An introduction to test theory.

A basic understanding of test theory is an important prerequisite before one may create or use a scale to measure behavior. This paper provides a basic review of the tenets of measurement theory. Descriptions of the different types of reliability (i.e., test-retest, parallel forms, split-halves, internal consistency) and validity (content, criterion-related, and construct) are defined and explained. Suggestions for test construction are advanced and techniques of generating and then narrowing a large pool of preliminary items are discussed. Finally, specific questions that should be asked before a test is used in a clinical or research setting are proposed.