Known groups method is a typical method to support construct validity and is provided when a test can discriminate between a group of individuals known to have a particular trait and a group who do not have the trait. Similarly, known groups may be studied using groups of individuals with differing levels/severities of a trait. Again the known groups methods will evaluate the test’s ability to discriminate between the groups based on the groups demonstrating different mean scores on the test. For example, a group of individuals known to be not depressed should have lower scores on a depression scale then the group known to be depressed. Foundations of Clinical Research: applications to practice, Portney LG, Watkins M, 3rd ed. Prentice-Hall, 2008