[BioC] Mann Whitney

[Patricia Garcia]

Hi
I'm trying to use a Mann-Whitney test in a PCR data, like this:


# Case the samples are similar:
x1 <- c(19.0370805,17.51822,18.524912)
y1 <- c(20.541484,22.039175,20.542968)
w1 <- wilcox.test(x1,y1, paired = FALSE, alternative = c("two.sided"))


        Wilcoxon rank sum test

    data:  m and f
    W = 0, p-value = 0.1
    alternative hypothesis: true location shift is not equal to 0

# Case the samples are not similar:
x2 <- c(3.9934205,    3.499646,    4.489782)
y2 <- c(20.541484,22.039175,20.542968)
w2 <- wilcox.test(m,f, paired = FALSE, alternative = c("two.sided"))


        Wilcoxon rank sum test

    data:  m and f
    W = 0, p-value = 0.1
    alternative hypothesis: true location shift is not equal to 0



I obtain the same result: pvalue > 0.05, so i don't reject the null 
hypothesis, that both samples came from the same distribution.
If i test other numbers the result is the same always.
Thanks.