Thomas J. Leeper’s research while affiliated with European School Of Economics and other places

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Publications (38)


This figure shows the estimates of the treatment effects for each policy. The policy stems are separated into the three policy categories and ordered within each category from the largest estimate (top) to the smallest estimate (bottom). The color indicates the percent aware of the parties’ positions on the issues. Green points and lines indicate high awareness and orange points and lines indicate low awareness. While partisan cues have generally positive effects, the magnitude of the effect varies substantially across issues (Color figure online)
This shows the relationship between the estimate of the treatment effect for each policy and the percent of respondents aware of the parties’ positions on the issue. The color and shape of the lines and points indicate the category to which each policy belongs. The effect of the partisan cue varies substantially, and the prior awareness of the parties’ positions explains much (about 60%) of that variation (Color figure online)
This shows the treatment effect as awareness varies averaging across policies. Notice that the effect is largest for issues with the lowest levels of awareness
This shows the relationship between the treatment effect and awareness for each category of policies. Notice that while the treatment effect increases with awareness, treatment effects are smallest for social policies and largest for economic policies
Generalizing Survey Experiments Using Topic Sampling: An Application to Party Cues
  • Article
  • Publisher preview available

March 2023

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63 Reads

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15 Citations

Political Behavior

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Thomas J. Leeper

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Scholars have made considerable strides in evaluating and improving the external validity of experimental research. However, little attention has been paid to a crucial aspect of external validity – the topic of study. Researchers frequently develop a general theory and hypotheses (e.g., about policy attitudes), then conduct a study on a specific topic (e.g., environmental attitudes). Yet, the results may vary depending on the topic chosen. In this paper, we develop the idea of topic sampling – rather than studying a single topic, we randomly sample many topics from a defined population. As an application, we combine topic sampling with a classic survey experiment design on partisan cues. Using a hierarchical model, we efficiently estimate the effect of partisan cues for each policy, showing that the size of the effect varies considerably, and predictably, across policies. We conclude with advice on implementing our approach and using it to improve theory testing.

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Forecast share of “Leave” votes. Distribution of forecasts of Leave votes. Respondents from control group only. Black line: Epanechnikov Kernel density
Forecast share of “Leave” votes by voting preferences and education. Estimates based on OLS regressions (Table A2 in Appendix A), controlling for socio-demographic variables (age, gender, ethnicity, and gross household income), assignment to treatment conditions, party identification, and the day of the interview. Center and right-hand plots: estimates based on interaction between voting preferences and low versus high education (Model 2 in Table A2). Vertical bars are 95% confidence intervals
Correlates of Forecast Accuracy. Estimates from OLS regression Model 1 in Table A3 in Appendix A. Forecast accuracy rescaled from 0 (minimum accuracy) to 100 (maximum accuracy). Horizontal bars are 95% confidence intervals
Treatment effects on Leave forecasts relative to control. Estimates based on OLS regression Model 1 in Table C1. The vertical dotted line corresponds to the control group. Thick/thin horizontal bars correspond to 90%/95% confidence intervals
Treatment effects on Leave forecasts by education levels. Estimates based on OLS regression Model 1 in Table C3. Assignment to treatment interacted with a dummy variable for low (below A level) versus high (A level or above) education (for complete regression models, see Table C3 in Appendix C). Thick/thin horizontal bars correspond to 90%/95% confidence intervals
What Influences Citizen Forecasts? The Effects of Information, Elite Cues, and Social Cues

August 2022

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57 Reads

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7 Citations

Political Behavior

The emergent literature on citizen forecasting suggests that the public, in the aggregate, can often accurately predict the outcomes of elections. However, it is not clear how citizens form judgments about election results or what factors influence individual predictions. Drawing on an original survey experiment conducted during the campaign for the United Kingdom’s Brexit referendum, we provide novel evidence of what influences citizen forecasts in a so-far unexplored context of direct democracy. Specifically, we investigate the effect of voting preferences and political sophistication, in addition to three “exogenous factors” that we manipulate experimentally—i.e., social cues, elite cues and campaign arguments. Our findings indicate that citizens are reasonably accurate in their predictions, with the average forecast being close to the actual result of the referendum. However, important individual heterogeneity exists, with politically sophisticated voters being more accurate in their predictions and less prone to wishful thinking than non-sophisticated voters. Experimental findings show that partisan voters adjust their predictions in response to cues provided by their favorite party’s elites and partly in response to campaign arguments, and the effects are larger for low-sophisticated voters. We discuss the mechanisms accounting for the experimental effects, in addition to the implications of our findings for public opinion research and the literature on citizen forecasting.


