2019–present. The National Health Interview Survey (NHIS) is a nationally representative household health survey of the U.S. civilian noninstitutionalized population. The NHIS data are used to monitor trends in illness and disability, track progress toward achieving national health objectives, for epidemiologic and policy analysis of various health problems, determining barriers to accessing and using appropriate health care, and evaluating Federal health programs. NHIS is conducted continuously throughout the year by the National Center for Health Statistics (NCHS). Public-use data files on adults and children with corresponding imputed income data files, and survey paradata are released annually. The NHIS data website (https://www.cdc.gov/nchs/nhis/data-questionnaires-documentation.htm) features the most up-to-date public-use data files and documentation for downloading including questionnaire, codebooks, CSV and ASCII data files, programs and sample code, and in-depth survey description. Most of the NHIS data are included in the public use files. NHIS is protected by Federal confidentiality laws that state the data collected by NCHS may be used only for statistical reporting and analysis. Some NHIS variables have been suppressed or edited in the public use files to protect confidentiality. Analysts interested in using data that has been suppressed or edited may apply for access through the NCHS Research Data Center at https://www.cdc.gov/rdc/. In 2019, NHIS launched a redesigned content and structure that differs from its previous questionnaire designs. NHIS has been conducted continuously since 1957.

NCHS has linked data from various surveys with death certificate records from the National Death Index (NDI). Linkage of the NCHS survey participant data with the NDI mortality data provides the opportunity to conduct a vast array of outcome studies designed to investigate the association of a wide variety of health factors with mortality. The Linked Mortality Files (LMF) have been updated with mortality follow-up data through December 31, 2019.

Public-use Linked Mortality Files (LMF) are available for 1986-2018 NHIS, 1999-2018 NHANES, and NHANES III. The files include a limited set of mortality variables for adult participants only. The public-use versions of the NCHS Linked Mortality Files were subjected to data perturbation techniques to reduce the risk of participant re-identification. For select records, synthetic data were substituted for follow-up time or underlying cause of death. Information regarding vital status was not perturbed.

The Research and Development Survey (RANDS) is a series of cross-sectional surveys using probability-sampled commercial survey panels. The seventh round of RANDS (RANDS 7) was administered by NORC at the University of Chicago using the AmeriSpeak Panel from November 3, 2022 to December 12, 2022. RANDS 7 contained the embedded probe questions and experiments as in previous rounds of RANDS. It included questions on firearm safety, chronic health conditions, and health and civic behaviors, and questions related to gender identity, traumatic brain injury and long symptoms of coronavirus disease (COVID-19). RANDS 7 has a known survey sampling design and can be used to produce nationally and sub-nationally representative estimates.