Analyzing Social Experiments as Implemented: A Reexamination of the Evidence from the Highscope Perry Preschool Program

59 Pages Posted: 24 Aug 2010 Last revised: 28 Aug 2010

See all articles by James J. Heckman

James J. Heckman

University of Chicago - Department of Economics; National Bureau of Economic Research (NBER); American Bar Foundation; Institute for the Study of Labor (IZA); CESifo (Center for Economic Studies and Ifo Institute)

Seong Moon

University of Chicago - Department of Economics

Rodrigo R. Pinto

University of Chicago - Department of Economics

Peter A. Savelyev

College of William and Mary - Department of Economics

Adam Yavitz

University of Chicago - Department of Economics

Multiple version iconThere are 2 versions of this paper

Date Written: July 2010

Abstract

Social experiments are powerful sources of information about the effectiveness of interventions. In practice, initial randomization plans are almost always compromised. Multiple hypotheses are frequently tested. "Significant" effects are often reported with p-values that do not account for preliminary screening from a large candidate pool of possible effects. This paper develops tools for analyzing data from experiments as they are actually implemented. We apply these tools to analyze the influential HighScope Perry Preschool Program. The Perry program was a social experiment that provided preschool education and home visits to disadvantaged children during their preschool years. It was evaluated by the method of random assignment. Both treatments and controls have been followed from age 3 through age 40. Previous analyses of the Perry data assume that the planned randomization protocol was implemented. In fact, as in many social experiments, the intended randomization protocol was compromised. Accounting for compromised randomization, multiple-hypothesis testing, and small sample sizes, we find statistically significant and economically important program effects for both males and females. We also examine the representativeness of the Perry study.

Suggested Citation

Heckman, James J. and Moon, Seong and Pinto, Rodrigo R. and Savelyev, Peter A. and Yavitz, Adam, Analyzing Social Experiments as Implemented: A Reexamination of the Evidence from the Highscope Perry Preschool Program (July 2010). NBER Working Paper No. w16238. Available at SSRN: https://ssrn.com/abstract=1664244

James J. Heckman (Contact Author)

University of Chicago - Department of Economics ( email )

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National Bureau of Economic Research (NBER)

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American Bar Foundation

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Institute for the Study of Labor (IZA)

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CESifo (Center for Economic Studies and Ifo Institute)

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Seong Moon

University of Chicago - Department of Economics ( email )

1126 East 59th Street
Chicago, IL 60637
United States

Rodrigo R. Pinto

University of Chicago - Department of Economics ( email )

1126 East 59th Street
Chicago, IL 60637
United States

Peter A. Savelyev

College of William and Mary - Department of Economics ( email )

Williamsburg, VA 23187-8795
United States
7573788654 (Phone)

Adam Yavitz

University of Chicago - Department of Economics ( email )

1126 East 59th Street
Chicago, IL 60637
United States

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