Dear SPMers
I have a few questions about some PPI-type analyses where the psychological
variable is group (patient vs. control). For preliminary analyses, I'm
interested in how the correlation between activity in region X and the rest
of the brain changes as a function of group. I intend to this by extracting
time series Y from various a priori-defined VOIs, entering them as
user-specified regressors into new subject-specific models, and then
performing 2-sample t tests on the contrast images resulting from these
regressor analyses.
My questions:
1) Is this a valid approach?
2) Do I need to mean correct my extracted Y time series before including as
regressors in new subject-specific model?
3) Do I need to include all original conditions (e.g. corresponding to main
effects of task) or just the Y time series regressor in the new analyses?
4) If I have extracted Y data from more than one VOI, should I examine each
associated regressor in separate subject-specific models, or can I analyze
all regressors together in 1 model per subject?
Any help would be greatly appreciated.
Many thanks.
Chloe
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