"Dupouey Jean-Luc" <[EMAIL PROTECTED]> wrote in
news:[EMAIL PROTECTED]:
On my system wilcox.test() exists, whereas wilcox_test() did not.
Help.search("wilcox_test") does not produce any clues. If you are using
a test from another package, you should specify which package the test
comes from. Web searching produces links to package coin.
Have you tried?
wtest <- by(mydata, mydata$myindice, function (x) {
wilcox_test(value~fact, data=x)})
----slight modification to the wilcox_test example data------
> mydata
pd age grp
1 0.80 At term 1
2 0.83 At term 2
3 1.89 At term 1
4 1.04 At term 2
5 1.45 At term 1
6 1.38 At term 2
7 1.91 At term 1
8 1.64 At term 2
9 0.73 At term 1
10 1.46 At term 2
11 1.15 12-26 Weeks 1
12 0.88 12-26 Weeks 2
13 0.90 12-26 Weeks 1
14 0.74 12-26 Weeks 2
15 1.21 12-26 Weeks 1
16 1.10 12-26 Weeks 2
> wilcoxtest <- by(mydata, mydata$grp, function(x)
+ {wilcox_test(pd~age, data=x)}
+ )
> wilcoxtest
Asymptotic Wilcoxon Mann-Whitney Rank Sum Test
data: pd by age (12-26 Weeks, At term)
Z = -0.4472, p-value = 0.6547
alternative hypothesis: true mu is not equal to 0
---------------------------------------------------
Asymptotic Wilcoxon Mann-Whitney Rank Sum Test
data: pd by age (12-26 Weeks, At term)
Z = -1.3416, p-value = 0.1797
alternative hypothesis: true mu is not equal to 0
--
David Winsemius
> I want to apply a Wilcoxon test on subsets of the data frame mydata,
> splitted using the myindice variable. When I send :
>
> wilcoxtest <- by(mydata, mydata$myindice, function(x)
> {wilcox_test(x$value~x$fact)})
>
> I get :
>
> Error in eval(expr, envir, enclos) : object "x" not found
>
> whereas
>
> wilcoxtest <- by(mydata, mydata$myindice, function(x)
> {wilcox.test(x$value~x$fact)})
> works !
> Why does it fail with the wilcox_test only? And, most important, how
> can I apply the wilcox_test function to subsets of mydata splitted
> according to mydata$myindice ?
>
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