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 Further, '' accuracy '' as a synonym for validity reflects an Outdated conceptualization of validity, which has been superseded by one that emphasizes that validity tells us what Conclusions Can be drawn about a person based on a test result.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. (c) 2006 Elsevier Inc. All rights reserved.