Hello, The other day I wrote about my SD() function did not work with NA in the input and it did not recognise the na.rm=T parameter. BDR ask me if I had another SD function loaded. I did not wrote any sd function but with ls() there it was sd <- function(x) sqrt(var(as.vector(x)), I found out that it came from BugsR\regression.r an interface to WinBugs from R written by Andrew Gelman of Columbia U. So if you use BugsR be sure to delete the redefinition of sd in regression R. If somebody has the email address of Andrew Gelman please forward this one to him so he can fix it for the next version. Thanks to all Heberto Ghezzo Ph.D. Meakins-Christie Labs McGill University Montreal - Canada