayed
Use the NOTE on page 1129 command at the beginning of a line that contains the comment.
Add comments that are not displayed
Place the symbol # anywhere on a line to tell Minitab to ignore the rest of the line. Text after # is not displayed in the
output when the macro is executed (even when you use ECHO).
Array table for OADESIGN
The following table shows all the legal commands and the full arrays to which they correspond.
Full orthogonal arrayCommand line
L4 (2**3)OADesign 4 2 K (K=1, 2, 3)
L8 (2**7)OADesign 8 2 K (K= 1, ... ,7)
L8 (2**4 4**1)OADesign 8 2 K 4 1 or OADesign 8 4 1 2 K (K = 1, 2, 3, 4)
L9 (3**4)OADesign 9 3 K (K= 1, 2, 3, 4)
L12 (2**11)OADesign 12 2 K (K = 1, . . . , 11)
L16 (2**15)OADesign 16 2 K (K = 1, . . . , 15)
L16 (2**12 4**1)OADesign 16 2 K 4 1 or OADesign 16 4 1 2 K (K = 1, . . . , 12)
L16 (2**9 4**2)OADesign 16 2 K 4 2 or OADesign 16 4 2 2 K (K = 1, ... , 9)
L16 (2**6 4**3)OADesign 16 2 K 4 3 or OADesign 16 4 3 2 K (K = 1, . . . , 6)
L16 (2**3 4**4)OADesign 16 2 K 4 4 or OADesign 16 4 4 2 K (K = 1, 2, 3)
L16 (4**5)OADesign 16 4 K (K = 1, . . . , 5)
1131
Minitab Statistical Software Supporting Concepts
Full orthogonal arrayCommand line
L16 (8**1 2**8)OADesign 16 8 1 2 K or OADesign 16 2 K 8 1 (K = 1, . . . , 8)
L18 (2**1 3**7)OADesign 18 2 1 3 K or OADesign 18 3 K 2 1 (K = 1, . . . , 7)
L18 (6**1 3**6)OADesign 18 6 1 3 K or OADesign 18 3 K 6 1 (K = 1, . . . , 6)
L25 (5**6)OADesign 25 5 K (K = 1, . . . , 6)
L27 (3**13)OADesign 27 3 K (K = 1, . . . , 13)
L32 (2**31)OADesign 32 2 K (K = 1, . . . , 31)
L32 (2**1 4**9)OADesign 32 2 1 4 K or OADesign 32 4 K 2 1 (K = 1, . . . , 9)
L36 (2**11 3**12)OADesign 36 2 K2 3 K3 or OADesign 36 3 K3 2 K2 (K2 = 1, . . . , 11; K3 = 1,
. . . , 12)
L36 (2**3 3**13)OADesign 36 2 K 3 13 (K = 1, 2, 3)
L54 (2**1 3**25)OADesign 54 2 1 3 K or OADesign 54 3 K 2 1 (K = 1, . . . , 25)
Assigning attributes to groups
Attributes—such as symbol types, line sizes, and area colors—are assigned to groups in the order the groups appear
in the worksheet for text data. For numeric data the groups are assigned from the least to the greatest values.
Assigning attributes with multiple graphs and groups
If you specify several graphs and several groups, then attributes are assigned to the groups and not the graphs.
In the example below, the PLOT command specifies two graphs, which are overlaid (the Advertis label does not appear).
The CONNECT subcommand does not specify a group variable, so the two line types are assigned to the two graphs.
The SYMBOL subcommand, however, has a group variable, AdAgency, so the two symbol types are assigned to the
two ad agencies.
Data
In ResinDefects.MTW: Discoloration Defects, Clump Defects, Hours Since Cleanse, Size of Screw
Dialog box, Step 1: Create the graph
1. Choose Graph > Scatterplot.
2. Choose Simple, then click OK.
3. In row 1 of the Data Source, enter Discoloration Defects in Y and Hours Since Cleanse in X. In row 2, enter Clump
Defects in Y and Hours Since Cleanse in X.
4. Click Multiple Graphs and select Overlaid on the Same Page. Click OK.
5. Click Data View and select Connect Line.
6. Click OK in each dialog box.
1132
Minitab Statistical Software Supporting Concepts
Dialog box, Step 2: Edit the graph
1. Double-click the symbols.
2. On the Groups tab, in Categorical Variable for Grouping, enter Size of Screw.
3. Click OK.
Session commands
Plot 'Discoloration Defects' * 'Hours Since Cleanse' 'Clump Defects' * 'Hours Since
Cleanse';
Overlay;
NoJitter;
Graph 6 4;
Legend;
Section 1;
Section 2;
Connect;
Symbol 'Size of Screw';
Title;
Footnote;
FPanel;
NoDTitle.
Graph output
Bar chart functions
You can create a bar chart of a function of the graph variable using the syntax CHART F(C...C) * C. The following functions
(F) are available:
SUM
Sum of values
1133
Minitab Statistical Software Supporting Concepts
COUNT
Number of values (frequency)
N
Number of nonmissing values
NMISS
Number of missing values
MEAN
Mean of values
MEDIAN
Median of values
MINIMUM
Minimum of values
MAXIMUM
Maximum of values
PERCENTILE
Use the Kth percentile to summarize the contents of the variable. Must also specify the subcommand PTILE K.
PBETWEEN
Use the percentage of values between two values to summarize the contents of the variable. Must also specify
the subcommand PBETWEEN K1 K2.
PEQUAL
Use the percentage of values equal to one or more values to summarize the contents of the variable. Must also
specify the subcommand PEQUAL K...K.
STDEV
Standard deviation of values
SSQ
Sum of squares of values
Base position for project lines, area, and bar
You can set the base position for project lines, area, and bar. The default base differs depending on the graph and the
data display.
Histogram with non-zero base
1134
Minitab Statistical Software Supporting Concepts
Interval plot with bars and non-zero base
Box-Behnken designs
The table below displays a summary of the Box-Behnken designs that are generated by Minitab.
For more information, go to BBDESIGN: Session command for creating a Box-Behnken design on page 342.
Default number of center
points
Optional number of blocksNumber of runsNumber of factors
31153
33274
62465
62546
62627
105 or 101309
10217010
Calculating a chi-square statistic for a
goodness-of-fit test using session commands
If you know the expected probability of the possible outcomes, you can calculate a chi-square statistic for a
goodness-of-fit test. This topic shows how to do that using session commands.
Equal probability of outcomes
Suppose you ask 20 people at a restaurant whether they prefer bread or rice. You expect that 10 will prefer bread and
10 will prefer rice. You conduct the survey and find that 5 people prefer bread, and 15 people prefer rice. To test
whether the observed values differ statistically from the expected values, enter the following commands.
SET C1
5 15 #(observed values)
END
SET C2
10 10 #(expected values)
END
LET K1 = SUM((C1 - C2)**2/C2) #(chi-square statistic)
PRINT K1
1135
Minitab Statistical Software Supporting Concepts
K1 contains the correct χ statistic, which is 5. To compute a p-value for that statistic, enter these commands.
CDF K1 K2; #(store the CDF in K2)
CHISQUARE 1. #(df = number of categories - 1)
LET K3 = 1 - K2 #(K3 contains the associated p-value)
PRINT K3
The p-value is 0.025, indicating a statistically significant difference between the values we observed and those we
expected to find.
Binomial case
Suppose you want to measure how often heads comes up in 5 tosses of a coin, and you repeat those 5 tosses many
times. If you toss 5 coins, the number of heads should follow a binomial distribution with n=5 and p=0.5. There are
six categories of outcomes: 0 heads in 5 tosses, 1 head in 5 tosses, 2 heads in 5 tosses, up to 5 heads in 5 tosses. You
toss coins a total of 3590 times.
SET C1
0 1 2 3 4 5 #(categories)
END
SET C2
100 524 1080 1126 655 105 #(observed values in each category)
END
PDF C1 C3; #(probability of success for each category)
BINOMIAL 5 0.5.
LET C4 = 3590 * C3 #(expected values)
LET K1 = SUM((C2 - C4)**2/C4)#(chi-square statistic)
PRINT K1.
CDF K1 K2; #(store the CDF in K2)
CHISQUARE 5. #(df = number of categories - 1)
LET K3 = 1 - K2 #(K3 contains the associated p-value)
PRINT K3
The p-value, stored in K3, is 0.00063, indicating a statistically significant different between what we observed and what
we expected.
Calculations for FFACTORIAL
In calculations for FFACTORIAL, Minitab first sets aside any center points and covariates, then checks the design to see
if it is orthogonal. If it is not, Minitab displays a message. Next, Minitab checks for collinearity. If there is a problem
with factors or blocks, Minitab displays a message and quits. If interaction terms are collinear with other terms in the
model, Minitab displays a message, removes the interaction terms, and proceeds. If the design is orthogonal, Minitab
also provides information about confounding for the terms it removes. Minitab then adds in any center points and
covariates and does a final collinearity check.
FFACTORIAL uses a regression approach to fit the model. This approach allows you to analyze nonorthogonal designs
(also called unbalanced designs) as well as orthogonal designs. However, if the design is large, especially if there are
many terms, the calculations might take a long time.
FFACTORIAL can fit models with up to 137 terms and up to 15-way interactions. However, on computers that have
limited worksheet space, Minitab might not be able to fit all 137 terms. For example, on a computer that has a worksheet
of 16,000, Minitab can fit only 64 terms.
Central composite designs
The following table is a summary of the designs that are created by Minitab's central composite design commands.
1136
Minitab Statistical Software Supporting Concepts
Rotatable?Orthogonal
blocks?
Default
alpha
Axial
center
points
Cube
center
points
Total
center
points
Cube
runs
Cube
blocks
Total
blocks
Total
runs
DesignFactors
Yes---1.4140---54---113Full2
YesYes1.41433641214Full2
Yes---1.6820---68---114Full3
NoYes1.68324681220Full3
NoYes1.68324682320Full3
Yes---2.0000---716---131Full4
YesYes2.000246161230Full4
YesYes2.000246162330Full4
Yes---2.3780---1032---152Full5
NoYes2.3664812321254Full5
NoYes2.3664812322354Full5
Yes2.0000---616132Half5
YesYes2.000167161233Half5
Yes---2.8280---1464---190Full6
YesYes2.8286814641290Full6
YesYes2.8286814642390Full6
YesYes2.8286814644590Full6
Yes---2.3780---932---153Half6
NoYes2.3662810321254Half6
NoYes2.3662810322354Half6
Yes---3.3640---1128---1152Full7
YesYes3.3641081812812160Full7
YesYes3.3641081812823160Full7
YesYes3.3641081812845160Full7
Yes---2.8280---1064---188Half7
YesYes2.8284812641290Half7
YesYes2.8284812642390Half7
YesYes2.8284812644590Half7
Yes---3.3640---10128---1154Half8
YesYes3.364881612812160Half8
YesYes3.364881612823160Half8
YesYes3.364881612845160Half8
Yes---2.8280---1064---190Quarter8
YesYes2.8282810641290Quarter8
YesYes2.8282810642390Quarter8
1137
Minitab Statistical Software Supporting Concepts
Rotatable?Orthogonal
blocks?
