A few questions regarding tbss_sym FA (pilot project) with a repeated-measures design (within-subjects) 4 subjects (n=4), scanned at two time points; initially and 8 months later.
The tbss guide suggests using the option -1 for left-right testing in randomise. I don’t think this randomise setting can be used for this project which has two factors: left vs right and time which is a total of 4 levels. This could be set-up as a 2 factor, 2-level Anova (asymmetry: left vs right, time: before and after 8 months), though pairwise test are ultimately needed.
I did use the glm_gui to attempt make 2-factor, 2-level design (n=4) and can forward it.
Any suggestions in helping to set up the appropriate design and “randomise” call (e.g. randomise -i all_FA_skeletonised_left_minus_right.nii.gz -o tbss -m mean_FA_symmetrised_skeleton_mask.nii.gz -1 -n 5000 --T2 -V) would be much appreciated.
Charlie
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