[R] Why warnings using lmer-model with family=binomial Hi all! My question is why, and what I can do about that  I sometimes, but not always, get warning-messages like nlminb returned message singular convergence (7)   in: LMEopt(x = mer, value = cv) or IRLS iterations for PQL did not converge when trying to fit a model looking like this:  lmer<-(cbind(Diseased,Healthy)~Fungus+(1|Family)+(1|Fungus:Family),  family="binomial") to four similar data sets? All four data sets consists of four columns;  Fungus (1 or 2), Family (1-30), Diseased and Healthy. An example: Fungus  Family          Diseased        Healthy 1               1               3               7 2               1               1               5 1               2               2               16 2               2               2               14 ...and so on up to totally 30 families. One of the data sets works perfectly fine and  gives no warnings, but for the others i get  different amount of warning messages. Between the  data sets it is only the number of diseased anf  healthy for each family and fungus that differ. Does anyone have any idea why this happens and  how I can get around it (I'm mainly interested in the interaction term...)? Grateful for any help /Ãsa __________________________________________________________________ Ãsa Granberg, Doktorand / Phd-student EvolutionÃ¤r ekologi Ekologi, miljÃ¶ och geovetenskap UmeÃ¥ Universitet 901 87 UmeÃ¥ Evolutionary ecology Department of Ecology and Environmental Science UmeÃ¥ University 901 87 UmeÃ¥, Sweden Phone: +46 (0)90 786 7461 Fax: +46 (0)90 786 6705 e-mail:asa.granberg@emg.umu.se ______________________________________________ R-help@stat.math.ethz.ch 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.