[R] R code for to check outliers

[Nordlund, Dan (DSHS/RDA)]

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Sajeeka Nanayakkara
> Sent: Wednesday, July 18, 2012 6:28 AM
> To: r-help at r-project.org
> Subject: [R] R code for to check outliers
> 
> 
> 
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>  What is the R code to check whether data series have outliers or not?
> 
> Thanks,
> 
> Sajeeka Nanayakkara
> 	[[alternative HTML version deleted]]

Sajeeka,

You have been given lots of good information and appropriate warnings.  Let me add another caveat to think about in the context of outliers/unusual values.  A value may only be unusual in a multivariate context.  If we have a dataset with human heights in it, a value of 73 inches would not be unusual.  If we then learned that this particular individual was female, it would be somewhat unusual but certainly within the realm of possibility.  If we then learn that the individual is 3 years old, it would be highly unusual.

So, you can see why people on the list are somewhat unwilling to say here is THE function "to check whether data series have outliers or not."

Now having said that, can you define what YOU mean by "outlier" and why you are concerned about finding them.  Someone may be able to offer advice that will help you achieve your goal.

Dan

Daniel J. Nordlund
Washington State Department of Social and Health Services
Planning, Performance, and Accountability
Research and Data Analysis Division
Olympia, WA 98504-5204