Tukey's Honestly Significant Difference (HSD)
David Mark Lane
The Tukey's honestly significant difference test (Tukey's HSD) is used to test differences among sample means for significance. The Tukey's HSD tests all pairwise differences while controlling the probability of making one or more Type I errors. The Tukey's HSD test is one of several tests designed for this purpose and fully controls this Type I error rate. Other tests such as the Newman −Keuls lead to an inflated Type I error rate in some situations. This entry describes how to conduct and interpret the Tukey's HSD test. It is rare for any two experimental treatments to have identical effects. For example, it is implausible that two drug treatments could produce the same relief from depression if measured to 100 decimal places. As a result, the role of inferential statistics in these situations is not to reject the null hypothesis of no difference, because that hypothesis is false on its ...