Legislative institutions structure and order the myriad topics addressed by legislators. Jointly considering both roll call votes and floor speech, we show that the contemporary US Senate is ordered around but two dimensions: one ideological and another capturing leadership. We characterize both word and vote choice in terms of the exact same ideal points and policy dimensions. These findings emerge from our method, Sparse Factor Analysis (SFA), designed to combine vote and textual data when estimating ideal points, word affect, and the underlying dimensionality. This contrasts with the single dimension that emerges from an analysis of votes alone, and with the more numerous dimensions that emerge from analyzing speech alone. We then show how SFA can leverage common speech in order to impute missing data, to estimate rank-and-file ideal points using only their words and the vote history of party leaders, and even to scale newspaper editorials.
With In Song Kim and John Londregan.
Technical Appendix here and Supplemental Results here.