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Hi Dr. Smith, Yes. These were done using fixed effects because the runs are collapsed for the same subject (from what I have read, this is the appropriate situation in which to use FE). Best, Ramy On Sun, Sep 29, 2013 at 3:42 AM, Stephen Smith <[log in to unmask]> wrote: > Hi - were you using fixed-effects at the higher level? > Cheers. > > > On 27 Sep 2013, at 20:05, ramy kirollos <[log in to unmask]> wrote: > > Hi there, > > I ran an experiment in which I had 4 runs and 4 conditions. It was the > first time I ran the experiment on a participant and had not properly > spread out all my conditions over all four runs. > > It is a pseudo-randomized blocked design in which all 4 conditions *should > * be in all 4 runs, however it happened that there was only 1 of the 4 > conditions in the fourth run, no other events happened during that run. > > From what I can tell, the lower level FEAT analysis worked out okay. > However, for a second level analysis in which I am collapsing the 4 runs, > it is giving me problems because the runs are asymmetrical. What I had to > do in the 4th run is set the absent conditions to "empty/zero" in order for > the 2nd level to run. > > I ran the gfeat and the images now show no activity for all comparisons in > which the conditions that I had set to empty in that 4th run. This is > strange since I only set them to zero in the 4th run. Has anyone had a > similar issue or know how to troubleshoot this? > > Thank you, > > Ramy > > > > --------------------------------------------------------------------------- > Stephen M. Smith, Professor of Biomedical Engineering > Associate Director, Oxford University FMRIB Centre > > FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK > +44 (0) 1865 222726 (fax 222717) > [log in to unmask] http://www.fmrib.ox.ac.uk/~steve > --------------------------------------------------------------------------- > > Stop the cultural destruction of Tibet <http://smithinks.net> > > > > >