About
- The National Health and Nutrition Examination Survey (NHANES) selects a group of people to represent everyone across the country.
- NHANES measures the health of people in that group who participate in the survey.
- This page provides information about how we select potential participants.
Our survey sample
The National Health and Nutrition Examination Survey (NHANES) selects a survey sample to represent people of all ages across the country. A survey sample is a small group selected from a larger group to represent the larger group. The NHANES sample represents all people across the United States—the U.S. population.
We intentionally increase the number of people in our sample from certain groups who may have different health outcomes. This is called oversampling. Oversampling helps us produce statistics that accurately represent the U.S. population.
Examples of groups we have oversampled include people who are—
- Children and adolescents
- 60 and older
- African American
- Asian
- Hispanic
The aging population has major effects on healthcare needs, public policy, and research priorities. The National Center for Health Statistics is working with public health agencies to learn more about the health of older Americans. NHANES is an important source of data for these efforts.
What participating involves
We invite everyone who participates in NHANES to —
- Answer interview questions about their health
- Visit our mobile exam center
- Complete an interview about the food, drinks, and supplements in their diet
We take a blood sample from and perform a dental exam for all but the youngest participants. We determine what other medical tests and procedures we will perform based on each participant's age.
Participants receive a report of their medical findings and a token of appreciation for their time. We keep all information we collect strictly confidential. Participant privacy is protected by law.