NATIONAL HEALTH INTERVIEW SURVEY

The National Health Interview Survey (NHIS) is an ongoing survey conducted throughout the year by the National Center for Health Statistics (NCHS) to monitor the health of the nation.  It has been conducted since 1957. The NHIS data are collected through an in-person survey using computer-assisted personal interviewing (CAPI) in households. The target universe is the civilian noninstitutionalized population residing in the 50 states and District of Columbia.

The NHIS questionnaire was redesigned in 2019 and now consists of Sample Child and Sample Adult questionnaires that include questions from four content areas:

1. Annual core (asked every year)
2. Rotating core (asked in some but not all years),
3. Sponsored content (topics of interest funded by other federal agencies or CDC centers)
4. Emerging topics (newer topics of interest that have not been researched in the general population)

For 2016-2025, the NHIS sample design was expected to produce interviews from 27,000 Sample Adults and 9,000 Sample Children from about 35,000 households, though this varies by year. In 2022, the Sample Adult size was over 27,000, the Sample Child size was over 7,000 from nearly 29,000 households. The NHIS uses geographically clustered sampling techniques using a sampling plan based on the preceding decennial Census.

The sample for the NHIS represents the 50 states and the District of Columbia. However, the lowest level of geography available in the public-use data files is Census region. Restricted, state-level geography is available through the network of Research Data Centers. The household response rate is about 50 percent (Centers for Disease Control and Prevention 2022).

The NHIS asks the respondent about insurance status and coverage type at the time of the survey. This survey also asks if the respondent has been uninsured for at least part of the year prior to the interview and if the respondent has been uninsured for more than a year at the time of the interview. The question includes a comprehensive roll of insurance options that include public program names specific to the state in which the interview is conducted, as well as open-ended response options. A verification question is included to confirm that respondents who did not respond that they were enrolled in any insurance programs are, in fact, uninsured.