operationalization of the concept. Alternative operationalizations are evident in the variety of types and numbers of questions used in various surveys to measure functioning and participation. Empirical evidence suggests that even minor variations in how one operationalizes the concept of disability can result in significant variations in the estimates of the population of persons with disabilities in the United States (see, for example, McNeil, 1993). Consideration of alternative design options for household-based survey measures of the population of persons with work disabilities requires that SSA invest in understanding how divergent measurement may affect estimates of the potential pool of applicants for SSA benefits as well as estimates of the population of potential beneficiaries.
The task of using household-based surveys for the measurement of persons with work disabilities is further complicated by the dynamic state of the field at the time of this writing. A number of research activities, both within the United States and internationally, related to the measurement of disability via the survey interview process, will most likely result in major changes to question wording and questionnaire design over the next decade. Several federal statistical agencies, including, but not limited to, the Bureau of Labor Statistics and the Bureau of Justice Statistics, are testing questionnaires to meet legislative or executive branch mandates related to the production of statistics by disability status. The adoption of the second revision of the International Classification of Impairments, Disabilities, and Handicaps (renamed ICIDH-2: International Classification of Functioning, Disability, and Health) by the 54th World Health Assembly provides a classification system and framework for the development of disability measures in surveys. Much of the international research on disability measurement is focused on the development of valid and reliable instruments that map conceptually to the ICIDH-2, including measurement of the environment. Other research activities are attempting to address gaps in the current state of knowledge concerning the measurement error properties of disability statistics
In light of the challenges facing SSA, this paper attempts to outline and discuss design options related to the measurement of persons with work disabilities and the measurement of persons eligible for SSA benefits. The paper examines a broad range of alternatives for SSA to consider, ranging from the development of its own data collection and measurement system3 to the use of other federal data collection efforts for ongoing monitoring. We begin by examining the disparities between the definition of persons with work disabilities used by SSA and the models