Articles & Chapters

Forthcoming. Modeling Unobserved Heterogeneity in Social Networks with the Frailty Exponential Random Graph Model. Political Analysis (with Janet M. Box-Steffensmeier and Jason W. Morgan ). Data | Bibtex | Abstract In the study of social processes, the presence of unobserved heterogeneity is a regular concern. It should be particularly worrisome for the statistical analysis of networks, given the complex dependencies that shape network formation combined with the restrictive assumptions of related models. In this paper, we demonstrate the importance of explicitly accounting for unobserved heterogeneity in exponential random graph models (ERGM) with a Monte Carlo analysis and two applications that have played an important role in the networks literature. Overall, these analyses show that failing to account for unobserved heterogeneity can have a significant impact on inferences about network formation. The proposed frailty extension to the ERGM (FERGM) generally outperforms the ERGM in these cases, and does so by relatively large margins. Moreover, our novel multilevel estimation strategy has the advantage of avoiding the problem of degeneration that plagues the standard MCMC-MLE approach.

Keywords: Exponential Random Graph Model (ERGM), Frailty terms, Frailty Exponential Random Graph Model (FERGM), Multiple membership mixed effects model, Monte Carlo experiments, Unobserved heterogeneity

Forthcoming. Mobilizing the Public Against the President: Congress and the Political Costs of Unilateral Action. American Journal Political Science (with Douglas L. Kriner). Appendix | Data | Bibtex | AbstractPrior scholarship overlooks the capacity of other actors to raise the political costs of unilateral action by turning public opinion against the president. Through a series of five experiments embedded on nationally representative surveys, we demonstrate Congress’ ability to erode support for unilateral actions by raising both constitutional and policy-based objections to the exercise of unilateral power. Congressional challenges to the unilateral president diminish support for executive action across a range of policy areas in both the foreign and domestic realm and are particularly influential when they explicitly argue that presidents are treading on congressional prerogatives. We also find evidence that constitutional challenges are more effective when levied by members of Congress than by other actors. The results resolve a debate in the literature and suggest a mechanism through which Congress might exercise a constraint on the president, even when it is unable to check him legislatively.

Keywords: Congress, Public opinion, Unilateral action, Unilateral power, Executive orders, Survey experiments, Presidency

Forthcoming. The Specter of Supreme Court Criticism: Public Opinion and Unilateral Action. Presidential Studies Quarterly (with Douglas L. Kriner). Appendix | Bibtex | AbstractThe conventional wisdom suggests that the judicial constraint on presidential unilateralism is weak: judicial challenges are rare, and successful ones rarer still. However, we argue that courts have grown increasingly assertive in checking important unilateral policy initiatives in both the foreign and domestic arenas. This judicial reassertion also raises the prospect that courts may exert a more informal constraint on presidential power. Utilizing two experiments embedded on nationally representative surveys, we find evidence that even speculation about a judicial challenge can erode public support for unilateral action. For some issues the effect may be conditional on diffuse support for the Court. Anticipations of these political costs may help explain the relative paucity of major unilateral actions.

Keywords: Supreme Court, Public opinion, Unilateral action, Unilateral power, Executive orders, Survey experiments, Presidency

Forthcoming. All the President's Senators: Presidential Co-Partisans and the Allocation of Federal Grants. Legislative Studies Quarterly (with Douglas L. Kriner and Andrew Reeves). Appendix | Bibtex | AbstractPrevious scholarship argues that House members’ partisan relationship to the president is among the most important determinants of the share of federal dollars they bring home to their constituents. Do presidential politics also shape distributive outcomes in the Senate? Analyzing the allocation of more than $8.5 trillion of federal grants across the states from 1984 to 2008, we show that presidential co-partisan senators are more successful than opposition party members in securing federal dollars for their home states. Moreover, presidents appear to target grants ex post to states that gain presidential co-partisans in recent elections.