Screenshot of choice given to respondents
Average marginal component effects (AMCEs) measuring outcome support for features of Brexit outcomes (full sample)
Marginal means measuring support for features of Brexit outcomes, separately for Leave and Remain voters. Note The gray vertical bar represents the grand mean for all respondents (0.5)
Differences between Remainers and Leavers in marginal mean support for each feature of Brexit outcomes
Marginal means of perceived outcome legitimacy, separately for Leave and Remain voters. Note The gray vertical bar represents the grand mean for all respondents (0.5)
Policy Preferences and Policy Legitimacy After Referendums: Evidence from the Brexit Negotiations

June 2022

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210 Reads

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20 Citations

Political Behavior

How do votes in direct democratic ballots translate into policy preferences about future outcomes and affect the perceived legitimacy of those outcomes? This article examines these questions in the context of sovereignty referendums: specifically, the 2016 referendum on British membership of the European Union (EU). While the referendum result gave the British government a mandate for Britain leaving the EU, it did not provide any firm guidance as to the kind of Brexit that voters would prefer and consider legitimate. To examine the perceived desirability and legitimacy of different Brexit outcomes, we conducted a nationally representative conjoint experiment measuring attitudes towards different possible negotiation outcomes. Our findings show that ‘Leave’ and ‘Remain’ voters were highly divided over what they wanted from Brexit on salient negotiation issues, but also that most voters did not regard any possible outcome as legitimate.


Raising the Floor or Closing the Gap? How Media Choice and Media Content Impact Political Knowledge

May 2020

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51 Reads

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16 Citations

Mass media are frequently cited as having the potential to inform the public, raising knowledge levels and reducing political knowledge gaps between citizens. But media are also seen as a force for segmentation, disengagement, and widening differences between citizens. If media have no effect on political knowledge, gaps between the engaged and disengaged persist regardless of who is exposed to news because no one learns. But gaps can also persist even if everyone learns from the news, particularly if learning effects are heterogeneous across those inclined and disinclined to seek out news and/or across environments that consist of different media alternatives. Yet past research on political communication has not sufficiently linked media choice to debates about possibly heterogeneous effects of media exposure on political knowledge levels. The present study contributes a novel and large-scale choice-based experiment on knowledge of the ongoing crisis in Syria that finds media effects are relatively homogeneous across those with different media preferences and across different media environments. This suggests that under most conditions – even when everyone learns from the news – knowledge gaps between the politically engaged and disengaged are widened or at least sustained after incidental exposure to politics. While closing such gaps may be impossible, the results have important implications for understanding how citizens learn about politics and how to study learning from self-selected media experiences.


Subjective importance and issue voting on the ANES, pt. 1. Notes: Markers provide the average marginal effect of issue distance by level of subjective issue importance (x-axis), with 95% confidence intervals
Subjective importance and issue voting on the ANES, pt. 2. Notes: Markers provide the average marginal effect of issue distance by level of subjective issue importance (x-axis), with 95% confidence intervals
Example of conjoint choice setting
Importance as moderator in Study 2. Notes: Markers provide the average marginal effect of issue distance, with 95% confidence intervals, by level of issue importance
More Important, but for What Exactly? The Insignificant Role of Subjective Issue Importance in Vote Decisions

March 2020

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197 Reads

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31 Citations

Political Behavior

The nature of democratic governance is intimately connected with how citizens respond to candidate position taking. But when will a generally uninformed public base its vote choices on candidate positions? Since Converse scholars have argued that citizens should place greater weight on candidate positions on issues they consider personally important. However, this claim has received mixed empirical support. We revisit this question with compelling new evidence. First, we expand the limited temporal focus of existing work in our first study where we analyze all available ANES data on importance and issue voting between 1980 and 2008. We then overcome endogeneity concerns through a nationally representative conjoint experiment in which we randomize two candidate’s positions on five issues. Results from both studies demonstrate that there is scant evidence that subjective issue importance consistently moderates the relationship between candidate positions and vote choices. We discuss the implications of these results for “issue public” theories of political engagement, for research on voting behavior, and for political representation.



Divided by the Vote: Affective Polarization in the Wake of the Brexit Referendum

February 2020

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1,400 Reads

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376 Citations

British Journal of Political Science

A well-functioning democracy requires a degree of mutual respect and a willingness to talk across political divides. Yet numerous studies have shown that many electorates are polarized along partisan lines, with animosity towards the partisan out-group. In this article, we further develop the idea of affective polarization, not by partisanship, but instead by identification with opinion-based groups. Examining social identities formed during Britain’s 2016 referendum on European Union membership, we use surveys and experiments to measure the intensity of partisan and Brexit-related affective polarization. The results show that Brexit identities are prevalent, felt to be personally important, and cut across traditional party lines. These identities generate affective polarization as intense as that of partisanship in terms of stereotyping, prejudice, and various evaluative biases, convincingly demonstrating that affective polarization can emerge from identities beyond partisanship.


