The Case for Randomized Field Trials in Economic and Policy Research

Social experiments have been used in research since the 1960s, yet the technique of controlled experimentation still arouses controversy among social scientists. The crucial element that distinguishes a controlled experiment from other forms of research is random assignment of treatment to the observational units of study. Because treatment differences in the sample occur as a result of random chance, the effects of the treatment on behavior can be measured with high reliability. This paper examines the advantages and disadvantages of experiments in comparison with other research techniques and describes the circumstances where randomized trials should be preferred over other methods.