I'm trying to set ut a freesurfer group analysis. In my fsgd file there are four groups/classes and 2 variables, like so:
GroupDescriptorFile 1 Title Class Class1 Class Class2 Class Class3 Class Class4 SomeTag
Variables Variable1 Variable2 Input subj1 Class1 49 1 Input subj2 Class2 50 2 Input subj3 Class3 51 3 Input subj3 Class4 52 4 Input...
I'm a bit puzzled as to how I should set up the contrasts. With DODS, there should be a matrix of 12 regressors, and I want to model how thickness varies with Variable2, ignoring the effects of Variable1 and Class. Should my contrast be
0 0 0 0 0 0 0 0 0.25 0.25 0.25 0.25 or 0 0 0 0 0 0 0 0 1 1 1 1
or something completely different?
I have tried both contrasts, and they yield identical (and plausible) results.
Kind Regards, Per Selnes