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...

Laboratory experiments are a widely used methodology for advancing causal knowledge in the physical and life sciences. With the exception of psychology, the adoption of laboratory experiments has been much slower in the social sciences, although during the last two decades, the use of lab...

This paper forecasts the life-cycle treatment effects on health of a high-quality early childhood program. Our predictions combine microsimulation using non-experimental data with experimental data from a midlife long-term follow-up. The follow-up incorporated a full epidemiological exam. The...

This paper examines the case for randomized controlled trials in economics. I revisit my previous paper "Randomization and Social Policy Evaluation" and update its message. I present a brief summary of the history of randomization in economics. I identify two waves of enthusiasm for the method...

This paper presents a new monotonicity condition for unordered discrete choice models with multiple treatments. Unlike a less general version of monotonicity in binary and ordered choice models, monotonicity in unordered discrete choice models along with other standard assumptions does not...

This paper quantifies the experimentally evaluated life-cycle benefits of a widely implemented early childhood program targeting disadvantaged families. We join experimental data with non-experimental data using economic models to forecast its life-cycle benefits. Our baseline estimate of the...

This paper estimates gender differences in life-cycle impacts across multiple domains of an influential enriched early childhood program targeted toward disadvantaged children that was evaluated by the method of random assignment. We assess the impacts of the program on promoting or alleviating...

This paper organizes and synthesizes the literature on early childhood education and childcare. In it, we go beyond meta-analysis and reanalyze primary data sources in a common framework. We consider the evidence from means-tested demonstration programs, large-scale means-tested programs and...

This paper synthesizes recent research in economics and psychology on the measurement and empirical importance of personality skills and preferences. They predict and cause important life outcomes such as wages, health, and longevity. Skills develop over the life cycle and can be enhanced by...

This paper examines the long-term impacts on health and healthy behaviors of two of the oldest and most widely cited U.S. early childhood interventions evaluated by the method of randomization with long-term follow-up: the Perry Preschool Project (PPP) and the Carolina Abecedarian Project (ABC)....