Dear FSL experts,
I'm new in FSL.
I'm trying to conduct TBSS ANOVA with three groups (let's say group "A," "B" and "C") with three covariates of nuisance (age, sex, and motion) to result in fail.
First, I would like to know the difference from three groups (F-values).
Then, I would like to conduct post-hoc independent t tests (A > B, A < b, A > C, A < C, B > C, B < C).
To my best guess, as far as I read the previous entries of this email list, I have made the design.mat, design.con and design.fts files as following (as the number of participants is large; 144, I showed only the first few rows in the design.mat files).
The design.mat file
/NumWaves 6
/NumPoints 144
/PPheights 1 1 1 1 1 1
/Matrix
1 0 0 23 1 1.9
0 1 0 7 1 1.8
1 0 0 12 1 2.0
0 0 1 8 0 2.8
The first column is "1" in case where the row is in group "A."
The second column is "1" in case where the row is in group "B."
The third column is "1" in case where the row is in group "C."
The 4th to 6th columns indicate age, sex, and motion, respectively.
...
The design.con files as following,
/NumWaves 6
/NumContrasts 6
/PPheights 1 1 1 1 1 1
/Matrix
1 -1 0 0 0 0
1 0 -1 0 0 0
0 1 -1 0 0 0
0 -1 1 0 0 0
-1 1 0 0 0 0
-1 0 1 0 0 0
My understanding is that the first row will give me the result of post-hoc test (A > B, with regressing out three covariates)
The design.fts file as following,
/NumWaves 6
/NumContrasts 1
/Matrix
1 1 1 0 0 0
And, radomise command as following,
randomise -i all_FA_skeletonised -o tbss -m mean_FA_skeleton_mask -d design.mat —t design.con -f design.fts -n 500 --T2
As a result, I receive a message saying;
"ERROR: Program failed
An exception has been thrown
Error: This (f)contrast appears to be rank defficient, please check your design."
If someone helps me put in the right direction, it would be greatly helpful and appreciated.
Best.
Yuta
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