There is not an error, per se. An ill-conditioned matrix means that your
design matrix has two or more columns that are too similar. Check your
continuous variables to see whether they are similar (eg, age and
education level). Finally, it is difficult to diagnose the problem
without more info, try looking at
surfer.nmr.mgh.harvard.edu/fswiki/BugReporting for better ways to report
problems.
doug
Juergen Haenggi wrote:
Dear Freesurfer experts
We have two problems with FS statistics.
One problem occurred when using mri_glmfit:
Matrix condition is 11198.7
ERROR: matrix is ill-conditioned or badly scaled, condno = 11198.7
Possible problem with experimental design:
Check for duplicate entries and/or lack of range of
continuous variables within a class.
I inspected the FSGD file but did not find any error!
There was a suggestion in the FS archives to look at the design matrix for
significant off-diagonal values but the design matrix (X.mat) was not
produced
Any idea where the problem is?
In another contrast the sig.mgh file produced huge values and the whole
brain is colored yellow (see attachment).
What happens here?
Thanks a lot in advance
Best regards
Juergen
-----------------------------------------------------------
Juergen Haenggi
Ph.D. (Dr. des.)
Division of Neuropsychology
Institute of Psychology
University of Zurich
Binzmuehlestrasse 14, PO Box 25
8050 Zurich, Switzerland
0041 44 635 73 97 (phone office)
0041 76 445 86 84 (phone mobile)
0041 44 635 74 09 (fax office)
BIN 4.D.04 (office room number)
[EMAIL PROTECTED] (email)
http://www.psychologie.uzh.ch/neuropsy/ (website)
http://www.juergenhaenggi.ch (private website)
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Douglas N. Greve, Ph.D.
MGH-NMR Center
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In order to help us help you, please follow the steps in:
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