Publications

Please reach out to me in case you do not have access to any of my publications. I am more than happy to help!

How Transformative are Transformative Agreements? Evidence from Germany Across Disciplines
Scientometrics, Vol. 129, 2024, pp. 1863–1889 -- Full Open Access
Research institutions across the globe attempt to change the academic publishing system as digitization opens up new opportunities, and subscriptions to the large journal bundles of the leading publishers put library budgets under pressure. One approach is the negotiation of so-called transformative agreements with large publishing firms. I study the so-called `DEAL' contracts between all German research institutions and Springer Nature and Wiley. By investigating 6.1 million publications in 5,862 journals covering eight fields in the years 2016 -- 2022 and applying a causal difference-in-differences design, I can identify whether the likelihood of a paper appearing in an eligible journal increases. The effect strongly depends on the discipline. While material science, chemistry, and economics shift towards these journals, all other disciplines in my sample do not react. Suggestive evidence hints at the market position of the encompassed publishers before the `DEAL' was established: Springer Nature and Wiley tend to benefit more from the contracts in disciplines in which they possessed a higher market share ex ante. The transformative vigor of these agreements seems to be limited and highlights that the developments in this intertwined market require further examination.

Vice Versa: The Decoupling of Content and Topic Heterogeneity in Collusion Research
Journal of Economic Surveys, December 2023 (online first) -- Full Open Access -- All code files are fully and freely available in a GitHub repository
Awarded with an Antitrust Writing Award 2024 in the category "Concerted Practices" by Concurrences and the George Washington University Law School
Collusive practices of firms continue to be a major threat to competition and consumer welfare. It should be of utmost importance for academic research to provide the theoretical and empirical foundations to antitrust authorities and enable them to develop proper tools to encounter new collusive practices. Utilizing topical natural language machine learning techniques allows me to analyze the body of economic research on collusion over more than 20 years in a novel way. I extract the underlying topics from the papers and conduct a large set of uni- and multivariate time series and regression analyses on their individual prevalences. I detect a notable tendency towards monocultures in topics and an endogenous constriction of the topic variety. In contrast, the overall contents and issues addressed by these papers have grown remarkably. This caused a decoupling: Nowadays, many datasets and cartel cases are studied but with a much smaller research scope. As economic research is crucial guidance for competition authorities, this may potentially affect the agencies' detection capability.

The role of gender and coauthors in academic publication behavior
Research Policy, Vol. 52 (10), December 2023 -  joint with Justus Haucap and Leon Knoke 

 We examine the negotiations for large-scale open access agreements between all German research institutions and the leading academic publishers to study two unique natural experiments on how changes in the attractiveness of journals as publication outlets affect the behavior of economists. First, there may be a reduced incentive to publish in Elsevier journals as German universities canceled their subscriptions to Elsevier, which publishes half of the leading journals in economics. Second, there is an increased incentive to publish in Springer Nature and Wiley journals. Both publishers entered into Open Access agreements with all German research institutions. Using 250,000 publications in economics from 2015 - 2022, we find a notable shift toward the eligible journals from Springer Nature and Wiley irrespective of gender. For Elsevier, the reactions differ. While females tend to opt out, males remain inert. In mixed teams, the dominant gender seems to drive behavior. Our findings may be more broadly applicable to the study of gender differences in competitive environments.
Freely accessible working paper version: CESifo Working Paper No. 10340 (the published version has been extended and revised)
Media Coverage: The Times of London, LSE Impact Blogpost of Abdelghani Maddi;  Own blog posts: LSE Impact Blog, INOMICS

Downstream Profit Effects of Horizontal Mergers: Horn & Wolinsky and von Ungern-Sternberg Revisited
B.E. Journal of Economic Analysis & Policy, Vol. 23 (4), 2023, pp. 981 - 1000 -- Full Open Access
Mergers between previously contending firms are a permanent challenge for policymaking as they potentially harm competition. The core incentive to merge is the prospect of higher joint profits of the previously independent firms after the merger. We discuss and compare the core assumptions of Horn & Wolinsky (1988) and von Ungern-Sternberg (1996) that lead to contrary results regarding the attractiveness of horizontal mergers of downstream firms in a 1:2 setting leading to a monopolized 1:1 setting. While the latter finds a merger beneficial for the downstream firms, it harms their joint profit, according to Horn & Wolinsky. We theoretically apply both models to the two settings. We also present extensive sample calculations that quantitatively confirm the two papers' core insights. Discussing and contextualizing the results, we provide a comprehensive overview of horizontal mergers in the downstream part of vertical structures with bargaining over linear input prices. Due to the continuing relevance of horizontal mergers for competition policy and, in particular, in light of the consolidation phase in tech start-ups, the topic is of enduring relevance in policymaking.

