Dear Armin,
as you have discovered, a paired t-test with just one pair will fail. If
you want to see the differences between two sessions for a single
subject, you can just subtract the con-images using e.g. ImCalc.
However, this doesn't give you any statistics. Alternatively, you could
analyse both sessions in a fixed effects model as separate sessions.
Hope this helps,
Volkmar
Am Freitag, den 04.07.2008, 15:16 +0100 schrieb Armin Blickenstorfer:
> Dear community,
>
> I'm trying to run a paired t-test on a single subject level. The subjects
> participated in 2 different days in the same experiment.
> So far, I've run for each day an fMRI model specification in which I've
> defined the single t-contrast of FES (functional electrical stimulation) vs.
> rest resulting in a con_0001 file.
> Then I've tried to calculate the paired t-statistics (see attached image) in
> that I've selected both con_0001 images out of the relevant folders
> (session1 & session2).
> Furthermore following options were chosen:
> - Independence: No
> - Variance: equal
>
> After running the estimation I get follwing error message:
>
> Please check your data: There are no significant voxels.
>
> The single con_0001 images look fine and different from each other. How can
> I subtract one from the other?
>
> Thank you for your help
>
> Armin Blickenstorfer
> PhD student
> University Hospital Zurich
> Institute of Neuroradiology
--
Volkmar Glauche
-
Department of Neurology [log in to unmask]
Universitaetsklinikum Freiburg Phone 49(0)761-270-5331
Breisacher Str. 64 Fax 49(0)761-270-5416
79106 Freiburg http://fbi.uniklinik-freiburg.de/
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