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$total_bites_rounded ~
age_class_back, random = ~food.dif.id, :
Argument "group" must be a character string specifying
the name of the grouping variable (also when "random" is
missing)
Here is what I have tried so far (along with some similar
variations):
model_nb<-glmm.admb(data$total_bites_rounded~age_class_back+(1|"subject")+(1|food.dif.id)+offset(log(forage_time)),data=data,family="nbinom")
modelnb<-glmm.admb(data$total_bites_rounded~age_class_back,
random=~food.dif.id, group="subject", data=data,
offset=offset,family="nbinom")
I am not sure what I am doing wrong. My model in lmer that
seemed to work was:
modelc<lmer(data$total_bites_rounded~age_class_back+(1|data$focal_individual)+(1|food.dif.id)+offset(log(forage_time)),family=poisson)
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,
Lizzy
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