Sample Selection Brochure

WHERE website?
HOW contact?

ATTACHMENT
13c

NHANES
website

National Health and Nutrition
Examination Survey

https://www.cdc.gov/nhanes

How are NHANES

participants selected?

Contact information
For more information
about the National Center
for Health Statistics, contact:
National Center for
Health Statistics
Information Dissemination Staff
3311 Toledo Road,
Room 4551, MS P08
Hyattsville, MD 20782-2064
CS306030

Telephone: (800) 232–4636
E-mail: cdcinfo@cdc.gov
Internet:
https://www.cdc.gov/nchs
For more information about
the National Health and
Nutrition Examination
Survey, visit the NHANES
website at
https://www.cdc.gov/nhanes

participants selected?
Neighborhoods

WHY me?

HOW was I selected?

How are NHANES

Why was I selected?
The U.S. population is made up of different types of people. In
order to produce reliable health statistics, each type of person
must be adequately represented in the sample. Every step in
selecting a particular person is a random selection. Each
person selected may represent as many as 65,000 or more
similar people in the United States. Similar to winning a lottery,
the chance of being selected is small, but ultimately there are
approximately 5,000 lucky winners each year in our survey.

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Stage 4
4
Sampling: Persons

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.

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Within each county, smaller areas (with a large
number of households in each area) are formed, and
about 24 of these small groups are selected.
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.
Selected households are asked to completed a short
survey about who lives at that address.
A computer algorithm randomly selects some or all
of the household members.

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