Identities and Intersectionality: A Case for Purposive Sampling in Survey‐Experimental Research

October 2019

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1,344 Reads

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96 Citations

This chapter begins by reviewing the strengths and weaknesses of various approaches for obtaining samples of intersectional identity groups, and then provides some empirical evidence for the viability of general population samples for providing large numbers of respondents from intersectional identity groups. Purposive sampling can be thought of as a subset of convenience sampling, in that respondents are chosen subjectively. While convenience sampling necessarily relies upon untestable assumptions rather than probability‐based sampling methods, the chapter argues that such methods may be more appropriate for survey‐experimental research than for observational research. For the purposes of experimental research on small intersectional identity groups, many purposive samples may be fit for use because they trade off design‐based representativeness against obtaining a sample size sufficiently large to powerfully estimate an experimental effect size.


Should We Worry About Sponsorship-Induced Bias in Online Political Science Surveys?

October 2019

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39 Reads

Journal of Experimental Political Science

Political scientists rely heavily on survey research to gain insights into public attitudes and behaviors. Over the past decade, survey data collection has moved away from personal face-to-face and telephone interviewing towards a model of computer-assisted self-interviewing. A hallmark of many online surveys is the prominent display of the survey’s sponsor, most often an academic institution, in the initial consent form and/or on the survey website itself. It is an open question whether these displays of academic survey sponsorship could increase total survey error. We measure the extent to which sponsorship (by a university or marketing firm) affects data quality, including satisficing behavior, demand characteristics, and socially desirable responding. In addition, we examine whether sponsor effects vary depending on the participant’s experience with online surveys. Overall, we find no evidence that response quality is affected by survey sponsor or by past survey experience.


Studying Identities with Experiments: Weighing the Risk of Posttreatment Bias Against Priming Effects

October 2019

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85 Reads

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56 Citations

Journal of Experimental Political Science

Scholars from across the social sciences argue that identities – such as race, ethnicity, and gender – are highly influential over individuals’ attitudes, actions, and evaluations. Experiments are becoming particularly integral for allowing identity scholars to explain how these social attachments shape our political behavior. In this letter, we draw attention to how identity scholars should approach the common practice of assessing moderators, measuring control variables, and detecting effect heterogeneity using covariates. Special care must be taken when deciding where to place measures of demographic covariates in identity-related experiments, as these cases pose unique challenges from how scholars traditionally approach experimental design. We argue in this letter that identity scholars, particularly those whose subjects identify as women or minorities, are often right to measure covariates of interest posttreatment.


Citations (32)


... Following Clifford, Leeper, and Rainey (2023), these candidate profiles can be understood as "different-but-similar experiments" aimed at testing the same general claims. That is, rather than relying on a single-vignette experiment that fixes various candidate characteristics-such as name, headshot, educational background, occupation, or political experience-I present each participant with eight (four in the national sample) "different-but-similar" experiments featuring eight (four) candidate profiles that differ between one another in these dimensions. ...

Reference:

The Right Kind of (Gay) Man? Sexuality, Gender Presentation, and Heteronormative Constrains on Electability
Generalizing Survey Experiments Using Topic Sampling: An Application to Party Cues

Political Behavior

... A society that provides the public with the means of cultivating virtues will be, arguably, a better-functioning political entity. Some attention has been paid specifically to deliberative virtues, that is, those virtues that are necessary to conduct good quality deliberation among citizens (Aikin & Clanton, 2010;Bächtiger et al., 2018;Ferris, 2019;Griffin, 2011;Grönlund et al., 2010;Miller, 1992). The idea of citizen participation through deliberation presupposes that people not only get a more direct influence on political decision-making, but are actively involved in the proceedings and discussions prior to making a decision. ...

The Oxford Handbook of Deliberative Democracy
  • Citing Article
  • September 2018

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Jane Mansbridge

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[...]

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Dennis F. Thompson

... News, political speeches, social media posts -citizens are constantly exposed to political communication, usually with the aim of persuading them to adopt a certain opinion about the issue of the day. A large body of research documents the substantial effects of persuasive communication on political attitudes (Busby et al. 2018;Leeper and Slothuus 2020;Zaller 1992). However, opinion manipulation often represents merely an intermediate goal in a greater effort to affect citizens' primary instrument of political influence: voting. ...

