Researchers interested in determining differences between the means of groups often employ analysis of variance (ANOVA) as a first test to determine whether differences exist. When the ANOVA test indicates that differences do exist among the group means, the next step involved is identifying which group means differ. This is typically done using either contrast tests or post hoc tests on the mean. One popular post hoc test to determine which group means differ is the Bonferroni procedure, named for Carlo E. Bonferroni, the Italian statistician who popularized the approach in the early 20th century. This entry further describes the procedure and how it is used to deal with experiment-wise error rates and for multiple comparisons.

The Bonferroni procedure is a very important tool in statistical ...