Hello all,
I have a question regarding the best way to obtain the group interaction
contrast for a 3x2 within subject design. The basic setup is that each
subject has 4 runs in which the same 8 conditions are present (3 factors
each at 2 levels). Since I'm only interested in these within subject
effect, I was thinking it might be easiest to boil down each interaction
to one image per subject so I can run a one sample t-test at the group
level. Just wanted to make sure this would be a valid way to do it:
At the second level for each subject, input the 8 condition vs. baseline
copes for each run. Set up a design matrix similar to the 3x2 ANOVA
example on the FEAT website in order to get the subject-specific
interaction contrasts. Then merge the resulting fstat images (for a
given interaction contrast) for each subject into a single 4d image and
run a one-sample t-test in randomise.
Does that sound ok?
Thanks so much for the help,
Jeremy
--
Jeremy A. Elman
Department of Psychology
University of California, Berkeley
Room 3210, Tolman Hall #1650
Berkeley, CA 94720-1650
510-643-5371 (phone)
510-642-5293 (fax)
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