AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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ns
October 05, 2019 12:36AM
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.

thank,
ns
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PPI- standardize beta values?

ns October 05, 2019 12:36AM