Dear SPM experts,

In my study, I have a 2 x 2 between-within design, where the between factor is group (patients vs control) and the within factor is task condition (i.e. congruent vs incongruent Stroop trials). I am interested in both main effects and the interaction effect.

I specified a full factorial model in SPM8, and am now in the process of running the analyses. However, I came across some earlier threads on this forum, which mentioned that the between-factor is actually not a valid contrast in the full factorial model. If this is correct, would it be ok (from a reviewers point of view) to just run a between-groups t-test to test for the main effect of group - while using the full factorial model to model the interaction effect and the within-group factor?

Any comments are highly appreciated!

Best regards,

-Lasse

IKKE SENSITIVT INNHOLD.