publications

2025

1. 

   The Zweitstimme Forecast for the German Federal Election 2025: Coalition Majorities and Vacant Districts

   Cornelius Erfort, Lukas F. Stoetzer, Thomas Gschwend, Elias Koch, Simon Munzert, and Hannah Rajski

   PS: Political Science & Politics, Feb 2025

   Abs DOI

   This article forecasts the German Federal Election of 2025. We used our previous forecasting models to provide national-level forecasts for party-vote shares and district-level outcomes for candidate votes. We show that the combination of both models allowed us to calculate forecasts for both coalition majorities in Parliament and "vacant districts" under recent electoral reforms.

2. 

   An Election Forecasting Model for Subnational Elections

   Lukas F. Stoetzer, Cornelius Erfort, Hannah Rajski, Thomas Gschwend, Simon Munzert, and Elias Koch

   Electoral Studies, Jun 2025

   Abs DOI

   While election forecasts predominantly focus on national contests, many democratic elections take place at the subnational level. Subnational elections pose unique challenges for traditional fundamentals forecasting models due to less available polling data and idiosyncratic subnational politics. In this article, we present and evaluate the performance of Bayesian forecasting models for German state elections from 1990 to 2024. Our forecasts demonstrate high accuracy at lead times of two days, two weeks, and two months, and offer valuable ex-ante predictions for three state elections held in September 2024. These findings underscore the potential for applying election forecasting models effectively to subnational elections.

2023

1. 

   The Role of Vote Advice Application in Direct-Democratic Opinion Formation: An Experiment from Switzerland

   Isabelle Stadelmann-Steffen, Hannah Rajski, and Sophie Ruprecht

   Acta Politica, Oct 2023

   Abs DOI

   In an increasingly digitized world, vote advice applications (VAAs) seem to be effective in providing voters with personalized information about their own positions vis-à-vis parties’ positions and specific policies. Even though electoral research has increasingly paid attention to the role VAAs play in voter’s opinion formation, very few studies have examined VAAs in the context of direct-democratic decisions. This article fills this gap by providing new insights into how VAAs affect individual decision-making in popular votes theoretically and empirically. We use novel data from the referendum campaign on the 2017 new energy law in Switzerland: a VAA experiment carried out in the framework of a three-wave panel survey. In the third wave, which took place a week before the referendum, respondents were randomly assigned to a treatment group and a control group; only the former was shown the VAA and made to use it. The results indicate two main takeaways. First, that using a VAA has a tangible effect inasmuch as the share of undecided voters is smaller among the treatment than among the control group. Second, VAA usage can have both a persuasive effect (i.e., it can change vote intentions) and an intensifying effect (i.e., it can strengthen voters’ preexisting intentions).