 |
 |
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. -------------------- 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) [log in to unmask] http://www.fmrib.ox.ac.uk/~steve ---------------------- 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 >