“Precision” and “Accuracy”: Two Terms That Are Neither

OBJECTIVE: In some publications, the terms "precision" and "accuracy" are used as if they were synonyms for "reliability" and "validity." METHODS AND RESULTS: This article shows that these terms are neither precise nor accurate when used in this way. Scales can demonstrate high test-retest or interrater reliability (i.e., they are "precise") but still be unreliable in certain circumstances; and "imprecise" scales can still show good reliability. Further, "accuracy" as a synonym for validity reflects an outdated conceptualization of validity, which has been superseded by one that emphasizes that validity tells us what conclusions can be drawn about a person based on a test result. CONCLUSION: The article ends with a call for the use of the more traditional terms as better reflecting the process of scale development and the uses to which they are put.