Holm Correction (Holm-Bonferroni)

The Holm correction, introduced by Sture Holm in 1979, is a step-down multiple-comparison procedure that controls the family-wise error rate (FWER) at level α while rejecting at least as many hypotheses as the classical Bonferroni correction. It orders the observed p-values from smallest to largest and compares each against a threshold that starts strict and relaxes as testing proceeds, making it uniformly more powerful than Bonferroni at the same level of error control.