Full_Name: Patrick Hodgson

Version: 2.0

OS: solaris 2.9

Submission from: (NULL) (65.94.128.161)

The value reported for the parameter W in the function wilcox.exact appears to

be incorrect. I have checked the reference in the help file for this function

(Myles & Hollander 1973, as well as 2nd ed. 1999 by same authors) and it is

clear that W is the sum of the ranks of the data set with the smaller number of

members.

Here is sample input/output:

> x<-c(1,2,3,4,5,6,7,8,9,10)

> y<-c(11,12,13,14,15)

> library(exactRankTests)

> wil<-wilcox.exact(x,y)

> wil

Exact Wilcoxon rank sum test

data: x and y

W = 0, p-value = 0.000666

alternative hypothesis: true mu is not equal to 0

In this case W should be the sum of the ranks of y (coincidentally also the

values of the y data)= 11+12+13+14+15 = 65.

W of zero is ridiculous.

Similarly, in this case W should be 2+4+6+8 = 20, not 10 as reported.

> x<-c(1,3,5,7,9)

> y<-c(2,4,6,8)

> wil<-wilcox.exact(x,y)

> wil

Exact Wilcoxon rank sum test

data: x and y

W = 10, p-value = 1

alternative hypothesis: true mu is not equal to 0

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