FSL Experts,
I am having a bit of a problem trying to figure out whether or not to use the -D option in randomise. I have found several emails regarding this issue (06/17/2010, 10/30/2010, 02/04/2008), but I am still confused. Currently, I have 3 nuisance variables (age, gender, and SES) and one variable of interest (RT). In this design I enter RAW values for ALL variables and include the -D option when running randomise. My contrasts looks like this (0 0 0 0 1) and (0 0 0 0 -1). Is this correct?
randomise -i all_FA_skeletonised -o tbss -m mean_FA_skeleton_mask -d design.mat -t design.con -D -n 5000 --T2 -V -x
Additionally, if I want to see if there is an interaction between 2 variables of interest and I have already demeaned them and created an interaction term for each subject do I need to use the -D option when running randomise? Example, 3 nuisance variables (age, gender, and SES) and 1 interaction term (demeaned and multiplied). Contrasts (0 0 0 0 1) and (0 0 0 0 -1). Is this correct?
Does -D demean each EV or does it depend on my contrasts? In other words, does it only demean the 1's in my contrast?
Cheers!
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