Dear Ana,
column 1/2 represent time points 1/2 for group 1 and columns 3/4 are linked to time points 1/2 for the 2nd group. Here are some examples for potential contrasts:
1 -1 0 0 time point 1 > 2 for group 1
0 0 1 -1 time point 1 > 2 for group 2
1 -1 -1 1 time point 1 > 2 & group 1 > 2 (interaction between time and group)
Best regards,
Christian
On Thu, 16 Apr 2015 19:22:12 +0100, Ana Carolina Coan <[log in to unmask]> wrote:
>Dear all,
>
>I am looking for some help to build the contrast map of a longitudinal VBM analysis. I have 2 groups of individuals (patients and controls) with 2 time points MRIs. My question is if patients have more atrophy than controls comparing the first and the second MRI. I am using VBM8 and I followed the steps of VBM8 toolbox manual for longitudinal analysis. This resulted in the matrix attached.
>Now I am not sure how to use the contrasts.
>
>Thanks, Ana Carolina
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