Dear SPM-users,
I have some questions regarding a flexible factorial design with 3 groups:
1. How to set up correctly a F-contrast for Group(3) x Time (2)? In the cat12 manual I found examples for 2 groups, but I am not sure about 3 groups. Is the following correct?
[ 1 -1 -1 1 0 0
0 0 1 -1 -1 1
-1 1 0 0 1 -1 ]
2. Is there a possibility (or necessity) to control for different scanner sites? The scanner for each subject is the same across time points, so it should not be necessary like sex covariates in flexible factorial designs, correct?
3. How to deal/control for a hardware change for (some) subjects between both time points? Could we use a covariate of no interest here in some way?
best,
Hannah & Dominik
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