How to work out critical value for Mann Whitney U test?

Question

I'm stuck.

I'm doing the mann whitney u test for my independent study

I have R at 24 and all the critical value tables I can find only go up to 20.

Any one have the calculation to it out for more than 20?

Answer 1

You can find an extended table for the test in

An Extended Table of Critical Values for the Mann-Whitney (Wilcoxon) Two-Sample Statistic, Roy C. Milton, Journal of the American Statistical Association, Vol. 59, No. 307 (Sep., 1964), pp. 925-934