National Longitudinal Study of Adolescent Health Strategies to Perform a Design-Based Analysis Using the Add Health Data

Abstract

of Child Health and Human Development with cooperative funding from 23 other federal agencies and foundations. Further information may be obtained by contacting [e-mail]. The Add Health Study is a nationally representative, probability-based survey of adolescents in grades 7 through 12 conducted between 1994 and 1996. The sample design used to collect the data has introduced a complexity to analysis. Failing to account for this complexity may result in biased parameter estimates and incorrect variance estimates. Hence, you must correct for design effects and unequal probability of selection to ensure that your results are nationally representative with unbiased estimates. Specialized, “user-friendly ” statistical software is now available for analyzing data from complex surveys. SUDAAN and STATA are two examples of this type of software. Using both SUDAAN and STATA, we show you how to incorporate characteristics of the sample design into an analysis so that your estimates and standard errors are unbiased. We will first present a simplified description of the Add Health sampling process including a description of the sample attributes and data elements needed for correctly analyzing the data when the unit of analysis is either the school or the adolescent. A brief description of