Grouping Variables
overview     see also 

To distinguish between data belonging to different groups, you can add categorical grouping variables to a graph. The grouping variables you use depend on the organization of the worksheet data. See Organizing Your Data. To specify the groups:

·    Choose a With Groups option from a gallery, then enter the grouping variables in the data source dialog box. Minitab assigns different data display attributes for each group, then creates a legend. You can add a grouping variable to a graph by double-clicking its data display (symbols or bars, for example) and choosing the Groups tab.

·    Click Multiple Graphs, click the By Variables tab, and enter the grouping variable. Different data displays are not assigned, because each group is displayed in a separate panel or graph. You can add a paneling variable to a graph by choosing Editor > Panel.

Data displays or panel arrangements are assigned according to the order the variables are specified in the dialog box. Compare the group order in these examples: 

When grouping by Year, AdAgency, and Quarter (above left):

1    Minitab selects rows with the lowest value in Year, 1991 (rows 1-4).

2    From those four rows, Minitab selects rows that have the earliest alphabetical order in AdAgency, Alpha (rows 3 and 4).

3    From those two rows, Minitab selects the row with the lowest Quarter, 3 (row 3), which makes row 3 the first group.

You can see how the order changes (above right) when Minitab selects first by Quarter, then by Year, and finally by AdAgency.

Whether you are creating a graph With Groups or using panels, missing groups values and empty cells can effect the look of your graph. See Using Group Options.