Hello FSL Experts, 

I am currently running a DTI analysis and had a mean_FA_skeleton question. After running a group of 40 subjects I realized that I needed to eliminate 7 subjects from my analysis. After eliminating these 7 subjects I started comparing the mean_FA_skeleton from the two analyses (n of 40 and n of 33) and realized there was a big shift in the mean_FA_skeleton in several regions (5 voxel shift; please see attached corpus callosum image). With only eliminating 7 of 40 subjects I am surprised to see such a big shift in the skeleton, however I suspect that this is the result of a different 'target' image when running tbss_2_reg -n. Would I be correct in my assumption?

Cheers, 

Duke