[R] glmmPQL / "system is computationally singular"
spencer.graves at pdf.com
Mon Jan 16 03:49:44 CET 2006
Did you try "traceback()"? What do you get?
I've had good luck with problems like this in listing the function
then using "debug" to review while I walk throught the code line by line.
This may not be the issue here, but with "family=binomial", if the
model being fit can achieve perfect separation, software of this type
might generate error messages similar to what you describe.
hope this helps.
David Reitter wrote:
> 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
>>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?
> David Reitter - ICCS/HCRC, Informatics, University of Edinburgh
> Blog: http://www.davids-world.com Homepage: http://www.david-
> R-help at stat.math.ethz.ch mailing list
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