Dear Charles,
|I performed two SPM analyses on a study first using SPM's global
|normalization and then using a data set I normalized outside of SPM. I
|set up about 30 contrasts on the first analysis and I would like to use
|those same contrasts on the second analysis. Will I have any problems if
|I just copy the old xCon.mat to the new analysis and then look at the
|results using the results gui?
As far as I know, there should be no problems (at least, I have done this
so if there are any problems I need to know about them!). Two caveats -
the design matrices of course should be the same, and the second
analysis xCon.mat should be replaced with the first analysis xCon.mat
before any contrasts have been entered and contrast images generated with
the second analysis xCon.mat.
When you select a contrast from the new analysis using the replacement
xCon.mat, SPM will still need to calculate the new contrast image
appropriate for this contrast on the new data, so the time saving will
just be in entering the contrasts rather than calculating them.
best wishes,
Geraint
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Dr. Geraint Rees
Wellcome Advanced Fellow Lecturer
California Institute of Technology Institute of Neurology
Division of Biology 139-74 University College London
Pasadena 12 Queen Square
California 91125 London WC1N 3BG
voice (626) 395-2880 voice (171) 833-7472
fax (626) 796-8876 fax (171) 813-1420
http://www.klab.caltech.edu/~geraint [log in to unmask]
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