Field experiments

A field experiment applies the scientific method to experimentally examine an intervention in the real world (or as many experimentalists like to say, naturally occurring environments) rather than in the laboratory. Field experiments, like lab experiments, generally randomize subjects (or other sampling units) into treatment and control groups and compare outcomes between these groups. Field experiments are so named in order to draw a contrast with laboratory experiments, which enforce scientific control by testing a hypothesis in the artificial and highly controlled setting of a laboratory. Often used in the social sciences, and especially in economic analyses of education and health interventions, field experiments have the advantage that outcomes are observed in a natural setting rather than in a contrived laboratory environment. For this reason, field experiments are sometimes seen as having higher external validity than laboratory experiments. However, like natural experiments, field experiments suffer from the possibility of contamination: experimental conditions can be controlled with more precision and certainty in the lab. Yet some phenomena (e.g., voter turnout in an election) cannot be easily studied in a laboratory.

Examples include:

The use of experiments in the lab and the field have a long history in the physical, natural, and life sciences. Geology has a long history of field experiments, since the time of Avicenna, while field experiments in anthropology date back to Biruni's study of India.Social psychology also has a history of field experiments, including work by pioneering figures Philip Zimbardo, Kurt Lewin and Stanley Milgram. In economics, Peter Bohm, University of Stockholm, was one of the first economists to take the tools of experimental economic methods and attempt to try them with field subjects. In the area of development economics, the pioneer work of Hans Binswanger in the late 1970s conducting experiments in India on risk behavior [1] should also be noted. The use of field experiments in economics has grown recently with the work of John A. List, Jeff Carpenter, Juan-Camilo Cardenas, Abigail Barr, Catherine Eckel, Michael Kremer, Paul Gertler, Glenn Harrison, Colin Camerer, Bradley Ruffle, Abhijit Banerjee Esther Duflo, Dean Karlan, Edward "Ted" Miguel, Sendhil Mullainathan, David H. Reiley, among others. Pa124

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