Thanks for the help so far. I'll look at mcmcglmm--a good idea, even though I was hoping to use R for my "quick" exploratory models before moving to WinBUGS. "Quickly exploring" with mcmc makes me nervous. David, would it be possible to help me with some references on using Gaussian errors for binary data which you mention below. I've read the Paper by Cheung, A modified least-squares regression approach to the estimation of risk difference, AJE 2007, 166:1337-1344 but was hoping to find some more on this. In particular, any references which say Gaussian errors are acceptable in mixed models would be most appreciated (I have an outcome prevalence in the 0.2's). Thanks again. David. P.S. Judging by the responses I've received, I can see Australia is not on holidays at the moment, unlike the Northern Hemisphere! Le 20 ao?t 09 ? 12:00, r-sig-mixed-models-request at r-project.org a ?crit :
Finally, there is some literature suggesting that the Gaussian LMM for binary data might not be too bad, especially if the probabilities are all >0.05.