Data were drawn from the 2004-2005 NESARC, a national survey of non-institutionalized adults aged 18+ in the United States residing in homes or group quarters. In 2001-2002, NESARC participants (N=43,093; response rate, 81% of those eligible) were initially interviewed. In 2004-2005, 34,653 were re-interviewed (86.7% of original sample; ineligible respondents included deceased, n=1403; deported, mentally or physically impaired, n=781; or on active duty in the armed forces, n=950). The cumulative response rate for the Wave 2 sample was therefore 70.2%. We used the data from Wave 2 because two additional states (Vermont and Montana) legalized medical marijuana between 2002 and 2004. More detail on the study methods is found elsewhere(Grant et al., 2009; Grant et al., 2004). The research protocol, including written informed consent procedures, received full ethical review and approval from the U.S. Census Bureau and the U.S. Office of Management and Budget.
