Dear listmembers, I've adjusted a mixed model with glmmPQL: nulo<-glmmPQL(POS~1,random=~1|GRUPO, family=binomial, data=new) and I've reched the following results: Linear mixed-effects model fit by maximum likelihood Data: new AIC BIC logLik 53238.5 53260.74 -26616.25 Random effects: Formula: ~1 | GRUPO (Intercept) Residual StdDev: 0.3402137 0.9952645 Variance function: Structure: fixed weights Formula: ~invwt Fixed effects: POS ~ 1 Value Std.Error DF t-value p-value (Intercept) 0.6214472 0.03723763 12025 16.68869 0 Standardized Within-Group Residuals: Min Q1 Med Q3 Max -1.7831032 -1.2642113 0.6508504 0.7058691 1.1945426 Number of Observations: 12227 Number of Groups: 202 Could someone clarify me? I don't understand why DF=12025 in the intercept t-test above, if the objective is to estimate only one mean for all groups (mean=0,6214472). I expected that this DF would equal 201, as I have 202 groups. Thanks in advance, Alex __________________________________________________________________________ Acabe com aquelas janelinhas que pulam na sua tela. AntiPop-up UOL - ?? gr??tis! http://antipopup.uol.com.br/