The National Health and Nutrition Examination Survey: Sample Design, 1999-2006

Abstract

Background: Data collection for the National Health and Nutrition Examination Survey (NHANES) comprises three levels: a household screener, an interview, and a physical examination. The primary objective of the screener is to determine whether any household members are eligible for the interview and examination. Eligibility is determined by the preset selection probabilities for the desired demographic subdomains. After selection as an eligible sample person, 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 eye and dental examinations, and the collection of blood and urine specimens for laboratory testing.

Objectives: This report will first describe the broad design specifications for the 1999-2006 survey including survey objectives, domain and precision specifications, operational requirements, sample design, and estimations procedures. Details of the sample design are divided into two sections. The first section (NHANES 1999-2001 Sample Design) broadly describes the sample design and various design changes during the first three years of the continuous NHANES (1999-2001). The second section (NHANES 2002-2006 Sample Design) describes the final sample design developed and applied for 2002-2006. Weighting and variance estimation procedures are presented in the same manner; however, to correspond to the public data release cycles, the weighting and variance sections are separated into those used for 1999-2002, and those used for 2003-2006. Much of this report is based on survey operations documents and sample design reports prepared by Westat. Documentation of the survey content, procedures, and methods to assess nonsampling errors are reported elsewhere.