Don, thanks for your reply.
Yes, my paradigm does have a third task C. Why would this third task knock out Option 1 as a possible method?
I was concerned about Option 2 because the "variance shared between your regressors A*phys and B*phys will NOT be captured by either regressor".
I misspoke when I used the term 'correlation'. What I meant was that I would run a regression/correlation to get the slope of the best-fit line.
For didactic reasons, let's assume I use Option 1 after all. Do I understand you correctly when I conclude that, yes, I can plot activity of Region 1 v activity of Region 2 and look at the slope of the best-fit line. If this single slope is statistically significantly different from zero, then I can conclude that there is a PPI effect?
Thanks for your insight. I greatly appreciate it.
Best,
- BettyAnn
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