Frequently Ask Questions

The National Health Interview Survey (NHIS) has monitored the health of the nation since 1957. NHIS data on a broad range of health topics are collected through personal household interviews. The survey’s main goal is to monitor the health of the U.S. population by collecting and analyzing data on health topics ranging from health insurance and doctor’s office visits to medical conditions, physical activity, and other health behaviors.

NHIS is a national survey conducted by the U.S. Census Bureau on behalf of the National Center for Health Statistics. NHIS is the principal source of information on the health of the civilian noninstitutionalized population of the United States and is one of the major data collection programs of the National Center for Health Statistics, which is part of the Centers for Disease Control and Prevention.

NHIS data are collected through personal household interviews. For more than 50 years, interviewers from the Census Bureau have visited homes in America to ask about a broad range of health topics. Survey results have been essential in providing data to track health status, health care access, and progress toward achieving national health objectives.

Survey results provide essential data to track the health status and health care access for all Americans.

NHIS data are important for monitoring progress toward national health objectives, evaluating health policies and programs, and tracking changes in health behaviors and health care use.

Government agencies, universities, private health planners, and researchers need and use NHIS data to identify and solve the nation’s health problems. The data are also used to determine how best to use available dollars and personnel to solve these health problems.

While best known for its 10-year population counts, the U.S. Census Bureau conducts many surveys. It has been collecting data for NHIS since the early 1960s. For more information from the Census Bureau about NHIS, click here.

Congress authorized the NHIS data collection in Section 306 of the Public Health Service Act (42 United States Code [U.S.C.] 242k). The U.S. Census Bureau is conducting this survey on behalf of the National Center for Health Statistics under the authority of Title 13, U.S.C., Section 8(b).

A household selected for NHIS will first receive a letter from the director of the National Center for Health Statistics. The letter provides information about the survey and informs the resident(s) that they can expect to be contacted by a U.S. Census Bureau interviewer in the near future.

The Census Bureau interviewer will conduct the interview at the respondent’s convenience. That means, if the respondent works, the interview can be scheduled after business hours or on the weekend. If daytime is preferable, that time can also be arranged. The survey takes an average of about 1 hour to do all the parts, depending on the size and health of family members.

The survey covers a wide range of topics like doctor visits, medical conditions, health insurance, physical activity, and injuries. We also ask questions that help us better understand the health information you give. For example, we ask about race, income, and permission to combine your answers with information from other places, like medical records. Most people have no difficulty with any of the questions in NHIS. However, others find some questions to be sensitive. You do not have to answer any questions you don’t want to.

The U.S. Census Bureau selected addresses across the entire country using scientific methods so that they represent all communities in the United States. Your household was selected to represent thousands of other households like yours. We cannot select anyone else if you do not participate, which may mean that households like yours are underrepresented in national estimates. These estimates are used by policy makers to determine needs for health services in our country. By participating, you perform a valuable public service for your family, community, and nation.

If you wish to verify that your address was selected for this survey, you can contact your Census Bureau Regional Office and they can verify for you whether your address was selected for a particular survey.

All Census Bureau employees identify themselves by name and carry a badge identifying him or her as a U.S. Census Bureau employee. They will be carrying a laptop with the Census Bureau logo on it to conduct the survey.

If you receive a call and wish to verify that the caller is a Census Bureau employee, you can call one of the regional offices or you can use the staff search on the Bureau’s website.

This is a survey of the nation’s health. We want to know how many people are sick and why they are sick. We also want to know how many people are healthy and what makes them healthy. Everyone’s answers are important.

Survey participation is voluntary. However, if you choose not to participate, we cannot select anyone else to replace you. This means that households like yours may be underrepresented in national estimates.

We take your privacy very seriously. We combine your answers with other people’s answers in a way that keeps everyone’s identity secret.

As required by federal law, your identity can be seen only by those NCHS employees and specially designated agents (such as the U.S. Census Bureau) who need that information for a specific reason. No one else can see your answers until all information that could identify you or your family has been removed.

Congress authorized the NHIS data collection in Section 306 of the Public Health Service Act (42 U.S.C. 242k). Strict federal laws prevent us from releasing information that could identify you or your family to anyone else without your permission. These laws are: Section 308(d) of the Public Health Service Act (42 U.S.C. 242m(d)); the Confidential Information Protection and Statistical Efficiency Act (CIPSEA, Title 5 of Public Law 107-347); and the Privacy Act of 1974 (5 U.S.C. § 552a).

Every National Center for Health Statistics employee, contractor, research partner, and agent has taken an oath to keep your information private. Anyone who willfully discloses ANY identifiable information about ANYONE in the survey could get a jail term of up to 5 years, a fine of up to $250,000, or both. Per the Federal Cybersecurity Enhancement Act of 2015 (6 U.S.C. §§ 151 & 151 note), your data are protected from cybersecurity risks through screening of the systems that transmit your data.

The responses that are collected from surveys conducted by U.S. Census Bureau field representatives and contact center staff are encrypted, both in transit and at rest on the Census Bureau’s servers. These servers are part of a stand-alone network that is not accessible by the Internet. These servers are constantly monitored for any signs of intrusions.

Data from NHIS, including your contribution if you participated in the survey, are collected into microdata files that are edited to remove all personal identifiers. These edited files are released to the public through the NHIS website. The data from these files are also statistically analyzed, and the results are published in several types of reports that are released over the Internet or in journal articles.

The collected data are used for research and statistical purposes only. When analytical reports are prepared and released by National Center for Health Statistics staff, individual answers have been combined with those of many other respondents, which safeguards the privacy of the persons who responded to the survey. No information that could identify any individual is publicly released.

More information about the available microdata files and reports is found on the NHIS website.

Depending on your question, you may wish to contact different resources.