The many faces of GESIS
Vita
Higher Education
Since 2022 Ph.D. Candidate, University of Mannheim: "Mitigating Nonresponse and Measurement Errors in Political Science Surveys by Accounting for Respondents' Political Interest"
10/2019 - 09/2022 M.A.
Empirical Research in Democracy, University of Mainz
09/2020 - 02/2021 Political and Social Sciences, Ghent University
10/2015 - 09/2019 B.A. Political Science, University of Hamburg
Work Experience
Since 2026 Doctoral Researcher: Simplified Survey Language to improve participation and response quality in web surveys, GESIS - Leibniz Institute for the Social Sciences
10/2022 - 12/2025
Doctoral Researcher:
Prediction-based Adaptive Designs for Panel Surveys,
GESIS - Leibniz Institute for the Social Sciences
07/2024 - 02/2025
Doctoral Researcher: Survey Data Collection and the Covid-19 Pandemic,
GESIS - Leibniz Institute for the Social Sciences
Research
Saskia Bartholomäus is a doctoral researcher in the department Data and Research on Society at GESIS - Leibniz Institute for the Social Sciences. Her current research focuses on data quality in social and political science surveys. In her dissertation, she investigates the non-response and attrition bias of non-voters in political science surveys, the resulting limitation of substantive research, and approaches to resolve the issue. In addition to the use of Adaptive Survey Designs, she is interested in imputation and weighting strategies to reduce political science surveys' selection biases.Publications
Journal article
Gummer, Tobias, Saskia Bartholomäus, and Bernd Weiß. 2026 (Forthcoming). "Respondents’ Preferred Survey Topics: Measurement and Prevalence." Survey Research Methods: .
Gummer, Tobias, Karolina von Glasenapp, Thomas Skora, Elias Naumann, Saskia Bartholomäus, and Sophia Piesch. 2026. "Survey Data Collection during the COVID-19 Pandemic in Germany: Recommendations for an Improved Data Collection Infrastructure." Health Policy 165 (March 2026): 105551. doi: https://doi.org/10.1016/j.healthpol.2025.105551.
Bartholomäus, Saskia, and Tobias Gummer. 2026 (Forthcoming). "Varying the Content of Political Science Surveys to Improve the Survey Experience and Data Quality of Politically Disengaged Respondents." Journal of Survey Statistics and Methodology: .
Gummer, Tobias, Karolina von Glasenapp, Thomas Skora, Saskia Bartholomäus, and Elias Naumann. 2025. "The Impact of the COVID-19 Pandemic on the Design of Repeated Cross-sectional and Panel Surveys in Germany." International Journal of Public Opinion Research 37 (4): edaf062. doi: https://doi.org/10.1093/ijpor/edaf062.
Data/Software
Bartholomäus, Saskia, and Tobias Gummer. 2025. PrADePS Pretest. doi: https://doi.org/10.7802/2635.
Skora, Thomas, Karolina von Glasenapp, Tobias Gummer, Saskia Bartholomäus, and Elias Naumann. 2024. SDCCP 2 - Survey Design of Longitudinal Surveys Before and During the Covid-19 Pandemic. doi: https://doi.org/10.7802/2759.
Presentation at a conference
Bartholomäus, Saskia. 2025. "Content Variation in Adaptive Survey Designs: Impact on Substantive Research and Missing Data Solutions." GOR 25: General Online Research Conference, 2025-04-01.
Bartholomäus, Saskia. 2025. "Content Variation in Adaptive Survey Designs: Impact on Substantive Research and Missing Data Solutions." ESRA 2025: 11th Conference of the European Survey Research Association, Utrecht (The Netherlands), 2025-07-15.
Collins, John, Saskia Bartholomäus, Tobias Gummer, Bernd Weiß, and Christoph Kern. 2025. "Prediction-based Adaptive Designs for Reducing Attrition Rates and Bias in Panel Surveys." ESRA 2025: 11th Conference of the European Survey Research Association, Utrecht (The Netherlands), 2025-07-17.
