Hello,
We are trying to analyze a study in which people receive blocks of heat pain alternating with no pain. Subjects rate their pain every TR. If we want to use pain rating as a covariate at each TR at the subject-level FEAT, is it necessary to demean the ratings by each subject's individual mean? The other option is to look at each pain block, and use the average rating at each block. If we chose to analyze the run by block, then do we demean these averages?
Also, after we run the subject-level analysis, we are interested in looking at differences between two groups. At the group level analysis, would you recommend using the average rating per subject for the entire run as a covariate? If we already account for these ratings in the individual subject analysis, is it necessary to put these into the group analysis?
Thank you,
Jodi
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