Dear SPM experts,
I have a 2x2 fMRI experiment (2 groups of subjects (A and B) scanned twice (before and after treatment). I have specified a Flexible Factorial model with 2 factors (group, independent,variance:unequal and scan, dependent, variance:equal), 2 main effects and 1 interaction(fig attached). I have followed the Jan Glasher and Darren Gitelman's tutorial on contrast specification for main effects and interaction, but am not sure about how to specify contrasts if I want to look at A1vsB1 and A2vsB2.
Would 1 -1 0 0 0 1 0 -1 0 be correct? (grA grB sc1 sc 2 A1 A2 B1 B2)
Thank you very much for your help!
Olga Prilipko, MD
Stanford Sleep Clinic