[R] permutation test on paired samples
Holger Taschenberger
Holger.Taschenberger at mpi-bpc.mpg.de
Thu Jul 12 20:26:45 CEST 2012
Hi,
I'm trying to run a permutation test on paired samples.
First I tried the package "exactRankTests":
require("exactRankTests")
x <- c(1.83,0.50,1.62,2.48,1.68,1.88,1.55,3.06,1.30)
y <- c(0.878,0.647,0.598,2.05,1.06,1.29,1.06,3.14,1.29)
wilcox.test(x,y,paired = TRUE,alternative = "greater")
perm.test(y,x,paired = TRUE,exact = TRUE,alternative = "greater")
Then I wanted to use the package 'coin':
require("coin")
x <- c(1.83,0.50,1.62,2.48,1.68,1.88,1.55,3.06,1.30)
y <- c(0.878,0.647,0.598,2.05,1.06,1.29,1.06,3.14,1.29)
xydat <- data.frame(y = c(y,x),x = gl(2,length(x)),block = factor(rep(1:length(x),2)))
wilcoxsign_test(y ~ x | block,data = xydat,alternative = "greater",distribution = exact())
oneway_test(y ~ x | block,data = xydat,alternative = "greater",distribution = exact())
While the results of the Wilcoxon test are the same for both packages
are the same, those of the permutation test are very different. So,
obviously I'm doing something wrong here. Can somebody please help?
Thanks a lot,
Holger
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