Hi Harry
As Martin said, longitudinal linear mixed-effects models (lme) are the recommended tool for analyzing longitudinal data obtained from the Freesurfer longitudinal image processing pipeline. The increase in power can be dramatic. Coming up there is a paper about this subject. We are working on making our lme tools available and easy to use but in the mean time, if you are interested, I can make available a link for you to download our Matlab-based lme toolbox.
Best -Jorge
De: Martin Reuter mreuter@nmr.mgh.harvard.edu Para: Harry Hallock hhal5293@uni.sydney.edu.au; Douglas N Greve greve@nmr.mgh.harvard.edu; "freesurfer@nmr.mgh.harvard.edu" freesurfer@nmr.mgh.harvard.edu Enviado: Domingo 14 de octubre de 2012 21:06 Asunto: Re: [Freesurfer] 3 Factor glm group analysis
Hi Harry.
I have some scripts to compute a slope into the time thickness or volume (linear fits) and then run a standard glm on that .
However, we recommend to run a linear mixed effects model (external software). We are working on making that available.
Best Martin
Harry Hallock hhal5293@uni.sydney.edu.au wrote: Thanks Doug!
If i wanted to add a third time-point, what would u suggest would be a good method to use for time x group interaction?
Harry
From: freesurfer-bounces@nmr.mgh.harvard.edu [freesurfer-bounces@nmr.mgh.harvard.edu] on behalf of Douglas N Greve [greve@nmr.mgh.harvard.edu] Sent: Wednesday, 10 October 2012 1:10 AM To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] 3 Factor glm group analysis
Hi Harry, I would do a time1-time2 subtraction (fscalc) and then do a 2 group analysis (search for "paired" on our wiki). doug
On 10/09/2012 12:45 AM, hhal5293@uni.sydney.edu.au wrote:
Hello,
We are currently doing a longitudinal Group Analysis using
FreeSurfer,
and were wondering if there is a way to run a 3 factor design (time is 2 levels, group is 2 levels, subject is 10 levels) using the mri_glmfit model, as i want to test the time by group interaction? Is there a way of writing this model in an FSDG file? If we can't do this using mri_glmfit, is it possible to do this using QDEC?
Regards, Harry
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