Hi
I'm afraid what you're doing doesn't make sense- copes are (contrasts between) regression coefficients not correlation coefficients.
Also, if you are using one of the non-ols group-level options the varcope is used to feed into the higher level calculations, so you need to leave the cope as it is.
Cheers.
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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director, Oxford University FMRIB Centre
FMRIB, JR Hospital, Headington,
Oxford. OX3 9 DU, UK
+44 (0) 1865 222726 (fax 222717)
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http://www.fmrib.ox.ac.uk/~steve
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On 29 Sep 2011, at 22:30, Aaron Kucyi <[log in to unmask]> wrote:
> Hi there,
>
> I ran a first-level resting state fMRI seed-based correlation analysis for a group of subjects using FEAT, and I obtained individual-level correlation maps. If I feed my COPE files into a higher-level group analysis using FLAME, I obtain nice zstat images that look like canonical resting state networks. However, I also tried taking my first-level COPEs and performing Fisher's r-to-z transform on these files before feeding them into a higher-level FEAT (with the intent of ensuring that the correlations are normally distributed). If I do this and select "inputs are 3D cope images" and Mixed Effects Simple OLS, my resulting COPE images are not in correlation units and the zstat images are blank.
>
> So I have the following questions:
> a) Am I running the higher-level FEAT on Fisher's transformed cope files correctly?
> b) If so (a), is there a way to convert the higher-level stats output files (cope, tstat, zstat) into correlation units?
> c) If so (b), would I expect to see zstat images that are similar to the ones I had obtained with FLAME (without Fisher's transform)?
>
> Thank you
>
> Kind regards,
>
> Aaron
>
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