Many thanks for taking the time to read this! I am looking at the repeatability of behaviour between re-sighted individuals across discrete time periods (annual breeding seasons). My approach was to run a GLM (with a logit link - the data are proportional, presence v. absence of behaviour) for each breeding season. I included the re-sighted individuals as a factor (categorical variable) (i.e. the models only contained individuals that were seen in all of the breeding seasons). Inevitably the variables that are retained in the best models are not the same for each breeding season and in one (out of 3 cases) individual is not retained within the best model (although I suspect that is a product of a considerably smaller sample size for that breeding season). I use the best model that has retained individual id and extract the coefficients of the individuals. I then use the ICC command in the package psych to test for repeatability in these values over the three breeding seasons. The results are in fact repeatable, which does support the basic analyses using just the behaviour (without trying to account for potential covariates), which is encouraging. However, I have had a look on nabble and other forms to see if this is at all statistically sound or if I am making a fundamental error in how I am treating the coefficients. I have found a couple of posts, but I don't think that they relate directly to my question. I appreciate that some may suggest using mixed-effects modelling with individual as a random effect. My issue is that the behaviours I am interested in are very rare and are best suited for a beta-binomial distribution (tested using Ben Bolker's script/e.g. in his book). And such a distribution is not available in lme4. Therefore, I'm trying to find another approach to assess whether individual is important in predicting a behaviour, and whether individuals are repeatable/consistent in this respect. Any advice would be most appreciated, Best wishes, Ross -- View this message in context: http://r.789695.n4.nabble.com/comparing-GLM-coefficients-repeatability-tp3772844p3772844.html Sent from the R help mailing list archive at Nabble.com.