Correlation plot

This macro produces a correlation plot for evaluating the orthogonality of a designed experiment. Correlation plots are typically used for screening experiments to evaluate the alias structure, but can also be used for other designs.

By default, the macro produces the correlation plot for the pairwise correlations for the main effects and the 2-way interactions. Optional subcommands are available to add the squared terms and to display the absolute values of the correlations. All input columns are standardized before the correlations are calculated.

Download the Macro

Be sure that Minitab knows where to find your downloaded macro. Choose File > Options > General. Under Macro location browse to the location where you save macro files.

Important

If you use an older web browser, when you click the Download button, the file may open in Quicktime, which shares the .mac file extension with Minitab macros. To save the macro, right-click the Download button and choose Save target as.

Download CORRPLOT.mac

Required inputs

At least 2 columns of data that represent the factors from a designed experiment or that represent continuous predictor columns.

Optional inputs

SQUARES: Use to create the pairwise correlations for a model that includes the main effects, two-way interactions, and the squared terms.
ABSOLEGEND: Use to display the color legend from 0 to 1 instead of -1 to 1.

Running the macro

Suppose you have a 6-factor design and the columns that represent the factors are in C5, C6, C7, C8, C9, and C10. To create a correlation plot for the main effects and two-way interactions, choose View > Command Line/History. Then, type the command:

%CORRPLOT C5-C10

Click Run.

To create the correlation plot that shows the correlations for the model that contains the main effects, two-way interactions, and the squared terms, choose View > Command Line/History. Then, type the commands:

%CORRPLOT C5-C10;
SQUARES.

Click Run.