Dear AFNI experts,
I completed a gPPI analysis following the step-by-step tutorial on AFNI website (https://afni.nimh.nih.gov/CD-CorrAna) and I have one question.
After the deconvolution and the t-test between my two conditions (threat and safe), I want to get the beta values for the two conditions for each subject to look at the relationship between functional connectivity and some self report measures. Based on the literature, I assume it’s safe to perform a simple subtraction between the betas (threat minus safe) to use in relationship with self reports.
However, looking at the beta values across subjects, the scale seems pretty large. Am I supposed to standardize these values? is it sufficient (and correct) to z score the betas for each condition before doing the subtraction?
I found a previous post on the message board (https://afni.nimh.nih.gov/afni/community/board/read.php?1,72915,72920), but I’m still not sure about how to proceed.