Dear Philipp,
how would you compute whole brain volume in this case?
Best,
-Lucas
> Hi,
>
> it seems some intermediate checks should be made on this data set, that may
> include:
> - import/first segmentaton successful (orientation etc.)
> - template generations 1 to 6 looking okay?
> - all individual results of warpings looking okay in terms of position?
>
> The initial threshold (analysis threshold) does not affect multiple test
> procedures per se, but it of
> course have an influence on the mass of voxels analysed. The mask should be
> checked; if the mask.img is
> plausible, i. e. covering the areas you want to test, then still a result
> in which "all is showing up"
> is not convinving.
>
> You then state "FWE corrected at p>0.0001" -
> If that indeed is the corrected threshold then in a VBM analysis in 99.5%
> of cases NOTHING should show up;
> also a VBM analysis that is robust to FWEcorr<0.05 is a generally a very
> strong result, so it is quite
> sure that something in the pipeline has gone wrong.
>
> If data are modulated, whole brain / skull size effects are contained, of
> course. Think of using appropriate
> covariates to correct for that. Other covariates such as age and gender
> might depend on specific features
> of your study and question.
>
> Hope this helps,
> Philipp
>
> Max Planck Institute of Psychiatry
> NMR Research Group
> Kraepelinstr. 2-10
> 80804 Munich
> Mail: [log in to unmask]
> Phone: 0049-89-30622-413
>
>
>
--
Lucas Eggert, M.Sc.
University of Osnabrück
Institute of Cognitive Science
Phone Office +49 (0)541 969 4428
Room 15/308
http://www.cogsci.uni-osnabrueck.de/~leggert/
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D-49074 Osnabrück
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