Thanks! The comments and the information provided were extremely helpful to me.
According to DRAFT r-sig-mixed-models FAQ, "do not compare lmer models with the corresponding lm fits, or glmer/glm; the log-likelihoods are not commensurate". The problem is not the link function but rather the different additive terms. Maybe, I made a mistake in explaining my problem I want to compare Model A whit model B in order to evaluate the significance of the random effects. A<-lmer(Ymat~stu+spi+(1|ber),data=data,family="binomial") B<-glm(Ymat~stu+spi,family="binomial",data=data) I'm looking for an alternative way. I made these questions to r-sig-mixed-mod...@r-project.org as you recommended. Thanks again for your time! Gabriela ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.