[R] Outlier statistics question
Jahan
jahan.mohiuddin at gmail.com
Tue Nov 30 21:15:40 CET 2010
I have a statistical question.
The data sets I am working with are right-skewed so I have been
plotting the log transformations of my data. I am using a Grubbs Test
to detect outliers in the data, but I get different outcomes depending
on whether I run the test on the original data or the log(data). Here
is one of the problematic sets:
fgf2p50=c(1.563,2.161,2.529,2.726,2.442,5.047)
stripchart(fgf2p50,vertical=TRUE)
#This next step requires you have the 'outliers' package
library(outliers)
grubbs.test(fgf2p50)
#the output says p<0.05 so 5.047 is an outlier
#Next, I run the test on the log(data)
log10=c(0.194,0.335,0.403,0.436,0.388,0.703)
grubbs.test(log10)
#output is that p>0.05 so we reject that there is an outlier.
The question is, which outlier test do I accept?
More information about the R-help
mailing list