Default
alpha
Axial
center
points
Cube
center
points
Total
center
points
Cube
runs
Cube
blocks
Total
blocks
Total
runs
DesignFactors
YesYes2.8282810644590Quarter8
Yes---3.3640---10128---1156Quarter9
YesYes3.364681412812160Quarter9
YesYes3.364681412823160Quarter9
YesYes3.364681412845160Quarter9
YesYes3.3640---10128---1158Eighth10
YesYes3.364481212812160Eighth10
YesYes3.364481212823160Eighth10
YesYes3.364481212845160Eighth10
Computing weights, or smoothed values
The smoothed values are obtained in one of two ways:
Using the ARIMA (0,1,1) model (without WEIGHT subcommand). In this method, the ARIMA model is fit to the data
using Minitab's ARIMA command. The predicted values from the ARIMA command are stored. These are the same
as the smoothed values, only lagged one period. There is no predicted value for period 1, so this must be obtained.
This is done by backcasting period 1. Thus, predicted in period 1 = [predicted in period 2 a(data in period 1)] /
(1 a).
Using the classical approach (with WEIGHT subcommand). In this method, the average of the first 6 (or N, if N <
6) data values is used to obtain the initial smoothed value. Once the initial smoothed value is obtained, subsequent
values are calculated from the formula: smoothed at period t = (a) * (data at period t) + (1 a) * (smoothed at
period t 1).
Data requirements and formats for attribute
agreement analysis
For attribute agreement analysis, data can be text or numeric. The assigned ratings can be nominal or ordinal:
Nominal data are categorical variables that have two or more levels with no natural ordering. For example, the
levels in a food tasting study may include crunchy, mushy, and crispy.
Ordinal data are categorical variables that have three or more levels with a natural ordering, such as strongly
disagree, disagree, neutral, agree, and strongly agree.
If the response is a text column and the data are ordinal, click in the column, then right-click and choose Column
Properties > Value Order to define a non-alphabetical ordering on the text values.
Data can be stacked in an attribute column or unstacked in multiple columns. For attribute column data, stack all of
the responses in one column and set up grouping indicator columns for the appraiser and part number. The grouping
indicators define each sample. Grouping indicators and responses can be text or numeric. For multiple column data,
responses for each appraiser and each trial are in separate columns.
1138
Minitab Statistical Software Supporting Concepts
The following worksheets contain the same data set, structured in both of the formats that you can use for attribute
agreement analysis.
Attribute column data
C3C2C1
ResponseAppraiserSample
GoodA1
GoodA1
BadB1
GoodB1
GoodA2
GoodA2
GoodB2
GoodB2
BadA3
GoodA3
BadB3
BadB3
GoodA4
GoodA4
GoodB4
GoodB4
BadA5
BadA5
GoodB5
BadB5
Multiple columns of data
C5C4C3C2C1
Appraiser B, Trial 2Appraiser B, Trial 1Appraiser A, Trial 2Appraiser A, Trial 1Sample
GoodBadGoodGood1
GoodGoodGoodGood2
BadBadGoodBad3
GoodGoodGoodGood4
BadGoodBadBad5
Note When your data are in multiple columns, you must enter the trials for each operator together, as shown above. The order of the trials
must be the same for each operator.
1139
Minitab Statistical Software Supporting Concepts
Default date/time formats
Minitab recognizes many date/time formats, including the following.
ExampleDescriptionFormat
5-January-16International dated-mmmm-yy
January 5Month and daymmmm d
5 JanuaryDay and monthd mmmm
5 January 16Day, month, and yeard mmmm yy
January 5, 16Month, day, and yearmmmm d, yy
Sunday, January 05, 2014Day of the week, month, date, and yeardddd, mmmm dd, yyyy
11:10:14.22 PM12-hour timeh:mm.ss.ss AM/PM
2193:44.123Elapsed time (minutes, seconds, thousandths of
a second)
[m]:ss.sss
5:23:14Elapsed time (hours, minutes, seconds)[h]:mm:ss
1.12:33Elapsed time (days, hours, minutes)[d].hh:mm
Minitab also recognizes variations of these formats. For example, Minitab recognizes mmmm d, yy (January 1, 14) and
also recognizes mmm dd, yyyy (Jan 01, 2014).
If you enter time components without a date or without AM/PM, such as 1:17, Minitab recognizes the value as an
elapsed time (one hour and 17 minutes) not as a specific time on the 12- or 24-hour clock.
Date/time formats from regional settings
Minitab recognizes the short date format, the long date format, the short time format, and the long time format from
your regional date and time settings on your computer. Minitab also recognizes date/time formats based on these
short and long formats. For example, regionally-based default formats for January 12, 2014 include.
ExampleRegional settingFormat
1/12/16English (United States)m/d/yy
16/1/12Chinese, Korean, or Japaneseyy/m/d
12/1/16English (United Kingdom) or French (France)d/m/yy
Minitab interprets 2-part dates (month and day, without the year) based on regional settings. For example, if the
regional setting is m/d/yy or yy/m/d, Minitab interprets 1/12 as January 12 of the current year. However, if the regional
setting is yy/d/m, Minitab interprets the 2-part date 1/12 as December 1 of the current year. Minitab always interprets
a 2-part date that includes a 4-digit year as a month and a year.
Separators and symbols
Default date components can be separated by (/), (-), or (.). All components must be separated by the same symbol
(except for the default format mmmm d, yy). For example, both 1/1/99 and 1-1-99 are valid, but 1/1-99 is not valid.
Default 12-hour time components can be AM/PM, am/pm, A/P, or a/p.
Square brackets are used to indicate elapsed time, with the brackets around the most significant time unit. For example,
[m]:ss represents elapsed time in minutes and seconds. If you enter time components without a date or without AM/PM
(such as 1:17) into the worksheet, Minitab recognizes the value as an elapsed time (one hour and 17 minutes) not as
1140
Minitab Statistical Software Supporting Concepts
a specific time on the 12- or 24-hour clock. The format for fraction of a second can be .s (tenths), .ss (hundredths), or
.sss (thousandths).
Note When the regional language is set to German, French, or Portuguese, the default decimal separator is a comma. For example, in
English a fraction of a second uses a period (ss.sss). But in the three languages previously mentioned, a fraction of a second uses a comma
(ss,sss).
Variations of default formats
Minitab also recognizes variations of the above default formats. For example, the time components h:mm:ss can be
added to a default date format to create a longer date-time format, such as m/d/yyyy h:mm:ss. In addition, some
date/time components (such as "d" or "mmmm") can be substituted with longer or shorter forms ("dd" or "mmm").
What the component can be substituted withDate component
ddd
mmm
yyyyyy
mmmmmmmm
hhh
sss
For example, Minitab recognizes mmmm d, yy (January 1, 16 but also recognizes mmm dd, yyyy (Jan 01, 2016).
Note In Korean and Japanese, mmm cannot be substituted for mmmm in a default format. In these languages, the mmm format for month
is a number only, which may create ambiguity with other default formats that use only a number to represent the month (mm and m).
Designs generated by FFDESIGN
The table below summarizes the designs generated by FFDESIGN. The number in a cell is the resolution of the unblocked
design.
Number of factors
15141312111098765432Number
of
runs
III
1
full
2
4
III
1
III
2
III
2
IV
4
full
4
8
III
1
III
2
III
2
III
4
III
4
III
4
III
4
IV
8
IV
8
IV
8
V
8
full
8
16
IV
8
IV
8
IV
8
IV
8
IV
8
IV
8
IV
8
IV
8
IV
8
VI
16
full
16
32
IV
16
IV
16
IV
16
IV
16
IV
16
IV
16
IV
16
V
16
VII
16
full
32
64
IV
16
IV
16
IV
16
IV
16
V
16
V
16
VI
16
VIII
32
full
64
128
1141
Minitab Statistical Software Supporting Concepts
Entering data for factor variables
You can enter numeric or text data to assign values to factor levels. For a numeric factor, Minitab designates the lowest
numeric value as the reference level. For a text factor, Minitab determines the reference level alphabetically.
Logistic regression creates a set of design variables for each factor in the model. Minitab uses the reference cell method
to code design variables that make up a factor. For each factor, Minitab creates the number of levels minus one design
variables.
Here are two examples of the default coding scheme.
Factor A with 4 levels
The reference level is 1.
A3A2A1
0001
0012
0103
1004
Factor B with 3 levels
The reference level is Humidity
B2B1
00Humidity
01Pressure
10Temperature
Use the REFERENCE subcommand to specify the reference level for a factor. Use the EFFECT subcommand to specify
effect coding instead of binary coding.
Entering data for response variables
The response variable data can be represented in various ways. Minitab provides four response variable
subcommands—FREQUENCY, ST, SF, and FT—to specify the form of the response data. The table below summarizes
the forms.
For examples, go to Examples of entering response data for logistic regression on page 1144.
Response
variable
subcommand
CommandsDescriptionHow the response
data is entered
NoneGZLMResponse column contains one row for each
observation, with additional column or columns
to specify the factor/covariate patterns
One column that
contains distinct values
OLOGISTIC
NLOGISTIC
FREQUENCYGZLMOne column contains the response values, one
column contains the frequencies associated with
Frequencies
OLOGISTIC
the response, with additional column or columns
1142
Minitab Statistical Software Supporting Concepts
Response
variable
subcommand
CommandsDescriptionHow the response
data is entered
to specify the factor/covariate patterns for each
frequency
NLOGISTIC
NoneGZLMTwo columns represent the response variable with
additional column or columns to specify the
factor/covariate pattern for each observation
Events and trials or
trials
BFFACTORIAL
BGFACTORIAL
BRSREGRESSION
BSCREEN
Entering patterned data for the SET session
command
SET: Session command for entering data into a column on page 80 provides shortcut ways to enter data that follow
many different kinds of patterns.
The following example shows how to set C3 with the numbers 1, 2, 3, 4, and 5. Note that a colon abbreviates the range.
SET C3
1:5
END
Observe the following rules:
1. A slash (/) indicates an increment.
2. Put lists you want repeated in parentheses.
3. No space between the repeat factor and the corresponding parenthesis.
4. If the repeat factor is before the parentheses, Minitab repeats the entire list; if it is after, Minitab repeats each
number in the range.
5. You cannot nest parentheses.
6. You can use a stored constant in place of any number. You can indicate a series of stored constants on the data
line with a "-" (K1-K5).
