> Robust Statisticians recommendends to standardize using e.g. > (X - median(X)) / ( MAD(X) / 0.675 ) Make that (X - median(X))/mad(X) The constant is already in mad() -- Bert Gunter Genentech Non-Clinical Statistics South San Francisco, CA "The business of the statistician is to catalyze the scientific learning process." - George E. P. Box