Measuring Legislator’s Ideological Position Using Pairwise-Comparisons

• In Event: Innovative Approaches to European Legislative Processes

Abstract

Policy preferences of individual legislators are relevant to many different area of the comparative research going back at least to early studies of representation in the 1960s. Several methodological advancements have advanced our understanding of ideological placement for political actors - ranging from scaling
of legislative roll-call voting in the United States to text-based classifications of political parties in Western Europe. A particularly thorny problem is estimating the ideology of individual preferences in legislatures where strong partisan
discipline occurs and only a few unconstrained votes are recorded.

In this paper, we offer a novel approach for estimating legislators' ideological positions. Our research design comprises four features. First, we survey members of parties' youth organization as they possess detailed knowledge about their elected representatives. Second, these national experts are asked to compare pairs of MPs along the left-right dimensions. Third, we use these data for estimating a Bradley-Terry model that delivers the ideological position of each MP. Finally, we validate our measure and benchmark it against existing alternatives. With this design,
we estimate the ideological position and its uncertainty of 709 members of the German Bundestag in 2019. Our model captures variation within and across political parties well.

Authors

• Christian Breunig, University of Konstanz

• Benjamin Guinaudeau

• Simon Roth