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Welcome NHANES Participants


If selected for this survey, your participation is important.


How was I selected?

Selection Stages diagram
Stage 1 All the counties in the United States are divided into 15 groups based on their characteristics. One county is selected from each large group, and together they form the 15 counties in the NHANES surveys for each year.
Stage 2 Within each county, smaller groups (with a large number of households in each group) are formed, and between 20 and 24 of these small groups are selected.
Stage 3 All of the houses or apartments within those selected small groups are identified, and a sample of about 30 households are selected within each group.
Stage 4a NHANES interviewers go to each selected household and ask for information (age, race, and gender) on all persons in the household.
Stage 4b A computer algorithm randomly selects some, all, or none of the household members.


What does participation involve?

First, we find out if you’re eligible. An NHANES interviewer will come to your home and ask you a few questions about you and the other members of your household. NHANES interviewers always have identification with them that they will show you immediately. Once you answer a few questions, the interviewer will let you know if you are needed to participate further. Click here if you are asked to participate in the next stage.


What are the benefits to me and my family?

If you participate in NHANES, you will find out more about your overall health and the health of your family than you ever would at a routine doctor’s visit. Your interviewer will explain the benefits of participation with you.


How do you keep my information secure?

NCHS is committed to protecting your privacy. More information on confidentiality can be found in our Confidentiality Brochure.


How do I know this is a legitimate survey?

NHANES has a long history (see history of NHANES); it has been in existence since 1960 and has surveyed over 190,000 people. NHANES was born out of the 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. Many organizations support our survey. For a full list of organizations that endorse NHANES, see letters of endorsement.


Watch the Participant Video


Who can I contact if I have questions?

To discuss the survey or to speak to our Senior Medical Officer, call us 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 concerns. Your call will be returned as soon as possible.
Thank you.