Again, it depends on what you are trying to do. WHY are you running PROC UNIVARIATE? What will you DO with the output? What will you DO with any outliers?

What does SAS mean by POSSIBLE outliers? Well, if you MUST use a strict cutoff, the default in SAS isn't bad. But then what? Let's say you find a lot of outliers, and that you check the data and find that it's legitimate data (one source of outliers is data entry error, coding problems etc). What will you do then? Why are there outliers? Is your data a sample from some population? If so, maybe the variable in question is heavy tailed in the population (e.g., income) in which case MAYBE you don't want the mean, but the median? But then, maybe you STILL want the mean. It depends what you are trying to do. Maybe the SAS default is NOT what you want. Maybe you want to delete the outliers, maybe not. Maybe you want to weight them somehow, or use trimming, or winsorizing, or something.....

You must provide context.

As someone said (I forget who) "There are no routine statistical questions, only questionable statistical routines".

Peter

Peter L. Flom, PhD Assistant Director, Statistics and Data Analysis Core Center for Drug Use and HIV Research National Development and Research Institutes 71 W. 23rd St New York, NY 10010 (212) 845-4485 (voice) (917) 438-0894 (fax)