Null Hypothesis Significance Testing Does Not Show Equivalence

Abstract

Null hypothesis significance testing (NHST) allows researchers to find differences between groups, such as differences between men and women, Blacks and Whites, or heterosexual and same-sex couples. In contrast, this article will show that NHST is mathematically incapable of allowing researchers to conclude that two groups are the same. Because of this, NHST leads to a research literature that emphasizes differences between groups and ignores similarities. To examine similarities between groups, either Bayesian statistics or confidence intervals should be used. Thus, Frost and Gola (2015) should have used one of these approaches when examining similarities between heterosexual and same-sex couples.