> Dear Manja,
>
> It is statistically valid for the threshold suggested by
> FDR to vary in
> the different hemispheres. The reason is that FDR defines a
> proportion,
> not an absolute. The FDR procedure suggests a p-value
> threshold with the
> property that of all positive results at that threshold,
> one can expect
> that no more than X percent are false positives (where X is
> the desired
> FDR rate). It is very possible that the threshold with this
> property would
> be different in the right compared to the left hemisphere.
>
> More informally, one is claiming that of all results
> declared
> "significant", X% are probably B.S. Since X is
> presumably small and the
> number of results large enough to be interesting, one can
> safely conclude
> that the experimental condition explains cortical variation
> at (most of)
> the locations indicated. Now divide the brain into
> subregions (perhaps
> right and left hemisphere, or perhaps something else) in
> each of which X%
> of the significant results are probably false. Then the
> claim that "X% of
> the overall results are probably false" is valid.
>
>
> +glenn
>
> ------------------------------------
> Here miracles become marvels, and
> marvels recurring wonders.
> -- William Beebe
>
> Dr. Glenn Lawyer
> +352 661 967 244
> Instituttgruppe for psykiatri
> Seksjon Vinderen
> PB 85 Vinderen
> 0319 Oslo
>
http://folk.uio.no/davidgl>
>
> _______________________________________________
> Freesurfer mailing list
>
Freesurfer@nmr.mgh.harvard.edu
>
https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer