Hi,
this is my first post here. I hope some VBM professionals can help me out.
I am running a 3-group VBM analysis on SPM8 and I want to compared the correlations between the GMV/WMV and a behavioural score.
I have selected:
1. Full factorial and defined a factor "group" with 3 levels
2. Loaded the GM (or WM in another batch) images in the respective cells and assigned levels 1, 2, or 3 accordingly.
3. Defined one covariate for the behavioural score in a single vector
4. Under interactions, I have chosen "with Factor 1". Centering is Overall mean.
As for the contrasts, for comparing Group 1 > Group 2: 0 0 0 1 -1 0 etc.
Have I carried out this correctly?
Additional question: If I want to use for example two nuisance covariates, could they be implemented in a normal fashion and then the contrasts would just be: for comparing Group 1 > Group 2: 0 0 0 1 -1 0 0 0 where the two last zeros are for covariates?
Thank you for your answers.
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