The Effectiveness of International Environmental Regimes: Comparing and Contrasting Findings from Quantitative Research1

This article uses quantitative methods to deepen and broaden our understanding of the factors that determine the effectiveness of international regimes. To do so, we compare and contrast the findings resulting from two major projects: the Oslo-Seattle Project and the International Regimes Database Project. The evidence from these projects sheds considerable light on the determinants of regime effectiveness in the environmental realm. Clearly, regimes do make a difference. By combining models and data from the two projects, we are able to move beyond this general proposition to explore the significance of a number individual determinants of effectiveness, including the distribution of power, the roles of pushers and laggards, the effects of decision rules, the depth and density of regime rules, and the extent of knowledge of the relevant problem. We show how important insights emerge not only from the use of statistical procedures to separate the effects of individual variables but also from the application of alternative techniques, such as Qualitative Comparative Analysis (QCA), designed to identify combinations of factors that operate together to determine the effectiveness of regimes. We use our results to identify a number of opportunities for additional research featuring quantitative analyses of regime effectiveness. Our goal is not to displace traditional qualitative methods in this field of study. Rather, we seek to sharpen a set of quantitative tools that can be joined together with the extensive body of qualitative studies of environmental regimes to strengthen our ability both to identify patterns in regime effectiveness and to explore the causal mechanisms that give rise to these patterns.