| Test for homogeneity of variance In Analysis of Variance, find s2 for each treatment.
Divide the largest value of s2
by the smallest value of s2
to get a variance ratio (F). It is safe to assume that
the variance is homogeneous if the calculated F value is
smaller than the value in the table at n-1
degrees of freedom (where n is the number of
replicates in each treatment)
| Degrees of
Freedom n-1 |
Number of treatments
____________________________________________
|
| |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
| 2 |
39.0 |
87.5 |
142 |
202 |
266 |
333 |
403 |
475 |
550 |
626 |
704 |
| 3 |
15.4 |
27.8 |
39.2 |
50.7 |
62.0 |
72.9 |
83.5 |
93.9 |
104 |
114 |
124 |
| 4 |
9.6 |
15.5 |
20.6 |
25.2 |
29.5 |
33.6 |
37.5 |
41.1 |
44.6 |
48.0 |
51.4 |
| 5 |
7.2 |
10.8 |
13.7 |
16.3 |
18.7 |
20.8 |
22.9 |
24.7 |
26.5 |
28.2 |
29.9 |
| 6 |
5.82 |
8.38 |
10.4 |
12.1 |
13.7 |
15.0 |
16.3 |
17.5 |
18.6 |
19.7 |
20.7 |
| 7 |
.99 |
6.94 |
8.44 |
9.70 |
10.8 |
11.8 |
12.7 |
13.5 |
14.3 |
15.1 |
15.8 |
| 8 |
4.43 |
6.00 |
7.18 |
8.12 |
9.03 |
9.78 |
10.5 |
11.1 |
11.7 |
12.2 |
12.7 |
| 9 |
4.03 |
5.34 |
6.31 |
7.11 |
7.80 |
8.41 |
8.95 |
9.45 |
9.91 |
10.3 |
10.7 |
| 10 |
3.72 |
4.85 |
5.67 |
6.34 |
6.92 |
7.42 |
7.87 |
8.28 |
8.66 |
9.01 |
9.34 |
| 12 |
3.28 |
4.16 |
4.75 |
5.30 |
5.72 |
6.09 |
6.42 |
6.72 |
7.00 |
7.25 |
7.43 |
| 15 |
2.86 |
3.54 |
4.01 |
4.37 |
4.68 |
4.95 |
5.19 |
5.40 |
5.59 |
5.77 |
5.95 |
| 20 |
2.46 |
2.95 |
3.29 |
3.54 |
3.76 |
3.94 |
4.10 |
4.24 |
4.37 |
4.49 |
4.59 |
| 30 |
2.07 |
2.40 |
2.61 |
2.78 |
2.91 |
3.02 |
3.12 |
3.21 |
3.29 |
3.36 |
3.39 |
| 60 |
1.67 |
1.85 |
1.96 |
2.04 |
2.11 |
2.17 |
2.22 |
2.26 |
2.30 |
2.33 |
2.36 |
| ¥ |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
1.00 |
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ANOVA?
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to two-way ANOVA?
|