Isserman’s Impact

Applications using quasi-experimental comparison group designs in regional science and geography have increased substantially over the last three decades, inspired by the work of Andrew Isserman and colleagues in the 1980s and 1990s, robust literatures on quasi-experimental design in fields like education and psychology, a vast program evaluation literature, observational studies methodology in statistics, and the growing interest in experimental and nonexperimental (natural) designs in empirical economics. This article discusses the state of quasi-experimental comparison group research today, with a primary focus on studies in which regions—census tracts, counties, cities, metropolitan areas, provinces, or states—are the units of analysis. There is still progress to be made in improving matching methods, making more extensive use of time-series designs, undertaking more systematic sensitivity testing and checks for the robustness of findings, focusing greater attention on effect heterogeneity and research designs that aid policy and program improvement, and improving the practice of regional quasi-experimental research generally.