This paper discusses how randomized social experiments operate as an instrumental variable. For two types of randomization schemes, the fundamental experimental estimation equations are derived from the principle that experiments equate bias in control and experimental samples. Using...

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. "Signicant" effects are often reported with p-values that do not account for...

The literature on skill formation and human capital development clearly demonstrates that early investment in children is an equitable and efficient policy with large returns in adulthood. Yet little is known about the mechanisms involved in producing these long-term effects. This paper presents...

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...