[R] GLMM: MEEM error due to dichotomous variables

[Michael Dewey]

At 14:31 07/08/2007, Elva Robinson wrote:
>I am trying to run a GLMM on some binomial data. My fixed factors 
>include 2 dichotomous variables, day, and distance. When I run the model:
>
>modelA<-glmmPQL(Leaving~Trial*Day*Dist,random=~1|Indiv,family="binomial")
>
>I get the error:
>
>iteration 1
>Error in MEEM(object, conLin, control$niterEM) :
>        Singularity in backsolve at level 0, block 1
>
> From looking at previous help topics,( 
> http://tolstoy.newcastle.edu.au/R/help/02a/4473.html)
>I gather this is because of the dichotomous predictor variables - 
>what approach should I take to avoid this problem?

I seem to remember a similar error message (although possibly not 
from glmmPQL). Does every combination of Trial * Day * Dist occur in 
your dataset?

You would find it easier to read your code if you used your space 
bar. Computer storage is cheap.


>Thanks, Elva.
>
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Michael Dewey
http://www.aghmed.fsnet.co.uk