Wave VI User Guide to Using Cross-Sectional and Longitudinal Weights

The National Longitudinal Study of Adolescent to Adult Health (Add Health) is a longitudinal study of a nationally representative sample of over 20,000 adolescents who were in grades 7-12 during the 1994-95 school year and who have been followed for six waves to date, most recently in 2022-2025. Over the years, Add Health has collected rich demographic, social, familial, socioeconomic, behavioral, psychosocial, cognitive, and health survey data from participants and their parents; a vast array of contextual data from participants’ schools, neighborhoods, and geographies of residence; and in-home physical and biological data from participants, including genetic markers, blood-based assays, anthropometric measures, and medications. Ancillary studies have added even more data over the years (Harris et al. 2019). The overall goal of Add Health Wave VI was to collect and disseminate the comprehensive data needed to best understand the social, economic, psychosocial, contextual, and biological determinants of health trajectories and disparities among this nationally representative cohort of Americans as they age into midlife. Wave VI of Add Health used a multifaceted, mixed-mode design similar to that used in Wave V. The Wave VI sample was split into two random subsamples, Samples 1 and 2. Similar to the mixed mode subsamples in Wave V (Samples 1, 2a and 3 in Wave V), the data collection for Sample 1 employed a mixed-mode, two-phase survey design. In the first phase, sample members were contacted primarily by mail, email or text message and asked to complete a web questionnaire. In the second phase, a subsample of nonrespondents was followed up through nonresponse follow-up (NRFU). Most of these cases were completed online, and others were completed via in-person interviews when needed. Similar to Sample 2b in Wave V, the data collection for Sample 2 in Wave VI largely employed an in-person interview collection mode. In addition, in Wave VI, Sample 2 nonrespondents were provided a web questionnaire as follow-up (an approach that was not used in Wave V).