4:1 expands to 4, 3, 2, 1
1:3/.5 expands to 1, 1.5, 2, 2.5, 3
3(1) expands to 1, 1, 1
3(1:3) expands to 1, 2, 3, 1, 2, 3, 1, 2, 3
(1:3)2 expands to 1, 1, 2, 2, 3, 3
3(1:3)2 expands to 1, 1, 2, 2, 3, 3, 1, 1, 2, 2, 3, 3, 1, 1, 2, 2, 3, 3
1143
Minitab Statistical Software Supporting Concepts
Restricted and unrestricted mixed models
A company ran an experiment to see how several conditions affect the thickness of a coating substance that it
manufactures. The experiment was run at two different times, in the morning and in the afternoon. Three operators
were chosen from a large pool of operators employed by the company. The manufacturing process was run at three
settings, 35, 44, and 52. Two determinations of thickness were made by each operator at each time and setting. Thus,
the three factors are crossed. One factor, operator, is random. The other factors, time and setting, are fixed.
The statistical model is as follows:
Y
ijkl
= μ + T
i
+ O
j
+ S
k
+ TO
ij
+ TS
ik
+ OS
jk
+ TOS
ijk
+ e
ijkl
where T
i
is the time effect, O
j
is the operator effect, and S
k
is the setting effect, and TO
ij
, TS
ik
, OS
jk
, and TOS
ijk
are the
interaction effects.
Operator, all interactions with operator, and error are random. The random terms are as follows:
O
j
TO
ij
OS
jk
TOS
ijk
e
ijkl
These terms are all assumed to be normally distributed random variables with mean zero and variances given by the
following:
var (O
j
) = V(O)
var (TOS
jkl
) = V(TOS)
var (TO
ij
) = V(TO)
var (e
ijkl
) = V(e) = σ
2
These variances are called variance components. The output from expected means squares contains estimates of these
variances.
In the unrestricted model, all these random variables are independent. The remaining terms in this model are fixed.
In the restricted model, any term which contains one or more subscripts corresponding to fixed factors is required to
sum to zero over each fixed subscript. In the example, this means:
Your choice of model does not affect the sums of squares, degrees of freedom, mean squares, or marginal and cell
means. It does affect the expected mean squares, error term for the F-tests, and the estimated variance components.
Examples of entering response data for logistic
regression
When the response variable is in one column that contains distinct values
When you enter the response as raw data, you do not need a response variable subcommand. The response column
will contain a limited number of distinct values—2 for binary responses, and 3 or more distinct values for ordinal and
nominal responses. The examples below all use the same binary response variable.
1144
Minitab Statistical Software Supporting Concepts
C4C3C2C1
CovarFactorResponse
1210
1211
1211
1211
1220
1221
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1211
1221
1221
1221
1221
1221
1221
1221
1221
1221
1221
1221
1221
1145
Minitab Statistical Software Supporting Concepts
C4C3C2C1
CovarFactorResponse
1221
1221
1221
1221
1221
1221
2410
2410
2410
2410
2410
2411
2411
2411
2411
2411
2411
2411
2411
2411
2411
2411
2411
2411
2411
2411
In this form, the response variable is in C1, the factor is in C3, and the covariate is in C4. To fit the full model, type:
GZLM;
BINOMIAL;
LOGIT;
RESPONSE C1;
CONTINUOUS C4;
CATEGORICAL C3;
TERMS C3|C4.
When the response variable is entered as frequencies
You can also represent the response data with one column of frequencies. For each row of data, the frequencies are
the number of times the response/factor/covariate pattern occurred. For example, the data used above could have
been entered in the following manner.
1146
Minitab Statistical Software Supporting Concepts
C4C3C2C1
CovarFactorCountResponse
12110
121191
12210
122191
24150
241151
24240
242161
50170
501131
50280
502121
1251110
125121
125290
1252111
2001190
200111
2002180
200221
This form represents the same binary data as above, however, the frequencies for each response/factor/covariate
pattern are in C2. To fit the full model, type the following:
GZLM;
BINOMIAL;
LOGIT;
RESPONSE C1;
FREQUENCY C2;
CONTINUOUS C4;
CATEGORICAL C3;
TERMS C3|C4.
When the response variable is entered as the number of events and trials
You can also enter the response variable as the number of events and trials. This method is available when you have
a binary response variable. GZLM, BFFACTORIAL, BRSREGRESS, BGFACTORIAL, and BSCREEN are examples of commands
that analyze binary response variables.
C4C3C2C1
CovarFactorTE
1212019
1222019
1147
Minitab Statistical Software Supporting Concepts
C4C3C2C1
CovarFactorTE
2412015
2422016
5012013
5022012
1251209
12522011
2001201
2002202
In this form, the data are represented by the number of successes in C1, and the number of trials in C2. To fit the full
model, type the following
GZLM;
BINOMIAL;
LOGIT;
RESPONSE C1 C2;
CONTINUOUS C4;
CATEGORICAL C3;
TERMS C3|C4.
A comparison of MSURFACE and RMCONTOUR
plots
Three-dimensional surface plots are oriented differently than response surface contour plots. You can generate a
three-dimensional response surface plot so that the view is similar to the associated response surface contour plot,
as follows:
1. Switch the x- and y-axes means with the SINGLE subcommand. Type the y-variable and the x-variable factors
respectively, as arguments.
2. Change where you view the plot from by changing the view position. Use the VPOSITION subcommand with −5
−4 3 as arguments.
Graphics options for MIXCONTOUR
MIXCONTOUR on page 391 supports the following graphics subcommands (and a few commands). Many of the
subcommands have subcommands of their own.
Scale
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
1148
Minitab Statistical Software Supporting Concepts
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999: When you
use AREA with MIXCONTOUR, you cannot use the following subcommands: BASE, ETYPE, ECOLOR, ESIZE, DIRECTION,
STRAIGHT, and STEP.
CONNECT: Session subcommand for connecting points with lines on page 1012: With CONNECT, the subcommands
ORDER, STRAIGHT, and STEP cannot be used.
SFIT: Session subcommand for specifying the attributes of the surface on a 3D surface plot on page 1079
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Region
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
1149
Minitab Statistical Software Supporting Concepts
Graphics options for MIXOVER
MIXOVER on page 399 supports the graphics subcommands (and a few commands) in the following table. The
subcommands are shown without syntax. Many of these subcommands have subcommands of their own. Click the
subcommand or command in the table for more information.
Scale
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Region
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graphics options for MIXSURFACE
MIXSURFACE: Session command for creating a surface plot on page 397 supports the graphics subcommands (and a
few commands) in the following table. The subcommands are shown without syntax. Many of these subcommands
have subcommands of their own. Choose a subcommand or command in the table below for more information and
examples.
1150
Minitab Statistical Software Supporting Concepts
Options
LBRIGHT: Session subcommand for specifying the brightness of the lights that illuminate a surface plot on page
1044
LIGHT: Session subcommand for specifying the position, color, and visibility of the lights that illuminate a surface
plot on page 1047
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CONNECT: Session subcommand for connecting points with lines on page 1012
SFIT: Session subcommand for specifying the attributes of the surface on a 3D surface plot on page 1079
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
VASPECT: Session subcommand for specifying the aspect ratio of the data box on page 1091
VBOX: Session subcommand for specifying the display of the box that surrounds the data on a graph on page 1092
VFIELD: Session subcommand for specifying the dimensions of the field of view in object units on page 1092
VPOSITION: Session subcommand for specifying the view position as a ratio on page 1092
VUP: Session subcommand for specifying which direction is up in relation to the data box on page 1092
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
1151
Minitab Statistical Software Supporting Concepts
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Region
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graphics options behavior that is specific to MIXSURFACE
The following is a summary of changes in the behavior of common graphics options with MIXSURFACE:
SYMBOL does not support symbol label functionality for three-dimensional surface plots.
The defaults for these subcommands vary depending on if you use menu commands or use MIXSURFACE from
the command line. These defaults are described in the subcommand descriptions.
With AXLABEL, the following subcommands are unusable: LABEL, LSHOW, and SECSCALE.
With CONNECT, the following subcommands are unusable: ORDER, STRAIGHT, and STEP.
Graphics options for MSURFACE
MSURFACE on page 1099 supports the graphics subcommands (and a few commands) in the following table. The
subcommands are shown without syntax. Many of these subcommands have subcommands of their own. Choose a
subcommand or command in the table below for more information and examples.
Scale
MGRID, NOGRID, and NOMGRID: Session subcommands for controlling the grid on a graph on page 1029
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
1152
Minitab Statistical Software Supporting Concepts
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
CONNECT: Session subcommand for connecting points with lines on page 1012
SFIT: Session subcommand for specifying the attributes of the surface on a 3D surface plot on page 1079
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
VASPECT: Session subcommand for specifying the aspect ratio of the data box on page 1091
VBOX: Session subcommand for specifying the display of the box that surrounds the data on a graph on page 1092
VFIELD: Session subcommand for specifying the dimensions of the field of view in object units on page 1092
VPOSITION: Session subcommand for specifying the view position as a ratio on page 1092
VUP: Session subcommand for specifying which direction is up in relation to the data box on page 1092
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graphics options behavior that is specific to MSURFACE
This is a summary of changes in the behavior of common graphics options with MSURFACE:
SYMBOL does not support symbol label functionality for three-dimensional surface plots.
The defaults for these subcommands vary depending on if you use menu commands or use MSURFACE from the
command line. These defaults are described in the subcommand descriptions.
With AXLABEL, LABEL, LSHOW, and SECSCALE cannot be used.
With CONNECT, the subcommands ORDER, STRAIGHT, and STEP cannot be used.
1153
Minitab Statistical Software Supporting Concepts
Graphics options for SIMPLEX
SIMPLEX on page 383 supports the graphics subcommands (and a few commands) in the following table. The
subcommands are shown without syntax. Many of these subcommands have subcommands of their own. Click the
subcommand or command in the table for more information.
Scale
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
1154
Minitab Statistical Software Supporting Concepts
TEXT: Session subcommand for displaying text on a graph on page 1088
Region
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graphics options for SPCONT
SPCONT on page 394 supports the graphics subcommands (and a few commands) in the following table. The
subcommands are shown without syntax. Many of these subcommands have subcommands of their own. Click the
subcommand or command in the table for more information.
Scale
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Data view
AREA: The session subcommand for shading the area below the data values to the base on page 999
CONNECT: Session subcommand for connecting points with lines on page 1012
SYMBOL: Session subcommand for displaying a symbol for each data value on page 1084
1155
Minitab Statistical Software Supporting Concepts
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
TEXT: Session subcommand for displaying text on a graph on page 1088
Region
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graphics options behavior that is specific to SPCONT
This is a summary of changes in the behavior of common graphics options with SPCONT. This information also appears
under the respective graphics options.
With AREA, the subcommands BASE, ETYPE, ECOLOR, ESIZE, DIRECTION, STRAIGHT, and STEP cannot be used.
With CONNECT, the subcommands ORDER, STRAIGHT, and STEP cannot be used.
1156
Minitab Statistical Software Supporting Concepts
Graphics options for SPSIMP
SPSIMP on page 385 supports the graphics subcommands (and a few commands) in the following table. The
subcommands are shown without syntax. Many of these subcommands have subcommands of their own. Click the
subcommand or command in the table for more information.
