Publications – Jelle Koedam

“The comparative meaning of political space: A comprehensive modeling approach” (with Garret Binding and Marco Steenbergen),
Political Science Research and Methods (2023).

In latent scaling applications, such as the positioning of political parties, differential item functioning (DIF) may occur because of measurement issues or because of substantive differences in the association between latent and manifest variables. While the first source of DIF has received considerable attention, the second has not, although it is of potential interest to comparative scholars. In this research note, we introduce a novel hierarchical Bayesian item response model that allows us to disentangle different sources of DIF. Drawing on the 2019 Chapel Hill Expert Survey (CHES), we highlight how the same issues are unequally politicized across Western Europe, and how some issues are less ideologically determined than others. Our model can be adapted to alternate settings, allowing researchers to shine a light on variation in, e.g., ideology, issue politicization, or party competition.

Political parties are often assumed to be adaptive, strategic organisations that continuously alter their policy positions to maximise electoral support. However, ideological continuity is an integral part of democratic representation as well. How do parties balance these seemingly conflicting roles? This study combines insights from spatial models of elections and cleavage theory to explain stability and change in European party positions. Embracing the multidimensionality of the policy space, I argue that a party’s reputation and durable party-voter linkages constrain positional change on its more salient, primary dimension. Yet, by remaining ideologically true to its supporters’ key concerns, a party can strategically shift on secondary issues outside of its core agenda. Cross-sectional time series analysis of party positions (1999–2019) across fourteen Western European countries confirms this prediction, especially for small to medium-sized and opposition parties. This finding has important implications for our understanding of party strategy and democratic representation.

Digital political advertising on social media is an integral part of modern election campaigns. It gives political parties a powerful new tool to target voters, but which voters do they pursue? Tapping into an ongoing debate about party strategy, we examine whether parties seek to maintain their existing demographic and regional strongholds, or whether they aim to expand their voter coalitions. While the (intended) audience of other campaign activities is often unknown, data from the Facebook ads archive provide information on their recipients’ gender, age, and subnational region. Our analysis across five countries, which further brings in recent survey and electoral data, suggests that coalition maintenance is the dominant party strategy for demographic groups. Parties that receive more support from a given gender or age group run ads that reach more members of that demographic group. Consistent with the literature that shows a gender and age gap in voting, left-wing parties are more likely to advertise to women than right-wing parties, and green parties disproportionately reach younger voters. The results for geographic groups are mixed. We do find that parties in majoritarian electoral systems pursue a narrower regional audience than their counterparts in proportional systems. This study is one of the first to explore the potential and limitations of Facebook ad audience data to speak to a targeting literature in need of more comparative research on multiparty systems.

In a multidimensional environment, parties may have compelling incentives to obscure their preferences on select issues. This study contributes to a growing literature on position blurring by demonstrating how party leaders purposively create uncertainty about where their party stands on the issue of European integration. By doing so, it theoretically and empirically disentangles the cause of position blurring—parties’ strategic behavior—from its intended political outcome. The analysis of survey and manifesto data across 14 Western European countries (1999–2019) confirms that three distinct strategies—avoidance, ambiguity, and alternation—all increase expert uncertainty about a party’s position. This finding is then unpacked by examining for whom avoidance is particularly effective. This study has important implications for our understanding of party strategy, democratic representation, and political accountability.

Why do parties change their policy positions? A growing literature suggests that the internal balance of power between leaders and activists affects how a party responds to changing environmental incentives. This paper explores when and how party organization matters for party strategy. It argues that a key prediction – that leadership-dominated and activist-dominated parties are responsive to the positional shifts of the mean voter and the party voter, respectively – is conditional on two factors, namely a party’s electoral performance and party system polarization. Cross-sectional time series analyses of fifty-five parties in 10 European democracies between 1977 and 2003 confirm that (1) leadership-dominated parties’ responsiveness to the mean voter decreases as their electoral fortunes improve, (2) increases as a party system becomes more polarized, while (3) activist-dominated parties more reliably follow the positional shifts of the party voter. This study’s findings have important implications for our understanding of how intra-party politics influences inter- party competition, and thus democratic representation more generally.

“Explaining the salience of anti-elitism and reducing political corruption for political parties in Europe with the 2014 Chapel Hill Expert Survey data” (with Jonathan Polk, Jan Rovny, Ryan Bakker, Erica Edwards, Liesbet Hooghe, Seth Jolly, Filip Kostelka, Gary Marks, Gijs Schumacher, Marco Steenbergen, Milada Vachudova, and Marko Zilovic),
Research and Politics (2017).

This article addresses the variation of anti-corruption and anti-elite salience in party positioning across Europe. It demonstrates that while anti-corruption salience is primarily related to the (regional) context in which a party operates, anti-elite salience is primarily a function of party ideology. Extreme left and extreme conservative (TAN) parties are significantly more likely to emphasize anti-elite views. Through its use of the new 2014 Chapel Hill Expert Survey wave, this article also introduces the dataset.

“Parliamentary parties in the Netherlands: Informal investiture behind closed doors” (with André Krouwel),
in Bjørn Erik Rasch, Shane Martin, and José Antonio Cheibub (eds.) Parliaments and Government Formation: Unpacking Investiture Rules. Oxford: Oxford University Press (2015).