Hello everyone. I am trying to conduct a three-way, fully repeated measures ANCOVA with SPSS 19 running on Mac OS 10.8.4. My dependent variable is continuous, my three independent variables are discrete/categorical, and my covariate is continuous and time-invariant/constant.
I would like to revive this post because it left off exactly where I need some help. I also though it would be a good idea to revive this post because an earlier post (Post subject: interpreting a three way interaction? Posted: Sat Mar 22, 2008 8:24 am) also left off exactly at this point.
When you have a fully repeated measures ANOVA and you enter your covariate in the covariate portion of the Repeated Measures GLM dialog box in the SPSS graphical user interface, your Tests of Within Subjects Effects table has two rows for every effect. For example, for the three-way interaction, I have Var1 * Var2 * Var3 and Var1 * Var2 * Var3 * covariate. In other words, for every main effect and interaction, I have Effect/Interaction and Effect/Interaction * covariate.
After much searching, I found this article on the IBM support website: <<http://www-01.ibm.com/support/docview.w ... wg21477023
>>. This was very helpful because it told me the following. "If you only run one model that includes the covariates, the covariates appear in the WS portion of the model as interactions with the WS factor. This is not the same as partialling the covariates from the WS factor; it is what it looks like --a set of interaction terms." However, it did not tell me what to do if I actually wanted to partial the covariates from the WS factor(s) or if that is even possible.