Hi Brunno,
> I am trying to definitely understand the RFT that is applied on FWE
> correction.
Good luck :)
> The data smoothness is calculated from intrinsic characteristics of the
> data right? So far, the extend threshold do not affects the statistical
> threshold but just suppress result information. Is it right?
The aim of FWE is to control for the effect of multiple comparisons. To
this effect, you could simply divide by the number of tests (Bonferroni)
which, however, usually is too strict for neuroimaging data as
neighboring voxels are not really independent of each other. Hence, one
tries to find the effective number of independent tests, ultimately
coming up with the Euler characteristics of the image. This can then be
used to derive the correction for multiple comparisons.
There is a more theoretical description here
(http://www.fil.ion.ucl.ac.uk/spm/doc/books/hbf2/pdfs/Ch14.pdf) and a
more illustrative talk here
(http://www.poirrier.be/~jean-etienne/presentations/rft/spm-rft-slides-poirrier06.pdf).
Hope this helps,
Marko
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
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http://www.medizin.uni-tuebingen.de/kinder/epn/
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