External Email - Use Caution        

Just to double check the numbers - I seem to have been getting into an error in how many columns in the FSGD it is expecting. 

I have 9 different sites, 4 different patient groups, and M/F -> 72 classes. 

I also am covarying for four different factors, so the contrast matrix I am making is 72*(4+1) long. Since I want to regress out the four factors completely, only the first 72 numbers in 360 contrast matters. My FSGD file has 4 columns e.g like 

Input GP0001 NCBostonM 60 12000 -0.01 -0.02 

It says ERROR: gdfReadV1: Input line 1, subjid = GP0001 

Found 4 variables, expected. 10 

Where is this 10 coming from? 

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From: Zeng,Victor (BIDMC - Keshavan - Psychiatry) <vzeng@bidmc.harvard.edu>
Sent: Monday, February 21, 2022 5:50:46 PM
To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
Subject: Re: [External] Re: [Freesurfer] classes for GLM analysis

 

Do you have a Freesurfer page I can read up on those hybrid ways just to see whether that could be an option? 

Also, although its a binary, you would recommend against have sex be a continuous measurement like age, due to the design of how the contrasts are determined? I.e continuous measurements aren't treated like integers 

Victor Zeng

Beth Israel Deaconess Medical Center

Keshavan Lab

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From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Douglas N. Greve <dgreve@mgh.harvard.edu>
Sent: Sunday, February 13, 2022 12:24 PM
To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
Subject: [External] Re: [Freesurfer] classes for GLM analysis

 

It is probably not going to work very well if you have some classes that only have one member. You can eliminate members of classes that only have a few members. If you really need to have those cases, there are hybrid ways to analyze the data (but you can't use an FSGD at that point)

On 2/6/2022 10:41 PM, Zeng, Victor (BIDMC - Keshavan - Psychiatry) wrote:

        External Email - Use Caution        

Hi all,

I am doing an analysis and generating the FSGD. I understand sex and race are classes in this context, but something I was also hoping to regress out is the effects of scanner/sequences. We have a large participant size, so we have around 10+ scanner/sequences, which makes for a large amount of classes combinations, with some having just 1 (if not zero) fitting into a class. 

Would you proceed with this nonetheless? If not, should scanner/sequence be something that we consider? Should we find some other way to adjust site (I don't think we can z-score...). Or can we consider site/scanner as a continuous variable

Victor Zeng

Beth Israel Deaconess Medical Center

Keshavan Lab

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