Hello,

I am looking at resting state ROI-to-ROI connectivity differences between 2 groups (YA and OA) that correlate with the behavioural variable D.
I have the groups coded as a second level covariate as described in the manual. I have the behavioural variable coded for each group separately (D_YA and D_OA) and the values are entered for each group member and zero's for non group members.

I want to look at the following:
1. ROI-to-ROI FC for YA and D - when I first ran this analysis, I selected D_YA and looked at the simple main effect of D_YA.
2. ROI-to-ROI FC for OA and D - I did the same as above except selected D_OA.
3. Differences between Analysis 1 and 2 groups and connectivity that correlates with D - So I selected D_YA and D_OA and set up the contrast as 1 -1.

However, I have been reading through all the posts on the forum and it seems as if this is incorrect and the correct way MAY be to do the following?
1. For analysis 1, select the group coding variable YA and then the behavioural coding variable D_YA and set up the contrast as 0 1 and then look at the main effect of D_YA - What is the differnece between this and the one above?
2. Same as analysis 2 - select group coding variable for OA and then D_OA and set up the contrast as 0 1. - Again what is the difference between this and how I ran it the first time?
3. More importantly, to look at group differences answers on the forum suggest that I should select the group variable for OA, YA, D_YA, D_OA and then set up the contrast as 0 0 1 -1

Can you or anyone who has experience with this advise as to which way is correct?

Thanks,
Areeba