Biostatistics

366 CHAPTER 8 ANALYSIS OF VARIANCE
6. Decision rule. Reject H 0 if the computed value of the test statistic is
equal to or greater than the critical value of F. The critical values of F for
testing the three hypotheses of our illustrative example are 2.76, 2.76,
and 2.04, respectively. Since denominator degrees of freedom equal to
64 are not shown in Appendix Table G, 60 was used as the denominator
degrees of freedom.
7. Calculation of test statistic. We use MINITAB to perform the
calculations. We put the measurements in Column 1, the row (factor
A) codes in Column 2, and the column (factor B) codes in Column 3. The
resulting column contents are shown in Table 8.5.6 . The MINITAB
output is shown in Figure 8.5.3.
TABLE 8.5.6 Column Contents for MINITAB Calculations,
Example 8.5.2
Row C1 C2 C3 Row C1 C2 C3
1 20 1 1 41 31 3 1
2 25 1 1 42 30 3 1
3 22 1 1 43 40 3 1
4 27 1 1 44 35 3 1
5 21 1 1 45 30 3 1
6 25 1 2 46 32 3 2
7 30 1 2 47 35 3 2
8 29 1 2 48 30 3 2
9 28 1 2 49 40 3 2
10 30 1 2 50 30 3 2
11 24 1 3 51 41 3 3
12 28 1 3 52 45 3 3
13 24 1 3 53 40 3 3
14 25 1 3 54 40 3 3
15 30 1 3 55 35 3 3
16 28 1 4 56 42 3 4
17 31 1 4 57 50 3 4
18 26 1 4 58 40 3 4
19 29 1 4 59 55 3 4
20 32 1 4 60 45 3 4
21 30 2 1 61 20 4 1
22 45 2 1 62 21 4 1
23 30 2 1 63 20 4 1
24 35 2 1 64 20 4 1
25 36 2 1 65 19 4 1
26 30 2 2 66 23 4 2
27 29 2 2 67 25 4 2
28 31 2 2 68 28 4 2
(Continued)