Boris Shor

A Bayesian Multilevel Modeling Approach to Time-Series Cross-Sectional Data

The analysis of time-series cross-sectional (TSCS) data has become increasingly popular in political science. Meanwhile, political scientists are also becoming more interested in the use of multilevel models (MLM). However, little work exists to understand the benefits of multilevel modeling when applied to TSCS data. We employ Monte Carlo simulations to benchmark the performance of a Bayesian multilevel model for TSCS data. We find that the MLM performs as well or better than other common estimators for such data. Most importantly, the MLM is more general and offers researchers additional advantages.

A Primary Cause of Partisanship? Nomination Systems and Legislator Ideology

Many theoretical and empirical accounts of representation argue that primary elections are a polarizing influence. Likewise, many reformers advocate opening party nominations to nonmembers as a way of increasing the number of moderate elected officials. Data and measurement constraints, however, have limited the range of empirical tests of this argument. We marry a unique new data set of state legislator ideal points to a detailed accounting of primary systems in the United States to gauge the effect of primary systems on polarization. We find that the openness of a primary election has little, if any, effect on the extremism of the politicians it produces.

Reform and Representation: A New Method Applied to Recent Electoral Changes

Can electoral reforms such as an independent redistricting commission and the top-two primary create conditions that lead to better legislative representation? We explore this question by presenting a new method for measuring a key indicator of representation – the congruence between a legislators ideological position and the average position of her districts voters. Our novel approach combines two methods: the joint classification of voters and political candidates on the same ideological scale, along with multilevel regression and post-stratification to estimate the position of the average voter across many districts in multiple elections. After validating our approach, we use it to study the recent impact of reforms in California, showing that they did not bring their hoped-for effects.

Polarization without Parties: Term Limits and Legislative Partisanship in Nebraska’s Unicameral Legislature

Despite a long history of nonpartisanship, the Nebraska state legislature has polarized rapidly within the past decade. Using interviews and campaign finance records, we examine politics in the modern Unicam to investigate nonpartisan polarization. We find that newly instituted term limits created opportunities for the state’s political parties to recruit and finance candidates in an increasingly partisan fashion. Social network analysis suggests that there is a growing level of structure to campaign donations, with political elites increasingly less likely to contribute across party lines. The results offer a compelling example of parties overcoming institutions designed to eliminate them.

Polarization without Parties

Despite a long history of nonpartisanship, the Nebraska state legislature has polarized rapidly within the past decade. Using interviews and campaign finance records, we examine politics in the modern Unicam to investigate nonpartisan polarization. We find that newly instituted term limits created opportunities for the state’s political parties to recruit and finance candidates in an increasingly partisan fashion. Social network analysis suggests that there is a growing level of structure to campaign donations, with political elites increasingly less likely to contribute across party lines. The results offer a compelling example of parties overcoming institutions designed to eliminate them.

Ideology and the US Congressional Vote

A large class of theoretical models posits that voters choose candidates on the basis of issue congruence, but convincing empirical tests of this key claim remain elusive. The most persistent difficulty is obtaining comparable spatial estimates for winning and losing candidates, as well as voters. We address these issues using candidate surveys to characterize the electoral platforms for winners and losers, and large issue batteries in 2008 and 2010 to estimate voter preferences. Questions that were answered by both candidates and citizens allow us to jointly scale these estimates. We find robust evidence that vote choice in congressional elections is both strongly associated with spatial proximity and that individual-level and contextual variables commonly associated with congressional voting behavior condition the magnitude of its importance. Our results have important implications for theories of voter decision-making and electoral institutions.

Methodological Issues in Bridging Ideal Points in Disparate Institutions in a Data Sparse Environment

In earlier work, we created Congressional common space scores for multiple state legislatures using bridge actors who served in both institutions. Here, we employ simulations to explore the general issues involved in bridging institutions in data-sparse environments, where only a few bridge actors exist to allow inter-institutional comparisons. We find that only a few such bridges are necessary to improve ideal point estimates of rescaled legislative chambers.

Party Competition, Party Polarization, and the Changing Demand for Lobbying in the American States

Interest system density influences internal dynamics within interest organizations, how they lobby, and policy conditions. But how do political conditions influence interest system density? How does politics create demand for interest representation? We examine these questions by assessing how legislative party competition and ideological distance between parties in state legislatures affect the number of lobby groups. After stating our theoretical expectations, we examine 1997 and 2007 data on legislative competition and party polarization to assess their influence on system density. We find mixed results: Whereas politics slightly influenced the structuring of nonprofit interest communities, they seem to have not affected the structuring of for-profit interest communities or interest communities as a whole.

Has the Top Two Primary Elected More Moderates

Party polarization is perhaps the most significant political trend of the past several decades of American politics. Many observers have pinned hopes on institutional reforms to reinvigorate the political center. The Top Two primary is one of the most interesting and closely-watched of these reforms: a radically open primary system that removes much of the formal role for parties in the primary election and even allows for two candidates of the same party to face each other in the fall. Here we leverage the adoption of the Top Two in California and Washington to explore the reform’s effects on legislator behavior. We find an inconsistent effect since the reform was adopted in these two states. The evidence for post-reform moderation is stronger in California than in Washington, but some of this stronger effect appears to stem from a contemporaneous policy change—district lines drawn by an independent redistricting commission—while still more might have emerged from a change in term limits that was also adopted at the same time. The results validate some claims made by reformers, but question others, and their magnitude casts some doubt on the potential for institutions to reverse the polarization trend.

Partisan Polarization in the United States: Diagnoses and Avenues for Reform

Over the several decades, observers of American politics have noted the sharp increase in partisanship and ideological polarization among members of Congress. While better ideological differentiation may provide voters clearer choices and increase accountability, the results of recent partisan and ideological battles have raised questions about the impact pf polarization on good governance.While much scholarly effort has gone into studying the root causes on congressional polarization, such research has been hampered by its sole reliance on the US House and Senate for data on legislative polarization. But new data on polarization of state legislatures provided by Shor and McCarty (2011) and updated with the generous support of the John and Laura Arnold Foundation expands our capacity to uncover the political, economic, and social factors that underlie our increasingly polarized system.In this report, we review the evidence concerning the polarization of the US Congress and supplement it with analyses based on the experience of polarization in the US states. We show that while there is variation in polarization across states, in aggregate the patterns are very similar to the national experience. Moreover, analyses of the causes of polarization at the national level are generally confirmed by the data on the states. The richer data from the sates, however, allows us to address new sets of questions which suggest some limited opportunities for reforms targeted at reducing polarization.