TY - JOUR AU - Abadie,Alberto AU - Diamond,Alexis AU - Hainmueller,Jens TI - Synthetic Control Methods for Comparative Case Studies: Estimating the Effect of California's Tobacco Control Program JF - National Bureau of Economic Research Working Paper Series VL - No. 12831 PY - 2007 Y2 - January 2007 UR - http://www.nber.org/papers/w12831 L1 - http://www.nber.org/papers/w12831.pdf N1 - Author contact info: Alberto Abadie John F. Kennedy School of Government Harvard University 79 JFK Street Cambridge, MA 02138 Tel: 617/496-4547 Fax: 617/496-5960 E-Mail: alberto_abadie@harvard.edu Alexis Diamond Political Economy and Government Harvard University 1737 Cambridge Street Cambridge, MA 02138 Tel: 617 868 1677 E-Mail: adiamond@fas.harvard.edu Jens Hainmueller E-Mail: jhainm@mit.edu AB - Building on an idea in Abadie and Gardeazabal (2003), this article investigates the application of synthetic control methods to comparative case studies. We discuss the advantages of these methods and apply them to study the effects of Proposition 99, a large-scale tobacco control program that California implemented in 1988. We demonstrate that following Proposition 99 tobacco consumption fell markedly in California relative to a comparable synthetic control region. We estimate that by the year 2000 annual per-capita cigarette sales in California were about 26 packs lower than what they would have been in the absence of Proposition 99. Given that many policy interventions and events of interest in social sciences take place at an aggregate level (countries, regions, cities, etc.) and affect a small number of aggregate units, the potential applicability of synthetic control methods to comparative case studies is very large, especially in situations where traditional regression methods are not appropriate. The methods proposed in this article produce informative inference regardless of the number of available comparison units, the number of available time periods, and whether the data are individual (micro) or aggregate (macro). Software to compute the estimators proposed in this article is available at the authors' web-pages. ER -