Keywords: Federal grants, Senate, Elections, Presidential co-partisans

Forthcoming. Who Votes for the Future? Information, Expectations and Endogeneity in Economic Voting. Political Behavior (with Dean Lacy). Appendix | Data | Bibtex | AbstractVoters' four primary evaluations of the economy - retrospective national, retrospective pocketbook, prospective national, and prospective pocketbook - vary in the cognitive steps necessary to link economic outcomes to candidates in elections. We hypothesize that the effects of the different economic evaluations on vote choice vary with a voter’s ability to acquire information and anticipate the election outcome. Using data from the 1980 through 2004 US presidential elections, we estimate a model of vote choice that includes all four economic evaluations as well as information and uncertainty moderators. The effects of retrospective evaluations on vote choice do not vary by voter information. Prospective economic evaluations weigh in the decisions of the most informed voters, who rely on prospective national evaluations when they believe the incumbent party will win and on prospective pocketbook evaluations when they are uncertain about the election outcome or believe that the challenger will win. Voters who have accurate expectations about who will win the election show the strongest relationship between their vote choice and sociotropic evaluations of the economy, both retrospective and prospec- tive. Voters whose economic evaluations are most likely to be endogenous to vote choice show a weaker relationship between economic evaluations and their votes than the voters who appear to be more objective in their assessments of the election. Economic voting is broader and more prospective than previously accepted, and concerns about endogeneity in economic evaluations are overstated.

Keywords: Economic voting, Information, Political sophistication, Uncertainty, Attribution, Presidential elections, Endogeneity

Forthcoming. Constitutional Qualms or Politics as Usual? The Factors Shaping Public Support for Unilateral Action. American Journal of Political Science (with Douglas L. Kriner). Appendix | Data | Bibtex | AbstractThe formal institutional constraints that Congress and the courts impose on presidential unilateral action are feeble. As a result, recent scholarship suggests that public opinion may be the strongest check against executive overreach. However, little is known about how the public assesses unilateral action. Through a series of five survey experiments embedded on nationally representative surveys, we examine the extent to which Americans evaluate unilateral action based on constitutional, partisan, and policy concerns. We find that Americans do not instinctively reject unilateral action as a threat to our system of checks and balances, but instead evaluate unilateral action in terms of whether it accords or conflicts with their partisan and policy preference priors. Our results suggest that the public constraint on presidential unilateral action is far from automatic. Rather, the strength and scope of this check is a variable product of political contestation in the public sphere.

Keywords: Public opinion, Unilateral action, Unilateral power, Executive orders, Survey experiments, Presidency
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2016. Presidential Primaries and Caucuses. Forthcoming at Oxford Bibliographies in Political Science, ed. Sandy Maisel, New York: Oxford University Press (with Corwin D. Smidt). Bibtex | AbstractA review of the current state of research on presidential nomination campaigns.

Keywords: Primaries, Caucuses, Nomination contests, Literature review

2016. Why Amicus Curiae Cosigners Come and Go: A Dynamic Model of Interest Group Networks. Proceedings of the International Workshop on Complex Networks and their Applications. Studies in Computational Intelligence (with Janet M. Box-Steffensmeier). Appendix | Bibtex | AbstractInterest groups use coalition strategies to exert influence, yet, like other political actors, they also withdraw from partnerships in the pursuit of other policy goals. We explore how interest group coalition strategies have changed over time and which factors determine whether interest groups relationships form and dissolve. Utilizing dynamic networks of a panel of interest groups derived from cosigner status to United States Supreme Court amicus curiae briefs, we illuminate the evolution of the social networks of frequent signers from the 1970s to the present day. A separable temporal exponential random graph model (STERGM) shows that the number of partners is important for formation but not dissolution, while industrial homophily helps both to make and maintain connections. In addition, statistical trends suggest that while networks change, a few players have acted continuously as coordination hubs for the bulk of the decades. However, a number of other key players in particular decades would be missed without a dynamic perspective.

