Validation
Akin to but seemingly more than the SIP, the QWB appears to rely upon the appropriateness of its initial process of item development and selection. Kaplan et al. (1976) explain how an extensive specialty by specialty review of medical reference works was conducted to list all the ways diseases and injuries could affect behaviour and role performance. This lead to items expressed in terms of behaviours (as opposed to capacities, as such phrasing was reported to cause under reporting of dysfunction), embodied in three functional scales, with survey instruments developed to classify a person into one only of the steps of each of the three scales.