Hi Rosie

It really depends on what your hypotheses are, but if you are covarying for age and gender in thickness you probably want to do so in an analysis of volume as well. The only real difference are (1) thickness doesn’t really need TBV covariation, and (2) thickness is a more localizable quantity than volume. Of course they are different neurobiologically as well, but from an analysis standpoint those are the two big differences

Bruce

From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> On Behalf Of Rosalia Dacosta Aguayo
Sent: Sunday, November 21, 2021 1:42 PM
To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edu>
Subject: [Freesurfer] Basic question

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Dear Freesurfer team,

I know this is a basic question, but I would like to be sure before proceeding. Are those statements below right?

For cortical thickness, I should covariate for age and sex

For volume, I should covariate only for TBV

Thank you for your time and your patience.

Best wishes,

Rosie