[R] High p-value

[Thomas Subia]

>From previous posting:

"This is my function:

wilcox.test(A,B, data = data, paired = FALSE)

It gives me high p value, though the median of A column is 6900 and B
column is 3500.

Why it gives p value high if there is a difference in the median?"

Let's examine your choice to use the Wilcoxon test with paired = FALSE.


If both A and B are given and paired is FALSE, a Wilcoxon rank sum test (equivalent to the Mann-Whitney test) is carried out. In this case, the null hypothesis is that the distributions of x and y differ by a location shift of mu and the alternative is that they differ by some other location shift (and the one-sided alternative "greater" is that A is shifted to the right of B). 

You observed that the medians are different. While the medians may be different, the test is dependent on ranks not medians.

HTH,

Thomas Subia