Hi, I have a question regarding a specific set of contrasts I'd like
run. Essentially I have three factors (Subject (22 total), Region (3
levels), Side (2 levels). I'd like to set up the following contrasts
in SPM:
1. (F) Main effect of region: zeros (1,22) -1 0 1 0 0 -.5 0 .5 -.5 0 .5
2. (F) Main effect of side: zeros (1,22) 0 0 0 1 -1 ? ? ? ? ? ?
3. (F) Interaction of region by side: zeros (1,22) ? ? ? ? ? ? ? ? ? ? ?
4. (T) Region 1 - (Region 2, 3): zeros (1,22) ? ? ? ? ? ? ? ? ? ? ?
5. (T) Region 2 - (Region 1, 3): zeros (1,22) ? ? ? ? ? ? ? ? ? ? ?
6. (T) Region 3 - (Region 1, 2): zeros (1,22) ? ? ? ? ? ? ? ? ? ? ?
7. (T) Side Right - Side Left: zeros (1,22) 0 0 0 1 -1 ? ? ? ? ? ?
8. (T) Side Right - Side Left: zeros (1,22) 0 0 0 -1 1 ? ? ? ? ? ?
I'm most confused about numbers 4, 5, 6 (how to contrast one Region
against the other two) and also how to represent the interaction
terms. I would greatly appreciate any assistance with this setup.
Thanks for your time,
Sincerely,
Lucina Uddin
Lucina Q. Uddin, Ph.D.
Stanford University
780 Welch Road, Rm 201
Stanford, CA 94304
(650) 721-6136
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