Dear SPM users,
I have a design with one event of interest and two orthogonalized parametric modulators (A and B).
Orthogonalization is required given the collinearity between A and B.
If I want to evaluate whole-brain functional connectivity with a specific VOI as a function of B, would it make sense to perform PPI with the VOI and the second, orthogonalized B modulator?
Best,
David
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