Here's some sample code (you may have to modify) to deal with the scores another way, I think. Set the whole scale to vary between 0 and 1, and then do a logit transformation, which AmII can also deal with. (This is mostly to get around the way you're dealing with 0 values.) Instead of taking 0 to be 0.1, you can add the infinitesimally small value (R has a super-tiny value that's almost but not quite zero) to zero and subtract it from your maximum value. yourvarsofinterest <- XXX for(i in yourvarsofinterest) { data[,i] <- ifelse(data[,i] >= 100, 1 - .Machine$double.eps, ifelse(data[,i] <= 0, .Machine$double.eps, data[,i] / 100)) } And to transform back (assuming five imputed sets, etc.): for(j in 1:5) for(i in yourvarsofinterest) { outdata0[[j]][,i] <- outdata0[[j]][,i] * 100 } -Nathan On 2 Apr 2008, at 10:59 AM, Qian Guo wrote: ---------- Nathan A. Paxton Ph.D. Candidate Dept. of Government, Harvard University Resident Tutor John Winthrop House, Harvard University napaxton AT fas DOT harvard DOT edu http://www.fas.harvard.edu/~napaxton = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ======================================================================== When you have to stay eight years away from California, you live in a perpetual state of homesickness. - Ronald Reagan The most courageous act is still to think for yourself. Aloud. -Coco Chanel = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = ========================================================================