The National Health and Nutrition Examination Surveys (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The NHANES combines personal interviews and physical examinations, which focus on different population groups or health topics. These surveys have been conducted by the National Center for Health Statistics (NCHS) on a periodic basis from 1971 to 1994. In 1999, the NHANES became a continuous program with a changing focus on a variety of health and nutrition measurements which were designed to meet current and emerging concerns. The sample for the survey is selected to represent the U.S. population of all ages. Many of the NHANES 2007–2008 questions also were asked in NHANES II 1976–1980, Hispanic NHANES 1982–1984, NHANES III 1988–1994, and NHANES 1999-2006. New questions were added to the survey based on recommendations from survey collaborators, NCHS staff, and other interagency work groups. Estimates for previously undiagnosed conditions, as well as those known to and reported by survey respondents, are produced through the survey.
In the 2003-2004 wave, the NHANES includes more than 100 datasets. Most have been combined into three datasets for convenience. Each starts with the Demographic dataset and includes datasets of a specific type.
1. National Health and Nutrition Examination Survey (NHANES), Demographic & Examination Data, 2003-2004 (The base of the Demographic dataset + all data from medical examinations).
2. National Health and Nutrition Examination Survey (NHANES), Demographic & Laboratory Data, 2003-2004 (The base of the Demographic dataset + all data from medical laboratories).
3. National Health and Nutrition Examination Survey (NHANES), Demographic & Questionnaire Data, 2003-2004 (The base of the Demographic dataset + all data from questionnaires)
Variable SEQN is included for merging files within the waves. All data files should be sorted by SEQN.
Additional details of the design and content of each survey are available at the NHANES website.
- Data File
- Cases: 10,122
Weight Variable: WTINT2YR, WTMEC2YR
- Data Collection
- Date Collected: January 2003 - December 2004
- Original Survey (Instrument)
- NHANES website
- Funded By
- National Center for Health Statistics (NCHS)
- Collection Procedures
- The most recent series of data collection waves for NHANES began in 1999. Every year, approximately 7,000 individuals, of all ages, are interviewed in their homes and of these; approximately 5,000 complete the health examination component of the survey. The health examinations are conducted in mobile examination centers (MECs). The surveys examine a nationally representative sample of approximately 5,000 persons each year. These persons are located in counties across the United States, 15 of which are visited each year. For NHANES 2003-2004, there were 12,761 persons selected for the sample, 10,122 of those were interviewed (79.3 percent) and 9,643 (75.6 percent) were examined in the MECs. NHANES 2003-2004 includes over-sampling of low-income persons, adolescents 12-19 years of age, persons 60 years of age and older, African Americans, and Mexican Americans. Modes of data collection across the NHANES waves have included audio computer-assisted self-interview (ACASI), computer-assisted personal interview (CAPI), computer-assisted self-interview (CASI), face-to-face interview, and on-site questionnaire.
- Sampling Procedures
- The NHANES survey design is a stratified, multistage probability sample of the civilian non-institutionalized United States population. The stages of sample selection are: (1) selection of Primary Sampling Units (PSUs), which are counties or small groups of contiguous counties; (2) segments within PSUs (a block or group of blocks containing a cluster of household); (3) households within segments; and (4) one or more participants within households. A total of 15 PSUs are visited during a 12-month time period. Please note that there are different target population groups for topics within and between questionnaire sections. Data users should review the survey questionnaire codebooks and frequencies by age to determine the target populations for each NHANES questionnaire section. Additional details of the design, content of each survey, and analytic guidelines are available at the NHANES website.
- Principal Investigators
- United States Department of Health and Human Services
Centers for Disease Control and Prevention
National Center for Health Statistics
- Related Publications
- Users should periodically check the NHANES website to determine if any new or revised data files have been released and if analytic guidelines have been updated. In addition, NHANES staff publishes authored/co-authored publications and posts them on the website.