[SciPy-user] help with scipy.stats.mannwhitneyu
Bruce Southey
bsouthey at gmail.com
Thu Feb 5 11:32:51 EST 2009
Stéfan van der Walt wrote:
> 2009/2/5 Sturla Molden <sturla at molden.no>:
>
>> On 2/5/2009 4:36 PM, josef.pktd at gmail.com wrote:
>>
>>
>>> According to wikipedia, Mann-Whitney-U is the Wilcoxon rank-sum test
>>> for independent samples, just a different name.
>>>
>> You should not trust Wikipedia.
>>
>
> Or, you can fix the entry on Wikipedia...
>
> Stéfan
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Or perhaps it is actually correct. My understanding (because I don't
want to do it) is that these are equivalent and all major stats packages
provide just one test. For example, Prof Brian Ripley's reply on the R list
https://stat.ethz.ch/pipermail/r-help/2005-May/071544.html
>/ I am hoping someone could shed some light into the Wilcoxon Rank Sum Test
/>/ for me? In looking through Stats references, the Mann-Whitney U-test and
/>/ the Wilcoxon Rank Sum Test are statistically equivalent.
/
Yes, but not numerically: they differ by a constant (in the data, a
function of the data size).
Bruce
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