[R] help with glmm.admb

Elizabeth C Eadie eeadie at unm.edu
Sat Sep 3 18:04:35 CEST 2011

R glmmADMB question
I am trying to use glmm.admb (the latest alpha version 
from the R forge website 0.6.4) to model  my count data 
that is overdispersed using a negative binomial family but 
keep getting the following error message:

Error in glmm.admb(data$total_bites_rounded ~ 
age_class_back, random = ~food.dif.id,  :
   Argument "group" must be a character string specifying 
the name of the grouping variable (also when "random" is 

Here is what I have tried so far (along with some similar 

random=~food.dif.id, group="subject", data=data, 

I am not sure what I am doing wrong. My model in lmer that 
seemed to work was:

Where age class is my one fixed variable and focal 
individual (=subject) and food id are my two random 
variables. I have tried a number of different things in 
glmm.admb like making subject a group and food id the 
random variable, and trying to write the commands in the 
lme format instead of the lmer format, but always get the 
same message. The message is confusing because I think 
that I do have a random variable as well as a group 
argument that is a character string. If anyone can see 
what I am doing wrong or has any suggestions I would 
really appreciate your thoughts.

Thank you,

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