Sure! We have been conducting analyses in a large sample of pairs of siblings to see the effect of prenatal exposures on cortical thickness. For the current analysis, we're looking at the effect of the exposure load (total # of exposures) on cortical thickness using a paired-difference model, so the covariant being used is the difference in exposure load between each pair. We're trying to figure out if it is possible to also covary for the family the siblings belong to (using the assigned Family ID), to see the effect of family on cortical thickness as well as exposure load. This was able to be done statistically, however we weren't sure if it could be done in Freesurfer, too. 

My apologies if this is still unclear - please let me know if you have any further questions. Thank you!

Best,
Casey

--


Casey Hopkinson

Clinical Research Coordinator
Brain Genomics Laboratory
Division of Psychiatric Neuroimaging
Massachusetts General Hospital
149 13th Street, Charlestown, MA, 02129
(p) 617.643.3215

From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Greve, Douglas N.,Ph.D. <DGREVE@mgh.harvard.edu>
Sent: Monday, August 19, 2019 6:29 PM
To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
Subject: Re: [Freesurfer] Help with using family as random effect in sibling study
 
I'm not sure I understand. Can you elaborate?

On 8/19/19 2:43 PM, Hopkinson, Casey E wrote:
> Hello!
>
> I am trying to generate significance maps for a paired-difference
> analysis of cortical thickness using multiple pairs of siblings, and
> was wondering if there is a way to incorporate the family ID as a
> random effect/covariate in Freesurfer. Is it possible for the family
> ID for each sibling pair to be used as a categorical/discrete variable
> to then see the effect of family on cortical thickness in addition to
> the main effects we are looking at? Any guidance would be greatly
> appreciated!
>
> Best,
> Casey
>
> *--*
>
> *
> *
>
> *Casey Hopkinson*
>
> Clinical Research Coordinator
> Brain Genomics Laboratory
> Division of Psychiatric Neuroimaging
> Massachusetts General Hospital
> 149 13th Street, Charlestown, MA, 02129
> (p) 617.643.3215
>
>
> _______________________________________________
> Freesurfer mailing list
> Freesurfer@nmr.mgh.harvard.edu
> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer


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