Assess the difference between one-tailed and two-tailed tests with examples.

Week 1 discussion | Statistics For Research Methods I

A one-tailed test is a statistical test that tests the difference between two values in a single direction. This means that the null hypothesis can only be rejected when the data suggests that there is an effect in one direction (either higher or lower). For example, if you are testing whether students who take a test prep course score higher on an exam than those who do not, then a one-tailed test would be used to determine if they scored significantly higher.

A two-tailed test is similar to a one-tailed test except it tests for differences in both directions. This means that the null hypothesis can be rejected if the data suggests there is an effect in either direction (higher or lower). For example, if you are testing whether students with different levels of prior knowledge score differently on an exam, then a two-tailed test would be used to determine if their scores were significantly different from each other.