[R-sig-ME] Error message when handling complete separation

D. Rizopoulos d@r|zopou|o@ @end|ng |rom er@@mu@mc@n|
Mon Oct 21 15:32:06 CEST 2019

In GLMMadaptive you can solve separation issues by including a penalty term for the coefficients. You may find an example on how to do this at the bottom of this vignette: https://drizopoulos.github.io/GLMMadaptive/articles/GLMMadaptive_basics.html


From: C. AMAL D. GLELE <altessedac2 using gmail.com<mailto:altessedac2 using gmail.com>>
Date: Monday, 21 Oct 2019, 13:21
To: R SIG Mixed Models <r-sig-mixed-models using r-project.org<mailto:r-sig-mixed-models using r-project.org>>
Subject: [R-sig-ME] Error message when handling complete separation

Hi, all.
When trying to handle a complete separation case
( initialmodel<-glmer(resp~treatment+(1|net),family=binomial,data=mydata) ,
where: treatment is a factor with 4 levels; net has 4 levels;
Warning message:
unable to evaluate scaled gradient Hessian is numerically singular:
parameters are not uniquely determined
Outputs: huge estimates, huges sderror and p-value=1 everywhere
to solve this, I tried the following fit;
= normal(cov=diag(9,4)))
but, I get the error message below:

Error in length(value <- as.numeric(value)) == 1L :
  pwrssUpdate did not converge in (maxit) iterations

1) what are the possible causes of such a problem?
2) how can I figure it out?
Thanks, in advance.

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