The Role of Theory in Field Experiments

We classify all published field experiments in five top economics journals from 1975 to 2010 according to how closely the experimental design and analysis are linked to economic theory. We find that the vast majority of field experiments (68 percent) are Descriptive studies that lack any explicit model; 18 percent are Single Model studies that test a single model-based hypothesis; 6 percent are Competing Models studies that test competing model-based hypotheses; and 8 percent are Parameter Estimation studies that estimate structural parameters in a completely specified model. We also classify laboratory experiments published in these journals over the same period and find that economic theory has played a more central role in the laboratory than in the field. Finally, we discuss in detail three sets of field experiments—on gift exchange, on charitable giving, and on negative income tax—that illustrate both the benefits and the potential costs of a tighter link between experimental design and theoretical underpinnings.