External Email - Use Caution Hi Carly,
plus, if I may answer in addition, make sure that the ICV differences are checked with sex as covariate, so that statement of yours is only valid, if analyzed also per sex separately, or with sex as covariate. Next, you should also (once) test for ICV-by-Dgx effects, as you cannot know in advance, if the relationship between ICV and local measures is the same. Best, Philipp Sämann ________________________________ Von: freesurfer-boun...@nmr.mgh.harvard.edu <freesurfer-boun...@nmr.mgh.harvard.edu> im Auftrag von Iglesias Gonzalez, Juan E. <jiglesiasgonza...@mgh.harvard.edu> Gesendet: Montag, 8. Juli 2024 19:39 An: Freesurfer support list Betreff: Re: [Freesurfer] Is ICV needed as a covariate if matched between groups It’s always a good idea to divide the volumes by ICV (or add ICV as a regressor). This is very unlikely, but what if your controls happened to have smaller heads than your patients? For peace of mind, I’d correct by ICV. Cheers, /Eugenio -- Juan Eugenio Iglesias http://www.jeiglesias.com From: freesurfer-boun...@nmr.mgh.harvard.edu <freesurfer-boun...@nmr.mgh.harvard.edu> on behalf of Carly McIntyre-Wood <mcint...@mcmaster.ca> Date: Monday, July 8, 2024 at 12:06 PM To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu> Subject: [Freesurfer] Is ICV needed as a covariate if matched between groups External Email - Use Caution Hi there, I am investigating differences in hipp/amyg volume between a patient and HC sample and am wondering if there is any reason I would still need to include ICV as a covariate if the groups do not differ on ICV (p=.793). Thanks so much, Carly
_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Mass General Brigham Compliance HelpLine at https://www.massgeneralbrigham.org/complianceline <https://www.massgeneralbrigham.org/complianceline> . Please note that this e-mail is not secure (encrypted). If you do not wish to continue communication over unencrypted e-mail, please notify the sender of this message immediately. Continuing to send or respond to e-mail after receiving this message means you understand and accept this risk and wish to continue to communicate over unencrypted e-mail.