How the News Media Persuades: Framing Effects and Beyond
  • Citing Article
  • May 2019

... Scholars have previously found that elite cues influence voter attitudes and behaviors. For example, Morisi and Leeper (2024) found that when individuals were informed that most political elites supported the UK's membership in the EU, their election predictions shifted to align with the stance of these elites. Similarly, elite cues were found to be a major factor for distrust in scientific experts during COVID-19 (Hamilton & Safford, 2021). ...

What Influences Citizen Forecasts? The Effects of Information, Elite Cues, and Social Cues

Political Behavior

... Multistakeholderism purports to provide transnational governance regimes with gold standard legitimacy and democratic legitimacy (Bernstein 2004;Nanz and Steffek 2004). While in democratic countries participation entails electoral mechanisms ensuring representation and accountability, multistakeholderism attempts to adapt core principles of democratic theory to a "beyond the state" context (Bäckstrand et al. 2010;Dingwerth 2007;Macdonald 2008;Risse 2006), shifting the focus from the "vote-centric" to the "talk-centric" side of democracy (Chambers 2003;Druckman, Leeper, and Slothuus 2018). As indicated, democratic legitimacy in multistakeholderism is derived from the deliberative model of democracy that provides all stakeholders the possibility of participating in the decision-making process through inclusive, fair, informed, rational, and respectful debate (Druckman, Leeper, and Slothuus 2018;Dryzek 2010;Elster 1998). ...

Motivated Responses to Political Communications
  • Citing Chapter
  • March 2018

... Recent scholarship finds a "correspondence between ideology (policy core beliefs) and coordinated activity" (Stritch 2015): Advocacy coalitions measured at the level of policy beliefs generally resemble those measured through coordinated activity, with some nuanced differences, reflected in more activity and participation in the policy belief layer of the network (Schaub and Metz 2020). Coordination is typically measured crosssectionally using questionnaires, making it difficult to measure change over time because retrospective answers are prone to recall bias and repeated interviews are subject to panel attrition due to the burden on interviewees (Coughlin 1990;Finney 1981;Geweke and Martin 2002;Janson 1990;Leeper 2019;Van Der Vaart et al. 1995). In contrast, belief development can be measured longitudinally without requiring actors' conscious acknowledgment of the process. ...

Where Have the Respondents Gone? Perhaps We Ate Them All
  • Citing Article
  • July 2019

Public Opinion Quarterly

... This shift towards direct democracy has significantly reduced the authority of political parties, which have traditionally played a central role in policymaking (Kölln, 2015;Issacharoff & Bradley, 2021). In representative democracy, parties shape policy by securing votes and making decisions within a fixed term, while direct democracy shifts more control to citizens, allowing them to influence policy directly (Hobolt et al., 2022;Topaloff, 2017). This creates tension between the power of political parties in representative democracy and the increased influence of citizens in direct democratic processes (Issacharoff & Bradley, 2021). ...

Policy Preferences and Policy Legitimacy After Referendums: Evidence from the Brexit Negotiations

Political Behavior

... Experimental studies, such as this one, are a highly promising arena in computational methods-powered political communication research in which treatments can be rolled out in realistic environments for participants of unprecedented counts (Bail et al., 2018;Leeper, 2020;Salganik & Watts, 2009;Siegel & Badaan, 2020). But while this allows for high experimental control and the identification of small effect sizes, once the number of available observations increases, researchers also have to adjust the criteria by which they interpret results (Japec et al., 2015). ...

Raising the Floor or Closing the Gap? How Media Choice and Media Content Impact Political Knowledge
  • Citing Article
  • May 2020

... This happens for two reasons. On the one hand, referendums may replicate the existing ideological polarization, which is defined as an extreme divide between opposing groups of public opinion (Atikcan and Öge 2012;Jacobson 2019;Hobolt et al. 2021). The two exclusive options on the ballot box do not provide the possibility of a consensus, which makes popular votes through referendums a somewhat natural step for societies characterized by cleavages or division. ...

Divided by the Vote: Affective Polarization in the Wake of the Brexit Referendum
  • Citing Article
  • February 2020

British Journal of Political Science

... The variable has a minimum of 0, a maximum of 100, a median of 57, a mean of 56.77, and a standard deviation of 32.21 with 21 non-responses. Figure 1 displays the distribution of the feeling thermometer ratings associated with support for the two judicial nominees of interest 14 to reduce the likelihood of priming effects (Klar et al. 2020). We chose to include our identity-based questions about partisanship at the end of our survey because of these trade-offs. ...

Studying Identities with Experiments: Weighing the Risk of Posttreatment Bias Against Priming Effects
  • Citing Article
  • October 2019

Journal of Experimental Political Science