What Cannot Be Cured Must Be Endured: The Long-Lasting Effect of a COVID-19 Infection on Workplace Productivity
Labour Economics, Vol. 79 (2022), 102281  -- Full Open Access -- joint with Kai Fischer and J. James Reade
The COVID-19 pandemic has triggered economic shock waves across the globe. Exploiting a natural experiment, this paper estimates how being infected with the virus shapes individual-level productivity after having recovered. Studying the performance of professional athletes in Germany and Italy and applying a staggered difference-in-differences design, we find that individual performance drops by around 6 percent after a previously infected athlete returns to the pitch. This striking deterioration remains persistent over time – amounting to 5 percent eight months after the infection. The effect increases with age and infection severity and is spread disproportionally over the course of a match. We detect no productivity effects for other respiratory infections. We take these findings as the first evidence that the pandemic might cause long-lasting effects on worker productivity and economic growth.

Media Coverage:
The Economist, The Guardian, The i newspaper, The Times, Marginal Revolution, Economic Observatory, The Article, Italy24 News, Royal Economic Society, Times of India
In German: Frankfurter Allgemeine Sonntagszeitung,FOCUS, n-tv ,  Rheinische Post, Frankfurter Rundschau,  Business Insider, Sport1, Spox, Hessich-Niedersächsische Allgemeine (HNA), Ökonomenstimme, Watson , Watson, ZM Online, heute.at (Austria)
Multimedia: Podcast 'Wieder was gelernt' @ ntv.de, TV: RTL aktuell (major German news magazine, 2.07 mio views), SKY Sport News HD
Other languages: L'Equipe, RTBF, Pesquisa FAPESP, RAI Sport

Our research evoked a broad reception and discussion in the public, among others, by the German Federal Minister of Health,  Prof. Karl Lauterbach.  Many academics discussed it, e.g.,  Florian Ederer, Arpit Gupta, Martin Halla, Jon M. Jachimowicz, Katy Milkman, Ethan Mollick, Lionel Page, Andreas Peichl, John Pfaff, Dina Pomeranz, and Joshua Tucker. The paper was previously circulated as "The Long Shadow of an Infection: COVID-19 and Performance at Work", DICE Discussion Paper 368, and U Reading Department of Economics Discussion Paper No. 2021-17 (the published version is extended and revised). Further materials: a video and slides of my presentation at the ROSES seminar

The Impact of the German 'DEAL' on Competition in the Academic Publishing Market
Managerial and Decision Economics, Vol. 42 (8), 2021, pp. 2027 - 2049  -- Full Open Access -- joint with Justus Haucap & Nima Moshgbar
The German DEAL agreements between German universities and research institutions on the one side and Springer Nature and Wiley on the other side facilitate easy open access publishing for researchers located in Germany. We use a dataset of all publications in chemistry from 2016 to 2020 and apply a difference-in-differences approach to estimate the impact on eligible scientists’ choice of publication outlet. We find that even in the short period following the conclusion of these DEAL agreements, publication patterns in the field of chemistry have changed, as eligible researchers have increased their publications in Wiley and Springer Nature journals at the cost of other journals. From that, two related competition concerns emerge: First, academic libraries may be, at least in the long run, left with fewer funds and incentives to subscribe to non-DEAL journals published by smaller publishers or to fund open access publications in these journals. Secondly, eligible authors may prefer to publish in journals included in the DEAL agreements, thereby giving DEAL journals a competitive advantage over non-DEAL journals in attracting good papers. Given the two-sided market nature of the academic journal market, these effects may both further spur the concentration process in this market.