No abstract

The definition of disability is of interest to disability policymakers and analysts because it has fundamental implications for eligibility for public programs, for the scope of legislation, and for the way disability prevalence is measured. The purpose of this article is to assess how an approach developed in economics to analyze issues related to the standard of living, the so-called capability approach, may help us understand disability at the conceptual level. The article first summarizes different theoretical models of disability (the medical model, the social model, the Nagi model, and the International Classification of Functioning, Disability and Health of the World Health Organization) and then presents the main components of the capability approach. The capability approach allows researchers to analyze (a) disability at the capability level; (b) potential disability; and, at the functioning level, (c) actual disability. This framework also helps explain how disability may result from three types of factors: the in-dividual's personal characteristics (e.g., impairment, age, race, gender), the individual's resources, and the individual's environment (physical, social, economic, political). The article explores some implications of the capability approach for analyzing the employment and the standard of living of persons with disabilities.

More quantitative evidence is needed using rigorous methods, for instance evidence based on longitudinal data and as part of policy evaluations. More internationally comparable data on disability is required for the quantitative evidence to develop, especially in low- and middle-income countries where studies are scarce. Qualitative and participatory research is also needed, especially to investigate unmet needs, and the consequences of extra costs.

Disability is found to be highly prevalent among adults, with an estimated global prevalence at 14%. Disability deserves enhanced policy attention and resources in public health and international development.