Mixed-design Analysis of Variance - Follow-up Tests

Follow-up Tests

When there is a significant interaction between a between-subject factor and a within-subject factor, statisticians often recommended pooling the between-subject and within-subject MS_error terms. This can be calculated in the following way:

MSWCELL = SS_BSError + SS_WSError / df_BSError + df_WSError

When following up interactions for terms that are both between-subjects or both within-subjects variables, the method is identical to follow-up tests in ANOVA. The MS_Error term that applies to the follow-up in question is the appropriate one to use, e.g. if following up a significant interaction of two between-subject effects, use the MS_Error term from between-subjects. See ANOVA.