Yes, for TBSS you probably want to use permutation simulation. BTW, why are you doing the group analysis in FreeSurfer? I think FSL offers TBSS group analysis. I'm not trying to steer you away from FreeSurfer, but it might make sense to stick with one software package.
doug
Jacobs H (NP) wrote:
Hi Doug,
Thank for you answer. Let me clarify a bit more. I want to know if there is a statistical way to define relevant clusters (instead of doing a bonferonni correction). I can imagine that cluster with a few voxels cannot be considered as statistical significant.
Heidi
-----Oorspronkelijk bericht----- Van: Douglas N Greve [mailto:greve@nmr.mgh.harvard.edu] Verzonden: 06 October 2010 20:40 Aan: Jacobs H (NP) CC: 'freesurfer@nmr.mgh.harvard.edu' Onderwerp: Re: [Freesurfer] Defining cluster threshold
Hi Heidi, I'm not sure what you are asking for. Do you want to find a p-value for the cluster you have found in your TBSS analysis? If so, you can use mri_glmfit-sim to perform a simulation (monte carlo or permutation).
doug
Jacobs H (NP) wrote:
Hi FreeSurfers,
I have done my DTI analyses (dt_recon with TBSS) and the statistical analyses in FreeSurfer. Now I have defined the clustersize with mri_volcluster, but I find this rather arbitrary. Is there a way to calculate a minimum size cluster threshold (by using for example a Monte Carlo simulation)?
Thanks! Heidi
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