Scale
NOFRAME: Session subcommand for suppressing lines and labels on a graph on page 1057
REFERENCE: Session subcommand for specifying the axis and location of reference lines on a graph on page 1073
SCALE: Session subcommand for customizing the axes and ticks of a graph on page 1076
TRANSPOSE and NOTRANSPOSE: Session subcommands for transposing the x- and y-axis on a graph on page 1091
Labels
AXLABEL: Session subcommand for customizing graph axis labels on page 1001
FOOTNOTE: Session subcommand for adding a footnote to a graph on page 1025
NODTITLE, NODSUBTITLE, and NODFOOTNOTE: Session subcommands for suppressing titles, subtitles, and footnotes
on a graph on page 1057
NOPERFOOTNOTE: Session subcommand for suppressing My Footnote on page 1058
SUBTITLE: Session subcommand for adding a subtitle to a graph on page 1083
TITLE: Session subcommand for adding a title to a graph on page 1089
Multiple graphs
OVERLAY: Session subcommand for combining graphs specified in a multiple graph command into a single graph
on page 1061
PANEL: Session subcommand for paneling graphs on page 1061
SAME: Session subcommand for specifying that one or more axes are the same for multiple graphs on page 1076
SEPARATE: Session subcommand for placing groups in separate graphs when you use a paneling variable on page
1079
Data options
NOEMPTY and NOMISS: Session subcommands for excluding missing data from graphs on page 1057
Annotation
ELLIPSE: Session subcommand for constructing an ellipse from points on a graph on page 1022
LINE: The session subcommand for constructing a line from points on a graph on page 1048
MARKER: Session subcommand for displaying a symbol at specified points on a graph on page 1050
POLYGON: Session subcommand for constructing a polygon from points on a graph on page 1063
RECTANGLE: Session subcommand for constructing a rectangle from points on a graph on page 1072
1157
Minitab Statistical Software Supporting Concepts
TEXT: Session subcommand for displaying text on a graph on page 1088
Region
FIGURE: Session subcommand for controlling the figure region within the graph region on page 1023
GRAPH: Session subcommand for controlling the graph region fill and border line on page 1028
LEGEND and NOLEGEND: Session subcommands for controlling the legend on a graph on page 1045
NOHLEGEND: Session subcommand for suppressing the legend of hold values on a graph on page 1058
Graph, input, and output
GSAVE: Session subcommand for saving a graph in a file on page 38
WTITLE: Session subcommand for specifying the title of the output pane on page 1093
Graphs that use groups with the data display
subcommands
PLOT: Session command for creating a scatterplot on page 947
BOXPLOT: Session command for creating a boxplot on page 975
MATRIXPLOT: Session command for creating a matrix of plots on page 952
TSPLOT: Session command for creating a time series plot on page 987
CHART: Session command for creating a bar chart on page 942
HISTOGRAM: Session command for creating a histogram on page 958
PLTX: Session command for creating a 3D scatterplot on page 995
SURFACEPLOT: Session command for creating a surface plot on page 996
The control charts and CONTOURPLOT: Session command for creating a contour plot on page 992 do not use grouping
variables with the Data Display subcommands. %graphs do not use data display subcommands.
How to enter data for ANOVA and GLM
The data set has the same structure in ANOVA on page 224 and GLM on page 227.
You need one column for each response variable and one column for each factor. This means there is one row of the
worksheet for each observation. This row contains the value of each response variable and the level of each factor.
Regardless of whether factors are crossed or nested, you use the same form for the data. Factor columns may be
numeric or text, and may contain any values. The levels do not need to be in any special order.
There is a restriction on the subscripts used for nested terms as nesting must be balanced. Suppose A has 3 levels,
and B is nested within A. If B has 4 levels within the first level of A, B must have 4 levels within the second and third
levels of A. Minitab will tell you if you have unbalanced nesting. In addition, the subscripts used to indicate the 4 levels
of B within each level of A must be the same. Thus, the four levels of B cannot be (1 2 3 4) in level 1 of A, (5 6 7 8) in
level 2 of A, and (9 10 11 12) in level 3 of A.
1158
Minitab Statistical Software Supporting Concepts
The patterned data capability of the SET on page 80 command can be helpful in entering the factor levels. For example,
to enter the level numbers for a three-way crossed design with 3 levels of 3 factors and 1 observations per cell, use:
set c1
(1:3)9
end.
set c2
3(1:3)3
end
set c3
9(1:3)1
end
How to enter data for CCHART
You must have at least one column containing the number of defects. Each row of a column should contain the number
of defects for one subgroup.
Suppose you collect data on the number of scratches found per square meter of finished surface each day. You sample
the same number of square meters each day. The number of defects is the number of scratches found on a given day.
Your data might like the Scratches column below.
C1
Scratches
2
3
1
3
0
4
When an observation is missing, a gap exists in the chart for that observation.
How to enter data for GCHART
To create a G chart, you can record your data in one of the following ways:
Dates of events
Number of opportunities between events
Number of opportunities until an event
Dates of events
When your data are entered as dates, Minitab calculates the number of days between events and plots each value on
the G chart. When you use dates, you should verify that the number of possible opportunities per day is fairly constant.
C1
Date of infection
4/17/16
1159
Minitab Statistical Software Supporting Concepts
C1
Date of infection
4/24/15
4/26/16
5/14/16
5/16/16
Number of opportunities between or until an event
You can record either the number of opportunities between events or the number of opportunities until an event
occurs.
Suppose infections occurred in the 4
th
, 16
th
, 27
th
, 50
th
, and 80
th
patient in an emergency room. If you record the number
of patients between events, the data are shown below in the Between column. If you record the number of opportunities
until an event, the data are shown below in the Until column.
C2C1
UntilBetween
1211
1110
2322
3029
If your data are recorded as the number of opportunities until an event, Minitab subtracts 1 from each value to convert
the data to number of opportunities between events and plots the converted values on the G chart.
How to enter data for NPCHART
You must have at least one column containing the number of defectives. Each row of a column should contain the
number of defectives for one subgroup. If the subgroup sizes are different, you must also include a column that
indicates the size of each subgroup. If the size is the same for each subgroup, you can enter the subgroup size directly
at the command line instead of providing a column.
Suppose that, at a manufacturing plant, you collect data each day on the number of parts that failed inspection. The
number of defectives is the number of parts that failed on a given day. The subgroup size is the number of parts that
you inspected that day. Your data might look like the table below.
Each row in the table represents a single day. The Failed column indicates the number of defectives for the day. The
Inspected column indicates the number of parts inspected that day.
C2C1
InspectedFailed
382
563
441
413
540
1160
Minitab Statistical Software Supporting Concepts
C2C1
InspectedFailed
354
Subgroup sizes that differ affect both the control limits and the center line. In general, the control limits are further
from the center line for smaller subgroups than they are for larger ones. You can force the control limits and center
line to be constant by entering a fixed subgroup size, for example the average subgroup size.
When an observation is missing, a gap exists in the chart for that observation.
How to enter data for PDIAGNOSTIC, PCHART, and
PPRIMECHART
You must have at least one column that contains the number of defectives. Each row of a column should contain the
number of defectives for one subgroup.
If the subgroup sizes are different, you must also include a column that indicates the size of each subgroup. If the size
is the same for each subgroup, you can enter the subgroup size directly at the command line instead of providing a
column.
Suppose that, at a manufacturing plant, you collect data each day on the number of parts that failed inspection. The
number of defectives is the number of parts that failed on a given day. The subgroup size is the number of parts that
you inspected that day. Your data might look like the table below.
Each row in the table represents a single day. The Failed column indicates the number of defectives for the day. The
Inspected column indicates the number of parts inspected that day.
C2C1
InspectedFailed
1142
1080
1333
802
1091
991
The P Chart and Laney P' Chart divide the number of defectives by the subgroup size to calculate the proportion of
defectives for each subgroup.
The control limits for the P Chart and Laney P' Chart change depending on the size of each subgroup. In general, the
control limits are further from the center line for smaller subgroups than they are for larger ones. You can force the
control limits to be constant by entering a fixed subgroup size, for example the average subgroup size.
When an observation is missing, a gap exists in the chart for that observation.
How to enter data for TCHART
To create a T chart, you can record your data in one of the following ways:
1161
Minitab Statistical Software Supporting Concepts
Dates and times of events
Time between events
Number of intervals between events
Dates and times of events
When your data are entered as dates and times, Minitab calculates the amount of time between events and plots each
value on the T chart.
C1
Date and time of patient fall
1/22/2016 8:05AM
1/25/2016 4:30PM
2/3/2016 5:45AM
2/5/2016 11:30AM
2/9/2016 9:30PM
Time between events
Time between events, also known as elapsed time, must be entered in the worksheet as hours, minutes, and seconds
(hh:mm:ss format). If you do not record seconds, Minitab reads the seconds as 00. For example, Minitab reads the first
value below as 80:25:00.
C1
Time between patient falls
80:25
205:15
53:45
106:00
Number of intervals between events
You can record the number of intervals between events as days or hours. The number of days or hours must be greater
than or equal to 0. A value of 0 indicates that two events happened simultaneously.
C1
Number of days between patient falls
3.33
8.5
2
4.5
1162
Minitab Statistical Software Supporting Concepts
How to enter data for UDIAGNOSTIC, UCHART, and
UPRIMECHART
You must have at least one column containing the number of defects. Each row of a column should contain the number
of defects for one subgroup.
If the subgroup sizes are different, you must also include a column that indicates the size of each subgroup. If the size
is the same for each subgroup, you can enter the subgroup size directly at the command line instead of providing a
column.
Suppose you collect data each day on the number of scratches found per square meter of finished surface. The number
of defects is the number of scratches found on a given day. The subgroup size is the number of square meters of
surface that was inspected that day. Your data might look like the table below.
Each row in the table represents a single day. The Scratches column indicates the number of defects found that day.
The Square Meters column indicates the number of square meters of surface that was inspected that day.
C2C1
Square MetersScratches
688
543
7111
678
739
561
The U chart and Laney U' chart divide the number of defects by the subgroup size to calculate the number of defects
per subgroup.
The control limits for the U chart and Laney U' chart change depending on the size of each subgroup. In general, the
control limits are further from the center line for smaller subgroups than they are for larger ones. You can force the
control limits and center line to be constant by entering a fixed subgroup size, for example the average subgroup size.
When an observation is missing, a gap exists in the chart for that observation.
How to enter subgroup data
You can structure your subgroup data in the worksheet down a column or across rows. The worksheets below contain
the same data, with subgroups of 5, structured both ways.
Subgroup data that is entered down a column
C1
40.13
39.68
40.84
41.52
40.02
1163
Minitab Statistical Software Supporting Concepts
C1
39.54
39.87
40.25
40.47
41.41
39.20
38.72
39.39
Subgroup data that is entered across rows
C5C4C3C2C1
40.0241.5240.8439.6840.13
41.4140.4740.2539.8739.54
39.3938.7239.2037.3639.64
40.0540.4839.9641.1539.15
Subgroups in rows
Use the RSUB subcommand to specify the data columns. The following command language specifies that the data is
in subgroups of size 5, placed in rows across five columns.
