Dear Fiona,
> I have been creating group comparisons with fMRI data. I am using basic
> models, no grand mean scaling, no masking of images, and no global
> calculation. The group analyses contain about 12 subjects. I have
> noticed that if I set the threshold at corrected 0.05 I get almost an
> entire brain of activation, which doesn't reflect any of the individual
> subject data. If I set the threshold at uncorrected 0.001 I get very
> small amounts of activation more in line with the individual subject
> data. Why would this be happening???
It may be because you not entered the correct data into the second
level analysis. If you restrict your 'basic design' analysis to
con???.img from a first-level, with one contrast image per subject,
then things should behave sensibly.
I hope this helps - Karl
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