Keywords: Supreme Court, Public opinion, Unilateral action, Unilateral power, Executive orders, Survey experiments, Presidency

2016. Superdelegates or Supertrustees? The Timing and Consistency of Superdelegate Decisions. Presidential Studies Quarterly, 46(3): 640-668 (with Erik D. Heidemann). Appendix | Bibtex | AbstractDo superdelegates heed public opinion in deciding whom to support in nomination contests or do they follow their own conscience? We examine both individual and environmental factors peculiar to superdelegate decision-making to ascertain whether and how they integrate populist considerations into their nomination choices. Via a survey of superdelegates in the 2008 presidential nomination contest, we analyze both the timing of a superdelegate’s decision as well as any change in their candidate preference. Superdelegates who prioritize constituent concerns endorse earlier but are no more or less likely to switch their candidate preference during the campaign.

Keywords: Superdelegates, Elite survey, Public opinion, Party nominations, 2008 campaigns, Survival analysis

2016. Judicial Networks. In Oxford Handbook of Political Networks, ed. Jennifer N. Victor, Mark Lubell and Alex Montgomery, New York: Oxford University Press (with Janet M. Box-Steffensmeier and Claire Leavitt). Bibtex| AbstractIn this chapter we present a comprehensive summary of the literatures benefiting from the study of judicial networks. We pay particular attention to networks where exciting scholarly advances are concentrated and those that show great promise in contributing to the literature on judicial behavior and extant decision-making models. Throughout our discussions, we identify the necessary tools and measures to study these networks and describe the varying processes of data collection while highlighting the strengths and weaknesses of both the classic and most recent literatures. We classify judicial networks into three broad types. First, we explore the literature on citations networks, or networks of judicial opinions linked by references to one another. Citation networks provide crucial insights into the foundations of judicial decision-making by exposing the opinions judges believe to be most significant. Second, we look at the networks created by considering the interactions between judges, law clerks, lawyers and other relevant figures, which we call prestige networks. Such networks have the potential to reveal possible peer effects among judges and the role of social and professional relationships in determining judicial outcomes. Finally, the developing literature on amicus curiae networks, which map connections between signatories of “friend of the court” legal briefs, help identify which extralegal actors enjoy the greatest influence on the courts. More importantly, perhaps, these networks expose the often secretive relationships among organized interests that are potentially relevant across branches of government and in a host of democracies.

Keywords: Courts, Judicial branch, Social networks, Citation networks, Prestige networks, Amicus curiae networks

2015. Issue-Specific Opinion Change: The Supreme Court and Health Care Reform. Public Opinion Quarterly, 79(4): 881-905 (with David M. Glick). Appendix | Bibtex | AbstractDid the Supreme Court decision in the Affordable Care Act case change public opinion about health care reform? We utilize a multi-wave panel design with observations collected just hours before and after the Court's decision to address macro-level questions concerning the Court's effect on opinion about health care reform generally and the individual mandate specifically. We show that support for health care reform remained constant despite significant positive movement on the mandate. We further exploit features of the panel to analyze this micro-level change and test hypotheses related to cognitive models, individual attributes, and assessments of the Court's legitimacy. Despite some evidence of micro-level variation, our findings ultimately point to a decision that induced a general, persistent, and relatively unconditional uptick in support for the provision the Court deemed constitutional.

Keywords: Supreme Court, Public opinion, Panel data, Health care, Mandate, Mixed-effects model

