Mann-Whitney U-test

Question 1

When is it used

Answer 1

Test of difference
Ordinal data
Independent groups design

Question 2

How do you use it?

Answer 2

1) set alternative hypothesis, one or two tailed
2) please raw data in table, one S. scores for group a and one for group B
3) rank each set of data, place all numbers together from group a and B, rank from low to high
4) add up each set of rands and calculate sum of ra and rb
5) calculate observed value of group a and B. Na and nb a number of participants
6) is the result in the right direction, if not accept Ho
7) find critical value U
8) accept/reject Ho