The Center for Positive/Empirical Analysis of Political Economy held a special seminar on December 7, 2023, entitled “Empirical Strategies Toward External Validity” by Professor Naoki Egami (Assistant Professor, Department of Political Science, Columbia University).
Dr. Egami is a highly recognized political scientist who specializes in statistical causal inference and machine learning as well as the application of newly developed methods to empirical research. He has numerous publications in top international journals in the field of political methodology. In this seminar, he spoke about his research on external validity, a topic of increasing interest in recent years when conducting causal inference in the social sciences.
With the rise of experimental research (survey, lab, and field experiments) in political science, our understanding of internal validity has deepened. At the same time, however, no systematic method has been established to test external validity, i.e., whether causal effects derived from experimental research on a particular case can be found in other contexts. Dr. Egami proposed a new method to improve external validity while ensuring internal validity: Multi-Site Causal Studies (MCS), in which multiple cases are selected and causal effects are estimated simultaneously through Synthetic Purposive Sampling. He also introduced a statistical package (spsR) that he developed to facilitate the application of this method to empirical studies.
Lively discussion between Prof. Egami and the participants followed the seminar: how to reconcile the trade-offs between budget constraints and the need to secure a certain number of respondents at each location to carry out experiments in multiple sites across contexts; how far researchers should seek generalizability of theory through improving external validity; and how we should pay greater attention to external validity.
After the seminar, a round-table discussion was held for students who wish to enter doctoral programs at graduate schools in the U.S.A. Dr. Egami enthusiastically answered questions from the participants, such as how to prepare an application and what academic life looks like in Ph.D. programs, and offered lots of helpful advice.
