hi guys thanks for your responses and guidances: I think both will be instructive for me.

Actually my interest in the subject is related to sample sizes that are pretty small, like definitely less than 12 per group or so and in actuality I am sort of more interested in the exact stratified wilcoxon (van elteren) type tests. The reason being that it does not seem that SAS has an exact version of that test implemented, although I suspect R does, but I have to find the package.

I sort was just looking for a way to easily QC the p-values I was getting out of my computer, I thought maybe there was an easy way to figure this quickly in excel, at least for reasonably small n. Maybe it will occur to me when I look at these references.

Thanks!

Hi Fed,

If I remember correctly the calculation should be fast until ~17, so 12 should be fast enough for any computer.

But why should you calculate yourself when you can use R?

The R cotains both the exact method and the approximation, but in case of ties it uses only the approximation!

wilcox.test(x1, x2, alternative = "two.sided", paired = FALSE, exact = TRUE)

If you have ties you may consider to calculate per the article I send before. (or use simulation)

Another option is to use the following online calculator, it gets the same results as R, and also lets you know the R alternative code.

The exact method is only until 20 for each group, so 12 should be okay.

https://www.statskingdom.com/170median_mann_whitney.html