Hi Laura,
the issue you are facing is not necessarily the size of your control
population but the fact that you do not have variance in one of your
"groups" (as n=1). Consequently, there are strong reservations against
doing it this way. However, the need you see of course is there, and
some groups have tried circumventing direct comparisons by creating
z-score maps of "the usual" activation pattern (see Mbwana et al.,
2009). Also, VBM faces similar issues and a recent paper by Mühlau et
al., 2009 includes some discussions on this issue. Perhaps this gives
you some pointers on where to begin.
Cheers,
Marko
Laura Bled wrote:
>
> Dear experts
>
> We are trying to find out what would be the most appropriate nr of
> control subjects for our clinical fMRI experiment. We want to compare
> single patients data to controls (a semantic task experiment). There are
> 3 runs, block design. In already acquired data the activation per
> subject, in controls or in patients is quite large. Is it appropriate to
> compare 12 controls and 1 patients (a t-test) ?
> I checked Rik Henson syntax on single case, but it's not quit the
> response i was looking
> for http://www.mrc-cbu.cam.ac.uk/people/rik.henson/personal/Henson_Singlecase_06.pdf
>
> Would be very grateful for any suggestions
>
> Laura
>
--
____________________________________________________
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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