Dear FSL experts,
I am reposting this question with the hope of making it more clear this time.
We have 130 subjects in 4 groups (3 patient groups X,Y,Z and a control group) and we compared the GM volumes between these groups in an ANOVA design.
We were asked by a reviewer to do a 'multiple regression with a group variable (e.g. X=4, Y=3, Z=2, Controls=1)' and, 'an independent estimation of group variables' to examine the continuum of GM abnormalities in this sample.
I was planning to give 4 for group X, 3 for Y, 2 for Z and 1 for controls, and demean these values and enter in EV1.
Assuming that we have 3 patients in each group the model would look like this:
Groups Ev1 Ev2
4 1 1.5
4 1 1,5
4 1 1,5
3 1 0,5
3 1 0,5
3 1 0,5
2 1 -0,5
2 1 -0,5
2 1 -0,5
1 1 -1,5
1 1 -1,5
1 1 -1,5
(I am not sure if I actually need EV1)
Contrast A: [ 0 1 ] for the areas with the GM volume increasing as we go from group x to controls (4 to 1)
Contrast B: [ 0 -1] for the areas with the GM volume increasing as we go from controls to group x (1 to 4)
Do think this is correct ?
If not what are your suggestions ?
Thank you very much
Cagri Yuksel
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