I’m the Deputy Head of the Digital Economy Department and Head of the Junior Research Group Digital Market Design at ZEW Mannheim. We conduct academic research, give advice to policymakers, industry practitioners, and the public based on our research, and develop talent.
You can find more details below and in my curriculum vitae.
Research
Digital & financial markets Market design Artificial intelligence Data economy
Published
Digital contact tracing creates a quid-pro-quo data market, effective only if participation is broad on the extensive margin and sustained on the intensive margin. Both margins lagged during SARS-CoV-2, limiting effectiveness. We review the literature on how to bolster adoption and use.
Policy brief Podcast
We test how uncertainty affects market liquidity using Hurricane Sandy as a natural experiment. The storm's unprecedented strength and course made damages in New York City highly uncertain. We compare stock liquidity of REITs with and without properties in the NYC evacuation zone before landfall using geolocation data. Affected REITs show reduced trading volume and wider bid-ask spreads, confirming theory on uncertainty's negative impact on liquidity.
Working papers
We study behavioral responses to a global outage of Meta's services with high-frequency tracking data. Key findings: Users primarily switched to other social media and messaging apps, some crossed service categories, substitution varied by demographics, multi-platform users switched more readily, switching increased as the outage continued, patterns differed between countries, and non-Meta service usage remained elevated post-outage.
Red teaming is frequently used to uncover unwanted behavior in generative AI models and systems. We provide a formal framework for designing red teaming markets. The framework addresses core operational questions: defining goals, incentivizing and coordinating red teamers, verifying proper conduct, and comparing results across models/systems. We explore these questions through theory, simulations, and experiments.
The double-descent phenomenon and the application context of machine learning models often yield non-standard utility functions, such as non-convex and non-monotonic function segments. We develop and illustrate a neural network architecture that can address such complex utility functions in interpretable ways. The architecture also allows us to estimate utility and demand functions simultaneously, which we illustrate in simulations.
Work in progress
We analyze early consumer adoption of generative AI services using large-scale, individual-level tracking data. The high-frequency and granular nature of the data allows us to model consumer choices at the finest temporal resolution, capturing precisely when users first engage with the technology, how their usage evolves over time and how it substitutes or complements other services.
We develop a method to experimentally induce non-usage of digital services by paying consumers to forgo individual services and service bundles in order to identify complements and substitutes from behavioral responses and approximate consumer welfare. A pilot study with a representative German sample revealed that consumers cannot reliably self-assess their willingness-to-accept, and that income effects from overly generous offers could distort measurements. We are currently looking for sources of funding to run a larger-scale experiment.
We define measurement order bias as arising from sampling units of observation in a non-random sequence, such as when geographic clustering occurs during data collection. This distorts the interpretation of intermediate outcomes. To address this, we propose a statistical test to detect the bias and a method to correct it in cases of repeatedly sampling the same or similar units of observation.
We test theoretical implications of Brown and MacKay (2025) on the effects of pricing speed differentials using high-frequency data on the population of German gas stations. We develop empirical measures for speed and commitment, the two core concepts of their model, and find evidence consistent with their predictions.
Advice
Policy makers Industry practitioners General public
AI policy
- Policy brief proposing a EU Safe Generative AI Innovation Program, December 2024
- Advice on developing harmonized standards to implement the EU AI Act as a member of the AI Expert Group, DIN Consumer Council, since 2023
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Formal and informal advice on using market design ideas for red
teaming generative AI models to implement the EU AI Act:
- Lunch debate in Brussels, April, 2024
- Policy brief, April, 2024
- Op-ed, April, 2024
- Workshop in Berlin with German federal ministries, October, 2023
- Ad-hoc advice to German federal ministries and the Chancellery, since 2023
- Op-ed on industrial policy under the guise of EU AI regulation, December 2023
- Regular participation in public fora, such as “Leibniz im Bundestag”, “Leibniz Book a Scientist” and Digilog, since 2022
Competition policy
- Proposal of designing pseudo-markets for digital services to sharpen digital market regulation:
- Workshop on European platform regulation, mostly with academic lawyers, in Heidelberg, September 2024
- Workshop on competition in digital markets with academic lawyers in Würzburg, September 2023
- Conference on market design and regulation with industry practitioners, regulators and policy makers in Darmstadt, May 2023
- Informal exchange with German competition authority and the EU's DG COMP, since 2023
Data economy
- Contributions to proposals to foster data sharing among firms addressed to industry practitioners as part of the IEDS research consortium as the work stream leader for data valuation, 2021-2024
- Informal advice on allocating research funding within medical research consortia based on the value of the data contributed by each consortium member to train a machine learning model used for medical diagnostics, 2021-2022
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Recommendations to increase the adoption of digital contact tracing
apps, which are effectively quid-pro-quo data markets, during the
SARS-CoV-2 pandemic:
- Podcast, February 2021
- Policy brief, December 2020
- Op-ed, May 2020
- Op-ed, April 2020
- Informal advice to German Federal Ministry of Health and Robert Koch Institute, 2021
Financial markets
- Advice on using new data sources and machine learning models for central banking and banking supervision as an external expert in the Big Data Working Group, Deutsche Bundesbank, 2015-2017
- Published monthly report on the results of the ZEW Financial Market Survey, Germany's best-known financial market expectations survey, and commented on the results in national and international media, 2014-2016
Talent
Advising Mentoring Teaching
Current advisees and mentees
- Jacob Schildknecht, doctoral candidate at ZEW since 2024
- Johannes Walter, doctoral candidate at ZEW since 2019, research stay at MIT Sloan School of Management in 2022, on the academic job market 2025/2026
- Sebastian Valet, doctoral candidate at ZEW since 2019, research stay at Harvard Business School in 2025, planning to be on the academic job market 2026/2027
Past advisees and mentees
- Markus Althanns, former research assistant in 2020, afterwards doctoral candidate in economics at ETH Zurich, most recently Executive Assistant to the CEO of Allianz Reinsurance
- Felix Tremöhlen, former research assistant and master thesis student in 2020, afterwards Strategic Marketing Specialist at BASF, most recently Global Senior Manager Licensing at BASF
- Nikolas Haring, former research assistant in 2018/2019, afterwards data scientist at BASF, most recently Senior Analyst at
- Tim Schäfer, former research assistant in 2018/2019, afterwards technical instructor at AWS, most recently Solutions Architect at AllCloud
Teaching
- Guest lectures on data markets on Master's level, EBS Universität, 2024
- Seminar on digital markets and platforms on Master's level, taught jointly with Achim Wambach, University of Mannheim, 2020
- Full-year PhD course on finding and developing research ideas, ZEW, 2019-2020