Analyzing Social Experiments as Implemented: A Reexamination of the Evidence From the HighScope Perry Preschool Program

James J. Heckman, Seong Hyeok Moon, Rodrigo Pinto, Peter A. Savelyev, Adam Yavitz

NBER Working Paper No. 16238
Issued in July 2010, Revised in December 2011

---- Acknowledgments ----

A version of this paper was presented at a seminar at the HighScope Perry Foundation, Ypsilanti, Michigan, December 2006; at a conference at the Minneapolis Federal Reserve in December 2007; at a conference on the role of early life conditions at the Michigan Poverty Research Center, University of Michigan, December 2007; at a Jacobs Foundation conference at Castle Marbach, April 2008; at the Leibniz Network Conference on Noncognitive Skills in Mannheim, Germany, May 2008; at an Institute for Research on Poverty conference, Madison, Wisconsin, June 2008; and at a conference on early childhood at the Brazilian National Academy of Sciences, Rio de Janeiro, Brazil, December 2009. We thank the editor and two anonymous referees for helpful comments which greatly improved this draft of the paper. We have benefited from comments received on early drafts of this paper at two brown bag lunches at the Statistics Department, University of Chicago, hosted by Stephen Stigler. We thank all of the workshop participants. In addition, we thank Amanda Agan, Mathilde Almlund, Joseph Altonji, Ricardo Barros, Dan Black, Steve Durlauf, Chris Hansman, Tim Kautz, Paul LaFontaine, Devesh Raval, Azeem Shaikh, Jeff Smith, and Steve Stigler for helpful comments. Our collaboration with Azeem Shaikh on related work has greatly strengthened the analysis in this paper. This research was supported in part by the American Bar Foundation, the Committee for Economic Development; by a grant from the Pew Charitable Trusts and the Partnership for America's Economic Success; the JB & MK Pritzker Family Foundation; Susan Thompson Buffett Foundation; Mr. Robert Dugger; and NICHD R01HD043411. The views expressed in this presentation are those of the authors and not necessarily those of the funders listed here, or of the National Bureau of Economic Research. Supplementary materials for this paper may be found at

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