Measuring Party Effects

43 Pages Posted: 13 Nov 2017 Last revised: 30 Aug 2018

See all articles by Adam Ramey

Adam Ramey

New York University Abu Dhabi

Date Written: April 8, 2018


Measuring party loyalty (and party effects, more broadly) in roll call voting has long been a contentious matter in the study of legislative behavior. While techniques for measurement in this arena are numerous, most of them suffer from a fatal flaw: they improperly (or insufficiently) separate measures of preferences from party effects.

A significant part of this measurement challenge is the identification of: (a) which roll calls leaders care about and, (b) in which direction do they desire their members to vote.

In this paper, we use a novel dataset of party leader speeches from the 101st to 113th Congresses to develop a model of party effects and measure them across members and time. Unlike existing techniques, we allow for party effects to vary across members, parties, and time. Critically, using this approach, we are able to estimate legislator ideology free of party and party loyalty effects independent of preferences. After validating these measures using examples from contemporary Congresses, we show that using our measures of loyalty calls in to question several findings in the existing literature on party effects. Namely, we show that, contrary to the findings of Minozzi & Volden (2013), ideological extremists are less loyal than moderates. Additionally, we find that the electoral costs of party loyalty are much more nuanced than the findings of Carson et al. (2010) and Canes-Wrone, Brady, & Cogan (2002).

Keywords: Congress, Ideal Points, Parties, Bayesian, Roll Call

Suggested Citation

Ramey, Adam, Measuring Party Effects (April 8, 2018). Available at SSRN: or

Adam Ramey (Contact Author)

New York University Abu Dhabi ( email )

PO Box 129188
Abu Dhabi
United Arab Emirates

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