Assume a researcher compared the performance of two independent groups of participants on an ordinal variable using the Mann–Whitney U test. The first group had 8 participants and the second group had 11 participants. 

a. Using a p level of 0.05 a nd a two-tailed test, determine the critical value. 

b. Assume the researcher calculated U1 = 22 and U2 = 17. Make a decision regarding the null hypothesis and explain that decision. 

c. Assume the researcher calculated U1 = 24 and U2 = 30. Make a decision regarding the null hypothesis and explain that decision. 

d. Assume the researcher calculated U1 = 13 and U2 = 9. Make a decision regarding the null hypothesis and explain that decision.