And if you are interested in models that predict values out near the edges of the range, you might want to look at quantile regression (see PROC QUANTREG). One of the advantages to 'linear regression' is that it handles ties much better than nonparametric regression (so long as they don't overwhelm the number of records), and with a range of 80, I am willing to wager that there are a large number of ties in the data. Steve Denham
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