XBAR;
RSUB C1-C5.
Subgroups or individual observations in columns: Individual observations
For commands that allow only a data column as an argument, specify the main command and the data column.
ICHART C1
Some commands that use this format include ICHART, MRCHART, IMRCHART, NNCAPA, and NNSIXPACK.
To enter the data for commands that analyze individuals data or subgroup data, specify the main command with the
data column and the size of the subgroup.
EWMACHART C1 1
Subgroups or individual observations in columns: Same-size subgroups
To enter the data, specify the main command with the data column and the size of the subgroup. The following
command language specifies to take the first 5 observations in C1 to be the first subgroup, the second 5 observations
to be the second subgroup, and so on.
XBARCHART C1 5
Some commands that use this format include BOXCOX, BWCHART, BWCAPA, BWSIXPACK, CAPA, CUSUM, EWMACHARRT,
GENVAR, MACHART, MEWMA, RCHART, RRUN, SCHART, SIXPACK, TSGV, TSQUARED, XBARCHART, XRCHART, XSCHART,
and ZONE.
1164
Minitab Statistical Software Supporting Concepts
Subgroups or individual observations in columns: Unequal-size subgroups
When subgroups are of unequal size, you must enter your data in one column, then create a second column of subscripts
which serve as subgroup indicators. In the following example, C1 contains the measurement data and C2 contains
subgroup indicators.
C2C1
139.68
140.84
141.52
240.02
239.54
239.87
240.25
240.47
241.41
339.20
338.72
339.39
Each time a subscript changes in C2, a new subgroup begins in C1. In this example, subgroup 1 has 3 observations,
subgroup 2 has 6 observations, and so on.
To enter the data, specify the main command with the data column and subgroup column.
XBARCHART C1 C2
Some commands that use this format include BOXCOX, BWCHART, BWCAPA, BWSIXPACK, CAPA, EWMACHART,
GENVAR, MACHART, MEWMA, RCHART, SCHART, SIXPACK, TSGV, TSQUARED, XBARCHART, CRCHART, XSCHART, and
ZONE.
How to specify the model for ATCLASS, GZLM,
OLOGISTIC and NLOGISTIC
OLOGISTIC on page 213 and NLOGISTIC on page 216 can fit models with the following:
Up to nine factors and up to 50 covariates
A binary, ordinal, or nominal response variable
Crossed or nested factors
Covariates that are crossed with each other or with factors, or nested within factors
ATCLASS on page 827 and GZLM on page 199 can fit models with any number of factors and responses, but do not
model nested terms.
1165
Minitab Statistical Software Supporting Concepts
Model continuous predictors as covariates, and categorical predictors as factors. The following are some examples. A
is a factor, X is a covariate, and Y is the response.
DescriptionCommand language
Fits a full model with a covariate crossed with a factor
GZLM;
RESPONSE Y;
CONTINUOUS X;
CATEGORICAL A;
TERMS A X A*X.
Fits a model with a covariate crossed with itself making a
squared term
OLOGISTIC Y = A X X*X;
FACTORS A.
Fits a model with a covariate nested within a factor
NLOGISTIC Y = A X(A);
FACTORS A.
The model for logistic regression is a generalization of the model used in Minitab's general linear model (GLM). Any
model that is fit by the GLM command can also be fit by the logistic regression commands. For a discussion of models
in general, go to How to specify the model in ANOVA on page 1169. In the logistic regression commands, Minitab
assumes any variable in the model is a covariate unless the variable is specified as a factor. The FACTORS subcommand
specifies which predictors are factors. In GLM, Minitab assumes any variable in the model is a factor unless the variable
is specified as a covariate.
The models for Minitab's generalized linear models and predictive analytics work differently. You indicate the type of
all of the predictors with the appropriate subcommand, CONTINUOUS or CATEGORICAL.
How to specify the model for factorial designs
The model for factorial designs consists of three parts: the response, factors, and the terms. You specify the response
with RESPONSE. Then, you specify up to 9 factors with FACTORS. Finally, you specify the terms with TERMS. Terms
consists of factors and the 2-way interactions that you want to include in the model.
Example of specifying a full quadratic model that has three factors
FFAC;
Response 'BeanYield';
Factors Nitrogen PhosAcid Potash;
Terms C5 C6 C7 C5*C5 C6*C6 C7*C7 C5*C6 C5*C7 C6*C7;
The method is the same as the one used for response surface designs, but abbreviations for response surface models
add square terms, such as C5*C5. Following are some examples.
Example of a main effects model that has four factors
TERMS C5 C6 C7 C8
Example of a model that has three factors with all two-way interactions
TERMS C5 C6 C7 C5*C6 C5*C7 C6*C7
Example of a model that has six factors with all two-way interactions that involve factor C5
TERMS C5 C6 C7 C8 C9 C10 C5*C6 C5*C7 C5*C8 C5*C9 C5*C10
Terms in the model are listed, separated by one or more blanks. Use an * (asterisk) to indicate an interactions term.
You can omit the quotation marks around variable names if the names start with a letter and contain only letters and
numbers. Otherwise, enclose the name in single quotation marks or refer to the column by number, such as C1 or C2.
A list of factors and interactions can be abbreviated. Enclose the list in parentheses and follow the parentheses by the
number 2. For example, the following pair of commands is equivalent:
TERMS (A B C D)2
1166
Minitab Statistical Software Supporting Concepts
TERMS A B C D A*B A*C A*D B*C B*D C*D
You can use a dash, as in the rest of Minitab, to indicate a list of factors. You can also use a dash to subtract a term.
Note These two uses of a dash do not conflict.
Following are some examples:
TERMS C4-C7
TERMS C4 C5 C6 C7
TERMS (A B C D)2 - A*B - B*C
TERMS A B C D A*C A*D B*D C*D
These techniques may be combined. For example:
TERMS (A-C)2 - A*B D A*D
TERMS A B C A*C B*C D A*D
When you specify a model that has more terms than your data will support, Minitab determines which squares and
interactions can be fit and fits just those.
How to specify the model for GLM
The model for GLM on page 227 is a generalization of the model used in ANOVA. Any model fit by ANOVA on page
224 can also be fit by GLM. For more information, go to How to specify the model in ANOVA on page 1169. In addition,
GLM allows continuous terms that are crossed with each other and with factors, and continuous terms nested within
factors. Here are some examples of these models. A is a factor and X is a continuous term.
DescriptionCommand language
Model to test homogeneity of slopes (covariate
crossed with a factor)
GLM;
RESPONSE Y;
CONTINUOUS X;
CATEGORICAL A;
TERMS A X A*X.
Same as previous model
GLM;
RESPONSE Y;
CONTINUOUS X;
CATEGORICAL A;
TERMS A X A*X.
Quadratic model in the covariate (covariate crossed
with itself)
GLM;
RESPONSE Y;
CONTINUOUS X;
CATEGORICAL A;
TERMS A X X*X.
Full quadratic in two covariates (two covariates
crossed)
GLM;
RESPONSE Y;
CONTINUOUS X Z;
CATEGORICAL A;
TERMS A X Z X*X Z*Z X*Z.
Separate slopes for each level of A (covariate nested
within a factor)
GLM;
RESPONSE Y;
CONTINUOUS X;
1167
Minitab Statistical Software Supporting Concepts
DescriptionCommand language
CATEGORICAL A;
TERMS A X;
NESTED X(A).
GLM models have some restrictions. For more information, go to Restrictions on GLM models on page 1179.
How to specify the model for response surface
designs
The models for response surface designs consist of three parts: the response, the factors, and the terms. You specify
the response with RESPONSE. Then, you specify up to 9 factors with FACTORS. Finally, you specify the terms with
TERMS. Terms consists of factors and the two-way interactions that you want to include in the model. For example,
the following specifies a full quadratic model that contains three factors.
RSREG;
Response 'BeanYield';
Factors Nitrogen PhosAcid Potash;
Terms C5 C6 C7 C5*C5 C6*C6 C7*C7 C5*C6 C5*C7 C6*C7;
The method is the same as the one used in factorial designs, but models for factorial designs cannot include squares.
Here are some examples:
Four factor main effects model
TERMS C5 C6 C7 C8
Three factors with all squares and all two-way interactions
TERMS C5 C6 C7 C5*C5 C6*C6 C7*C7 C5*C6 C5*C7 C6*C7
Six factors with all two interactions that involve factor C5
TERMS C5 C6 C7 C8 C9 C10 C5*C5 C5*C6 C5*C7 C5*C8 C5*C9 C5*C10
Terms in the model are listed, separated by one or more blanks. Use an * to indicate an interactions term. You may
omit the quotation marks around variable names if the names start with a letter and contain only letters and numbers.
Otherwise, enclose the name in single quotes or refer to the column by number such as C1 or C2.
A list of factors and interactions can be abbreviated. Enclose the list in parentheses and follow the parentheses by the
number 2. For example, the following pair of commands is equivalent
TERMS (A B C D)2
TERMS A B C D A*A B*B C*C D*D A*B A*C A*D B*C B*D C*D
You can use a dash, as in the rest of Minitab, to indicate a list of factors. You can also use a dash to subtract a term.
Note These two uses of a dash do not conflict.
The following are some examples:
TERMS C4-C7
TERMS C4 C5 C6 C7
TERMS (A B C D)2 - A*A - A*B - B*C
TERMS A B C D B*B C*C D*D A*C A*D B*D C*D
1168
Minitab Statistical Software Supporting Concepts
These techniques may be combined. For example:
TERMS (A-C)2 - A*B D A*D
TERMS A B C A*A B*B C*C A*C B*C D A*D
When you specify a model that has more terms than your data will support, Minitab determines which squares and
interactions can be fit and fits just those.
How to specify the model in ANOVA
ANOVA uses a simplified version of a model as it appears in many textbooks. The following table shows some examples.
BooksMinitabType of model
y
ijk
= mu + a
i
+ b
j
+ ab
ij
+ e
k(ij)
ANOVA Y = A B A*BTwo factors crossed
y
ijkl
= mu + a
i
+ b
j
+ c
k
+ ab
ij
+ ac
ik
+
bc
jk
+ abc
ijk
+ el
(ijk)
ANOVA Y = A B C A*B A*C B*C
A*B*C
Three factors crossed
y
ijkl
= mu + a
i
+ b
j(i)
+ c
k(ij)
+ e
l(ijk)
ANOVA Y = A B(A) C(AB)Three factors nested (B nested within A,
and C nested within A and B)
y
ijkl
= mu + a
i
+ b
j(i)
+ c
k
+ ac
ik
+ bc
jk(i)
+ e
l(ijk)
ANOVA Y = A B(A) C A*C B*C(A)Crossed and nested design (B nested within
A, and both crossed with C)
Notice that in Minitab's models, we omit the subscripts, mu, e, and +'s that appear in textbook models. An * is used
for an interaction term. Parentheses are used for nesting. For example, when B is nested within A, we write B (A), and
when C is nested within both A and B, we write C (A B). Terms in parentheses are always factors in the model and are
listed with blanks between them. Thus, D*F (A B E) is correct but D*F (A*B E) and D (A*B*C) are not. Also, parentheses
are not used inside parentheses. Thus, C (A B) is correct but C (A B (A)) is not.
