National health and nutrition examination survey: sample design, 2011-2014.

Background Data collection for the National Health and Nutrition Examination Survey (NHANES) consists of a household screener, an interview, and a physical examination. The screener primarily determines whether any household members are eligible for the interview and examination. Eligibility is established using preset selection probabilities for the desired demographic subdomains. After an eligible sample person is selected, the interview collects person-level demographic, health, and nutrition information, as well as information about the household. The examination includes physical measurements, tests such as hearing and dental examinations, and the collection of blood and urine specimens for laboratory testing. Objectives This report provides some background on the NHANES program, beginning with the first survey cycle in the 1970s and highlighting significant changes since its inception. The report then describes the broad design specifications for the 2011-2014 survey cycle, including survey objectives, domain and precision specifications, and operational requirements unique to NHANES. The report also describes details of the survey design, including the calculation of sampling rates and sample selection methods. Documentation of survey content, data collection procedures, estimation methods, and methods to assess nonsampling errors are reported elsewhere.