Reliability And Validity (Including Responsiveness)

Abstract

Abstract An understanding of the reliability and validity of health-related quality of life (HRQoL) measurement is needed to develop or select the best HRQoL measures for any given application. This chapter summarizes reliability and validity, and how these properties are used to evaluate HRQoL survey instruments. Reliability refers to the extent to which a measure yields the same number or score each time it is administered, all other things being equal (i.e., true change has not occurred in the attribute being measured). Classical test theory regards observed responses as consisting of the sum of true score and error. True score for an individual is assumed to be invariant on repeated measurements. However, two parallel measurements will.