From: JP <jeanpaul.ebejer_at_inhibox.com>

Date: Tue, 03 May 2011 09:33:25 +0100

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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. Received on Thu 05 May 2011 - 06:25:05 GMT

Date: Tue, 03 May 2011 09:33:25 +0100

How do I calculate the Z score and r value - please (once I have the p values)?

2011/5/2 Uwe Ligges <ligges_at_statistik.tu-dortmund.de>:

*> To get the statsitics, you will have to run each wilcox.test manually. the
**> pairwise... version just extracts the p-values and adjusts them.
**>
**> Uwe Ligges
**>
**>
**> On 28.04.2011 15:18, JP wrote:
**>>
**>> Hi there,
**>>
**>> I am trying to do multiple pairwise Wilcoxon signed rank tests in a
**>> manner similar to:
**>>
**>> a<- c(runif(1000, min=1,max=50), rnorm(1000, 50), rnorm(1000, 49.9,
**>> 0.5), rgeom(1000, 0.5))
**>> b<- c(rep("group_a", 1000), rep("group_b", 1000), rep("group_c",
**>> 1000), rep("group_d", 1000))
*

>> pairwise.wilcox.test(a, b, alternative="two.sided",

*>> p.adj="bonferroni", exact=F, paired=T)
**>>
**>> This gives me the following output:
**>>
**>> group_a group_b group_c
**>> group_b<2e-16 - -
**>> group_c<2e-16 0.25 -
**>> group_d<2e-16<2e-16<2e-16
**>>
**>> (which is kind of expected since group_b and group_c have similar
**>> distributions)
**>>
**>> I have found that when doing a wilcoxon signed ranked test you should
**>> report:
**>>
**>> - The median value (and not the mean or sd, presumably because of the
**>> underlying potential non normal distribution)
**>> - The Z score (or value)
**>> - r
**>> - p value
**>>
**>> My questions are:
**>>
**>> - Are the above enough/correct values to report (some places even
**>> quote W and df) ? What else would you suggest?
**>> - How do I calculate the Z score and r for the above example?
**>> - How do I get each statistic from the pairwise.wilcox.test call?
**>>
**>> Many Thanks
**>> JP
**>>
**>> ______________________________________________
**>> 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.
**>
*

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