The inflation of Type I error rates is thought to be one of the causes of the replication crisis. Questionable research practices such as p -hacking are thought to inflate Type I error rates above their nominal level, leading to unexpectedly high levels of false positives in the literature and, consequently, unexpectedly low replication rates. In this article, I offer an alternative view.

In this paper (Rubin, 2022), I make two related points: (1) researchers should halve two-sided p values if they wish to use them to make directional claims, and (2) researchers should not halve their alpha level if they’re using two one-sided tests to test two directional null hypotheses.