Measuring Legislative Preferences

Innovation in the estimation of spatial models of roll-call voting has been one of the most important developments in the study of Congress and other legislative and judicial institutions. The popularity of ideal point estimation is due to its close link to theoretical work on legislative politics and collective decision-making. Several of the paradigms and models of contemporary legislative decision-making are based on spatial representations of preferences hence ideal estimation is very significant in studies on legislatures, and on courts and executives. This article aims to provide a general and a less technical overview of the literature on ideal point estimation. It makes explicit comparisons to interest group ratings in order to highlight the advantages and disadvantages of ideal point estimation in applied work.