A professor has two classes in psychology: a morning class of 9 students, and an afternoon class of 12 students. On a final examination scheduled at the same time for all students, the classes received the grades shown in Table 1. Can one conclude at the 0.05 significance level that the morning class performed worse than the afternoon class? Work the problem first by hand, supplying all the details for the Mann-Whitney U test. Follow this with the MINITAB solution to the problem.
Table 1
|
Morning Class
|
73
|
87
|
79
|
75
|
82
|
66
|
95
|
75
|
70
|
|
|
|
|
Afternoon Class
|
86
|
81
|
84
|
88
|
90
|
85
|
84
|
92
|
83
|
91
|
53
|
84
|