oh, yes, that is correct for DOSS

On 4/26/2022 3:38 PM, Laura Willers de Souza wrote:

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Ok.
In this case I used the DOSS model (I tested the interaction before and it was not significant). So wouldn't the two groups have the same slope?
But the beta values extraction file has only 3 lines (image below).


To extract the beta values I used this command:
mri_segstats --seg lh.CU_CI_CSF_doss.glmdir/cortisol.diff/perm.th20.neg.sig.ocn.mgh --i lh.CU_CI_CSF_doss.glmdir/beta.mgh --excludeid 0 --avgwf lh.CU_CI_CSF.cortisol.beta.clusters.dat

Thank you so much,
Laura.

De: Douglas N. Greve <dgreve@mgh.harvard.edu>
Enviado: terça-feira, 26 de abril de 2022 15:01
Para: Laura Willers de Souza <laura.w.desouza@hotmail.com>
Cc: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
Assunto: Re: [Freesurfer] Beta values (resubmitting)
 
3rd line for the slope of CU, 4th line for the slope of CI

On 4/25/2022 4:03 PM, Laura Willers de Souza wrote:

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Thanks so much!

 

I would also like to confirm that I am interpreting the beta values correctly for a second model.

 

Model 2: Two Groups, One Covariate

Contrasts (DOSS): difference between the group intercepts; covariate effect.



The fsgd file looks like this:

GroupDescriptorFile 1

Title CU_CI_CSF
MeasurementName thickness
Class CU
Class CI
Variables cortisolCSF
Input 011_S_0003_S9128 CI 2.397895273
Input 022_S_0004_S9233 CI 2.772588722
Input 011_S_0005_S9137 CU 3.044522438
Input 011_S_0008_S9196 CU 2.397895273
Input 011_S_0010_S8800 CI 2.151762203 

... (n=300)


The file with the beta values contains 3 lines (image below).

  • The first line would be the beta value for the intercept of the 1st group; the second line for the intercept of the 2nd group; and the third line for the slope of the covariate?
    • Thus the glm equation for the 1st cluster would be:
    • 1st group ---- cortical thickness = 2.64 - 0.12X + n
    • 2nd group --- cortical thickness = 2.54 – 0.12X + n

 

Am I interpreting correctly?

 

Thank you very much for all the help!


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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