From 1963 through 1996, the NHIS questionnaire was printed as a paper booklet. The interviewer read the questions and wrote the answers in the booklet. Results were subsequently keyed into a computer in preparation for data processing.
From 1997 through 2003, the NHIS used CASES software for computer-assisted personal interviewing (CAPI). The interviewer read the questions from a laptop screen and entered the responses directly into the laptop.
In 2004, the NHIS CASES software was replaced by BLAISE CAPI software. This technology continues to the present.
Major changes in physical activity questions
In 1975, questions on leisure-time physical activity were first introduced in the NHIS as part of a special topic supplement.
In 1985, the NHIS became the federal government's tool for monitoring progress toward National Health Objectives for Physical Activity. A set of questions about more than 22 leisure-time sports activities, including frequency, duration, and intensity of each activity during the past 2 weeks, was included in supplements variously titled "Health Promotion and Disease Prevention" and "Healthy People" that were fielded in 1985, 1990, 1991, 1995, and 1998.
In 1997, questions on usual leisure-time physical activity were first included in the NHIS annual core questionnaire, in the Sample Adult component. These questions have remained unchanged since mid-year 1997.
In 1998, the NHIS questionnaire included both the 2-week sports activity questions (in the Healthy People supplement questionnaire) and the usual leisure-time physical activity questions (in the annual Sample Adult core questionnaire). Both sets of questions were asked of the same sample adult respondents in the same interview. For a comparison of these two physical activity measures, see Comparison of Two Sets of Physical Activity Questions.