R help - May 2009 - minmun p-value for wilcox.test and correlation

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.

Charles
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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.

Peter

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

charles78 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.
> 
> Charles
It's mainly a printing issue (and to some extent historical, because 
small p-values in the upper tail were generated by subtraction and could 
underflow if < 2.2e-16):

 > wilcox.test(1:100,101:200)

	Wilcoxon rank sum test with continuity correction

data:  1:100 and 101:200
W = 0, p-value < 2.2e-16
alternative hypothesis: true location shift is not equal to 0

 > wilcox.test(1:100,101:200)$p.value
[1] 2.562144e-34

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