Dear Andrew
    I am also hoping to perform a similar 2x2 repeated measures anova in NBS. I have two groups in patients with migraine（Group A：n=29; Group B：n=25）who received two therapy method,separately.(Group A: received real vagus nerve stimulation; Group B received sham Vagus nerve stimulation). so I had four groups(Group A1:before real stimulation,Group A2: after real stimulation, Group B1: before sham stimulation,Group B2: after sham stimulation ).
    I am interested in the main effects of stimulation and time,but more specifically in the interaction effect between stimulation and time. My main issue has been the design matrix and the contrast. Can you help me? Any help would be greatly appericiated.

Sincerely,
zhangyue