On 17 Jan 2002 00:05:02 -0800, [EMAIL PROTECTED] (Håkon) 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/ =================================================================
