Section 12.1 Summary

1. Analysis of variance (ANOVA) is an inferential method for testing whether the means of different populations are equal. The null hypothesis always states that all the population means are equal, and the alternative hypothesis always states that not all the population means are equal. ANOVA works by comparing (a) the variability in the sample means and (b) the variability within each sample. If (a) is large compared with (b), this is evidence that the true means are not all equal and we should reject the null hypothesis.
2. ANOVA is usually performed using the -value method and technology.