Welcome NHIS Participants

If you have already been a survey participant, thank you! If you have been notified that your household has been selected for the National Health Interview Survey (NHIS) and you are thinking about becoming a survey participant, we hope these answers to some frequently asked questions will help you understand why your participation is so important. In order for the results from the NHIS to accurately represent the health of the nation, respondents selected must be from a random sample. If you were selected to participate in this survey, your answers count toward finding out about the health of our nation.

The National Center for Health Statistics (NCHS), a part of the U.S. Centers for Disease Control and Prevention (CDC), is responsible for this survey. It is a nationwide survey concerned with the health of the U.S. population and factors that affect people’s health.

What is the National Health Interview Survey?

The National Health Interview Survey (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 (NCHS), which is part of the U.S. Centers for Disease Control and Prevention (CDC).

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

Click here to download a copy of the NHIS brochure [PDF - 712 KB], which provides more information about the survey.

Why is this survey being conducted?

The main objective of the NHIS is to monitor the health of the U.S. population through the collection and analysis of data on a broad range of health topics. The National Health Survey Act of 1956 provided for a continuing survey and special studies to secure accurate and current statistical information on the amount, distribution, and effects of illness and disability in the United States and the services rendered for or because of such conditions. The NHIS was initiated in July 1957.

Why is it important to participate?

Your household was selected to represent thousands of other households like yours. Your address is part of a scientifically chosen sample. 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 country.

What type of information is collected?

The NHIS has several main sections. The Family Core questionnaire collects information on everyone in the family, including household composition; basic demographic characteristics such as age, sex, race and ethnicity, and income; health insurance coverage; information for linking to administrative data bases; and basic indicators of health status and utilization of health care services.

In addition, from each family in the NHIS, one sample adult and, if applicable, one sample child are randomly selected, and information on each is collected with the Sample Adult Core and the Sample Child Core questionnaires. Because some health issues are different for children and adults, these two questionnaires differ in some items, but both collect basic information on health status, health care services, and health-related behavior.

Also, each year, supplemental questions are added to collect more detailed information on core topics and/or to respond to new public health data needs as they arise. These supplements are sponsored by other agencies than NCHS.

Why ask questions about age, race, ethnicity, and income?

Age, race and ethnicity, and income are often associated with differences in health status and the use of health care services. A major strength of this survey lies in the ability to analyze health characteristics classified according to persons’ demographic and socioeconomic characteristics. For example, this information is very useful to analysts who are trying to understand differences in how we use health care services and to enable planners to direct resources to subpopulations most in need.

How do I know this is a legitimate survey?

The National Center for Health Statistics contracts with the U.S. Census Bureau, whose interviewers collect the survey data. All personnel involved with the collection of data are employed by the U.S. government. They have been trained by the U.S. Census Bureau according to procedures specified by NCHS and have signed a statement guaranteeing the confidentiality of your data. Each interviewer carries a badge identifying him/her as a U.S. Census Bureau employee.

Who asks the questions?

Data are collected through personal household interviews conducted by interviewers employed and trained by the U.S. Census Bureau according to procedures specified by NCHS.

Do I have to participate in the survey?

Participation by those randomly selected for the survey is very important to accurately represent all types of households and families in the United States, regardless of health status. Survey participation is voluntary; however, we cannot select anyone else to replace you if you were selected and do not participate, which may mean that households like yours are underrepresented in national estimates. The confidentiality of your responses is assured under Section 308(d) of the Public Health Service Act. Many people find the interview to be interesting and enjoyable. The annual response rate of NHIS is nearly 90% of the eligible households in the sample.

Who needs to participate in the interview?

For the Family questionnaire, all adult members of the household 17 years of age and over who are at home at the time of the interview are invited to participate and to respond for themselves. For children and for adults not at home during the interview, information is provided by a responsible adult family member (18 years of age and over) residing in the household.

For the Sample Adult questionnaire, one adult per family is randomly selected; these individuals must respond for themselves to the questions in this section unless they are physically or mentally incapable of answering. In that case, a knowledgeable adult in the family or a caretaker may answer the questions for the selected person.

Information for the Sample Child questionnaire is obtained from a knowledgeable adult in the household.

How long does it take?

The survey takes an average of about an hour to do all the parts, depending on the number and health of your family members.

Is my information kept confidential?

The confidentiality of responses is assured under Section 308(d) of the Public Health Service Act. The National Center for Health Statistics has many procedures in place to prevent the disclosure of your data to others. Some of these procedures include data encryption, secure data networks, and many other security mechanisms following strict federal mandates. Responses are collected by the U.S. Census Bureau and securely transmitted to NCHS, where the data undergo edits and removal of personal identifiers prior to being collected into public use files. The collected data are used for research and statistical purposes only. When analytic reports are prepared and released by NCHS staff, your answers have been combined with those of many other respondents. No information that could identify any individual is publicly released. More information on how your privacy is respected is available here.

How are NHIS data and reports released to the public?

Data from the 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 NCHS staff, individual answers have been combined with those of many other respondents, which safeguards the privacy of the individuals 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

How can I contact you for more information?

For more information about the NHIS, recent reports, and data, visit the NHIS website or call or write to us at:

Division of Health Interview Statistics
National Center for Health Statistics
Centers for Disease Control and Prevention
3311 Toledo Road, Room 2217
Hyattsville, Maryland 20782-2003
(301) 458-4901 or (301) 458-4001

You may also email us at NHIS@CDC.GOV

For publications and information:

Data Dissemination Branch
National Center for Health Statistics
Centers for Disease Control and Prevention
3311 Toledo Road, Room 5407
Hyattsville, Maryland 20782-2003
1 (800) 232-4636