I am doing a repeated measures ANCOVA analysis, with three factors. The first between-subject factor is gender (female, male), the second between-subject is treatment (present vs. absent), and the third is a within-subject factor: scores at two time points(i.e., time1 and time2). There is a three-way interaction, and I need to do simple effects test to examine the three way interaction, that is, holding treatment constant at the "present" level and then holding treatment constant at the "absent" level.
Could you please tell me the SAS code or SPSS syntax? Thanks.