These 4 surveys were the National Survey of Family Growth (NSFG, 2002 and 2006–2008), the National Survey of Drug Use and Health (NSDUH, 2002–2009), the National Health and Nutrition Examination Survey (NHANES, 1999–2008), and the General Social Survey (GSS, 2000–2008). Relevant characteristics of each survey—including website addresses for further information about the sampling methods, human subjects review, response rates, and weighting—are presented in Table 1. Notably, all surveys were household-based probability samples and 3 of the 4 surveys used audio computer-assisted self-interview to collect information on injection drug use.
