To use group options
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1    In the data source dialog box, click Data Options.

2    Click the Group Options tab.

3    Check Include missing as a group to include observations with missing group values. Resulting graphs include the observations and leave the missing grouping variable label blank.

4    Check Include empty cells to include group level not represented by the combination of two or more grouping variables. Resulting graphs include empty placeholders for these levels.

5    Click OK.