[R] system is exactly singular

From: <rab45+_at_pitt.edu>
Date: Thu 11 Aug 2005 - 07:40:44 EST


When trying to fit a generalized linear mixed model using glmmPQL:

> fit0 <- glmmPQL(ifelse(response=="A",1,0)~gender,data=set1,

    random=~1|subject,family=binomial)
iteration 1
Error in solve.default(pdMatrix(a, fact = TRUE)) :

        Lapack routine dgesv: system is exactly singular

Could this be occuring because the paired responses for each subject are always the same? If this were the case, what would be the best way to handle this situation?

I replaced the response variable with fake data that are not always the same for each pair and then I don't get this (or any) error message.

Rick B.



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