Hi Aga, your commands look right. For the DOF, it should be the sum of 
the DOFs from all the runs (probably won't make much of a difference). 
Smoothing is a bit of an issue when you want to look at individual 
results. Technically, you should smooth before you do the first level 
analysis (ie, before your compute the varcope), but this would require 
doing the FEAT analysis directly on surface data. Smoothing after 
computing the varcope means that the varcope will not be accurate (it 
will be too large). The penalty is that you will see less activation 
than you should. At the group level, this is not such a big deal because 
you're either not using the varcope or you are using it as a weight.
doug

Agnieszka Burzynska wrote:
> Dear all,
> I am combining 3 runs of a subject using fixed effects GLM and I wanted to
> make sure I am doing the right thing.
>
> For each subject I use:
> mri_glmfit --y 3runs/lh.cope1.mgh --yffxvar 3runs/lh.varcope1.mgh --ffxdof
> 126 --osgm --glmdir 3runs/lh.osgm.ffx --surf fsaverage lh --label
> $SUBJECTS_DIR/fsaverage/label/lh.cortex.label --fwhm 5
>
> , while lh.cope1.mgh contains the concatenated cope1 images of the same
> subject in fsaverage space (the same for varcope1).
>
> 1) Is it the right way?
> 2) I took DOF from subjectX.feat/stats/dof of one of the runs. Is it
> correct?
> 3) The functional data has not been smoothed in the 1st level analysis in
> FSL (as recommended), and also not smoothed during sampling the copes to a
> common space. Therefore I want to smooth it here for the first time, but
> only with 5mm. Does it sound right?
>
> Cheers,
> Aga
>
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>
>
>   

-- 
Douglas N. Greve, Ph.D.
MGH-NMR Center
gr...@nmr.mgh.harvard.edu
Phone Number: 617-724-2358 
Fax: 617-726-7422

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