To display a boxplot with multiple y's and groups
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1    Choose Graph > Boxplot.

2    Under Multiple Y's, choose With Groups. Click OK.

3    In Graph Variables, enter one or more columns of data. Minitab displays all columns on the same graph.

4    In Categorical variables for grouping (1-3, outermost first), enter one to three columns containing grouping (categorical) variables. The first variable you enter is the outermost categorical variable on the scale and the last variable is the innermost.

5    Under Scale Level for Graph Variables, choose one of the following:

·    Graph variables displayed outermost on scale to make the graph variables the outermost groups.  

·    Graph variables displayed innermost on scale to make the graph variables the innermost groups.

6    If you like, use any dialog box options, then click OK.