Hi Gwenaėlle,
thanks for your quick reply. Then I assume second approach is better than the first one for my model.
I would be safe if I have done well,
could you please help me with this?
I have 4 groups to contrast FA values:
1.- Healthy (EV3)
2.- Disease 1 (EV1)
3.- Disease 2 (EV4)
4.- Disease 3 (EV2)
If i choose second approach i have to run in Glm an ANOVA 4-group unpaired and not a t-test (as it would be the case of the firts approach), is that right?
My principal question is about the design matrix. I think that I have run well the EV's (4 EV's with their respectives 1 and 0 according to their corresponding group). I didn't add any covariate.
However I am not pretty sure if i did well in the "Contrast and F-test" option:
I did 6 contrast -->
/ContrastName1 Healthy (EV3) > Disease1 (EV1)
/ContrastName2 Healthy (EV3) < Disease1 (EV1)
/ContrastName3 Healthy (EV3) >Disease2 (EV4)
/ContrastName4 Healthy (EV3) <Disease2 (EV4)
/ContrastName5 Healthy (EV3) >Disease3 (EV2)
/ContrastName6 Healthy (EV3) <Disease3 (EV2)
Matrix
EV1 EV2 EV3 EV4
-1.000000e+00 0.000000e+00 1.000000e+00 0.000000e+00
1.000000e+00 0.000000e+00 -1.000000e+00 0.000000e+00
0.000000e+00 0.000000e+00 1.000000e+00 -1.000000e+00
0.000000e+00 0.000000e+00 -1.000000e+00 1.000000e+00
0.000000e+00 -1.000000e+00 1.000000e+00 0.000000e+00
0.000000e+00 1.000000e+00 -1.000000e+00 0.000000e+00
I have not selected anything in the F-test option (i.e. F-test=0). Is that correct?
Then I saved the matrix.
Next, I have run randomise with this format:
randomise
-i all_FA_skeletonised.nii -m mean_FA_skeleton_mask.nii -o
resultados_TBSS -d matriz
.
mat
-t matriz
.c
on
-n 5000
--T2
-V
Did I follow well all procedures? I appreciate very much your help.
Bests regards,
Patricia.