The National Health Examination Survey, Cycle III (NHES III) was conducted on a nationwide probability sample of 7,514 youths 12-17 years of age. Of the 7,514 youths selected for the sample, 6,768 (90 percent) were examined. Adjusted sampling weights were computed in order to inflate the sample so as to closely reflect the 23 million youths in the U.S. population at that time in terms of age, sex, and certain other demographic characteristics. Because the same basic sampling plan was used in Cycle III as in the earlier Cycle II, nearly one-third of the children examined in Cycle II were also examined in Cycle III. In the Cycle III Extended Data Tape (EDT), provision has been made for the user to identify sample persons examined in both surveys and to create from the Cycle II Integrated Data Tape (IDT) and the Cycle III EDT a composite data set for longitudinal studies.
The NHES III data contains responses to detailed questionnaires for medical and developmental histories; responses to school questionnaires; results of medical, dental, and psychological examinations, and vision and hearing tests; anthropometric measurements; and certain x-rays and laboratory tests.