Research Interests

Political behavior and quantitative methods, policy-based voting and party competition, mass opinion and preference formation, regression for categorical data and discrete choice modeling

Peer-Reviewed JournaL articles

Mauerer I., & Tutz G. (2024). "Vote Choices and Valence: Intercepts and Alternate Specifications". Political Analysis. FirstView:1-18. doi:10.1017/pan.2023.43 Open Access

Valence is a crucial concept in studying spatial voting and party competition. The widely adopted approach is to rely on intercepts of vote choice models and to infer, based on their size and direction, how valence affects party strategies in empirical settings. The approach suffers from fundamental statistical flaws. This contribution provides the statistical fundamentals to advance the empirical modeling of valence. It proposes an appropriate modeling approach to interpret intercepts as valences and alternate specifications to parameterize the effects of valence.


Mauerer, I. & Tutz, G. (2023). "Heterogeneity in General Multinomial Choice Models." Statistical Methods & Applications 32: 129–148. doi:10.1007/s10260-022-00642-5 Open Access


Different voters behave differently at the polls, different students make different university choices, or different countries choose different health care systems. Many research questions important to social scientists concern choice behavior, which involves dealing with nominal dependent variables. Drawing on the principle of maximum random utility, we propose applying a flexible and general heterogeneous multinomial logit model to study differences in choice behavior. The model systematically accounts for heterogeneity that classical models do not capture, indicates the strength of heterogeneity, and permits examining which explanatory variables cause heterogeneity. As the proposed approach allows incorporating theoretical expectations about heterogeneity into the analysis of nominal dependent variables, it can be applied to a wide range of research problems. Our empirical example uses individual-level survey data to demonstrate the benefits of the model in studying heterogeneity in electoral decisions.


Thurner, P.W., Klima, A., Küchenhoff, H., Mauerer, I., Mang, S., Walter-Rogg, M., Heinrich, T., Knieper, T. & Schnurbus, J. (2022). "Micromotives of Vote Switchers and Macrotransitions: The Case of the Immigration Issue in a Regional Earthquake Election in Germany 2018." Politische Vierteljahresschrift [German Political Science Quarterly] 63: 663–684. doi: 10.1007/s11615-022-00411-9

Open Access


Which issue-related motives underlie voters’ decision to switch parties at the polls? Do switchers stick to the newly chosen party, or do they oscillate in a short-term way at intermediate elections? Relying on the behavioral theory of elections, we assumed aspiration-based voting of boundedly rational voters. We elicited issue-related switch and stay motives in an open-ended survey question format to identify the individual dominant aspirational frame. We traced the respondents’ voting trajectories over three consecutive elections, including two state (2013 and 2018) elections in Bavaria (Germany) and one German federal election (2017). We focused on one of the most polarizing and salient issues in these elections, namely immigration. The case of reference is the 2018 Bavarian state election. Here, the incumbent majoritarian center-right party Christian Social Union tried to deter the entry of the right-wing populist party Alternative for Germany by adapting to it on the immigration issue in tone and position. The selected case allows assessment of the impact of issue-based adaptive behavior of the incumbent party at the level of the voters’ switch or stay choices. We estimated the direction and number of voter flows for two interelection sequences of different lengths between different types of polls (federal and state). Our transition estimates are based on the hybrid multinomial Dirichlet model, a new technique integrating individual-level survey data and official aggregate data. Our estimates uncover substantial behavioral differences in the immigration issue public.


Mauerer, I. (2020). "The Neglected Role and Variability of Party Intercepts in the Spatial Valence Approach." Political Analysis 28(3): 303–317. doi:10.1017/pan.2019.41 Open Access


Editors' Choice Article 2020


Empirical applications of the spatial theory of elections typically rely on the discrete choice framework to arrive at probabilistic voting models. Whereas in the classic model voter choice is solely a function of spatial proximity, neo-Downsian models also incorporate voter-specific nonpolicy attributes, which are represented by sociodemographic characteristics. One prominent line of such probabilistic  models, Schofield’s Valence Model, additionally includes party valences into voter utility functions. The model rests on the estimated party intercepts to measure the valence advantages empirically. The party intercepts are ordered based on their values, and then this valence ranking is used further to predict equilibrium locations. The paper demonstrates that this measurement strategy  does not provide unique results in fully specified models due to central properties of discrete choice models and the specific nature of party intercepts in these models. Drawing on a simple example based on mass election surveys from Germany, it is shown that the valence ranking, the crucial factor to investigate how valence differences affect the nature of spatial competition, is highly sensitive to arbitrary coding decisions. As a consequence, it is impossible to represent valence with the constants and to infer something substantial from the resulting valence ranking.


