[R] wilcox.test returning 'NA' p-value

[Ista Zahn]

Hi Ambar,

v1 and v2 are constants. they need to be variables.

try e.g.,

v1 <- c(0.021, 0.022, 0.022, 0.022, 0.022, 0.022)
v2 <- c(0.021, 0.022, 0.022, 0.022, 0.022)
wilcox.test(v1, v2, PAIRED=FALSE)

-Ista
On Thu, Nov 5, 2009 at 7:23 PM, Ambar Amarelo <ambar.amarelo at gmail.com> wrote:
> Hi folks, sorry for this beginner question but what means a p-value = NA on
> a menn-whitney test?
>
> v1 <- c(0.022, 0.022, 0.022, 0.022, 0.022, 0.022)
> v2 <- c(0.022, 0.022, 0.022, 0.022, 0.022)
> wilcox.test(v1, v2, PAIRED=FALSE)
>
> W = 15, p-value = NA
>
> I know that there's no statistical difference between v1 and v2, so why my
> p-value is not ONE ??
>
> Can I consider p-value= NA  as ONE ??
> what i do when get this type of value on wilcox.test ???
>
>
> PS: sorry for my bad english.
>
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-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org