[R] glmmPQL / "system is computationally singular"

From: David Reitter <david.reitter_at_gmail.com>
Date: Wed 11 Jan 2006 - 05:37:06 EST


Hi,

I'm having trouble with glmmPQL from the MASS package. I'm trying to fit a model with a binary response variable, two fixed and two random variables (nested), with a sample of about 200,000 data points.

Unfortunately, I'm getting an error message that is difficult to understand without knowing the internals of the glmmPQL function.

> model <- glmmPQL(primed ~ log(dist) * role , random = ~ dist |
> target.utt / prime.utt , family=binomial(link = "logit"),
> data=data.utts, niter=5, verbose = TRUE)
> Loading required package: nlme
> iteration 1
> iteration 2
> iteration 3
> Error in solve.default(pdMatrix(a, fact = TRUE)) :
> system is computationally singular: reciprocal condition
> number = 8.65949e-32
> In addition: Warning messages:
> 1: Singular precision matrix in level -1, block 4
> 2: Singular precision matrix in level -1, block 4
> 3: Singular precision matrix in level -1, block 4
> 4: Singular precision matrix in level -1, block 4
> 5: Singular precision matrix in level -1, block 4

Any suggestions? Will a larger dataset (possible) solve the problem?

Thanks
David

--
David Reitter - ICCS/HCRC, Informatics, University of Edinburgh
Blog: http://www.davids-world.com   Homepage: http://www.david- 
reitter.com

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Received on Wed Jan 11 05:43:05 2006

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