Rutger, I'm assuming: input 1 is subject1 conditionA input 2 is subject1 conditionB input 3 is subject2 conditionA input 4 is subject2 conditionB etc. Your right in that you need a group mean EV for each subject. However, you need just one EV for the paired difference (EV1 = [1 -1 1 -1 1 -1]). See the Paired Two-Group Difference (Two-Sample Paired T-Test) example in the FEAT web pages for how to do this: http://www.fmrib.ox.ac.uk/fsl/feat5/detail.html#higher Cheers, Mark. Mark Woolrich. Oxford University Centre for Functional MRI of the Brain (FMRIB), John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK. Work: +44-(0)-1865-222782, Mobile: +44-(0)-7808-727745 On Thu, 22 Jan 2004, Goekoop, R. wrote: > Dear FSL-users, > > I'd like to create a single contrast between two paired 1st level > cope-images using a 2nd-level analysis: > > Input: Group: EV1 EV2 EV3 > 1 1 1 0 0 > 2 1 -1 0 0 > 3 1 0 1 0 > 4 1 0 -1 0 > 5 1 0 0 1 > 6 1 0 0 -1 > ... > > Since each EV only contains data from a single subject, would it still be > necessary to include group mean EVs, indicating which inputs belong together > (i.e. are derived from the same subject, are paired), for example: > > ...EV4 EV5 EV6... > 1 0 0 > 1 0 0 > 0 1 0 > 0 1 0 > 0 0 1 > 0 0 1 > ... > > Or would it suffice just to specify EVs1-3 (see above), > > Thanks a lot, > > Rutger Goekoop > > Drs. R. Goekoop, MD. > Department of Neurology > Vrije Universiteit Medical Centre > De Boelelaan 1117, P.O. Box 7057 > 1007 MB Amsterdam, the Netherlands > Phone: 0031-20-4440316 > E-mail: <mailto:[log in to unmask]> >