Dear R-users, I was doing some Poisson regression using the geepack package and I found a "strange" behaviour of the geeglm command when defining an offset. Maybe it's my limited knowledge of R syntax, or maybe it's something else.
Let's make an example. After loading the geepack library, you may write model=geeglm(y~covariates+offset(log(xxx)),data=data,family=poisson,id=idx) which is equivalent to model=geeglm(y~covariates,offset=log(xxx),data=data,family=poisson,id=idx) however, the command works also with the syntax model=geeglm(y~covariates,offset(log(xxx)),data=data,family=poisson,id=idx) giving different (wrong) results! I discovered it because I was calculating some incidence rates by hand and then comparing with the glm estimates. In the manual, indeed, the way in which the offset should be written is not so easy to understand. Thanks for any response, Mattia Prosperi -- View this message in context: http://www.nabble.com/a-bug-in-the-offset-parameter-syntax-in-the-geepack-package--tp25047143p25047143.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.