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Measuring Political Positions from Legislative Speech

  • Benjamin E. Lauderdale (a1) and Alexander Herzog (a2)

Existing approaches to measuring political disagreement from text data perform poorly except when applied to narrowly selected texts discussing the same issues and written in the same style. We demonstrate the first viable approach for estimating legislator-specific scores from the entire speech corpus of a legislature, while also producing extensive information about the evolution of speech polarization and politically loaded language. In the Irish Dáil, we show that the dominant dimension of speech variation is government–opposition, with ministers more extreme on this dimension than backbenchers, and a second dimension distinguishing between the establishment and anti-establishment opposition parties. In the U. S. Senate, we estimate a dimension that has moderate within-party correlations with scales based on roll-call votes and campaign donation patterns; however, we observe greater overlap across parties in speech positions than roll-call positions and partisan polarization in speeches varies more clearly in response to major political events.

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Authors’ note: Replication materials are available online as Lauderdale and Herzog (2016). We thank Ken Benoit, Royce Carroll, Justin Grimmer, Paul Kellstedt, Lanny Martin, Scott Moser, Adam Ramey, Randy Stevenson, Georg Vanberg, two anonymous reviewers, and the editor of this journal for their comments and feedback. Supplementary materials for this article are available on the Political Analysis Web site.

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Political Analysis
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