Using Process Tracing to Evaluate Formal Models

Political scientists frequently use qualitative evidence to support or evaluate the empirical applicability of formal models. Despite this widespread practice in international relations and comparative politics, neither the qualitative methods literature nor research on empirically evaluating formal models systematically address the topic. This paper offers three contributions to bridge this gap. First, it demonstrates that formal models and qualitative evidence are frequently combined in current research. Second, it argues that process tracing is a valuable tool for empirically assessing models because they share a common focus on understanding causal mechanisms. The third and main contribution is to provide new guidelines for using process tracing that focus on issues specific to the modeling enterprise, illustrated with numerous examples from international relations and comparative politics. These standards establish new common ground to help political scientists use qualitative evidence more effectively to evaluate formal models