National Health Interview Survey (NHIS)

Years Available
1957 to present
Mode of Collection
Sample survey: personal interviews in households using computer-assisted personal interviewing (CAPI).
The National Health Interview Survey (NHIS) monitors the health of the civilian non-institutionalized U.S. population through the collection and analysis of data on a broad range of health topics. A major strength of this survey lies in its ability to analyze health measures by many demographic and socioeconomic characteristics. During household interviews, NHIS obtains information on activity limitation, illnesses, injuries, chronic conditions, health insurance coverage (or lack thereof), utilization of health care, and other health topics.
Selected Content
In 2019, the NHIS questionnaire was redesigned to increase relevance, enhance data quality, and minimize respondent burden. It consists of fourcomponents: the annual core, rotating core, sponsored content, and emergingcontent. The annual core contains the same questions from year to year, andthese questions focus on demographic characteristics, health insurance, chronicconditions, health care access and use, health-related behaviors, andfunctioning and disability. The rotating core consists of questions that will be included in the interview periodically and include expanded content onmental health, service utilization, preventive services, health relatedbehaviors, injuries, and chronic pain. Sponsored content, funded by otherfederal agencies, has included questions on food security, cancer control andprevention, complementary and integrative health, noncigarette tobacco productuse, and immunizations. Emerging content includes new topics of growinginterest that may be added by NCHS, generally for one year.
Population Covered
The U.S. civilian noninstitutionalized population.
NHIS is a cross-sectional household interview survey. Data are collected continuously throughout the year from January to December. Sample is distributed across all 50 states and the District of Columbia approximately proportional to population size. The sample design follows a probability design that permits the representative sampling of households and certain non-institutional group quarters. The sample design is redesigned approximately every 10 years; a new sample design was implemented in 2016. Data are comparable between the current and previous 2006-2015 sample design. In January 2019, the NHIS implemented a redesigned questionnaire and survey structure. One "sample adult" aged 18 years or older and one "sample child" aged 17 years or younger (if any children live in the household) are randomly selected from each household following a brief screener that identifies the age, sex, race, and ethnicity of everyone who usually lives or stays in the household. Information about the sample adult is collected directly from the sample adult, while information about the sample child is collected from a parent or adult who is knowledgeable about and responsible for the health care of the sample child. Much of the content that was previously collected in the family section of the survey is now collected within the sample adult and sample child questionnaires. The 2019 questionnaire redesign and the anticipated resulting break in trends for a number of estimates provided an opportunity to evaluate weighting processes that had been in place since 1997. Based on that evaluation, the 2019 weighting process was updated to include person-level weighting classes based on response propensity and calibration based on more detailed demographic data. Starting from 2019, data are weighted to produce national estimates using the following components: the reciprocal of the probability of selection; household- and person-level nonresponse adjustments based on the inverse of the median response propensity within the propensity quintile, and raking adjustments to the U.S. population by age, sex, race-ethnicity, education, Census Division and MSA.
Response Rates and Sample Size
An estimated 27,000 sample adult and 9,000 sample child interviews are expected to be available annually for analysis in the 2019 redesigned NHIS. Response rates for the 2019 NHIS are not yet available. The redesign allows for data users to pool two or more years of sample if needed to produce reliable estimates for population subgroups.
Interpretation Issues
The 2019 questionnaire redesign may create comparability issues in trend data before and after the redesign.