This paper shows how the productive interplay of theory and experimental work has furthered our understanding of credit markets in developing countries. Descriptive facts motivated a body of theory, which in turned motivated experiments designed to test it. Results from these experiments reveal both the success and the limits of the theory, prompting new work to refine it. We argue that the literature on credit can be a template research in other domains.
Until recently rigorous impact evaluations have been rare in the area of finance and private sector development. One reason for this is the perception that many policies and projects in this area lend themselves less to formal evaluations. However, a vanguard of new impact evaluations on areas as diverse as fostering microenterprise growth, microfinance, rainfall insurance, and regulatory reform demonstrates that in many circumstances serious evaluation is possible. The purpose of this paper is to synthesize and distil the policy and implementation lessons emerging from these studies, use them to demonstrate the feasibility of impact evaluations in a broader array of topics, and thereby help prompt new impact evaluations for projects going forward.
We present new evidence on the randomization methods used in existing experiments, and new simulations comparing these methods. We find that many papers do not describe the randomization in detail, implying that better reporting is needed. Our simulations suggest that in samples of 300 or more, the different methods perform similarly. However, for very persistent outcome variables, and in smaller samples, pair-wise matching and stratification perform best and appear to dominate the rerandomization methods commonly used in practice. The simulations also point to specific recommendations for which variables to balance on, and for which controls to include in the ex post analysis.
Experimental economists believe (and enforce the idea) that researchers should not employ deception in the design of experiments. This rule exists in order to protect a public good: the ability of other researchers to conduct experiments and to have participants trust their instructions to be an accurate representation of the game being played. Yet other social sciences, particularly psychology, do not maintain such a rule. We examine whether such a public goods problem exists by purposefully deceiving some participants in one study, informing them of this fact, and then examining whether the deceived participants behave differently in a subsequent study. We find significant differences in the selection of individuals who return to play after being deceived as well as (to a lesser extent) the behavior in the subsequent games, thus providing qualified support for the proscription of deception. We discuss policy implications for the maintenance of separate participant pools.
Randomized experiments have become a popular tool in development economics research and have been the subject of a number of criticisms. This paper reviews the recent literature and discusses the strengths and limitations of this approach in theory and in practice. We argue that the main virtue of randomized experiments is that, owing to the close collaboration between researchers and implementers, they allow the estimation of parameters that would not otherwise be possible to evaluate. We discuss the concerns that have been raised regarding experiments and generally conclude that, although real, they are often not specific to experiments. We conclude by discussing the relationship between theory and experiments.
This paper surveys evidence from recent randomized evaluations in developing countries on the impact of price on access to health and education. Debate on user fees has been contentious, but until recently much of the evidence was anecdotal. Randomized evaluations across a variety of settings suggest prices have a large impact on take-up of education and health products and services. While the sign of this effect is consistent with standard theories of human capital investment, a more detailed examination of the data suggests that it may be important to go beyond these models. There is some evidence for peer effects, which imply that for some goods the aggregate response to price will exceed the individual response. Time inconsistent preferences could potentially help explain the apparently disproportionate effect of small short-run costs and benefits on decisions with long-run consequences.