• Bayesian estimation;
  • Item response theory;
  • Random- and fixed effect models;
  • Roll call data;
  • Vote cast data

Summary.  Ideal point estimation is an important tool to study legislative and judicial voting behaviours. We propose a hierarchical ideal point estimation framework that directly models complex voting behaviours on the basis of the characteristics of the political actors and the votes that they cast. Through simulations and empirical examples we show that this framework holds good promise for resolving many unsettled issues, such as the multi-dimensional aspects of ideology, and the effects of political parties. As a companion to this paper, we offer an easy-to-use R package that implements the methods discussed.