Hi All, I am using the glmer function to adjust a simple model (mod1) with Poisson response variable and random intercept. When I use logLik(mod1) I obtain a value different from if I calculate the log-likelihood using the pdf. Someone could explain if I have an error? This is the code for the example: sigma <- 5 x1 <- rnorm(n=15) u <- rnorm(n=5,mean=0,sd=sigma) mu <- exp( -1.5 + 2 * x1 + rep(u,each=3) ) y <- rpois(n=15,lambda=mu) grupo <- rep(1:5,each=3) #! The mod is mod1 <- glmer(y~x1+(1|grupo),family=poisson(link = "log"),nAGQ=20) #! loglik for mod1 using logLik function logLik(mod1) #! loglik for mod1 again but using the pdf sum( dpois(x=y,lambda=exp(mod1 at eta),log=TRUE) ) When sigma=0 the obtain results match. -- View this message in context: http://r.789695.n4.nabble.com/A-question-about-loglik-in-GLMM-tp4474739p4474739.html Sent from the R help mailing list archive at Nabble.com.