One-way ANOVA
Are three teaching methods equally effective?
Method A — mean 76.0
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Method B — mean 82.0
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Method C — mean 72.0
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Grand mean = 76.7. Between-group variability: 253.3. Within-group variability: 120.0.
| Source | SS | df | MS | F |
|---|---|---|---|---|
| Between | 253.3 | 2 | 126.7 | 12.67 |
| Within | 120.0 | 12 | 10.0 | — |
| Total | 373.3 | 14 | — | — |
Fail to reject H₀ (F = 12.67 ≤ 19.45) — methods look equal.
Critical F(0.05, 2, 12) = 19.45. ANOVA compares group means by comparing two variance estimates.