[R] minmun p-value for wilcox.test and correlation

Uwe Ligges ligges at statistik.tu-dortmund.de
Thu May 21 16:36:27 CEST 2009

Peter Flom wrote:
> charles78 <huz88 at hotmail.com> wrote 
>> I have a stupid question on how to get the real p-values for wilcox.test and
>> correlation.  the minmun can be reached is 2.2E-16 using the R version
>> 2.6.2.  I do not think it is the R version causing this but other issues.
>> Any help is highly appreciated.
> Can I ask why you want this?
> I'm curious.

I'm also curious. Anyway, you can get the calculated value by:


Note that printing of htest objects results always in the above 
mentioned minimum for very small values, because we cannot be sure about 
numerical precision, particularly also in the far from centre regions of 
a distribution... (and since you should not report a p-value of exactly 
0 that may numerically arise when doing such computations).

Uwe Ligges

> Peter
> Peter L. Flom, PhD
> Statistical Consultant
> www DOT peterflomconsulting DOT com
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