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Who are participants?
The information gathered by NHANES provides a snapshot of the health and nutrition of the U.S. population. Because of this, persons in this survey are from a broad range of age groups and racial/ethnic backgrounds. Each participant represents approximately 50,000 other U.S. residents. The identities of our participants are held strictly confidential.

How was I selected?
Participants are selected through a complex statistical process using the most current Census information. In simple terms, NHANES divides the United States into communities. The communities are divided into neighborhoods. The neighborhoods are selected at random. From each neighborhood, housing units are selected at random.  Selected households are approached by our interviewers who ask residents a few short questions to determine if their household is eligible for the study. (You may have received our introductory letter, sent to "resident" at your home address.)

You have a unique health profile; if you are selected to be a participant, no other person can be substituted for you.  You were selected based on your age, gender, and racial/ethnic background.  No one can take your place in this survey.

How do I know this is a legitimate survey?
NHANES History - NHANES has a long history; it has been in existence since the early 1960s and has surveyed over 140,000 people. NHANES was born out of The National Health Survey Act, 1956. This law authorized a survey to provide current statistical data on the amount, distribution, and effects of illness and disability in the United States.

Past Participants - Participants have gained new insight into their health and have enjoyed taking part in the survey. The feedback we have received from participants includes:

bullet graphic"My daughter and I went through the survey and exam and we were both glad we did it. Everyone was so nice."

bullet graphic"I was impressed by how professional everyone was."

bullet graphic"I think it is great that the government helps keep us informed about health issues."

bullet graphic"I was impressed by all of the high tech equipment."

Other Organizations - Additionally, many national and local organizations, such as the AARP, NAACP, and the National Council of La Raza endorse NHANES through letters of endorsement.

Staff - The NHANES staff consist of professional individuals with a variety of health, research, and academic backgrounds. The staff at the mobile examination center include: a doctor, a phlebotomist, health technicians and highly trained interviewers. The home interviewers have varied backgrounds in fields such as social work, the military, and education.  The staff at headquarters include: medical doctors, PhDs, nurses, health educators, and engineers.

Is my information confidential?
Public laws keep all information participants give confidential. We will hold all data we collect in the strictest confidence. We gather and protect all information in keeping with the requirements of Federal Law: the Public Health Service Act (42 USC 242k) authorizes collection and Section 308(d) of that law (42 USC 242m), the Privacy Act of 1974 (5 USC 552A), and the Confidential Information Protection and Statistical Efficiency Act (PL 107-347)prohibit us from giving out information that identifies you or your family without your consent. This means that we cannot give out any fact about you, even if a court of law asks for it. We will keep all survey data safe and secure. When we allow researchers to use survey data, we protect your privacy. We assign code numbers in place of names or other facts that could identify you.

What are the Benefits of Participating?
Examination - Many of the measurements and tests performed in the Mobile Exam Center are unique, and they are not commonly done in doctor's offices during routine physical exams. The DXA body scan is used to measure bone density.  This is a chance for you to have many important tests and gain additional health information about yourself.  These tests are done at no expense to you. To determine which tests you will have click here.

**This exam is not a substitute for your regular health care examination.

Report of Findings - You will receive results from your examination.  You will get a preliminary report of findings when you leave the mobile exam center.  Some results, like those for sexually transmitted disease (STD) tests are not put in writing but you will be given a toll-free number, a password, and the dates to call for your results. A final report of findings will be sent to you in the mail 12-16 weeks after your exam. These results are yours to discuss with your doctor or keep for your own medical records.  To view an example of a Final Report of Findings click here. Your Final Report of Findings will be mailed to your home.

Contributing to the Health Knowledge in the U.S. - Information gathered from NHANES has been used to influence policy and improve the health of the U.S. population in many ways.  Data Accomplishments

A Cash Remuneration - All participants, regardless of age, are given a cash payment as a "thank-you" for their time and effort. NHANES will also reimburse participants for transportation and baby/elder care.

What is Involved in Participating?
There are two main parts to this survey, the home interview and the health examination.

The Interview
An NHANES interviewer will come to your home to talk to you about the survey. This interviewer should present a photo identification badge which identifies this person as being from the National Health and Nutrition Examination Survey.  The interviewer will ask you a few questions to see if you qualify to participate. If you do, the interviewer will set up an appointment with you for an in-home interview. During this interview you will be asked questions about your health, disease history, and diet. The interview is approximately one hour and responses are recorded on a laptop computer.

Examples of  questions:

bullet graphicHas a doctor or other health professional ever told you that you had arthritis?

bullet graphicHave you heard of MyPyramid?

Again, anything you say during this interview is confidential.  At the end of your interview, an appointment will be made at our Mobile Examination Center.

The Health Examination
The Mobile Exam Center (MEC) is made up of four trailers, linked sideways, which contain high-tech medical equipment. The MEC is situated in a location convenient for participants. The NHANES staff can help you with transportation to the MEC if needed.  To view the MEC, click here for a virtual tour.

You will have a health examination consisting of a number of measurements and tests. The exams  will depend on your age and gender and current medical conditions. To determine which tests you will have click here.

**This exam is not a substitute for your regular health care examination. There will be no invasive internal exam and no drug testing.

Who can I contact if I have questions?
To discuss any aspect of the survey, you can make a free call to Dr. Kathryn Porter of the U.S. Public Health Service at 1-800-452-6115.  If you have questions about your rights as a survey participant, call the Research Ethics Review Board at the National Center for Health Statistics at 1-800-223-8118. Leave a brief message containing your name, phone number, and your NHANES survey concerns. Your call will be returned as soon as possible. Thank you.


This page last reviewed October 25, 2007

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Centers for Disease Control and Prevention
National Center for Health Statistics
Hyattsville, MD