Hello, I have a response variable that is a time series of 0's and 1's. And a couple of continous explanatory variables. I would like to fit a gamm with auto-correlation and binomial distribution using gamm in mgcv. Something simple like: tmp<-gamm(y ~ s(x), correlation=corAR1(), binomial) However, I read in various messages on this newsgroup that glmmPQL (used by gamm) is using an overdispersion parameter. Does this make my approach invalid? Thanks for any answer, Piet Bell --------------------------------- [[alternative HTML version deleted]]