1. Apply the sign test to the above example. Did the results change? Which test is more powerful, the sign test or the Wilcoxon signed-rank test? Why?
2. Suppose we compare four instructors for consistency of grading. Use the following table to apply the Kruskal-Wallis test to determine whether there is a difference among instructors.
Grade Counts for Students by Instructor
|
Instructor
|
|
|
Grade
|
1
|
2
|
3
|
4
|
Row Totals
|
|
A
|
4
|
10
|
6
|
20
|
40
|
|
B
|
14
|
6
|
7
|
10
|
37
|
|
C
|
17
|
9
|
8
|
5
|
39
|
|
D
|
6
|
7
|
6
|
5
|
24
|
|
F
|
2
|
6
|
1
|
10
|
19
|
|
Total # of students
|
43
|
38
|
28
|
50
|
159
|