SPMers -
I'll describe my 2nd-level design matrix. I have 15 subjects and I'm bringing up their first level (TaskA - Baseline) contrast images to a one-sample T test. I also have a behavioral test score (collected out of the magnet) for these 15 subjects (we can call it TEST). I've set the covariate (TEST) to have an interaction with the first factor (TaskA - Baseline). Given the first column in the design matrix is the contrast images and the second is my covariate, for the following T contrast vectors I would love input on whether 1) is it valid, and 2) how one would interpret the results.
[1 0]
[0 1]
[.5 .5]
[1 -1]
[-1 1]
Thank you for any and all help you can provide.
Scott Burns
Neuroimaging Analyst
Education and Brain Sciences Research Lab
Kennedy Center
Vanderbilt University
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