Hello,
I am using Qdec to analyze thickness (etc) using various IVs (e.g., Verbal IQ) while controlling for cortical grey matter volume (or ICV) as a nuisance factor. With the exception of the IV Sex, every time I run the analysis it goes into an endless loop, sporadically stating that the "Matrix is Ill-conditioned". It doesn't work with discrete or continuous variables. It also happens for the other DVs, like Sulc.
Has anyone ran into this problem before? I couldn't find it on the listserv archives.
Thank you for your help,
Adam
Hi Adam, try rescaling the brain volume to be around 1 (demeaning it might help too). The next version of FS will remove these scaling problems. doug
Adam David Felton wrote:
Hello,
I am using Qdec to analyze thickness (etc) using various IVs (e.g., Verbal IQ) while controlling for cortical grey matter volume (or ICV) as a nuisance factor. With the exception of the IV Sex, every time I run the analysis it goes into an endless loop, sporadically stating that the "Matrix is Ill-conditioned". It doesn't work with discrete or continuous variables. It also happens for the other DVs, like Sulc.
Has anyone ran into this problem before? I couldn't find it on the listserv archives.
Thank you for your help,
Adam
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Adam David Felton -
Douglas N Greve