- Thread starter JRA
- Start date

It is based on rank ordering all of the values and seeing if one group had more highly ranked values than the other group. So yeah, I would imagine if you had a significant value you could try to discern which group had more highly ranked observations.

More specifically, if we're looking at just two groups (making the KW test equivalent to a Mann-Whitney test), then the null hypothesis being tested is that:

If you randomly select an observation Y1 from Population 1 and randomly select an observation Y2 from Population 2, then the probability that Y2 is greater than Y1 is exactly 0.5.

do you mean in general, or in my R code?

The version of PS that I have seen so far is calculated on the basis of the U statistic. I believe that bootstrapping (or better yet, randomizing) PS in order to attach a p value would not be difficult to implement, but I have not the statistical background to say that it would be theoretically sound.

I happen to see the use of PS in a couple of articles, but it would be interesting googling a bit to see what pops up.

Best

Gm