made available, will provide further clarity on temporal trends. However, policy positions are fluid. For example, in 2011 policy statements from the Justice Department (Grim, 2011) contradicted the earlier Ogden memo (Ogden, 2009), and in 2012, as noted earlier, Colorado voters passed Amendment 64, legalizing the recreational use of marijuana and possession of up to one ounce of marijuana for those at least 21 years of age; recreational marijuana sales in Colorado began in January 2014. Such changes would complicate interpretation of any temporal changes seen in these or subsequent years. Fourth, we conducted multiple tests using eight outcome variables and three age groups. Our results should therefore be interpreted cautiously. Lastly, the majority of Colorado's medical marijuana dispensaries are located in the Denver metropolitan area (CDPHE). Given that some Colorado communities have banned medical marijuana dispensaries or have very few registered patients, considering Colorado as a whole may limit our ability to discern more fine-grained within-state geographic effects.
