Dear Serge,
If you use a 'subject-separable' design matrix (ie. you include a mean
response for each subject) then for the multi-subject fixed effects
analysis (method 2) the estimates of the regression
parameters, and therefore the contrasts, will be identical to those
obtained using method 1.
So the two approaches will give you identical results.
If you have
lots of memory on your computer then method 2 may be better in terms
of you having to do less key-strokes.
All the best,
Will.
Serge RUFF wrote:
> Dear SPMers and staff, I wonder what is better for a random effect
> analysis : 1. To use con*.img images from each single-subject analysis
> (little SPM.mat easuy to load) or 2. To use con*.img images from
> single-subject contrasts of a global multi-subjects analysis (big
> SPM.mat not so easy to load...) Thanks a lot Serge RUFFINSERM U455
--
William D. Penny
Wellcome Department of Cognitive Neurology
University College London
12 Queen Square
London WC1N 3BG
Tel: 020 7833 7478
FAX: 020 7813 1420
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URL: http://www.fil.ion.ucl.ac.uk/~wpenny/
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