The 4 groups I'm testing are: CU cortisol low; CU cortisol high; CI cortisol low; CI cortisol high.

So if I found a significant cluster for this contrast, can I interpret that the cortical thickness of this region of the cluster is affected by both the diagnosis and cortisol levels?

In this case I made the correction of multiple comparisons with positive direction. That means that the worse the diagnosis and the cortisol levels (CI cortisol high) the more the cortical thickness of this region of the cluster will be affected, or to draw this conclusion would I need the results of the other contrasts as well?

No, that was only for interactions between the covariates and the groups

On 2/17/2022 10:05 AM, Laura Willers de Souza wrote:

External Email - Use Caution

Hello FreeSurfer Developers,

I am performing a GLM analysis to assess cortical thickness between 4 groups, without any covariates. I followed exactly what is on the wiki MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be https://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf4G0V

In a previous analysis (MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be https://www.mail-archive.com/freesurfer@nmr.mgh.harvard.edu/msg71673.html), Dr Douglas had told me that before any analysis I should test whether the interaction is significant or not.

I would like to know if this also applies to this case, the interaction being tested by contrast number 7 of the wiki.

Thanks in advance!

Best,

Laura Willers de Souza

Master Student in Biochemistry

Zimmer Lab - Federal University of Rio Grande do Sul

- Porto Alegre/RS - Brazil
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