A Bayesian Hierarchical Topic Model for Political Texts: Measuring Expressed Agendas in Senate Press Releases.

Studies of political communication lack comprehensive methods to efficiently measure the priorities political actors emphasize in statements. To address this limitation, I derive a statistical model that attends to the structure of political rhetoric when measuring expressed priorities: statements are naturally organized by author. The expressed agenda model exploits this structure to simultaneously estimate the topics in the texts, as well as the attention political actors allocate to the estimated topics. I apply the method to a collection of over 24,000 press releases from senators in 2007: an ideal medium to measure how senators explain their work in Washington to constituents. A set of examples validates the measures of priorities and demonstrates the model's ability to test theories of how legislators explain work in Washington to constituents. The statistical model is available in a free software package for the R computing language. ..PAT.-Unpublished Manuscript [ABSTRACT FROM AUTHOR]