2015. Political Constraints on Unilateral Executive Action. Case Western Reserve Law Review, 65(4): 897-931 (with Douglas L. Kriner). Bibtex | AbstractPundits, politicians, and scholars alike have decried the dramatic expansion of presidential unilateral power in recent decades. Such brazen assertions, against which Congress and the courts have offered seemingly feckless resistance, have led many to decry the emergence of a new “imperial presidency.” From a political science perspective, however, perhaps the more puzzling question is the relative paucity , not the proliferation of unilateral actions. Why do presidents not act unilaterally to bring an even wider range of policies into closer alignment with their preferences? The dominant paradigm in political science scholarship emphasizes Congress ’s institutional weakness when confronting the unilateral president. It correctly notes that presidents, in all but the rarest of circumstances, can act with impunity, secure in the knowledge that legislative efforts to undo their unilateral initiatives will fail. However, much scholarship overlooks the critical importance of political costs in constraining the unilateral president, and how other institutions—even when they cannot legally compel the president to change course—can affect presidential strategic calculations by raising these costs. We illustrate our argument with a pair of case studies: President Obama’s halting unilateral policy response to the immigration crisis, and his abrupt about-face on unilateral action against the Assad regime in Syria. In these cases, we argue that calculations about the informal political costs of unilateral action affected both the timing and content of presidential policy decisions. When contemplating unilateral action, presidents anticipate more than whether they can defeat legislative efforts to overturn their unilateral initiatives. They also consider the political costs of acting unilaterally and weigh them against the benefits of doing so. Paying greater attention to these political constraints on unilateral action affords a more accurate picture of the place of the unilateral presidency within our separation of powers system in the contemporary era.

Keywords: Executive orders, Unilateral action, Unilateral power, Obama, Immigration, Syria, Political costs

2015. Chief Justice Roberts's Health Care Decision Disrobed: The Microfoundations of the Court's Legitimacy. American Journal of Political Science, 59(2): 403-418 (with David M. Glick). Appendix | Data | Bibtex | AbstractThe 2012 challenge to the Affordable Care Act was an unusual opportunity for people to form or reassess opinions about the Supreme Court. We utilize panel data coupled with as-if random assignment to reports that Chief Justice Roberts' decision was politically motivated to investigate the microfoundations of the Court's legitimacy. Specifically, we test the effects of changes in individuals' ideological congruence with the Court and exposure to the non-legalistic account of the decision. We find that both affect perceptions of the Court's legitimacy. Moreover, we show that these mechanisms interact in important ways and that prior beliefs that the Court is a legalistic institution magnify the effect of updating ones ideological proximity to the Court. While we demonstrate that individuals can and did update their views for multiple reasons, we also highlight constraints which allow for aggregate stability in spite of individual level change.

Keywords: Supreme Court, Legitimacy, Diffuse support, Public opinion, Ideology, Panel data, Health care
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🏆Winner of the 2015 Best Article Award by the Law and Courts Section of the American Political Science Association.

2015. Mass Preferences on Shared Representation and the Composition of Legislative Districts. American Politics Research, 43(3): 451-478 (with Todd Makse). Appendix | Bibtex | AbstractScholars of redistricting often discuss communities of interest as a guideline for drawing districts, but scholarship offers little guidance on how citizens construe communities and interests in the context of representation. In this paper, we seek to better understand how citizens' perceptions of people and places affect preferences regarding representation. Using an original survey conducted in fifteen Massachusetts communities, we explore whether citizens have meaningful preferences about the communities with whom they share the same representative. To the extent they do, we test whether these preferences are driven by considerations of geography or other factors such as partisanship, race, and socioeconomic status. Our findings not only offer the opportunity to refine the concept of communities of interest to account for voter preferences, but more broadly speak to the literature on the increasingly political nature of residential preferences and their impact on political attitudes, participation, and voting behavior.

Keywords: Communities of interest, Redistricting, Representation, Residential preference, Massachusetts

2015. Comparing Membership Interest Group Networks Across Space and Time, Size, Issue and Industry. Network Science, 3(1): 78-97 (with Janet M. Box-Steffensmeier). Appendix | Bibtex | AbstractWe compare and contrast the network formation of interest groups across industry and issue area. We focus on membership interest groups, which by virtue of representing the interests of voluntary members, face particular organizational and maintenance constraints. To reveal their cooperative behavior we build a network data set based on cosigner status to United States Supreme Court amicus curiae briefs and analyze it with exponential random graph models (ERGMs) and multidimensional scaling. We find that while many of the same factors shape membership networks, religious, labor and political organizations do not share the same struc- ture as each other or as the business, civic and professional groups. Our methodological approach culminates in a clear and compact spatial representation of network similarities and differences.

