[R] Simple General Statistics and R question (with 3 line example) - get z value from pairwise.wilcox.test

[JP]

Thanks Uwe,

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

Many Thanks
JP



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
>>
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>