Next section: Introduction to pairwise comparisons

The probability that at least one of the tests will result in a Type I error is called the experimentwise error rate (EER). Statisticians differ in their views of how strictly the EER must be controlled. Some statistical procedures provide strict control over the EER whereas others control it to a lesser extent. Naturally there is a tradeoff between the Type I and Type II error rates. The more strictly the EER is controlled, the lower the power of the significance tests.

The remaining sections in this chapter discuss tests used to supplement the finding of a significant ANOVA. Pay particular attention to the tradeoffs among three conflicting goals:

- to extract all information from the data that is
meaningful,
- to control the EER, and
- to achieve a high level of power.

Next section: Introduction to pairwise comparisons