The Third National Health and Nutrition Examination Survey, (NHANES III), 1988-94, (Series 11, No. 4A) The National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC) collects, analyzes, and disseminates data on the health status of U.S. residents. The results of surveys, analyses, and studies are made known through a number of data release mechanisms including publications, mainframe computer data files, CD-ROMs (Search and Retrieval Software, Statistical Export and Tabulation System (SETS)), and the Internet. The National Health and Nutrition Examination Survey (NHANES) is a periodic survey conducted by NCHS. The third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988 through 1994, was the seventh in a series of these surveys based on a complex, multi-stage sample plan. It was designed to provide national estimates of the health and nutritional status of the United States' civilian, noninstitutionalized population aged two months and older. This release, Series 11 No. 4A, contains priority toxicant reference range study data. This release does not replace the previous NHANES III data releases (series 11 Nos. 1A, 2A, 3A and 6A). Table 1. Available NHANES III Data +---------------------+-------- +---------+------------------------------------+ |Data Release Number |Release |Size in |Data Files / Description | | |Date |Megabytes| | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |January | 2.7 |Healthy Eating Index (HEI) Data File| |Series 11, No. 6A, |2000 | |and documentation includes number | |ASCII Version | | |of servings by Food Guide Pyramid | | | | |food groups and HEI | |---------------------|---------|---------|------------------------------------+ |NHANES III, 1988-94, |October | 54 |Supplemental Nutrition Survey of | |Series 11, No. 5A, |2000 | |older Americans (SNS)contains | |ASCII Version | | |subsets of individual foods | | | | |and total nutrients intake data | | | | |files and documentation | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |September| 0.5 |Priority toxicant reference range | |Series 11, No. 4A, |2000 | |study data file and documentation | |ASCII Version | | | | |(this release) | | | | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |July | 33 |Second exam sample files for | |Series 11, No. 3A, |1999 | |dietary recall, examination, | |ASCII Version | | |laboratory, additional laboratory | | | | |analytes and documentation | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |April | 407 |Dietary recall (replacement), | |Series 11, No. 2A, |1998 | |electrocardiography, laboratory | |ASCII Version | | |(additional analytes), and | | | | |vitamins/medicines data files and | | | | |documentation | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |October | 285 |Adult and youth household | |Series 11, No. 1, |1997 | |questionnaire, examination, and | |Revised SETS Version | | |laboratory data files and | |1.22a | | |documentation, plan and operation, | | | | |analytic and reporting guidelines, | | | | |weighting and estimation | | | | |methodology, field operations, | | | | |non-response bias | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |July | 454 |Adult and youth household | |Series 11, No. 1A, |1997 | |questionnaire, dietary recall, | |ASCII Version | | |examination, and laboratory data | | | | |files and documentation | +---------------------+---------+---------+------------------------------------+ |NHANES III, 1988-94, |July | 285 |Adult and youth household | |Series 11, No. 1, |1997 | |questionnaire, examination, and | |SETS Version 1.22a * | | |laboratory data files and | | | | |documentation | +---------------------+---------+---------+------------------------------------+ |NHANES III Reference |October | 152 |Plan and operation, analytic and | |Manuals and Reports |1996 | |reporting guidelines, weighting and | |October 1996 | | |estimation methodology, field | | | | |operations, non-response bias | +---------------------+-------- +---------+------------------------------------+ * Do not use this CD-ROM It had technical problems and has been superseded by the revised SETS version 1.22a, Series 11, No. 1, released in October 1997. There are four files on this release: the ReadMe.txt file (this file), VOC.DAT (the priority toxicant reference range study ASCII data file), VOC.DOC (the corresponding documentation), and VOC.SAS (to create a SAS data set from the ASCII file.) Guidelines for Data Users o NHANES III survey design and demographic variables are found on the Household Adult Data File, Household Youth Data File, the Laboratory Data File and the Examination Data File. In preparing a data set for analysis, other data files should be merged with either or both of the Adult Household Data File or the Youth Household Data File to obtain many important analytic variables. o All of the NHANES III public use data files are linked with the common survey participant identification number (SEQN). Merging information from multiple NHANES III data files using this variable ensures that the appropriate information for each survey participant is linked correctly. o NHANES III public use data files do not have the same number of records on each file. The Household Questionnaire Files (divided into two files, Adult and Youth) contain more records than the Examination Data File because not everyone who was interviewed completed the examination. The Laboratory Data File contains data only for persons aged one year and older. The Individual Foods Data File based on the dietary recall, the Prescription Medication Data File, and The Vitamin and Minerals Data File all have multiple records for each person rather than the one record per sample person contained in the other data files. o For each data file, SAS program code with standard variable names and labels is provided as separate text files. This SAS program code can be used to create a SAS data set from the data file. o Modifications were made to items in the questionnaires, laboratory, and examination components over the course of the survey; as a result, data may not be available for certain variables for the full six years. In addition, variables may differ by phase since some changes were implemented between phases. Users are encouraged to read the Notes sections of the file documentation carefully for information about changes. o Extremely high and low values have been verified whenever possible, and numerous consistency checks have been performed. Nonetheless, users should examine the range and frequency of values before analyzing data. o Confidential and administrative data are not available or released to the public. Additionally, some variables have been recoded to protect the confidentiality of the survey participants. For example, all age-related variables were recoded to 90+ years for persons who were 90 years of age or older. o Although the data files have been edited carefully, it is possible that errors may still exist. Please notify NCHS staff (301-436-8500) of any suspected errors in the data file or the documentation. Refer to the NCHS website at www.cdc.gov/nchswww/ for updates to these data files. Analytic Considerations o No formal statistical sampling procedures were used to recruit volunteers for the priority toxicant reference range study. Because the sample for this study is not statistically based, sample weights cannot be used in analyses of these data. As a result of this, estimates obtained from analyses of these data cannot be weighted. Therefore, representative estimates for the U.S. population cannot be calculated. Referencing or Citing NHANES III Data o In publications, please acknowledge NCHS as the original data source. For instance, the reference for the NHANES III Priority Toxicant Reference Range Study Data File on this release is: U.S. Department of Health and Human Services (DHHS). National Center for Health Statistics. Third National Health and Nutrition Examination Survey, 1988-1994, NHANES III Priority Toxicant Reference Range Study Data File (Series 11, No. 4A). Hyattsville, MD: Centers for Disease Control and Prevention, 2000. Using the files on this release To access a documentation file open it in a word processor, set the margins to zero and the font to Courier 12 point. View or print any pages needed. For SAS users, open the SAS program for the data set required into Program Manager. Change the FILENAME statement as needed for the operating system To create a permanent SAS data set change the DATA statement. If space is limited, consider adding a KEEP statement to specify the variables of interest. The data files may be used in other analysis packages by using the field positions found in the index portion of the corresponding documentation. Problems Using the Data NHANES III is a rich source of data and NCHS encourages you to use the data for research and analysis. However, the dataset is large and complex and familiarity with data file manipulation and analysis is required. NCHS does not have the resources to perform analyses, check results, debug programs or do literature review for your work. Thorough review of the extensive documentation on the planning of the survey, analytic guidelines and individual datasets should resolve most questions. If you still have questions after careful review of the documentation, please contact the Data Dissemination Branch at (301) 458-4636.