Browse 114 concepts used in the study of religion, review how survey researchers measured them in the past, and quickly compare the results of more than 7,600 survey questions.
The archive is a collection of surveys, polls, and other data submitted by the foremost scholars and research centers in the world. Review and analyze data online, or download free of charge.
Examine the religious composition, religious freedoms, demographics, constitutional clauses, survey findings and multiple social and political measures for 250 nations.
View maps of the United States and individual states for hundreds of variables, including congregational membership, census data, crime statistics and many others.
Generate congregational membership reports for any county, state and urban area in the United States using data collected by the Religious Congregations & Membership Study.
The profiles chart schisms and mergers, document membership trends, offer basic descriptions, and link to additional resources for more than 400 past and present American religious groups.
Browse dozens of topics from a major national survey of religious congregations. See how the responses vary by the size, religious family and region of the congregation.
Browse dozens of topics covered by major national surveys. See how the responses vary by demographic categories and, when available, how they change over time.
View maps of the United States and individual states for hundreds of variables, including congregational membership, census data, crime statistics and many others.
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 HANES 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 2005-2006 wave, the NHANES includes over 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, 2005-2006 (The base of the Demographic dataset + all data from medical examinations).
2. National Health and Nutrition Examination Survey (NHANES), Demographic & Laboratory Data, 2005-2006 (The base of the Demographic dataset + all data from medical laboratories).
3. National Health and Nutrition Examination Survey (NHANES), Demographic & Questionnaire Data, 2005-2006 (The base of the Demographic dataset + all data from questionnaires)
Not all files from the 2005-2006 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 -- First Day) Examination: Dietary Interview (Individual Foods -- Second Day) Examination: Food Frequency Questionnaire -- DietCalc Output Examination: Physical Activity Monitor Questionnaire: Dietary Supplement Use -- Ingredient Information Questionnaire: Dietary Supplement Use -- Supplement Blend Questionnaire: Dietary Supplement Use -- Supplement Information Questionnaire: Dietary Supplement Use -- 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.
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 2005-2006, there were 12,862 persons selected for the sample, 10,348 of those were interviewed (80.45 percent) and 9,950 (77.36 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 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.
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, DHANES staff publishes authored/co-authored publications and post them on the website.