Several special rules apply only to the ANOVA command. You may omit the quotes around variable names. Because
of this, variable names used in ANOVA must start with a letter and contain only letters and numbers. Alternatively, you
can use C1, C2, etc., to denote data columns. You can use special symbols in a variable name, but then you must
enclose the name in single quotes, as on other Minitab commands. You may not put any extra text on the ANOVA
line, except after the symbol #.
You can fit reduced models. For example, Y = A B C A*B is a three-factor model with just one two-way interaction.
Models, however, must be hierarchical. For example, if the term A*B*C is in the model then the terms A B C A*B A*C
B*C must also be in the model. And if B(A) is in the model, then A must be also.
Because models can be quite long and tedious to type, two shortcuts have been provided. A vertical bar (or an
exclamation point) indicates crossed factors, and a minus sign removes terms.
Each pair of commands below is equivalent.
ANOVA Y=A|B|C
ANOVA Y=A B C A*B A*C B*C A*B*C
ANOVA Y=A|B|C - A*B*C
ANOVA Y=A B C A*B A*C B*C
ANOVA Y=A B|C E
ANOVA Y=A B C B*C E
ANOVA Y=A|B|C|D - A*B*C - A*B*C*D
1169
Minitab Statistical Software Supporting Concepts
ANOVA Y=A B C D A*B A*C A*D B*C B*D C*D A*B*D A*C*D B*C*D
ANOVA Y=A|B(A)|C
ANOVA Y=A B(A) C A*C B*C(A)
In general, all crossings are done for factors separated by bars unless the cross results in an illegal term. For example,
in the fifth example, the potential term A*B(A) is illegal and Minitab automatically omits it. Note, if a factor is nested
you must indicate this when using the bar, as in the fifth example with the term B(A).
Several response variables can be included with one model. For example, the following commands perform three
separate analyses, one for Y1, one for Y2, and one for Y3. The residuals for the first response variable are stored in C21;
for the second, in C22; and for the third, in C23.
ANOVA Y1 Y2 Y3=A B;
RESIDUALS C21-C23.
How to specify the model in MGAGE
Use * to indicate an interaction term. For example, A*B is the interaction of the factors A and B.
Use ( ) to indicate nesting. When B is nested within A, type B(A). When C is nested within both A and B, type C(A
B). Terms in parentheses are always factors in the model and are listed with blanks between them.
Use | or ! to abbreviate a model to indicate crossed factors.
Use to remove terms.
Examples
Two factors crossed: A B A*B
Three factors crossed: A B C A*B A*C B*C A*B*C
Three factors nested: A B(A) C(A B)
Crossed and nested (B nested within A, and both crossed with C): A B(A) C A*C B*C(A)
Rules
You must specify a hierarchical model.
Crossed factors: If an interaction term is included, all lower order interactions and main effects that comprise the
interaction term must appear in the model. For example, if the A and B interaction is included, denoted as A*B,
then the A and B main effects terms must be included as well.
Nested factors: If a nested factor is included in the model then the factor(s) in which they are nested must be
included. If a factor is nested within multiple factors, then the interaction terms for the parent factors must be
included. You cannot include interaction terms for nested factors and the factors they are nested within. For example,
if C is nested in A and B, then A, B, and A*B must be included and A*C and B*C cannot be included.
When a term contains both crossing and nesting, put the * first, as in C*B(A), not B(A)*C
Terms in parentheses are always factors in the model and are listed with blanks between them. Thus, D*F (A B E) is
correct but D*F (A*B E) and D (A*B*C) are not. Also, parentheses are not used inside parentheses. Thus, C (A B) is correct
but C (A B (A)) is not.
Several special rules apply to the MGAGE command. You may omit the quotes around variable names. Because of this,
variable names used in MGAGE must start with a letter and contain only letters and numbers. Alternatively, you can
use C1, C2, etc., to denote data columns. You can use special symbols in a variable name, but then you must enclose
the name in single quotes, as for other Minitab commands.
1170
Minitab Statistical Software Supporting Concepts
Shortcuts
Because models can be quite long and tedious to type, two shortcuts have been provided. A vertical bar (or an
exclamation point) indicates crossed factors, and a minus sign removes terms.
Each pair of commands below is equivalent.
MGAGE Y=A|B|C
MGAGE Y=A B C A*B A*C B*C A*B*C
MGAGE Y=A|B|C - A*B*C
MGAGE Y=A B C A*B A*C B*C
MGAGE Y=A B|C E
MGAGE Y=A B C B*C E
MGAGE Y=A|B|C|D - A*B*C - A*B*C*D
MGAGE Y=A B C D A*B A*C A*D B*C B*D C*D A*B*D A*C*D B*C*D
MGAGE Y=A|B(A)|C
MGAGE Y=A B(A) C A*C B*C(A)
In general, all crossings are performed for factors that are separated by bars unless the cross results in an illegal term.
For example, in the fifth example, the potential term A*B(A) is illegal and Minitab automatically omits it. Note, if a
factor is nested you must indicate this when using the bar, as in the fifth example with the term B(A).
Missing values in exponential smoothing
Because of the nature of the computations, you cannot use the exponential smoothing commands on a time series
column containing missing values (*). So what can you do if there are missing observations? Here is a possible solution:
If you have seasonal data, execute DECOMP on page 872 on the series. Replace the missing values in the series with
the corresponding fitted values computed by DECOMP.
If you do not have seasonal data, replace each missing value with the mean of one or two observations immediately
before and after the missing value. Another easy way to replace missing observations for non-seasonal data is to
execute MA on page 882 on the series and replace the missing value with the fitted value computed by MA.
Missing values in factorial, response surface, and
mixture designs
When Minitab fits factorial, response surface, and mixture models, if any column contains missing data, Minitab excludes
the entire observation (row) from all calculations.
If you enter more than one response variable, Minitab handles missing data in a multivariate way. When the value of
one response variable is missing for an observation (row), Minitab excludes that row in calculations for all the response
variables, and displays a message. You might want to repeat the analysis separately for each response variable.
1171
Minitab Statistical Software Supporting Concepts
Notes on subcommands that store descriptive
statistics (STATS command)
Include as many of the subcommands that store statistics as you wish, depending on which statistics you want to
compute. Most often, you will use these subcommands to compute statistics for each group included in the BY columns.
The number of columns you list with any of these subcommands must equal the number of columns listed on the
main STATS: Session command for storing descriptive statistics on page 143 command line, with one exception: If you
omit columns from the STATS command line and use the BY subcommand, then you may store these statistics: N,
NMISS, COUNT, CUMN, PERCENT, and CUMPERCENT. In this case, each subcommand must list one (and only one)
column for storage.
Numbers for colors to use in session commands
Minitab provides the colors shown below. The subcommand argument is the number for the color. The color names
correspond to the color names in the dialog box.
Dark Wine
80
Dark Blue
72
Indigo
64
Very Dark
Green
56
Dark Yellow
48
Chestnut
40
Dark Brown
32
Dark Red
24
Black
16
Dark
Magenta
81
Eggplant
73
Teal
65
Forest
57
Olive
49
Tangerine
41
Ginger
33
Red
25
Slate
17
Burgundy
82
Blue
74
Cerulean
66
Spinach
58
Chlorophyll
50
Orange
42
Mustard
34
Rose
114
Stone
18
Violet
83
Royal
Purple
75
Azure
67
Dark Green
59
Lime
51
Gold
43
Copper
116
Terra Cotta
26
Dark Gray
19
Purple
84
Medium
Blue
126
Turquoise
68
Moss
60
Chartreuse
52
Yellow
44
Wheat
35
Brick
27
Medium
Gray
20
Grape
85
Dark Azure
76
Cyan
69
Sage
61
Green
120
Saffron
118
Peach
36
Wine
28
Gray
21
Plum
128
Lilac
77
Aqua
124
Dark Cyan
62
Apple
53
Lemon
45
Coral
37
Salmon
29
Light Gray
112
Magenta
86
Dark Sky
Blue
127
Light Cyan
70
Sea Green
63
Light Green
54
Light Yellow
46
Tan
38
Pink
30
Very Light
Gray
22
Neon Pink
87
Light Sky
Blue
78
Light Blue
71
Willow
122
Very Light
Green
121
Light
Orange
47
Light Beige
39
Light Pink
31
Pale Gray
113
Dark Pink
129
Lavender
79
Pale Blue
125
Spring
Green
123
Pale Green
55
Pale Yellow
119
Pale Beige
117
Pale Pink
115
White
23
1172
Minitab Statistical Software Supporting Concepts
Numbers for fill types to use in session commands
Minitab provides the following fill types for graph spaces (legend, area, region, bar, and so on). The subcommand
argument is the number for the fill type.
DescriptionFill typeNumber
None (transparent)0
Solid background1
Right hatch foreground2
Left hatch foreground3
Right and left hatch foreground4
Horizontal hatch foreground5
Vertical hatch foreground6
Horizontal and vertical hatch foreground7
Dots foreground8
Squares foreground9
Numbers for line types to use in session commands
Minitab provides the following line types for graph objects. The subcommand argument is the number for the line
type.
DescriptionLine typeNumber
None0
Solid1
Dashes2
Dots3
Dash 1-Dot4
Dash 2-Dot5
Dash 3-Dot6
Long dashes7
1173
Minitab Statistical Software Supporting Concepts
Numbers to use for symbols and markers in session
commands
Minitab provides the following symbols and markers for graphs. The subcommand argument is the number that
corresponds to the symbol/marker type.
DescriptionSymbolNumber
Circle1
Plus2
Cross3
Asterisk4
Dot5
Solid circle6
Dot circle7
Plus circle8
Cross circle9
Circle circle10
Square11
Solid square12
Dot square13
Cross square14
Diamond15
Solid diamond16
Dot diamond17
Plus diamond18
Triangle19
Solid triangle20
Dot triangle21
Triangle right22
Solid triangle right23
Dot triangle right24
Triangle left25
1174
Minitab Statistical Software Supporting Concepts
DescriptionSymbolNumber
Solid triangle left26
Dot triangle left27
Triangle down28
Solid triangle down29
Dot triangle down30
Overview of DDE session commands
The DDE dialog boxes do not generate command language as other Minitab dialog boxes do. If you want to perform
DDE actions from the Command Line pane or in a macro, use the DDE session commands below.
