Jan 1, 1992
Published in: Measuring Functioning and Well-Being: The Medical Outcomes Study Approach / edited by Anita L. Stewart and John E. Ware, Jr., (Durham, N.C.: Duke University Press, 1992), Chapter 18, p. 309-324
Posted on RAND.org on January 01, 1992
Validity refers to the extent to which a score measures what it is intended to measure and does not measure what it is not intended to measure, and the extent to which a measure is useful scientifically. Validity studies increase understanding of the meaning of a score and the meaning of differences or changes in that score. Validating a health measure or a set of health measures is the process of accumulating many different kinds of evidence to determine the most appropriate interpretation(s) of a health score. Because health measures can be used for different purposes, validity needs to be evaluated separately for each purpose. However, there are no standard guidelines available for validating health measures. The MOS team used standards derived from those used to validate psychological and education measures: content validity, content validity of a battery, content validity of a scale, criterion validity, criterion-related validity, predictive validity, construct validity, convergent validity, discriminant validity, multitrait-multimethod approach, known-groups validity, factorial validity, interpretability of scale scores, incremental validity, response bias, validity generalization. This chapter provides an overview of the essential steps in validating health measures, describes the present MOS approaches to validity, and suggests methods that can be undertaken in the future. This approach to validity is comprehensive. The health measures in the MOS were derived from measures that have been widely used and validated. The validity history of a measure is thus an important component. The chapter is useful as a methodological guide to others attempting to validate health measures. Specific standards for validating health measures need to be developed and published. This chapter is intended to provide a first step toward published guidelines.