Hannah Rajski hannah.rajski@uni-mannheim.de Cornelius Erfort cornelius.erfort@uni-wh.de
Version: MZES Social Science Data Lab, 2025-05-21
The Zweitstimme.org project presents a comprehensive approach to forecasting the 2025 German federal election, combining multiple methodologies to predict both party vote shares (Zweitstimme) and constituency-level outcomes (Erststimme). This presentation showcases three distinct forecasting approaches: a dynamic Zweitstimme model, a proportional swing Erststimme model, and citizen forecasting. The project also communicated the forecasts and their uncertainties to the public, with results being shared in various media outlets.
đ Slides
Hannah Rajski is a PhD candidate in Political Science at the Graduate School of Economic and Social Sciences at the University of Mannheim. She works in the project Election Forecasts for the German Federal Election 2025. Her main research interests lie in quantitative methods, comparative politics, and political sociology with a focus on political behaviour and elections. In her dissertation she analyses votersâ expectations about election outcomes and how these can be aggregated into citizen forecasts. Hannah holds a bachelorâs degree in Politics, Administration and International Relations from Zeppelin University, Friedrichshafen, Germany and a masterâs degree in Politics and Public Administration from the University of Konstanz, Germany.
Cornelius Erfort is Postdoc at the Witten/Herdecke University, working on the project Election Forecasts for the German Federal Election 2025. His general interests are in comparative politics and quantitative methods. More specifically, he is working on voter targeting, interest groups, and voting behavior. In his dissertation, he analyzed how parties use the target and tailor their digital election ads. He was a member of the Research Training Group DYNAMICS which is jointly organized by Humboldt-Universität zu Berlin and the Hertie School.