Holm’s sequential Bonferroni procedure is a statistical procedure used to correct familywise Type I error rate when multiple comparisons are made. A more robust version of the simple Bonferroni correction procedure, Holm’s sequential Bonferroni procedure is more likely to detect an effect if it exists. This entry describes the rationale of the Holm’s sequential Bonferroni procedure and the steps to conduct it.

In 1978, Sture Holm invented Holm’s sequential Bonferroni procedure, as an adjustment to the simple Bonferroni procedure. When a researcher achieves statistical significance on an overall test involving three or more groups, post hoc tests are used to determine which pairs are significantly different statistically. In post hoc tests, the critical levels for all paired comparisons have to be adjusted, so that the overall ...