Dear all,
We're currently having problems with our design matrices/contrast
analysis that I'd appreciate some help on. (FYI: SPM5, Matlab 7.6).
Originally, our design matrices were occasionally showing differing
numbers of columns as well as grey bars indicating that the betas were
not uniquely specificied. Following Rik Henson's link yesterday I turned
SPM's "auto-orthogonaliser" off and this resulted in matrices with the
correct number of columns - but now showing the black lines that were
previously (presumably) being excluded which explained the different
sized matrices - many thanks for that.
However, we still have the problem of columns that are
non-uniquely-specified - which cannot be used in any contrasts (the
contrast manager will not permit a "1" on any columns that had this
(grey box)).
Rather than explain the whole design, I wondered if anyone had any good
advice on how generally to deal with betas not being uniquely specified
- for example, is it best to drop the whole session? Can the contrast
manager's refusal to run be over-ridden?
I want to be able to batch process the contrasts and so ideally don't
want to end up with different columns numbers with different parameters
for each subject etc as this would mean I'd have to manually enter
contrasts for each subject and with N=36 that'd take some time.
If anyone has any thoughts on the best way forward that would be much
appreciated.
James Gilleen
IOP
London, SE5 8AF
tel: 0207 848 0542
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