Dear colleagues,
I would be very grateful if anybody would have an idea how to solve the
following problem:
I set up a 3 factorial mixed effects design with 24 subjects using the
flexible factorial design option in SPM5. I have one wihtin-subject factor
(2 levels: condition) and one between-subject factor (2 levels: group). I
modelled the subject effect as the first factor. The design matrix was
estimated but when I try to calculate contrasts, SPM tells me that my
contrasts are invalid.
The first contrast is testing condition 1 > condition 2 and I defined it as
follows:
[zeros(1,24), 1, -1]
Any contrast with less then 25 columns is working but whenever I try to
define a contrast for my experimental factors, I get an error message.
I am quite sure that there is an answer to this in the depth of the archive
but unfortunately I could not find it.
Thanks in advance for your invaluable support,
Peter
--
Peter Kirsch, PhD
Division for Imaging in Pychiatry
Central Institute of Mental Health
J 5
D-68159 Mannheim, Germany
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