We ran a four-way ANOVA on RT (reaction time) data with 4 independent within-subject variables. The analysis revealed a number of significant main effects and interactions. Among them there was a significant three-way interaction of three IVs: A (before vs. after), B (type 1 vs. type 2), & C (short vs. long).
We would like to run separate post hoc analyses. Purpose: to see if the interaction of A & B was only significant for one level of C (short or long).
Please advise, we are using version 13 of SPSS.
Many many thanks in advance.