Hello all,
I'm looking to do some comparisons between summed effect size in an ROI
between group-level contrasts. I was wondering if there is a way to
save the effect size of each voxel in an ROI (for a given contrast). I
wanted to sum up the activity for each voxel in a few contrasts, and
then do some simple t-test in SPSS to see if there is a net advantage in
one contrast or the other for a specific ROI.
I guess my first question is, is this possible to do in SPM and how?
But second, is this a valid approach? We wanted to be able to pick up
small differences in an ROI and we thought, it might be the case that
each voxel in an ROI slightly more active in one contrast than another,
but since each voxel is only slightly more active you wouldn't see a
significant difference for any one voxel. However if you summed up
activity across all the voxel activities, then you might see a difference.
Thanks in advance!
Cheers,
Jason
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