Data were drawn from Add Health (K.M. Harris et al., 2009), an ongoing national-representative longitudinal study to address health, behaviors, and relationships from adolescence through adulthood. The study began with approximately 90,000 adolescents sampled in school in 1994-1995; 20,745 of these underwent in-depth home interviews (1995, age 12-21). Waves 2 through 4 attempted re-interview of respondents who underwent the in-depth interviews at Wave 1. However, children who graduated high school were not included in the Wave 2 sample unless they were part of a sibling sub-study; therefore the mean age of the Wave 2 sample is slightly lower than the mean age of the Wave 1 sample (Wave 1: 16.03; Wave 2: 15.99). Respondents that were no longer in high school at the Wave 2 interview, however, remained eligible for the Wave 3 and 4 interviews and were recontacted. We analyzed data on non-Hispanic Whites and Blacks with a sample weight at Wave 1 (N=14,101). Sample sizes in remaining interview waves were as follows: 1996 (Wave 2, N=10,203), 2001-2002 (Wave 3, N=10,786), and 2007-2008 (Wave 4, N=11,365). Further details on the study design can be found elsewhere (K.M. Harris et al., 2009).