Type of macrosDDE session commands to usePurpose
Global macros and Execs onlyXDADD on page 57Add a link
Global macros and Execs onlyXDREMOVE on page 61Remove a link
Global macros and Execs onlyXDREMOVE on page 61, then XDADD
on page 57 with different
subcommands
Change a link
Global macros and Execs onlyXDACTIVATE on page 57Activate a link
Global macros and Execs onlyXDDEACTIVATE on page 59Deactivate a link
All macrosXDGET on page 60Perform a one-time data transfer
All macrosXDEXEC on page 60Execute an internal command
Pearson residuals
The Pearson residuals are elements of the Pearson chi-square, that can be used to detect ill-fitted factor/covariate
patterns. The Pearson residual defined for the jth factor/covariate pattern is given by:
Notation
y
j
The number of successes for the j
th
factor/covariate pattern
m
j
The number of trials for the jth factor/covariate pattern
The estimated probability for the j
th
factor/covariate pattern.
1175
Minitab Statistical Software Supporting Concepts
Plackett-Burman designs
In all cases except n = 28, you can specify the design by providing only the first column.
In the table below, we give this first column (written as a row to save space). This column is permuted cyclically to get
an (n 1) x (n 1) matrix. Then, a last row of all minus signs is added.
For n = 28, we start with the first 9 rows. These rows are then divided into 3 blocks of 9 columns each. Then the 3
blocks are permuted (row-wise) cyclically and a last column of all minus signs is added to get the full design.
Each design can have up to k = (n 1) factors. If you specify a K that is less than (n 1), just the first k columns are
used.
8 Runs
+ + + - + - -
13 Runs
+ + - + + + - - - + -
16 Runs
+ + + + - + - + + - - + - - -
20 Runs
+ + - - + + + + - + - + - - - - + + -
24 Runs
+ + + + + - + - + + - - + + - - + - + - - - -
28 Runs
+ - + + + + - - - - + - - - + - - + + + - + - + + - +
+ + - + + + - - - - - + + - - + - - - + + + + - + + -
- + + + + + - - - + - - - + - - + - + - + - + + - + +
- - - + - + + + + - - + - + - - - + + - + + + - + - +
- - - + + - + + + + - - - - + + - - + + - - + + + + -
- - - - + + + + + - + - + - - - + - - + + + - + - + +
+ + + - - - + - + - - + - - + - + - + - + + - + + + -
+ + + - - - + + - + - - + - - - - + + + - + + - - + +
+ + + - - - - + + - + - - + - + - - - + + - + + + - +
32 Runs
- - - - + - + - + + + - + + - - - + + + + + - - + + - + - - +
36 Runs
- + - + + + - - - + + + + + - + + + - - + - - - - + - + - + + - - + -
40 Runs (note, derived by duplicating the 20 run design)
+ + - - + + + + - + - + - - - - + + - + + - - + + + + - + - + - - - - + + -
44 Runs
1176
Minitab Statistical Software Supporting Concepts
+ + - - + - + - - + + + - + + + + + - - - + - + + + - - - - - + - - - + +- + - + + -
48 Runs
+ + + + + - + + + + - - + - + - + + + - - + - - + + - + + - - - + - + - + + - - - - + - - - -
Prompting a user for information
READ, SET, and TSET have a special feature that allows you to ask users questions and then use their answers in the
macro. A macro will pause for user input if you use READ, SET, or TSET with the subcommand FILE with the special file
name TERMINAL. TERMINAL tells Minitab to wait for input from the keyboard. READ, SET, and TSET also have other
subcommands.
Reading in data from a text file
Most applications, such as spreadsheets and data bases, can save data in an ASCII file, also called a data or text file.
You can use READ (for information, go to READ data into a matrix on page 43 or READ data into columns on page
41) or SET on page 80 to import this type of file into Minitab. Minitab assumes the default file extension DAT for use
with data files. You do not need to type DAT as part of the file name within single quotation marks if the file has a DAT
extension. For example, the following commands import the file named MYDATA.DAT into C1 through C10. MYDATA
contains 10 columns of numbers, separated by spaces or commas.
READ C1-C10;
FILE "MYDATA".
If the file is not in your default directory, include the path information as part of the file name within single quotation
marks. If the file extension is not DAT, include the file extension as well.
If the file includes text columns, if the columns are separated by tabs, or if missing values are designated by a blank,
you must use additional subcommands.
Note The menu command File > Open Worksheet also opens ASCII (text) files, and many other types of files as well. The menu command
provides options that are not available with READ or SET.
Generalized linear model diagnostics and residual
analysis
Following any modeling procedure, you should assess the validity of your model. The generalized linear model (GZLM)
command includes a collection of subcommands that store residuals and diagnostic statistics. These residuals and
diagnostic statistics allow you to do the following:
identify factor/covariate patterns which are poorly fit by the model
identify factor/covariate patterns which have a strong influence on the estimated parameters
identify factor/covariate patterns which have a large leverage
Hosmer and Lemeshow suggest that you interpret these diagnostics jointly to understand any potential problems with
the model.
Use the stored statistics to identifyWhat the subcommand storesSubcommand
Poorly fit factor/covariate patternsPearson or deviance residualsRESIDUALS
1177
Minitab Statistical Software Supporting Concepts
Use the stored statistics to identifyWhat the subcommand storesSubcommand
Poorly fit factor/covariate patternsStandardized Pearson residuals or standardized
deviance residuals
SRESIDUALS
Poorly fit factor/covariate patternsDeleted Pearson residuals or deleted deviance
residuals
TRESIDUALS
Poorly fit factor/covariate patternsChanges in the Pearson chi-square when the j
th
factor/covariate pattern is removed
DCHISQUARE
Poorly fit factor/covariate patternsChanges in the deviance when the j
th
factor/covariate
pattern is removed
DDEVIANCE
Factor/covariate patterns with a strong
influence on parameter estimates
Changes in the coefficients when the j
th
factor/covariate pattern is removed, based on
standardized Pearson residuals
DSBETA
Factor/covariate patterns with a strong
influence on parameter estimates
Changes in the coefficients when the j
th
factor/covariate pattern is removed, based on
Pearson residuals
DBETA
Factor/covariate patterns with a large
leverage
Leverages of the j
th
factor/covariate patternHI
The analyses store deviance residuals unless you use the subcommand PEARSON. The GZLM command has a collection
of residual plots. On these plots, you can use Minitab's graph brushing capabilities to identify poorly fit and influential
factor/covariate patterns.
Residual analysis and regression diagnostics
Further analysis usually follows the fitting of any type of model, such as regression. The most important part is the
plotting of residuals. For example, many analyses rely on the assumption that residuals are normally distributed and
are constant, that is, the residuals do not exhibit a trend as a function of the response variable. Minitab provides
subcommands to graphically illustrate whether or not these assumptions have been met.
Graph subcommand to useWhat you want to plot
GHISTOGRAMHistogram of the residuals
GNORMALNormal plot of the residuals
GFITS
Residuals versus fits ( )
GORDERResiduals versus order
GFOURPACKA layout of a histogram of the residuals, normal plot of the
residuals, residuals versus fits, and residuals versus order
residuals versus predictor variables
GVARIABLEResiduals versus predictor variables
You can specify the type of residual to plot-raw residuals, standardized residuals, or Studentized deleted residuals-using
the RTYPE subcommand. You can also store these residuals using the subcommands RESIDUALS, SRESIDUALS, and
TRESIDUALS, respectively.
In addition, REGRESS has a collection of subcommands (HI, RESIDUALS, TRESIDUALS, COOKD, DFITS) that store
diagnostics to help you find unusual observations. You should check unusual observations to make sure they are
correct. If correct, you should try to understand why they are unusual and what effect they have on the regression
equation.
1178
Minitab Statistical Software Supporting Concepts
Restrictions on GLM models
Although models can be unbalanced in GLM on page 227, they must be "full rank". Thus, there must be enough data
to estimate all the terms in your model. For example, suppose you have a two-factor crossed model with one empty
cell. Then you can fit the model GLM Y = A B, but not GLM Y = A B A*B. Don't worry about figuring out whether or
not your model is of full rank. Minitab will tell you if it is not. In most cases, eliminating some of the high order
interactions in your model (assuming, of course, they are not important) will solve your problem.
There is a restriction on the subscripts used for nested terms as nesting must be balanced. Suppose A has 3 levels,
and B is nested within A. If B has 4 levels within the first level of A, B must have 4 levels within the second and third
levels of A. Minitab will tell you if you have unbalanced nesting. In addition, the subscripts used to indicate the 4 levels
of B within each level of A must be the same. Thus, the four levels of B cannot be (1 2 3 4) in level 1 of A, (5 6 7 8) in
level 2 of A, and (9 10 11 12) in level 3 of A.
Session commands that are not allowed in macros
Commands and subcommands that open different projects or restart Minitab are not allowed in macros. In addition,
local macros cannot include commands that do the following:
Make different worksheets active.
Require Minitab to pick storage locations after the last column in use.
Where subcommands are listed below, the command itself is permitted. For example, you can use the COPY command
in local macros, if you do not use the NEWWS, AFTER, or STORE subcommands.
Not allowed in local macros
COPY
NEWWS
AFTER
STORE
EXECUTE
NEW
RETRIEVE
SAVE
SORT
NEWWS
SPLIT
STACK
NEWWS
SUBSET
TRANSPOSE
NEWWS
AFTER
1179
Minitab Statistical Software Supporting Concepts
UNSTACK
NEWWS
AFTER
WOPEN
WORKSHEET
Not allowed in global macros
NEW
PROJECT
RESTART
RETRIEVE
PROJECT
Simplex lattice design descriptions
Number of components (q)Degree of design (m)
2 to 101
2 to 202
2 to 173
2 to 114
2 to 85
2 to 76
2 to 67
2 to 58
2 to 59
2 to 510
Time unit subcommands
Use these subcommands to specify when consecutive observations in a given variable were made. Use START and
INCREMENT to specify the starting point of the first observation and the frequency of consecutive points, all in terms
of the given unit. For example, a series of observations beginning in March and taken every other month thereafter
would be represented by the following commands.
MONTH;
START 3;
INCREMENT 2.
These subcommands specify the rate at which data were collected, not the number and frequency of ticks on the
resulting graph. For information on tick placement and custom labels, go to SCALE on page 1076.
You can specify up to three time unit subcommands in one of the following combinations.
1180
Minitab Statistical Software Supporting Concepts
Supported combinationsTime units
DAY; HOUR
DAY; HOUR; MINUTE
HOUR; MINUTE
HOUR; MINUTE; SECOND
MINUTE; SECOND
Clock
DAY; MONTH
DAY; MONTH; YEAR
MONTH; YEAR
MONTH; QUARTER
MONTH; QUARTER; YEAR
QUARTER; YEAR
Calendar
A scale level is shown for each time unit. You can specify a start value for each.
INDEX
Specifies that consecutive integers be used on the time scale. The default START value is 1, and all integers are
valid START arguments.
STAMP C [C...C]
Specify up to three columns that contain the time values for the observations.
SECOND
Specifies that observations were taken in units of seconds. The default START value is 0, and 0 through 59 are
valid START arguments.