Keywords: Interest groups, membership organizations, coalition strategies, amicus curiae briefs, exponential random graph models, multidimensional scaling

2014. Following the Money: Super PACs and the 2012 Presidential Nomination. Presidential Studies Quarterly, 44(3): 410-430 (with Corwin D. Smidt). Bibtex | AbstractThe entrance of Super Political Action Committees (Super PACs), outside groups with no caps on fundraising or independent expenditures, prompts a reexamination of the role of money in campaigns and elections. We investigate the influence of Super PAC expenditures in the 2012 Republican nomination contest. A compressed calendar makes nomination campaigns expensive and money crucial, especially for lesser-known candidates, such that outside expenditures likely made a difference. Indeed, we find Super PACs helped to extend Santorum’s long-shot candidacy but also helped Romney by weakening momentum from Gingrich and Santorum wins. Using panel data of candidate dynamics, we also find that candidate and Super PAC expenditures within various key primary states reactively complement each other. However, we do not find dispositive evidence that Super PACs coordinate with campaigns, thereby acting, at least in this context, within the bounds of their legally mandated independence.

Keywords: Super PACs, Seemingly unrelated regression, Campaign fundraising, Campaign expenditures, 2012 nomination contest, Coordination

2014. The Evolution and Formation of Amicus Curiae Networks. Social Networks, 36: 82-96 (with Janet M. Box-Steffensmeier). Appendix | Correction | Bibtex | AbstractThis paper sheds light on two age-old questions of interest group behavior: how have interest group coalition strategies changed over time and which factors determine whether interest groups work together? Through the creation of a new network measure of interest group coalitions based on cosigner status to United States Supreme Court amicus curiae briefs, we illuminate the central players and overall characteristics of this dynamic network from 1930 to 2009. We present evidence of an increasingly transitive network resembling a host of tightly grouped factions and leadership hub organizations employing mixed coalition strategies. We also model the attribute homophily and structure of the present-day network. We find assortative mixing of interest groups based on industry area, budget, sales and membership.

Keywords: Interest groups, Coalition strategies, Amicus curiae briefs, Social networks, Exponential random graph model

2014. Deus ex Machina: Candidate Web Presence and the Presidential Nomination Campaign. Political Research Quarterly, 67(1): 108-122 (with Corwin D. Smidt and Costas Panagopoulos). Appendix | Bibtex | AbstractUsing data from the 2008 presidential nomination contest, we offer systematic tests of the relationships between traditional campaign factors, the Internet and campaign performance. We find that claims of the Internet’s relevance to modern campaigns are warranted, as it is a unique facet of campaigns and significantly improves candidates’ financial and electoral support. The Internet is especially helpful to candidates in generating small-donor contributions and in maximizing contributions after early primary victories. Overall, these findings suggest that the Internet offers a viable mechanism for long-shot candidates to overcome the resource demands of the current presidential nomination system.

Keywords: Internet, Web presence, Campaign contributions, Polls, Presidential primary, Long-shots, Frontrunners, Campaign dynamics
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🏆Winner of the 2014 Best PRQ Article Award.

2013. Quality Over Quantity: Amici Influence and Judicial Decision Making. American Political Science Review, 107(3): 1-15 (with Janet M. Box-Steffensmeier and Matthew P. Hitt). Data | Bibtex | AbstractInterest groups often make their preferences known on cases before the U.S. Supreme Court via amicus curiae briefs. In evaluating the case and related arguments, we posit that judges take into account more than just the number of supporters for the liberal and conservative positions. Specifically, judges’ decisions may also reflect the relative power of the groups. We use network position to measure interest group power in U.S. Supreme Court cases from 1946 to 2001. We find that the effect of interest group power is minimal in times of heavily advantaged cases. However, when the two sides of a case are approximately equal in the number of briefs, such power is a valuable signal to judges. We also show that justice ideology moderates the effect of liberal interest group power. The results corroborate previous findings on the influence of amicus curiae briefs and add a nuanced understanding of the conditions under which the quality and reputation of interest groups matter, not just the quantity.

