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Hi guys, I'm a beginner in Freesurfer and I want to perform an analysis of the difference between 3 groups in cortical thickness,volume and area having age, mean thickness and etiv as covariate.
my design matrix for 3 groups comparison as "1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 (LR-HR)
1 0 -1 0 0 0 0 0 0 0 0 0 0 0 0 (LR-MDD)
0 1 -1 0 0 0 0 0 0 0 0 0 0 0 0 (HR-MDD)
If possible, I would like to know how my contrasts change when I wish to test the change in thickness with age, after removing the group effects. Another question I have is how can I create contrasts to control etiv between groups, like 2x2 comparison. I'm sorry if I was not clear... thanks
Fernanda
my FSGD file is
GroupDescriptorFile 1 Title MyStudy
Class LR
Class HR
Class MDD
Variables age meanThick totalarea eTIV Input Sub001 LR 14.3 1350519.71 1954527.71 1552459.71 Input Sub002 MDD 15.7 1558515.86 1689767.98 1809809.87