Design and estimation for the national health interview survey, 2006-2015.

OBJECTIVES: This report presents an overview, a detailed description of the sample design features, and estimation structures for the 2006-2015 National Health Interview Survey NHIS). It fulfills the same role for the current 2006-2015 NHIS design as NCHS Series 2, No. 130, "Design and Estimation for the National Health Interview Survey, 1995-2004" provided for the previous design, which was extended through 2005. METHODS: The 2006-2015 NHIS sample design uses cost-effective complex sampling techniques including stratification, clustering, and differential sampling rates to achieve several objectives, among them improved reliability of racial, ethnic, and geographical domains. This report describes these methods. RESULTS: This report presents operating characteristics of NHIS 2006-2015. The general sampling structure is presented, along with a discussion of weighting and variance estimation techniques. This report is intended for general users of NHIS data systems.

Delivery of a small for gestational age infant and greater maternal risk of ischemic heart disease.

BACKGROUND: Delivery of a small for gestational age (SGA) infant has been associated with increased maternal risk of ischemic heart disease (IHD). It is uncertain whether giving birth to SGA infant is a specific determinant of later IHD, independent of other risk factors, or a marker of general poor health. The purpose of this study was to investigate the association between delivery of a SGA infant and maternal risk for IHD in relation to traditional IHD risk factors. METHODS AND FINDINGS: Risk of maternal IHD was evaluated in a population based cross-sectional study of 6,608 women with a prior live term birth who participated in the National Health and Nutrition Examination Survey (1999-2006), a probability sample of the U.S. population. Sequence of events was determined from age at last live birth and at diagnosis of IHD. Delivery of a SGA infant is strongly associated with greater maternal risk for IHD (age adjusted OR; 95% CI: 1.8; 1.2, 2.9; p = 0.012). The association was independent of the family history of IHD, stroke, hypertension and diabetes (family history-adjusted OR; 95% CI: 1.9; 1.2, 3.0; p = 0.011) as well as other risk factors for IHD (risk factor-adjusted OR; 95% CI: 1.7; 1.1, 2.7; p = 0.025). Delivery of a SGA infant was associated with earlier onset of IHD and preceded it by a median of 30 (interquartile range: 20, 36) years. CONCLUSIONS: Giving birth to a SGA infant is strongly and independently associated with IHD and a potential risk factor that precedes IHD by decades. A pregnancy that produces a SGA infant may induce long-term cardiovascular changes that increase risk for IHD.

The 2006-2010 National Survey of Family Growth: sample design and analysis of a continuous survey.

OBJECTIVE: The National Survey of Family Growth (NSFG) collects data on pregnancy, childbearing, men's and women's health, and parenting from a national sample of women and men 15-44 years of age in the United States. This report describes the sample design for the NSFG's new continuous design and the effects of that design on weighting and variance estimation procedures. A working knowledge of this information is important for researchers who wish to use the data. Two data files are being released--the first covering 2.5 years (30 months) of data collection and the second after all data have been collected. This report is being released with the first data file. A later report in this Series will include specific results of the weighting, imputation, and variance estimation. METHODS: The NSFG's new design is based on an independent, national probability sample of women and men 15-44 years of age. Fieldwork was carried out by the University of Michigan's Institute for Social Research (ISR) under a contract with the National Center for Health Statistics (NCHS). In-person, face-to-face interviews were conducted by professional female interviewers using laptop computers. RESULTS: Analysis of NSFG data requires the use of sampling weights and estimation of sampling errors that account for the complex sample design and estimation features of the survey. Sampling weights are provided on the data files. The rate of missing data in the survey is generally low. However, missing data were imputed for about 600 key variables (called "recodes") that are used for most analyses of the survey. Imputation was accomplished using a multiple regression procedure with software called IVEware, available from the University of Michigan website.

National Survey of Family Growth, Cycle 6: sample design, weighting, imputation, and variance estimation.

OBJECTIVES: Cycle 6 of the National Survey of Family Growth (NSFG) was conducted by the National Center for Health Statistics in 2002 and early 2003. This report describes how the sample was designed, shows response rates for various subgroups of men and women, describes how the sample weights were computed to make national estimates possible, shows how missing data were imputed for a limited set of key variables, and describes the proper ways to estimate sampling errors from the NSFG. The report includes both nontechnical summaries for readers who need only general information and more technical detail for readers who need an in-depth understanding of these topics. METHODS: The NSFG Cycle 6 was based on an independent, national probability sample of men and women 15-44 years of age. It was the first NSFG ever to include a national sample of men 15-44 as well as a sample of women. Fieldwork was carried out by the University of Michigan's Institute for Social Research (ISR) under a contract with NCHS. In-person, face-to-face interviews were conducted by professional female interviewers using laptop computers. In all, 12,571 women and men-7,643 females and 4,928 males-were interviewed, the largest NSFG ever done. RESULTS: Analysis of NSFG Cycle 6 data requires the use of sampling weights and estimation of sampling errors that accounts for the complex sample design and estimation features of the survey. Examples of how to use several available software packages that incorporate complex design features in estimation, such as SAS, SUDAAN, and STATA, are presented.