Specify Within-Subjects Factor

Click the Within Effects button on the ANOVA/MANOVA Quick Specs dialog box - Quick tab to display the Specify within-in subjects factor dialog box

In this dialog box, specify the within-subject (repeated measures) factor and the respective number of levels (see also the GLM Introductory Overview for a discussion of repeated measures ANOVA). In short, the variables in the dependent variable list are assigned to levels for the repeated measures factor. Note that with the ANOVA module, you can specify only one within-subject (repeated measures) factor. If you want to specify multiple repeated measures factors, use the General Linear Models module.

If the factor specified in this dialog box does not account for all of the previously selected dependent variables (via the Variables button), a MANOVA will be performed. See Multiple Dependent Measures (MANOVA) and  ANOVA/MANOVA Notes - Specifying Within-Subjects Univariate Designs for further details.