"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."


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 Further, "accuracy" as a synonym for validity reflects an outdated conceptualization of validity, which has been superseded by one that emphasizes that validity tells us what conclusions can be drawn about a person based on a test result.


CONCLUSIONS
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.
Baycrest Centre for Geriatric Care, Department of Psychiatry, Kunin-Lunenfeld Applied Research Unit, University of Toronto, 3560 Bathurst Street, Toronto, Ontario M6A 2E1, Canada. dstreiner@klaru-baycrest.on.ca
David L
DL
Streiner
Geoffrey R
GR
Norman
D006305:Health Status Indicators; D006801:Humans; D015588:Observer Variation; D015203:Reproducibility of Results; D009626:Terminology as Topic