In this paper, we systematically analyze the empirical importance of standard conditions for the validity and generalizability of field experiments: the internal and external overlap and unconfoundedness conditions. We experimentally varied the degree of overlap in disjoint sub-samples from a...

In this paper, we systematically analyze the empirical importance of standard conditions for the validity and generalizability of field experiments: the internal and external overlap and unconfoundedness conditions. We experimentally varied the degree of overlap in disjoint sub-samples from a...

Clinical trials following the "gold standard" of random assignment frequently use independent lotteries to allocate patients to treatment and control arms. However, independent assignment can generate treatment and control arms that are unbalanced (i.e. treatment and control populations with...

This study investigates how to use regression adjustment to reduce variance in experimental data. We show that the estimators recommended in the literature satisfy an orthogonality property with respect to the parameters of the adjustment. This observation greatly simplifies the derivation of...

This paper describes a number of strategies that experimenters may use to improve the external validity of their own findings, and of their research field as a whole. The paper emphasizes a dynamic view of research processes, in which learning about treatment and treatment adoption does not...

This paper provides novel insights into the science of scaling by examining an educational mentoring program in Mexico. Our analysis encompasses two separate field experiments, and takes advantage of a unique opportunity to learn from the government's implementation of the program on a large...

This study examines whether charitable giving increases if donors have more choice about how their donations are used. In a field experiment, employees of large Albanian companies were asked to donate to projects administered by Down Syndrome Albania. Treatments varied in whether participants...

Models of job tournaments and competitive workplaces more generally predict that while individual effort may increase as competition intensifies between workers, the incentive for workers to cooperate with each other diminishes. We report on a field experiment conducted with workers from a...

Models of job tournaments and competitive workplaces more generally predict that while individual effort may increase as competition intensifies between workers, the incentive for workers to cooperate with each other diminishes. We report on a field experiment conducted with workers from a...

Models of job tournaments and competitive workplaces more generally predict that while individual effort may increase as competition intensifies between workers, the incentive for workers to cooperate with each other diminishes. We report on a field experiment conducted with workers from a...