Yes, first line intercept, 2nd line slope

On 4/12/2022 3:44 PM, Laura Willers de Souza wrote:

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Hey! I'm resending this email because I think it got lost on the list.

Hello FreeSurfer Developers,
 

I'm extracting beta values ​​from some analyzes and I would like to know if I'm extracting and interpreting these values ​​correctly.

 
To extract the beta values ​​I used this command:

mri_segstats --seg lh.cortisol_CSF.glmdir/cortisol_CSF_slope/perm.th20.neg.sig.ocn.mgh --i lh.cortisol_CSF.glmdir/beta.mgh --excludeid 0 --avgwf lh.cortisol_CSF.beta.clusters.dat

 
The model consists of 1 group and 1 covariate.
I used the contrasts for intercept and slope.
The fsgd file looks like this:
 
GroupDescriptorFile 1                 
Title cortisol_CSF                    
Class Main                     
Variables      cortisol_CSF           
Input   011_S_0003_S9128       Main    2.397895273
Input   022_S_0004_S9233       Main    2.772588722
Input   011_S_0005_S9137       Main    3.044522438
Input   011_S_0008_S9196       Main    2.397895273
Input   011_S_0010_S8800       Main    2.151762203
... (n=300)
The beta values ​​extraction file contains 2 lines (image below).

  •  Would the first line be the beta value for the intercept and the second line for the slope?
  • Thus the glm equation for the 1st cluster would be: cortical thickness = 2.57 - 0.12X + n
Is this correct?

Thank you very much in advance.

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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