This is a follow-up on the post below. I am trying to set up a design matrix to feed randomise. I have carefully read FEAT + randomise documentations and searched through the archives, but I am still confused.
I have 2 groups (control and experimental, 10 subjects each) and each subject is scanned in two sessions (pre and post). We expect the experimental group to show increased FA in the post session compared to pre, whereas the control group should show less or no increment. So, this is the main question I would like to answer with my design/contrast(s).
Suppose that I have 3 subjects per group. This is the design matrix that I finally made:
EV1 EV2 EV3 EV4 EV5 EV6 EV7 EV8 EV9
Subj 1, control, pre: -1 -1 0 1 0 0 0 0 0
Subj 2, control, pre: -1 -1 0 0 1 0 0 0 0
Subj 3, control, pre: -1 -1 0 0 0 1 0 0 0
Subj 1, control, post: -1 1 0 0 0 0 1 0 0
Subj 2, control, post: -1 1 0 0 0 0 0 1 0
Subj 3, control, post: -1 1 0 0 0 0 0 0 1
Subj 4, experim, pre: 1 0 -1 1 0 0 0 0 0
Subj 5, experim, pre: 1 0 -1 0 1 0 0 0 0
Subj 6, experim, pre: 1 0 -1 0 0 1 0 0 0
Subj 4, experim, post: 1 0 1 0 0 0 1 0 0
Subj 5, experim, post: 1 0 1 0 0 0 0 1 0
Subj 6, experim, post: 1 0 1 0 0 0 0 0 1
This is made intuitively and I don't know if it makes any sense... If yes, how could I set up the contrast? Any suggestions, examples for dummies, etc will be very welcome.
Thanks in advance,
Miguel