is given to the source.

We are grateful to Arias Wan whose undergraduate thesis started us on this project and to Claudia Olivetti, Daniele Paserman and participants in seminars and workshops at Boston University, Federal Reserve Bank of Chicago, American Institutes for Research, CNA, Abt Associates and the US Census for helpful comments. The usual caveat applies. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications