Re: [R] system is exactly singular

From: <rab45+_at_pitt.edu>
Date: Thu 11 Aug 2005 - 07:50:27 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.
>
>

Sorry, I forgot that a variable like gender will be the same for both responses.

Rick B.



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