Keywords: Interest groups, Supreme Court decisions, Amicus curiae briefs, Social networks, Eigenvector centrality, Ideology

2013. Crowdsourcing Panel Studies and Real-Time Experiments in MTurk. The Political Methodologist, 20(2): 27-33 (with David M. Glick). Bibtex | AbstractWhile researchers conducting quick experiments and pilot studies currently appear to make the most use of Amazon’s Mechanical Turk (MTurk) as a subject recruitment tool, it is capable of supporting more ambitious research designs, many of which would be otherwise infeasible for most researchers. Specifically, researchers with a modest budget can use MTurk to recruit participants for customized and flexible panel studies. Because it is a cloud based environment, it is easy to recontact respondents, which helps limit panel attrition. Moreover, when used in tandem with online survey software, panel waves can be quickly fielded around imminent and recent political events, rather than at constant intervals or other times determined well in advance. Thus, MTurk’s attributes allow researchers to affordably collect individual level data for pre-post comparisons that can be combined with real-time experimental treatments. In this piece we briefly discuss our own experience conducting panel studies in MTurk and provide some basic instructions for researchers looking to do the same. We utilize the design and data from one of our own recent studies to discuss how we took advantage of MTurk and suggest some avenues for future research.

Keywords: MTurk, Cloud computing, Panel data, Real-time experiments, Foreseeable events

2013. Comparing Chinese and U.S. Media Coverage of the Global Recession: Linking the Economy, News and Public Expectation. In Media Discourses about Crisis, ed. Valentina Marinescu and Silvia Branea, Bucharest, Romania: Bucharest University Press (with Denis Wu). Bibtex | AbstractThis study examines the relationships among economic news coverage, the state of the economy, and perceptions about the economy in both China and the U.S. surrounding the three- year recession period of 2008-2010. U.S. news coverage about the economy is found to be domestically focused, more negative and responsive to the economic situation; whereas the Chinese coverage appears to be independent of the state of the economy as well as the perceptions of it. Additionally, we found two feedback loops between the media and economic expectations in the U.S., and between Leading Economic Indicators (LEI) and expectations in China. In all, the models suggest vitally different dynamics among the media, the public expectation, and the economy in China and in the U.S. The findings shed light on economic communication and behavioral economics.

Keywords: Media, Political Communication, China, United States, Recession, Vector Auto-regression

2012. More Bang for the Buck: Campaign Spending and Fundraising Success. American Politics Research, 40(6): 949-975 (with Corwin D. Smidt). Appendix | Bibtex | AbstractCan candidates spend their way into financial success? We propose that the 2007 presidential money primary offers unprecedented leverage to evaluate spending’s influence since it allows for sharper controls of confounding factors. Our results demonstrate that greater candidate spending on fundraising- related efforts is associated with significant future financial benefits. We estimate that, prior to the primaries, increases in spending have an equal or larger payoff than increases in a candidate’s viability and find different types of spending are beneficial for frontrunner and long-shot candidates. The results consistently indicate greater early spending works to advantage candidates, suggesting a lack of initial resources is a significant obstacle for candidates who seek to financially benefit from their campaign’s performance.

Keywords: Money primary, Campaign expenditures, Viability, Frontrunners, Long-shots, Campaign fundraising, Campaign dynamics

2012. Still Part of the Conversation: Iowa and New Hampshire’s Say within the Invisible Primary. Presidential Studies Quarterly, 42(3): 597-621 (with Corwin D. Smidt). Bibtex | AbstractWe propose that the extant literature has underestimated the central roles of Iowa and New Hampshire within the invisible primary and, thus, party nominations. Since candidates and the news media focus disproportionately on these states early in the nomination season, impressions of candidate performance within these states have a disproportionate influence on the invisible primary long before their actual outcomes are observed. Using a Bayesian vector autoregression we find that polls within Iowa and New Hampshire have a more consistent influence on candidates’ levels of national news media coverage and national polling than vice versa. We also find that campaign contributions are as responsive to early state polls as they are to national forces or campaign activities. Although these findings do not dispute that candidates need a broad basis of national support to win a party’s nomination, they explain why candidates continue to campaign early and intensely in these first-in-the-nation contests.