Thurner, P. W., Mauerer, I., Bort, M., Klima, A. & Küchenhoff, H. (2020). "Integrating Large-Scale Online Surveys and Aggregate Data at the Constituency Level: The Estimation of Voter Transitions in the 2015 British General Elections." Survey Research Methods 14(5): 461–476. doi:0.18148/srm/2020.v14i5.7628 Open Access


What have been the underlying voter shifts that led to the victory of the Conservative Party in the 2015 British general election – against all predictions by pollsters? Analyses of voter transitions based on (online) surveys and recall questions are plagued by sampling and response biases, whereas aggregate data analyses are suspect of the well-known ecological fallacy. We propose a systematic statistical combination of individual-level survey and administrative data at the constituency level to identify regional electoral shifts between the 2010 to 2015 British general elections. The large-scale individual-level data collected by the British Election Study Internet Panel (BESIP) allow us to locate more than 28,000 respondents in their constituencies. We estimate voter transitions based on a recently developed Bayesian Hierarchical Hybrid Multinomial Dirichlet (HHMD) model. We discover substantial deviances from pure survey-based estimations of transition matrices.


Mauerer, I., Pößnecker, W., Thurner, P. W., & Tutz, G. (2015). "Modeling Electoral Choices in Multiparty Systems with High-Dimensional Data: A Regularized Selection of Parameters Using the Lasso Approach." Journal of Choice Modelling 16: 23-42. doi: 10.1016/j.jocm.2015.09.004


The increased usage of discrete choice models in the analysis of multiparty elections faces one severe challenge: the proliferation of parameters, resulting in high-dimensional and difficult-to-interpret models. For example, the application of a multinomial logit model in a party system with J parties results in maximally J−1 parameters for chooser-specific attributes (e.g., sex and age). For the specification of alternative-specific attributes (usually: positions on issues and issue distances), maximally J parameters for each political issue can be estimated. Thus, a model of party choice with five parties based on three political issues and ten voter attributes already produces 59 possible coefficients. As soon as we allow for interaction effects to detect segment-specific reactions to issues, the situation is even aggravated. In order to systematically and efficiently identify relevant predictors in voting models, we derive and use Lasso-type regularized parameter selection techniques that take into account both individual- and alternative-specific variables. Most importantly, our new algorithm can handle for the first time the alternative-wise specification of the attributes of alternatives. Applying the specifically adjusted Lasso method to the 2009 German Parliamentary Election, we demonstrate that our approach massively reduces the models' complexity and simplifies their interpretation. Lasso-penalization clearly outperforms the simple ML estimator. The results are illustrated by innovative visualization methods, the so-called effect star plots.


Mauerer, I., Thurner, P. W., & Debus, M. (2015). "Under Which Conditions do Parties Attract Voters’ Reactions to Issues? Party-Varying Issue Voting in German Elections 1987-2009." West European Politics 38(6): 1251–1273.

doi: 10.1080/01402382.2015.1026562


Are voters’ choices influenced by parties’ position-taking and communication efforts on issues during a campaign? And if so, do voters’ reactions to issues differ across parties? This article outlines a research design for the statistical identification of party-varying issue reactions within the established paradigm of the Spatial Theory of Voting. Using a special feature of conditional logit and probit models – i.e. the estimation of alternative-specific coefficients instead of fixed ‘generic’ issue distance effects – it is possible to detect asymmetrically attached issue saliencies at the level of the voters, and hence at the demand-side of politics. This strategy opens a new way to systematically combine insights obtained by saliency approaches with the Spatial Theory of Voting. An application to the German parliamentary elections from 1987 to 2009 demonstrates that it is predominantly parties taking polar positions – and, more specifically, niche parties taking polar positions – that induce such asymmetric issue voting.


Contributions to edited volumes

Thurner, P.W., Küchenhoff, H., Walter-Rogg, M., Heinrich, T., Klima, A., Knieper, T., Haupt, H. Mauerer, I., Mang, S. & Schnurbus, J. (2023). "Die Universitätsstudie Bayernwahl 2018 (USBW18): Design und ermittelte Wählerwanderungen." In Die Landtagswahl 2018 in Bayern, edited by Walter-Rogg, M. & Heinrich, T., pp. 21-63. Wiesbaden: Springer VS.


