Look at minitab's "trimmed mean." It is a Tukey (I think) invention w/5% chopped from each end, leaving the central 90%. For the high variance, high skew, common world, a good approach.
On Tue, 29 Jan 2002, Rich Ulrich wrote: > On 17 Jan 2002 00:05:02 -0800, [EMAIL PROTECTED] (Hekon) wrote: > > > I have noticed a practice among some people dealing with enterprise > > data to cut the left and right tails off their samples (including > > census data) in both dependent and independent variables. The reason > > is that outliers tend to be extreme. The effects can be stunning. How > > is this practice to be understood statistically - as some form of > > truncation? References that deal formally with such a practice? > > This is called "trimming" - 5% trimming, 25% trimming. > The median is what is left when you have done "50% trimming." > > Trimming by 5% or 10% reportedly works well for your > measures of 'central tendency', so long as you *know* > that the extremes are not important. > > I don't know what it is that you refer to as 'enterprise data.' > > -- > Rich Ulrich, [EMAIL PROTECTED] > http://www.pitt.edu/~wpilib/index.html > > > ================================================================= > Instructions for joining and leaving this list, remarks about the > problem of INAPPROPRIATE MESSAGES, and archives are available at > http://jse.stat.ncsu.edu/ > ================================================================= > ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at http://jse.stat.ncsu.edu/ =================================================================
