Spatial Models of Legislative Effectiveness

Spatial models of policymaking have evolved from the median voter theorem to the inclusion of institutional considerations such as committees, political parties, and various voting and amendment rules. Such models, however, implicitly assume that no policy is better than another at solving public policy problems and that all policy makers are equally effective at advancing proposals. We relax these assumptions, allowing some legislators to be more effective than others at creating high‐quality proposals. The resulting Legislative Effectiveness Model (LEM) offers three main benefits. First, it can better account for policy changes based on the quality of the status quo, changing our understanding of how to overcome gridlock in polarized legislatures. Second, it generalizes canonical models of legislative politics, such as median voter, setter, and pivotal politics models, all of which emerge as special cases within the LEM. Third, the LEM offers significant new empirical predictions, some of which we test (and find support for) within the U.S. Congress.