Statistical notes for clinical researchers: post-hoc multiple comparisons

For comparison of three or more group means we apply the analysis of variance (ANOVA) method to decide if all means are equal or there is at least one mean which is different from others. If we get a significant result, we can conclude a global decision that there is difference in group means. However then we need to know what specific pairs of group means show differences and what pairs do not. The procedure is performed by post-hoc multiple comparison procedures.