Since 1957, the National Center for Health Statistics (NCHS) annually conducts a National Health Interview Survey (NHIS), which consists of a core questionnaire and supplements. The core questionnaire is aimed at a continuous assessment and analysis of health trends in the United States, and its topics--basic health, socioeconomic, and demographic data--do not vary much across years. Each year, one or more supplements are added to this core questionnaire to reflect public health data needs. Recent supplement topics included cancer risk factors, youth risk behaviors, knowledge and attitudes about AIDS, and child health.

The 1994-1995 National Health Interview Survey on Disability (NHIS-D) was one of the supplements to the 1994 and 1995 NHIS core questionnaires. Due to the low prevalence of disabilities among noninstitutionalized civilians, the NHIS-D was collected over two years, from January 1994 to December 1995. The NHIS-D was designed to meet the need for data on the prevalence and nature of disability in the U.S. since the establishment of the Americans with Disabilities Act (ADA) in 1990. One of the main objectives of the NHIS-D was to develop a survey instrument that would provide useful disability measures while accommodating social, administrative, and medical considerations, so that the data could be analyzed by a variety of agencies and programs. Also, the NHIS-D was designed to collect data to facilitate public health policy and provide descriptive baseline statistics on the effects of disabilities. The NHIS-D, Phase I questionnaire was administered at the same time as the NHIS core questionnaire and the other supplements. Given the limited amount of time allocated for the disability supplement, the NCHS decided to conduct a two-phase data collection with two separate questionnaires on disability. Eligibility for the NHIS-D, Phase II was based on the responses to the Phase I disability supplement, as well as the core questionnaire topics on activity limitation, and the family resource supplement regarding the receipt of disability benefits. The Phase II survey began in August 1994 with sample numbers of 20,410 in 1994 and 12,378 in 1995, and it was completed in 1997. This follow-up survey data on disability (1994-1995 NHIS-D, Phase II) will be archived in RADIUS during fall of 1998 and will include ID variables for linking Phase I and II datasets.

The sample size for Phase I is 202,560 (107,469 in 1994 and 95,091 in 1995). The decrease in sample size for the 1995 survey reflects a change in the sample design as well as the federal government furlough, which reduced the time for data collection.