Hello all,
The archive is a bit confusing to me regarding setting up voxelwise linear
regression with randomise/tbss. I am using FSL 4.1.4.
Is the following set up correct in order to answer the question: Does some
measured value X correlate with FA values, with age as a confound variable?
I have run tbss with my subject pool and generated all_FA_skeletonised etc.
I have demeaned X and age, and then generated a design.mat file, eg:
EV1(X) EV2 (age)
-1 -2
1 2
0.25 1.5
-0.75 0
-0.5 -1.5
I set up a single contrast:
[1,0]
I submit the following:
randomise -i all_FA_skeletonised -o output -m mask -d design.mat -t
design.con -n 500 -V --T2 -D
I get an ouput_corrp_tstat1 image. thresholding at 0.95-1 should give
clusters with p<0.05.
Prior posts mention using an EV (constant); It's not clear to me to what this is
referring, and when I use EV1 with a constant of 1 for everyone (as I don't
want to split them into separate groups), I get an error regarding one of my
EVs not being demeaned. This just doesn't seem right to me, so I'd like to
know if the above example is correct or if I'm missing something obvious.
Thank you,
Joe
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