Hi Reut,
I think this is simply because you've got a small sample of 8 subjects and, depending on which contrast you're looking at, the number of permutations required for exhaustive test are different.
I'm not sure though how 840 permutations are exhaustive for correlations in 8 subjects (cf end of randomise manual for counting the number of permutations). Matt, Tom, how is this calculated if not n! ?
Hope this helps,
Gwenaelle
> Hi
> I have been trying to run tbss randomise (for correlation
> between a group of 8 subject's DTI data and their
> behavioral scores) for some reason the TBSS stops after 840
> permutation on a certain t -test (I have no idea which one
> but it looks like it's the same one every time) the stats
> directory then contains all the required tbss files
> but i don't know if it means anything. the same thing
> happened for the same Glm with deifferent dffusion devices
> (FA and L23) however it didn't haqppen when i run the
> randomise with a different Glm containing different test
> scores of the same 8 subjects
>
> what can be the reason and how can i fix it?
>
> attached is the Glm used when the permutaions stopped in
> case it is the problem.
> thanks
> reut
--------------------------------------------------------------------
Gwenaëlle Douaud, PhD
FMRIB Centre, University of Oxford
John Radcliffe Hospital, Headington OX3 9DU Oxford UK
Tel: +44 (0) 1865 222 523 Fax: +44 (0) 1865 222 717
www.fmrib.ox.ac.uk/~douaud
--------------------------------------------------------------------
|