[R] How to apply the Wilcoxon test to a hole table at once?
Steven McKinney
smckinney at bccrc.ca
Sat Oct 24 06:04:26 CEST 2009
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Iurie Malai
> Sent: Friday, October 23, 2009 10:46 AM
> To: r-help at r-project.org
> Subject: [R] How to apply the Wilcoxon test to a hole table at once?
>
>
> Hi,
>
> I have a data set:
>
> > Dataset
> X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17
> 1 user1 m 22 19 28 24 12 18 9 7 4 5 4 7 5 7 9
> 2 user2 f 25 19 23 18 18 15 6 8 6 6 7 10 7 7 7
> 3 user3 f 28 21 24 18 15 12 10 6 7 9 5 10 5 9 5
> 4 user4 f 26 19 26 21 12 18 6 6 5 1 3 8 6 5 6
> 5 user5 m 21 22 26 18 9 6 4 6 1 7 2 4 4 6 4
> 6 user6 m 24 8 25 12 18 12 7 8 4 1 4 6 7 5 6
> ...............................................................
> 71 user71 m 18 4 10 6 3 6 9 5 10 8 4 5 6 5 5
>
> I can apply the Wilcoxon test on each column one by one, but how to do
> this
> on the hole table at once?
>
> > wilcox.test(X3 ~ X2, alternative="two.sided", data=Dataset)
>
> Wilcoxon rank sum test with continuity correction
>
> data: X3 by X2
> W = 439, p-value = 0.1291
> alternative hypothesis: true location shift is not equal to 0
>
> >
Here's one way to do it (using airquality dataset)
> lapply(airquality[1:4], function(x) wilcox.test(x ~ Month, alternative="two.sided", data=airquality, subset = Month <= 6))
$Ozone
Wilcoxon rank sum test with continuity correction
data: x by Month
W = 82, p-value = 0.1925
alternative hypothesis: true location shift is not equal to 0
$Solar.R
Wilcoxon rank sum test with continuity correction
data: x by Month
W = 391.5, p-value = 0.8354
alternative hypothesis: true location shift is not equal to 0
$Wind
Wilcoxon rank sum test with continuity correction
data: x by Month
W = 566, p-value = 0.1461
alternative hypothesis: true location shift is not equal to 0
$Temp
Wilcoxon rank sum test with continuity correction
data: x by Month
W = 78, p-value = 2.400e-08
alternative hypothesis: true location shift is not equal to 0
Warning messages:
1: In wilcox.test.default(x = c(41L, 36L, 12L, 18L, 28L, 23L, 19L, :
cannot compute exact p-value with ties
2: In wilcox.test.default(x = c(190L, 118L, 149L, 313L, 299L, 99L, :
cannot compute exact p-value with ties
3: In wilcox.test.default(x = c(7.4, 8, 12.6, 11.5, 14.3, 14.9, 8.6, :
cannot compute exact p-value with ties
4: In wilcox.test.default(x = c(67L, 72L, 74L, 62L, 56L, 66L, 65L, :
cannot compute exact p-value with ties
# Sanity check:
> wilcox.test(Temp ~ Month, alternative="two.sided", data=airquality, subset = Month <= 6)
Wilcoxon rank sum test with continuity correction
data: Temp by Month
W = 78, p-value = 2.400e-08
alternative hypothesis: true location shift is not equal to 0
Warning message:
In wilcox.test.default(x = c(67L, 72L, 74L, 62L, 56L, 66L, 65L, :
cannot compute exact p-value with ties
>
# Same as lapply loop result
HTH
Steven McKinney
Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre
>
> I researched on this, but I can't find a solution.
> I would really appreciate any help.
>
> P.S. Excuse my lack of terminology :).
>
> Iurie Malai
> Moldova Pedagogical State University
> --
> View this message in context: http://www.nabble.com/How-to-apply-the-
> Wilcoxon-test-to-a-hole-table-at-once--tp26030572p26030572.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.
More information about the R-help
mailing list