Does the health and nutritional status of Americans change over time?

NHANES: Assessing the health and nutritional status of Americans over time


The National Health and Nutrition Examination Survey (NHANES) assesses the health and nutritional status of adults and children in the U.S. The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiological measurements, as well as laboratory tests administered by highly trained medical personnel. Westat has been involved since the early 1980s, including the Hispanic HANES and NHANES III and IV.


For the National Center for Health Statistics (NCHS), Westat is conducting NHANES through interviews and extensive physical examinations performed in specially equipped mobile examination centers that travel from site to site.

As NHANES is a continuous survey with year-round data collection, each year our field staff are dispatched to 15 counties across the country to conduct interviews and extensive physical examinations with approximately 5,000 Americans of all ages.

We employ approximately 80 full-time traveling staff to conduct the study, including 2 medical teams and a group of household interviewers managed by home-based supervisors. An experienced team of research and IT professionals supervise the advance arrangements for data collection, monitor the progress and quality of data collection, and prepare and process all survey data.

An integrated survey information system supports all aspects of sampling, data collection, survey monitoring, and data management. This system operates across a wide area network that provides near real-time communication between the examination centers, NCHS, and Westat.

This study uses Blaise, a comprehensive commercial off-the-shelf (COTS) survey processing system. It provides integrated multimode support for computer-assisted survey data collection.


The findings from NHANES help determine the prevalence of major diseases and risk factors for diseases.

They also help to develop sound public health policy, direct and design health programs and services, and expand the health knowledge for the nation.


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