A growing literature establishes that high quality early childhood interventions targeted toward disadvantaged children have substantial impacts on later life outcomes. Little is known about the mechanisms producing these impacts. This paper uses longitudinal data on cognitive and personality traits from an experimental evaluation of the influential Perry Preschool program to analyze the channels through which the program boosted both male and female participant outcomes. Experimentally induced changes in personality traits explain a sizable portion of adult treatment effects.

High-quality early childhood programs have been shown to have substantial benefits in reducing crime, raising earnings, and promoting education. Much less is known about their benefits for adult health. We report the long-term health impacts of one of the oldest and most heavily cited early childhood interventions with long-term follow-up evaluated by the method of randomization: the Carolina Abecedarian Project (ABC). Using recently collected biomedical data, we find that disadvantaged children randomly assigned to treatment have significantly lower prevalence of risk factors for cardiovascular and metabolic diseases in their mid-30s. The evidence is especially strong for males. The mean systolic blood pressure among the control males is 143, while only 126 among the treated. One in four males in the control group is affected by metabolic syndrome, while none in the treatment group is. To reach these conclusions, we address several statistical challenges. We use exact permutation tests to account for small sample sizes and conduct a parallel bootstrap confidence interval analysis to confirm the permutation analysis. We adjust inference to account for the multiple hypotheses tested and for nonrandom attrition. Our evidence shows the potential of early life interventions for preventing disease and promoting health.

Standard-Nutzungsbedingungen:Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden.Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen.Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. www.econstor.eu Terms of use: Documents in D I S C U S S I O N P A P E R S E R I E S ABSTRACT The Rate of Return to the High/Scope Perry Preschool ProgramThis paper estimates the rate of return to the High/Scope Perry Preschool Program, an early intervention program targeted toward disadvantaged African-American youth. Estimates of the rate of return to the Perry program are widely cited to support the claim of substantial economic benefits from preschool education programs. Previous studies of the rate of return to this program ignore the compromises that occurred in the randomization protocol. They do not report standard errors. The rates of return estimated in this paper account for these factors. We conduct an extensive analysis of sensitivity to alternative plausible assumptions. Estimated social rates of return generally fall between 7-10 percent, with most estimates substantially lower than those previously reported in the literature. However, returns are generally statistically significantly different from zero for both males and females and are above the historical return on equity. Estimated benefit-to-cost ratios support this conclusion.JEL Classification: D62, I22, I28

A substantial literature shows that U.S. early childhood interventions have significant long-term economic benefits. There is little evidence on this question for developing countries. We report substantial effects on the earnings of participants in a randomized intervention conducted in 1986–1987 that gave psychosocial stimulation to growth-stunted Jamaican toddlers. The intervention consisted of weekly visits from community health workers over a 2-year period that taught parenting skills and encouraged mothers and children to interact in ways that develop cognitive and socioemotional skills. The authors re-interviewed 105 out of 129 study participants 20 years later and found that the intervention increased earnings by 25%, enough for them to catch up to the earnings of a non-stunted comparison group identified at baseline (65 out of 84 participants).

A growing literature establishes that high quality early childhood interventions targeted toward disadvantaged children have substantial impacts on later life outcomes. Little is known about the mechanisms producing these impacts. This paper uses longitudinal data on cognitive and personality traits from an experimental evaluation of the influential Perry Preschool program to analyze the channels through which the program boosted both male and female participant outcomes. Experimentally induced changes in personality traits explain a sizable portion of adult treatment effects. Keywords cognitive traits; personality traits; externalizing behavior; academic motivation; factor analysis; human capital; human development; early childhood interventions; social experiments; Perry Preschool program; experimentally estimated production functions A growing literature establishes that early childhood environments substantially impact later life outcomes (e.g., Knudsen et al., 2006 and Almond and Currie, 2011. Less is known about the channels through which early environments operate to produce their long term effects. This paper examines the sources of the success of the Perry Preschool program, a flagship early childhood intervention in the US. 1 The Perry program was a randomized trial that targeted disadvantaged, low IQ African American children ages 3-4. After two years, all participants left the program and enteredCorrespondence to: Peter Savelyev. The paper was presented at a Public Policy and Economics Seminar at the Harris School, University of Chicago, October, 2009, attended by Diane Schatzenbach. 1 The formal name of the program is the "HighScope Perry Preschool Program" (see Schweinhart et al., 2005). NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript the same public school. Data were collected for treatment and control groups through age 40. Heckman et al. (2010a) and Conti et al. (2012) show that the Perry program significantly enhanced adult outcomes including education, employment, earnings, marriage, and participation in healthy behaviors, and reduced participation in crime. 2 We summarize many of these findings in Table 1. All treatment effects displayed there are statistically significant and survive adjustments for multiple hypothesis testing. 3 Heckman et al. (2010b) show that the internal rate of return to the program for both boys and girls is a statistically significant 6-10 percent per year-above the historical return to equity. 4 Positive effects of the Perry program have become a cornerstone of the argument for preschool programs (e.g., Shonkoff and Phillips, 2000). Currently, about 30 percent of all Head Start centers nationwide offer a version of the Perry curriculum (ICPSR, 2010). 5 Previous studies of Perry focus on estimating treatment effects and do not attempt to explain their sources. 6 This paper identifies the psychological skills changed by the Perry program and decomposes the treatment effects on adult outcomes displayed in T...