Collins, John, Saskia Bartholomäus, Tobias Gummer, Bernd Weiß, and Christoph Kern. 2025. "Prediction-based Adaptive Designs for Reducing Attrition Rates and Bias in Panel Surveys." AAPOR 2025: 80th Annual Conference, St. Louis (USA), 2025-05-14.
Bartholomäus, Saskia, Tobias Gummer, and Tanja Kunz. 2025. "The Impact of Different Adaptive Survey Design Approaches on Data Quality: Evidence from the GESIS Panel." ESRA 2025: 11th Conference of the European Survey Research Association, Utrecht (The Netherlands), 2025-07-17.
Bartholomäus, Saskia, Katharina Pfaff, and Sylvia Kritzinger. 2025. "Using Missing Data Strategies to Correct for Biases in Political Self-Selection Questionnaires." ESRA 2025: 11th Conference of the European Survey Research Association, Utrecht (The Netherlands), 2025-07-18.
Bartholomäus, Saskia. 2024. "Does a Questionnaire’s Content Matter? Experimental Evidence on the Use of Different Treatments to Improve Retention Rates of Politically Disengaged Persons in Longitudinal Political Science Surveys." ECPR General Conference 2024, Dublin (Ireland), 2024-08-13.
Bartholomäus, Saskia. 2024. "Increasing Biases in Political Science Surveys due to Negative Survey Experiences: Reasons and Solutions for the Attrition of Politically Disengaged Persons in Probability and Nonprobability-based Panels." DVPW - Methods Section: Annual Conference 2024, Bamberg (Germany), 2024-04-26.
Bartholomäus, Saskia, and Tobias Gummer. 2023. "Why Content Matters: Improving Non-Voters’ Survey Experience by Varying the Content of Political Questionnaires." ECPR General Conference 2023, Prague (Czech Republic), 2023-09-08.
Bartholomäus, Saskia, and Tobias Gummer. 2023. "Why Content Matters: Improving Respondents’ Survey Experience by Varying the Content of Questionnaires." ESRA 2023: 10th Conference of the European Survey Research Association, Milan (Italy), 2023-07-21.
Presentation not at a conference
Bartholomäus, Saskia. 2025. "Mitigating the Risk of Non-response Biases in Political Science Surveys by Accounting for Respondents’ Political Interest." German Politics and Political Sociology Research Colloquium JGU, Mainz (Germany), 2025-01-09.
Bartholomäus, Saskia. 2025. "Mitigating the Risk of Nonresponse and Measurement Errors in Political Science Surveys by Accounting for Respondents’ Political Interest." PAN-Metrics Seminar of the Department of Computational Social Sciences, Polish Academy of Sciences, Warsaw (Poland), 2025-06-16.
Bartholomäus, Saskia. 2024. "Comparing Different Approaches to Reduce Attrition Bias in Political Surveys. Potentials and Risks." Thought Summit on The Future of Survey Science: Cornell University, Ithaca (New York), 2024-09-23.
Bartholomäus, Saskia. 2024. "Comparing Different Approaches to Reduce Attrition of Political Disengaged Respondents in Political Science Surveys: Potentials and Risks." GESIS Research Day 2024, Cologne (Germany), 2024-10-10.
Bartholomäus, Saskia. 2024. "Mitigating the Risk of Attrition Bias by Accounting for Panelists’ Topic Preferences. Evidence from the GESIS Panel." Social Science Research Colloquium RPTU, Kaiserslauern (Germany), 2024-11-20.
Bartholomäus, Saskia. 2024. "Reducing Political Science Surveys’ Attrition Bias Without Limiting Substantive Research: Potentials of Adaptive Survey Design and Weighting Strategies." PSRT 2024: 8th GESIS Political Science Research Roundtable, Mannheim (Germany), 2024-10-23.