Die bayerische Landtagswahl 2018 war durch ein hohes Maß an Wählervolatilität geprägt. Jedoch konnte nicht nur die AfD Stimmen hinzugewinnen, auch den Grünen ist es gelungen, 2018 Wähler anderer Parteien für sich zu gewinnen. Der vorliegende Beitrag beschreibt Herkunft, Richtung und Stärke der Wechselwählerströme bei der bayerischen Landtagswahl 2018. Basierend auf dem von Klima et al. (2016, 2019) entworfenen Hybrid-Modell zur Schätzung von Wählerwanderungen werden georeferenzierte Aggregatdaten sowie umfragebasierte Individualdaten der USBW18 herangezogen, um nicht nur die Zu- und Abwanderungen in den Elektoraten der einzelnen Parteien zwischen den Landtagswahlen 2013 und 2018, sondern auch zwischen der Bundestagswahl 2017 und der Landtagswahl 2018 zu quantifizieren. Somit stellt der Beitrag eine wesentliche Erweiterung der bisher nur für München vorliegenden Schätzung der Wechselwählerströme mittels der Hybrid-Modelle (Klima et al., 2017) dar, indem einerseits die räumliche Perspektive auf ganz Bayern ausgeweitet und andererseits die Wechselneigung zwischen Wahlen auf unterschiedlichen Ebenen des politischen Systems analysiert wird.

Thurner, P. W., Kunz, F., Miclut, A., Mauerer, I., Klima, A. & Küchenhoff, H. (2021). "Die Schätzung von Wählerwanderungen zwischen den Bundestagswahlen 2013–2017 mit Hilfe von Online-Paneldaten und Aggregatdaten in Hybridmodellen." In Wahlen und Wähler – Analysen aus Anlass der Bundestagswahl 2017, edited by Weßels, B. &  Schoen, H., pp. 205–226. Wiesbaden: Springer VS.


Die elektorale Volatilität zwischen den Bundestagswahlen (BTW) 2013 und 2017 ist die höchste seit 1953 (vgl. Emanuele 2015). Gerade bei so außergewöhnlichen Dynamiken, die zudem zu strukturellen Veränderungen von Parteiensystemen führen – wie in diesem Falle zum Neueintritt der rechten Partei Alternative für Deutschland (AfD) in den Bundestag –, stellt sich drängend die Frage nach den zugrunde liegenden Wählerwanderungen auf der Ebene von Individuen. Diese sind nicht aus den Prozentpunktdifferenzen der Parteienverluste und -gewinne abzulesen, auch nicht auf noch so feiner territorialer Gliederungsebene. Daher müssen entweder surveybasierte Verfahren zum Einsatz kommen oder Schätzverfahren, die von speziellen Annahmen abhängen und auf aggregierten Wahlergebnissen basieren. Die wissenschaftliche Grundlagenforschung zur validen Bestimmung entsprechender Übergangsmatrizen war, auch international, immer schon erstaunlich dünn gesät.


Mauerer, I. & Schneider, M. (2019). "Perceived Party Placements and Uncertainty on Immigration in the 2017 German Election." In Jahrbuch für Handlungs- und Entscheidungstheorie Volume 11, edited by M. Debus, Tepe, M. & Sauermann, J., pp. 117–143. Wiesbaden: Springer Nature. doi: 10.1007/978-3-658-23997-8


Almost all national election studies contain policy scales that are intended to measure where respondents perceive parties or candidates on central campaign issues. These placements form the basis for models of survey responses, party perceptions, and voter choice. It is well known that the placements might be affected by uncertainty. We use the finite mixture model `BetaBin' to study response patterns to party placements on policy issues. The model consists of a placement part and an uncertainty part. Whereas the placement part of the model accounts for lower and higher placements on the ordinal scales, the uncertainty component accounts for tendencies to locate the parties on the middle or at the extremes of the policy scales. We use the 2017 German national election and apply the model to the immigration issue. Our results demonstrate that uncertainty strongly influences the respondents' perceptions of most parties. Neglecting this structure leads to worse models as indicated by performance measures.


Thurner, P. W., Mauerer, I., & Binder, M. (2011). Parteienspezifisches Issue Voting bei den Bundestagswahlen 2002 bis 2009. In Wählen in Deutschland. Politische Vierteljahresschrift, Sonderheft 45, edited by R. Schmitt-Beck, Baden-Baden: Nomos, 302–320. [Link]