Three classes in elementary statistics are taught by three different persons: a regular faculty member, a graduate teaching assistant, and an adjunct from outside the university. At the end of the semester, each student is given a standardized test. Five students are randomly picked from each of these classes, and their scores are as shown in Table.
|
Table
|
|
|
Faculty
|
Teaching assistant
|
Adjunct
|
|
93
|
88
|
86
|
|
61
|
90
|
56
|
|
87
|
76
|
73
|
|
75
|
82
|
90
|
|
92
|
58
|
47
|
(a) Construct an analysis-of-variance table and interpret your results.
(b) Test at the 0.05 level whether there is a difference between the mean scores for the three persons teaching. Assume that the conditions of completely randomized design are met.