Keywords: Invisible primary, Bayesian vector autoregression, Campaign contributions, Polling, Early states, New Hampshire, Iowa, News media

2011. Riding the Waves of Money: Contribution Dynamics in the 2008 Presidential Nomination Campaign. Journal of Political Marketing, 10: 1-23 (with Corwin D. Smidt). Bibtex | AbstractThe 2008 primary was the most nuanced and expensive nomination contest in history. We investigate how this massive battle for contributions played out over 2007 and the first half of 2008 by analyzing the daily dynamics of candidate contributions using the Federal Elections Commission’s collection of individual contributions. Not surprisingly, Giuliani and Clinton were the leaders in contribution momentum during the latter parts of the so-called money primary. This pattern abruptly changed in 2008 as both parties experienced a structural change in contribution flows. While Iowa and New Hampshire placements helped their causes, the South Carolina primary was by far the most rewarding early contest for Obama and McCain. Furthermore, primary victories do not benefit all candidates equally, as Clinton and Huckabee gained far less than their counterparts in response to their early victories.

Keywords: Presidential nomination contests, Momentum, Campaign contributions, Early states, Campaign dynamics, Bayesian state space model, Kalman filter

2011. Correlation. In “International Encyclopedia of Political Science,” ed. Bertrand Badie, Dirk Berg-Schlosser, and Leonardo Morlino, Thousand Oaks, CA, Sage Publications. Bibtex

2009. Speeding Up R for Windows. The Political Methodologist, 17(1): 4-11 (with Joshua A. Morris). Bibtex | AbstractTo what extent do different Windows PC characteristics increase the modeling efficiency of R? Do some programs or versions of R run better on different PCs? And for which kinds of models do enhanced PCs and clusters diminish processing time? This research note seeks to provide novice to intermediate level R users with a framework for understand- ing the benefits of explicit parallel processing and upgrades in PC hardware for large datasets and computationally burdensome models. We compare the relative benefits of each optimization with simple efficiency tests. In addition, we provide basic R code to make the transition to parallel processing easier for novice users without networked labs or cluster access.

Keywords: Computing, Computational clusters, R, CRAN, Parallel processing, Memory

2007. Changing Horses in Wartime? The 2004 Presidential Election. Political Behavior, 29: 279-304 (with Herbert F. Weisberg). Bibtex | AbstractThe literature makes clear that foreign policy affects voting, but it does not lead to clear expectations as to how a war will affect voting. Will views about the advisability of the war predominate? Or will the indirect effect through the incumbent’s image be more important? Will a war crowd out other potential issues, particularly domestic ones? This paper addresses these questions through a series of focused analyses of NES survey data. We find that an increase in strong Republican partisans clinched the election for President Bush. The Iraq War was not a direct vote gainer for the President, but the larger War on Terrorism burnished his image as a leader, at least long enough to win the election. Likewise, the cultural war allowed President Bush to retain some of the votes that he might otherwise have lost due to the unpopularity of the Iraq War.

Keywords: Presidential election, Foreign policy, Wartime elections, NES, Iraq War, War on Terrorism, Culture war, Voting behavior


2017. Applied Social Science Methodology: An Introductory Guide. Cambridge University Press (with John Gerring).

In progress. Informal Constraints: Public Opinion and Unilateral Presidential Action (with Douglas L. Kriner).

In progress. The Visible Primary: How Modern Presidential Nominations Remake Candidates, Insiders, and Mass Coalitions (with Corwin D. Smidt).


Data collection
Amicus Curiae Networks
The Visible Primary
Public Opinion around Foreseeable Events
The Ohio Political Survey (TOPS)

PolMeth XXV: Learning from the Campaign Environment
PolMeth XXVI: Issues, Media and Momentum in the 2008 Primary