National Health and Nutrition Examination Survey (NHANES), Demographic and Questionnaire Data, 2001-2002
SummaryThe 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 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 2001-2002 questions also were asked in NHANES II 1976-1980, Hispanic HANES 1982-1984, NHANES III 1988-1994. New questions were added to the survey based on recommendations from survey collaborators, NCHS staff, and other interagency work groups.
In the 2001-2002 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, 2001-2002 (the base of the Demographic dataset + all data from medical examinations).
2. National Health and Nutrition Examination Survey (NHANES), Demographic & Laboratory Data, 2001-2002 (the base of the Demographic dataset + all data from medical laboratories).
3. National Health and Nutrition Examination Survey (NHANES), Demographic & Questionnaire Data, 2001-2002 (the base of the Demographic dataset + all data from questionnaires).
Not all files from the 2001-2002 wave are included. This is for two reasons, both of which related to the merging variable (SEQN). For a subset of the files, SEQN is not a unique identifier for cases (i.e. some respondents have multiple cases) or SEQN is not in the file at all. The following datasets from this wave of the NHANES are not included in these three files and can be found individually from the NHANES website at the CDC:
Examination: Dietary Interview (Individual Foods File)
Examination: Dual Energy X-ray Absorptiometry (DXX)
Examination: Dual Energy X-ray Absorptiometry (DXX)
Questionnaire: Analgesics Pain Relievers
Questionnaire: Dietary Supplement Use -- Ingredient Information
Questionnaire: Dietary Supplement Use -- Supplement Blend
Questionnaire: Dietary Supplement Use -- Supplement Information
Questionnaire: Drug Information
Questionnaire: Dietary Supplement Use -- Participants Use of Supplement
Questionnaire: Physical Activity Individual Activity File
Questionnaire: Prescription Medications
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 FileCases: 11039
Weight Variable: WTINT2YR, WTINT4YR, WTMEC2YR, WTMEC4YR
Data CollectionJanuary 2001 - December 2002
Original Survey (Instrument)NHANES website
Funded ByNational Center for Health Statistics (NCHS)
Collection ProceduresThe 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. 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 2001-2002, there were 13,156 persons selected for the sample, 11,039 (84 percent) of those were interviewed and 10,477 (80 percent) were examined in the MECs. 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 ProceduresThe 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. NHANES 2001-2002 includes over-sampling of low-income persons, adolescents 12 to 19 years of age, persons 60 or more years of age, African Americans and Mexican Americans. 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 InvestigatorsUnited States Department of Health and Human Services
Centers for Disease Control and Prevention
National Center for Health Statistics