[R] Weights in glmmPQL

Spencer Graves spencer.graves at pdf.com
Wed Apr 12 03:01:20 CEST 2006


	  Do some of your observations have weights=0?  If yes, that might be 
the problem.  I don't know the details, but some functions like glm have 
an argument 'subset' and might give inappropriate answers with weights = 
0.

	  Beyond that, I just got 69 hits for RSiteSearch("glmmPQL weights"). 
Some of these might interest you.  In particular, you might also try 
fitting the same model using lmer associated with the lme4 package;  for 
that see the vignettes in the lme4 and MlmRev packages.

	  If you would like further help from this listserve, please provide a 
simple, self-contained, reproducible example as suggested in the posting 
guide! "www.R-project.org/posting-guide.html".  Without it, I'm just 
guessing, and some who could help more than I can don't bother.

	  hope this helps,
	  spencer graves

Nelson, Kerrie wrote:

> Hello,
> 
> I am using the R function glmmPQL to fit a logistic GLMM, with weights.
> I am finding that I get fairly different parameter estimates in glmmPQL
> from fitting the full dataset (with no "weight" statement) and an
> equivalent, shorter dataset with the weights statement.  I am using the
> weights statement in the 'glmmPQL' function exactly as in the 'glm'
> function.  I also tested my dataset in the glm function and successfully
> got the correct results using the full (with no weights) and the shorter
> dataset (with weights).
> 
> Is the weight statement in glmmPQL intended to be applied in a different
> way to a dataset than how it is used in the glm function?
> 
> Thank-you for your help and any suggestions,
> 
> Kerrie 
> 
> +++++
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