Anna M. Wilke and Macartan Humphreys. 2022. “Field Experiments, Theory, and External Validity.” In: Luigi Curini, Robert Franzese (eds). The SAGE Handbook of Research Methods in Political Science and International Relations, 2, Pp. 1007 – 1035.
Critics of field experiments lament a turn away from theory and criticize findings for weak external validity. In this chapter, we outline strategies to address these challenges. Highlighting the connection between these twin critiques, we discuss how structural approaches can both help design experiments that maximize the researcher’s ability to learn about theories and enable researchers to judge to what extent the results of one experiment can travel to other settings. We illustrate with a simulated analysis of a bargaining problem to show how theory can help make external claims with respect to both populations and treatments and how combining random assignment and theory can both sharpen learning and alert researchers to over-dependence on theory.