NHANES III (National Health and Nutrition Examination Survey, Phase III) The NHANES III dataset is the third wave of the U.S. National Health and Nutrition Examination Survey, conducted by the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC) from 1988 1994. It comprises a nationally representative probability sample of 39,695 individuals ( 2 months old) who underwent household interviews, standardized physical examinations, and extensive laboratory testing. Variables span demographics, dietary intake, health behaviour questionnaires, clinical measurements (e.g., blood pressure, anthropometry), biochemical markers (lipids, glucose, heavy metals), environmental exposures, and biospecimen inventories. The survey s purpose is to monitor the health and nutritional status of the civilian, non institutionalized U.S. population, providing a baseline for trend analysis and informing public health policy. Researchers use NHANES III to estimate disease prevalence (obesity, diabetes, hypertension), evaluate risk factor associations, validate clinical instruments, and develop predictive models. Key features that set NHANES III apart include its two phase design (1988 1991 1991 1994), a high examination response rate (~78 %), extensive laboratory and biospecimen collections (allowing later genetic and exposome studies), and thorough documentation with SAS/DAT files and a detailed data dictionary. These attributes make NHANES III a cornerstone resource for epidemiology, health services research, and methodological development.