Thanks for this.
> How are you modeling the random effects? With a random intercept or both random intercept and slope?
I have started with both random intercept and slope, but then I have tried also with each on its own (only slope, only intercept) and the one with only intercept seems to be a bit different (less activation in all clusters) from the other two which do not differ. How do I peek the 'right' one? Should be my decision theory-driven? Or, for instance, can I extract the betas from a significant cluster and run a LME in SPSS to predict the best model and generalize that approach to all voxels?
> Does the average covariate value differ much between the two levels of the within-subject factor?
Not really, I have run a t-test and they don't differ (p=0.4).
