Hi R-Help! I used R2WinBUGS and WinBUGS directly on the same model just to compare. It seems I am still making a mistake: after running the function bugs() I tried to plot the posteriors of the parameters by using read.bugs() to convert the output to an mcmc object and then plot.mcmc() to plot the densities. Using the same model, the same number of iterations, the same initial values and the same data I get completely different plots for the densities (e.g. the range of one parameter in R2WinBUGS is from 0 to 8 but in WinBUGS only from 1.5 to 3)??? That means my results are different, too. Also, on the plot it says N=345 which is not what I specified in the bugs() function (I specified 12000 iterations). Below I put some of the code I used (if that helps): parameters <- c("tau","C0","st90","C0.pop","st90.pop","tau.cpop","tau.stpop","st90.pop80") inits <- inits <- function(){ list(tau = rep(1, 17),tau.cpop = 0.2, tau.stpop = 1) } mcmcA <- bugs(dataA,inits,parameters,modelA,n.chains=3,debug=T,n.iter=12000,n.burnin=2001, bugs.directory="c:/Program Files/WinBUGS14",working.directory="C:/Documents and Settings/Daikon/Roche/R2WinBUGS Output",codaPkg=T) codaA1 <- read.bugs(mcmcA[1]) plot(codaA1) THANKS A LOT!! -- Hadassa Brunschwig Birmannsgasse 10A CH-4055 Basel Switzerland Phone: +41 78 797 6065 Email: h.brunschwig at utoronto.ca