One-tailed vs two-tailed tests

A one-tailed test checks for an effect in a specific direction—either greater than or less than a certain value—indicating a particular hypothesis. For example, testing if a new drug improves recovery time. A two-tailed test looks for any difference, whether the effect is better or worse, without specifying direction. For instance, testing if a new method changes results in either way. The main difference is the focus: one-tailed tests detect effects in one direction, while two-tailed tests consider both directions, offering a more general assessment of differences or effects.