http://www.stfm.org/fmhub/fm2007/February/Anthony132.pdf Eliminating Bias in Randomized Controlled Trials: Importance of Allocation Concealment and Masking Best, Paul __________________________________________________________________ The new Internet Explorer® 8 - Faster, safer, easier. Optimized for Yahoo! Get it Now for Free! at http://downloads.yahoo.com/ca/internetexplorer/