Lawshe Content Validity Ratio

The Lawshe content validity ratio (CVR) is a simple, quantitative method for judging whether the items of a test or measure actually represent the content they are meant to cover, based on the agreement of a panel of subject-matter experts. Charles Lawshe introduced it in 1975 to address a gap in personnel testing: content validity had long been treated as a matter of judgment with no number attached, leaving practitioners unable to defend item retention decisions objectively. Lawshe's insight was to ask experts a focused question, is this item essential, useful but not essential, or not necessary, and to convert the proportion who call an item essential into a ratio that ranges from minus one to plus one. Items whose CVR exceeds a critical value tied to panel size are retained, and the average CVR of retained items gives a content validity index for the whole instrument. The method's clarity made it a durable standard in test development. It is especially common in human resources, nursing, and health-measure validation.