> Ok, I emailed the report and ls -lR. Here is a possible issue:
> It's possible that since avwmerge is trying to merge together 102
> masks/copes/etc. that it runs out of memory and fails to produce the merged
Yes, that seems very likely as your input files seem fine. How much
RAM/SWAP do you have?
> If I created a gfeat for each subject that merged the 3 runs together, and
> then ran a gfeat for every contrast (using the copes from the individual
> subject gfeat), would this be statistically valid?
Yes, this is fine. You would very slightly lose some variance modelling
power by separating the levels in this way, but because you have so many
subjects the difference is probably very tiny, so this should be fine.
Note - you won't expect to see any activation for the 3-run individual
subjects analyses as this is mixed effects.
However, this may not be necessary if you have enough RAM/swap on your
Stephen M. Smith DPhil
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve