John Malone wrote:
Hi!
I'm trying to implement an outlier test once/row in a large dataframe.
Ideally, I'd do this then add the Pvalue results and the number flagged as
an outlier as two new separate columns to the dataframe. Grubbs outlier
test requires a vector and I'm confused how to make each row of my dataframe
a vector, followed by doing a Grubbs test for each row containing the vector
of numbers I want to perform the outlier test on.
I'm new to R and no doubt this is a simple problem. Any help you might
provide would be greatly appreciated.
Many thanks in advance!!
[[alternative HTML version deleted]]
John - you would be making a strong normality assumption. You might
reject H0 using Grubbs' test just because of non-normality, or you might
fail to reject it just because of non-normality. Is it really this
straitforward to declare something an outlier? What does outlier really
mean?
The following is must reading.
@Article{fin06cal,
author = {Finney, David J.},
title = {Calibration guidelines challenge outlier
practices},
journal = The American Statistician,
year = 2006,
volume = 60,
pages = {309-313},
annote = {anticoagulant
therapy;bias;causation;ethics;objectivity;outliers;guidelines for
treatment of outliers;overview of types of outliers;letter to the editor
and reply 61:187 May 2007}
--
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University
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