Dear list, 
I am trying to use MuMIn to compare all possible mixed models using the dredge function on binomial data but I am getting an error message that I cannot decode. This error only occurs when I use glmer. When I use an lmer analysis on a different response variable every works great. 

Example using a simplified glmer model
global model: 
mod<- glmer(cbind(st$X2.REP.LIVE, st$X2.REP.DEAD) ~ DOMESTICATION*GLUC + (1|PAIR), data=st, na.action=na.omit , family=binomial) 

The response variables are the number of survival and dead insects (successes and failures)
DOMESTICATION is a 2 level factor.
GLUC is a continuous variable.
PAIR is coded as a factor or character (both ways fail).

This model functions correctly but when I try it with dredge() I get an error. 

g<- dredge(mod, beta=F, evaluate=F, rank='AIC')
Error in sprintf(gettext(fmt, domain = domain), ...) : 
  invalid type of argument[1]: 'symbol'

When I try with another rank the same thing happens:
chat<- deviance(mod)/58
g<- dredge(mod, beta=F, evaluate=F, rank='QAIC', chat=chat)
Error in sprintf(gettext(fmt, domain = domain), ...) : 
  invalid type of argument[1]: 'symbol'

Any suggestions would be greatly appreciated

thanks

Martin Turcotte, Ph. D.
mart.turcotte@gmail.com





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