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Estimating Intra-Party Preferences: Comparing Speeches to Votes*

  • Daniel Schwarz, Denise Traber and Kenneth Benoit

Well-established methods exist for measuring party positions, but reliable means for estimating intra-party preferences remain underdeveloped. While most efforts focus on estimating the ideal points of individual legislators based on inductive scaling of roll call votes, this data suffers from two problems: selection bias due to unrecorded votes and strong party discipline, which tends to make voting a strategic rather than a sincere indication of preferences. By contrast, legislative speeches are relatively unconstrained, as party leaders are less likely to punish MPs for speaking freely as long as they vote with the party line. Yet, the differences between roll call estimations and text scalings remain essentially unexplored, despite the growing application of statistical analysis of textual data to measure policy preferences. Our paper addresses this lacuna by exploiting a rich feature of the Swiss legislature: on most bills, legislators both vote and speak many times. Using this data, we compare text-based scaling of ideal points to vote-based scaling from a crucial piece of energy legislation. Our findings confirm that text scalings reveal larger intra-party differences than roll calls. Using regression models, we further explain the differences between roll call and text scalings by attributing differences to constituency-level preferences for energy policy.

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Daniel Schwarz is postdoctoral research fellow in the Center of Competence for Public Management, University of Bern, Schanzeneckstrasse 1, 3001 Bern, Switzerland, and Department of Methodology, London School of Economics and Political Science, Columbia House, Houghton Street, London WC2A 2AE, UK ( Denise Traber is postdoctoral researcher in the Department of Political Science, University of Zurich, Affolternstrasse 56, 8050 Zurich, Switzerland ( Kenneth Benoit is Professor of Political Science Research Methodology in the Department of Methodology, London School of Economics and Political Science, Columbia House, Houghton Street, London WC2A 2AE, UK, and Department of Political Science, Trinity College, 3 College Green, Dublin 2, Ireland ( This research was supported by the European Research Council grant ERC-2011-StG 283794-QUANTESS and the Swiss National Science Foundation Fellowship grant PA00P1_134188.