MINUTE
Specifies that observations were taken in units of minutes. The default START value is 0, and 0 through 59 are
valid START arguments.
HOUR
Specifies that observations were taken in units of hours. The default START value is 0, and 0 through 23 are valid
START arguments.
DAY
Specifies that observations were taken in units of days. The default START value is 1, and 1 through 31 are valid
START arguments, depending on the month.
MONTH
Specifies that observations were taken in units of months. The default START value is 1, and 1 through 12 are
valid START arguments.
QUARTER
Specifies that observations were taken in units of quarters. The default START value is 1, and 1 through 4 are valid
START arguments.
YEAR
Specifies that observations were taken in units of years. The default START value is 1900, and all positive integers
from 1000 to 4000 are valid START arguments.
1181
Minitab Statistical Software Supporting Concepts
START K [K...K]
START C
Specifies the starting point of the given unit or units. START takes as many arguments as there are time unit
subcommands. The Start values should be applied from outermost to innermost scale levels, the opposite of
calendar combinations. You may also enter a column containing the start values. If you have multiple graph
variables you can enter one set of START values for all, or one for each.
INCREMENT K
Specifies the time scale increment. INCREMENT always refers to the smallest specified time unit subcommand
and its argument is in terms of this unit. An argument of 1 assigns successive observations to consecutive seconds,
minutes, hours, and so on. An argument of 2 assigns successive observations to every other second, minute, hour,
and so on.
Using groups in graphs
You define groups by specifying one, two, or three group variables with data display subcommands in graphs that can
use groups with data display subcommands. For more information, go to Graphs that use groups with the data display
subcommands on page 1158.
The distinct values of a single variable or the combinations of distinct values of several variables define the groups.
The following table below defines groups in five different ways. For numeric variables, such as Quarter (Qtr) or Year
(Yr), groups are assigned in increasing order of the values of the group variable. For text variables, such as AdAgency,
groups are defined in the order of appearance in the data set. The first value of AdAgency is Omega, so it is group 1.
The second distinct value to appear is Alpha, so it is group 2.
C9C8C7C6C5C4C3C2C1
Groups AdA by YGroups Y by AdAGroups AdAgencyGroups YrGroups QtrAdAgencyYrQtrRow
11111Omega201511
11112Omega201522
32213Alpha201533
32214Alpha201544
44221Alpha201615
44222Alpha201626
23123Omega201637
23124Omega201648
When you use several group variables, the values of the first variable vary the slowest, the second vary the second
slowest, and the last vary the fastest. This means that specifying group variables in a different order can affect which
group comes first, second, and so on.
For example, look at the fourth group definition, Year by AdAgency. The first group is the first Year and first AdAgency;
the second group is still the first Year but now the second AdAgency. The third group is the second Year and first
AdAgency; the fourth group is the second Year and second AdAgency. The last group definition, AdAgency by Year,
uses the same variables but in the opposite order. Notice how the group assignments change.
For more information on groups, go to Assigning attributes to groups on page 1132 and Assigning attributes with
multiple graphs and groups on page 1132.
1182
Minitab Statistical Software Supporting Concepts
Using READ with FORMAT
When you use READ and have typed all your data, type END on page 38 in the first three spaces of the next line.
For more information, go to READ data into a matrix on page 43 or READ data into columns on page 41.
Numbers that are read under F format must be typed in the spaces indicated by the format, with no extra text.
Numbers should normally be typed right-justified (that is, with no blanks following the number in the field).
Currency values that are read under C format must be typed in the spaces indicated by the format, with no extra
text other than the currency symbol. Currency values should normally be typed right-justified (that is, with no blanks
following the number in the field).
You can indicate missing data by putting a single * in the field or by leaving the field blank. A count of blank fields
is given after all the data have been read.
If there are errors or warnings, fairly extensive messages are given for the first 10 rows.
Use a comma to separate format items.
Using READ without subcommands
READ (for information, go to READ data into a matrix on page 43 or READ data into columns on page 41) ignores
text on data lines. However, a data line cannot begin with a valid command name.
You can type data with or without a decimal point and in exponential (scientific) notation. Thus, the following values
are all valid and equivalent:
123.4
1.234E+2
1.234E2
You can use the missing data code (*) as data.
READ ignores lines that are blank or that contain only spaces.
For information on using READ to put numbers into a matrix, go to READ data into a matrix on page 43.
You can type comments on a data line after the symbol #.
You cannot enter stored constants (such as K1) in place of numbers on a data line after READ, but you can with
SET on page 80.
If a row is incomplete—that is, it contains fewer values than are listed as columns on the main READ command
line—then Minitab reads all the values in the row and sets the end values in the row as missing.
Using the SYMBOL and COLOR subcommands for
PLOT
The data display subcommands determine the basic appearance of a graph produced by a supported graph command.
You can specify more than one data display subcommand in a graph (for example, using SYMBOL and CONNECT
together). You can also specify the same data display subcommand several times in the same graph (for example,
using two SYMBOL commands to identify distinct points differently).
Many data display subcommands have subcommands of their own. This section discusses how the data display
subcommands work in general.
1183
Minitab Statistical Software Supporting Concepts
Minitab allows you to display different subsets of points in several ways. You can display:
Every point on the graph in the same way (Graph Mode)
Each individual point on a graph differently (Point Mode)
Points belonging to different groups differently (Group Mode)
These concepts are explained using one graph (PLOT), one data display subcommand (SYMBOL), one of the
subcommands of SYMBOL (COLOR), and the Marketing Data. Minitab uses integers for the colors. For the examples
in this section, we use the colors 1 = black, 2 = red, 3 = green, and 4 = blue.
If you use only one argument with COLOR, the argument applies to every point on the graph (this is Graph mode.).
For example:
PLOT Sales*Advertis;
SYMBOL;
COLOR 4.
displays all points with the same symbol type and colors all the symbols the same.
If you use several arguments with COLOR, and no arguments with SYMBOL, the COLOR arguments are applied to
successive points in the data set (hence, Point mode). For example:
PLOT Sales*Advertis;
SYMBOL;
COLOR 1 1 1 2 1 1 1 1.
colors the first 8 points the color that corresponds to 1 except the fourth, which is the color that corresponds to 2.
Further points are the default color.
Group mode
Suppose we add a grouping variable, Year, which divides the data into two groups, 1 and 2 (Group mode):
PLOT Sales*Advertis;
SYMBOL Year.
automatically gives points for each year a different symbol type and a different color.
This automatic assignment of different symbol types to different groups continues if you use COLOR, SIZE, ETYPE,
ECOLOR, or ESIZE. For example:
PLOT Sales*Advertis;
SYMBOL Year;
COLOR 4.
gives the points for each year a different symbol type with the same color.
If we use two arguments with COLOR (or TYPE, SIZE, ETYPE, ECOLOR, or ESIZE), the first applies to the first group and
the second to the second group, and so on (still Group mode). For example:
PLOT Sales*Advertis;
SYMBOL Year;
COLOR 2 3.
colors all symbols in first year the color that corresponds to 2 and all symbols in the second year the color that
corresponds to 3.
Now let's look at multiple graphs, first without a grouping variable. If we use just one argument with COLOR, then all
points in all graphs are given the same color. If we use several arguments with COLOR, then the arguments are assigned
to the points. For example:
PLOT Sales*Year Advertis*Year;
SYMBOL;
COLOR 2 3.
colors the first point in both graphs the color that corresponds to 2 and the second point in both graphs the color
that corresponds to 3.
1184
Minitab Statistical Software Supporting Concepts
If you have several graphs in one command and use a grouping variable with SYMBOL, then the colors are assigned
to the different groups, not the different graphs. For example:
PLOT Sales*Year Advertis*Year;
SYMBOL AdAgency;
COLOR 2 3.
makes the first group in AdAgency the color that corresponds to 2 in both graphs. The second group in AdAgency is
the color that corresponds to 3 in both graphs.
To assign different colors to different graphs when using groups, use separate PLOT commands.
Using the POSITION and MODEL subcommands
The POSITION subcommand allow you to affect graph elements (such as data labels, symbols, boxes, bars, or axis
labels) for specific data values. The MODEL subcommand extends this capability to paneled graphs.
The green boxplot in the Cycles panel is POSITION 1; MODEL 1. The yellow boxplot to its right is POSITION 2; MODEL
1.
The blue boxplot in the FlashRecov panel is POSITION 1; MODEL 2. The orange boxplot to its right is POSITION 2;
MODEL 2.
The following session commands create this graph.
BOXPLOT CYCLES * FORMULATION FLASHRECOV * FORMULATION;
PANEL;
IQRBOX;
POSITION 1;
MODEL 1;
TYPE 8;
COLOR 50;
ENDPOSITION;
POSITION 2;
MODEL 1;
TYPE 2;
COLOR 43;
ENDPOSITION;
POSITION 1;
MODEL 2;
TYPE 7;
COLOR 62;
ENDPOSITION;
POSITION 2;
MODEL 2;
TYPE 9;
1185
Minitab Statistical Software Supporting Concepts
COLOR 27;
ENDPOSITION;
TYPE 4;
COLOR 50;
OUTLIER;
TITLE;
PSIZE 14;
FOOTNOTE;
FPANEL;
NODTITLE.
Valid format items
DescriptionFormatItem
For reading numbers.F formatFw
Fw is the basic format item. Fw reads a number from a field of width w. For
example, F10 says to read the number in the next 10 spaces.
For reading numbers with number of decimal places.F formatFw.d
The format, Fw.d, inserts a decimal point d spaces from the right of the number.
Regardless of local regional settings for language, a period character must be
placed before the specified number of decimal places. For example, F10.4 takes
the number from the next 10 spaces on the data line, and inserts a decimal point
before the last 4 digits. If there is a decimal point in the number, it overrides the
d.
For text (alpha) data.A formatAw
The A format item is for text (alpha) data. The field width, w, may be up to 80.
Columns input with the A format can be output by WRITE: Session command
for writing data to the screen or a data file on page 49 and PRINT: Session
command for displaying columns, constants, or matrices in the output pane on
page 40, with or without a FORMAT subcommand, and can be converted to
numbers with CONVERT: Session command for converting text data to numeric
data, and numeric data to text data on page 121.
For date/time data.DT formatDT
The DT format is a special format unique to Minitab for reading date/time data.
The example DT8m/d/yy reads data from the first 8 spaces in the format m/d/yy
into a date/time column. You need to provide a space value for the width only
if you are reading from a file.
For percentages with numbers of decimal places.% format%w.d
The %w.d format is for reading percentage data. Minitab formats percentage
data as numeric data.
Skips a space.X formatX
Repeat factorn
Open parenthesis(
Close parenthesis)
1186
Minitab Statistical Software Supporting Concepts
DescriptionFormatItem
Separates format items.Comma,
Moves to a new data line.Slash/
Iw
Gw
Gw.d
Ew
Ew.d
Dw
Dw.d
1187
Minitab Statistical Software Supporting Concepts