Dear SPM'ers,
I have setup a flexible factorial model with three factors:
1. subject (18 subjects per measurement) (indepency=yes variance=equal)
2. time (3 measurements) (indepency=no variance=equal)
3. condition (4 different contrasts) (indepency=no variance=equal)
I specifief all scans and added the following matrix (54*4):
1 1 1 1
1 1 1 2
1 1 1 3
1 1 1 4
1 1 2 1
...
...
1 18 3 3
1 18 3 4
For the results I am interested in:
a. whether the activation pattern at measurement 1 is the same as the activation patterns at measurements 2 and 3 for a specific condition (T1C1=T2C1=T3C1)
b. which brain areas are active for a specific condition over time (positive effect of C1 for example)
Now I have ceated two main effects (Time and Condition) and an interaction effect (time*condition).
The problem is that I can't figure out how to define the correct contrasts (e.g. contrasts weights) and I am not sure whether I used the correct main and interaction effects.
Can someone please help me?
Thanks!
Bianca
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