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Benoit, Kenneth, Schwarz, Daniel, and Traber, Denise. 2012. ‘The Sincerity of Political Speech in Parliamentary Systems: A Comparison of Ideal Points Scaling Using Legislative Speech and Votes’. Paper presented at the 2nd Annual Conference of EPSA. Berlin, 19–21 June.
Benoit, Kenneth, and Laver, Michael. 2006. Party Policy in Modern Democracies. London and New York: Routledge.
Benoit, Kenneth, and Lowe, Will. 2013. ‘Validating Estimates of Latent Traits from Textual Data Using Human Judgment as a Benchmark’. Political Analysis 21:298313.
Blaser, Cornelia, van der Heiden, Nico, Mahnig, Fabian, and Milic, Thomas. 2003. Analyse der eidgenössischen Abstimmungen vom 18. Mai 2003. Number 81 in “VOX”. Bern and Zürich: GfS-Forschungsinstitut and Institut für Politikwissenschaft, Universität Zürich.
Carey, John M. 2007. ‘Competing Principals, Political Institutions, and Party Unity in Legislative Voting’. American Journal of Political Science 51(1):92107.
Carey, John M. 2009. Legislative Voting and Accountability. New York: Cambridge University Press.
Carrubba, Clifford J., Gabel, Matthew, Murrah, Lacey, Clough, Ryan, Montgomery, Elizabeth, and Schambach, Rebecca. 2006. ‘Off the Record: Unrecorded Legislative Votes, Selection Bias and Roll-Call Analysis’. British Journal of Political Science 36(4):691704.
Carrubba, Clifford, Gabel, Matthew, and Hug, Simon. 2008. ‘Legislative Voting Behavior, Seen and Unseen: A Theory of Roll-Call Vote Selection’. Legislative Studies Quarterly 33(4):543572.
Clinton, Joshua, Jackman, Simon, and Rivers, Douglas. 2004. ‘The Statistical Analysis of Roll Call Data’. American Political Science Review 98(2):355370.
Cox, Gary W., and McCubbins, Mathew D.. 1993. Legislative Leviathan. Party Government in the House. Berkeley and Los Angeles, CA: University of California Press.
Damgaard, Erik. 1995. ‘How Parties Control Committee Members’. In Herbert Döring (ed.), Parliaments and Majority Rule in Western Europe. 308324. Frankfurt a.M./New York: Campus/St. Martin’s Press.
Döring, Herbert. 1995. ‘Time as a Scarce Resource: Government Control of the Agenda’. In Herbert Döring (ed.), Parliamentary and Majority Rule in Western Europe. 223246. Frankfurt a.M./New York: Campus/St. Martin’s Press.
Hertig, Hans-Peter. 1980. Partei, Wählerschaft oder Verband? Entscheidfaktoren im eidgenössischen Parlament. Bern: Francke Verlag.
Hix, Simon. 2004. ‘Electoral Institutions and Legislative Behavior: Explaining Voting Defection in the European Parliament’. World Politics 56(2):194223.
Hug, Simon. 2010. ‘Selection Effects in Roll Call Votes’. British Journal of Political Science 40(1):225235.
Hug, Simon, and Schulz, Tobias. 2007. ‘Left-Right Positions of Political Parties in Switzerland’. Party Politics 13(3):305330.
Imai, Kosuke, King, Gary, and Lau, Olivia. 2007. Zelig: Everyone’s Statistical Software. Available at, accessed 1 September 2014.
Ladner, Andreas. 2007. ‘Political Parties’. In Ulrich Klöti, Peter Knoepfel, Hanspeter Kriesi, Wolf Linder and Yannis Papadopoulos (eds), Handbook of Swiss Politics. 159188. Zürich: Neue Zürcher Zeitung Publishing.
Laver, Michael, and Benoit, Kenneth. 2002. ‘Locating TDs in Policy Spaces: Wordscoring D´ail Speeches’. Irish Political Studies 17(1):5973.
Laver, Michael, Benoit, Kenneth, and Garry, John. 2003. ‘Estimating the Policy Positions of Political Actors Using Words as Data’. American Political Science Review 97(2):311331.
Linder, Wolf. 2010. Swiss Democracy: Possible Solutions to Conflict in Multicultural Societies. London: Palgrave Macmillan.
Lowe, Will. 2008. ‘Understanding Wordscores’. Political Analysis 16(4):356371.
Mayhew, David R. 1974. Congress: The Electoral Connection. New Haven, CT: Yale University Press.
Monroe, Burt L., and Maeda, Ko. 2004. ‘Talk’s Cheap: Text-Based Ideal Point Estimation’. Paper Presented to the Political Methodology Society. Palo Alto, CA, 29–31 July.
Owens, John E. 2006. ‘Explaining Party Cohesion and Discipline in Democratic Legislatures: Purposiveness and Contexts’. In Reuven Y. Hazan (ed.), Cohesion and Discipline in Legislatures. Political Parties, Party Leadership, Parliamentary Committees and Governance. 1240. London and New York: Routledge.
Poole, Keith T., and Rosenthal, Howard. 1997. Congress: A Political-Economic History of Roll Call Voting. Oxford and New York: Oxford University Press.
Proksch, Sven-Oliver, and Slapin, Jonathan B.. 2010. ‘Position Taking in European Parliament Speeches’. British Journal of Political Science 40:587611.
Proksch, Sven-Oliver, and Slapin, Jonathan B.. 2012. ‘Institutional Foundations of Legislative Speech’. American Journal of Political Science 56(3):520537.
Schwarz, Daniel. 2009. Zwischen Fraktionszwang und freiem Mandat. Eine Untersuchung des fraktionsabweichenden Stimmverhaltens im schweizerischen Nationalrat zwischen 1996 und 2005. Norderstedt: BoD.
Schwarz, Daniel, Bächtiger, André, and Lutz, Georg. 2011. ‘Switzerland: Agenda-Setting Power of the Government in a Separation-of-Powers Framework’. In Bjørn Erik Rasch and George Tsebelis (eds), The Role of Governments in Legislative Agenda Setting. 127144. Oxon and New York: Routledge.
Slapin, Jonathan B., and Proksch, Sven-Oliver. 2008. ‘A Scaling Model for Estimating Timeseries Party Positions from Texts’. American Journal of Political Science 52(3):705722.
Slapin, Jonathan B., and Proksch, Sven-Oliver. 2010. ‘Look Who’s Talking: Parliamentary Debate in the European Union’. European Union Politics 11(3):333357.
Traber, Denise, Hug, Simon, and Sciarini, Pascal. 2014. ‘Party Unity in the Swiss Parliament: The Electoral Connection’. The Journal of Legislative Studies 20(2):193215.
VanDoren, Peter M. 1990. ‘Can We Learn the Causes of Congressional Decisions from Roll-Call Data?’. Legislative Studies Quarterly 15(3):311340.
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Political Science Research and Methods
  • ISSN: 2049-8470
  • EISSN: 2049-8489
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