Political Expression of Academics on Twitter. Joint with Thiemo Fetzer.
Nature Human Behaviour, 2025. Access: Paper 🔓, Website, Twitter Thread. Paper's Backstory
Coverage: Marginal Revolution, Matthew Yglesias, Noahpinion.blog, VoxEU, Times Higher Education (article; Op-ed), American Saga
Academics have traditionally played a vital role in both the generation and dissemination of knowledge, ideas and narratives. Social media, relative to traditional media, provides for new and more direct ways of science communication. Yet, since not all academics may engage with social media, the sample that does so may have an outsize influence on shaping public perceptions of academia more broadly through at least two channels: the set topics they engage with and through the particular style and tone of communication. This paper describes patterns in academics' expression online found in a newly constructed global dataset covering over 100,000 scholars linking their social media content to academic record. We document large and systematic variation in politically salient academic expression concerning climate action, cultural, and economic concepts. We show that these appear to often diverge from general public opinion in both topic focus and style.
Local Decline and Populism. Joint with Thiemo Fetzer and Jacob Edenhofer.
Economics Letters, 2025. Access: Paper 🔓, Twitter Thread.
Coverage: The Guardian, FAZ (German), The Conversation, VoxEU, Uni of Warwick, CAGE (1, 2)
Support for right-wing populist parties is characterised by considerable regional heterogeneity and especially concentrated in regions that have experienced economic decline. It remains unclear, however, whether the spatial externalities of local decline, including homelessness and crime, boost support for populist parties, even among those not directly affected by such decline. In this paper, we contribute to filling this gap in two ways. First, we gather novel data on a particularly visible form of local decline, high-street vacancies, that comprise 83,000 premises in England and Wales. Second, we investigate the influence of local decline on support for the right-wing populist UK Independence Party (UKIP) between 2009 and 2019. We find a significant positive association between high-street vacancy rates and UKIP support. These results enhance our understanding of how changes in the lived environment shape political preferences and behaviour, particularly in relation to right-wing populism.
Network Determinants of Cross-Border Media Coverage of Natural Disasters. Joint with Thiemo Fetzer
Acceptance-in-Principle at Nature Human Behaviour. Access: Paper
Climate change is increasing the frequency and severity of natural disasters worldwide. Media coverage of these events may be vital to generate empathy and mobilize global populations to address the common threat posed by climate change. Using a dataset of 466 news sources from 123 countries, covering 135 million news articles since 2016, we apply an event study framework to measure cross-border media activity following natural disasters. Our results shows that while media attention rises after disasters, it is heavily skewed towards certain events, notably earthquakes, accidents, and wildfires. In contrast, climatologically salient events such as floods, droughts, or extreme temperatures receive less coverage. This cross-border disaster reporting is strongly related to the number of deaths associated with the event, especially when the affected populations share strong social ties or genetic similarities with those in the reporting country. Achieving more balanced media coverage across different types of natural disasters may be essential to counteract skewed perceptions. Further, fostering closer social connections between countries may enhance empathy and mobilize the resources necessary to confront the global threat of climate change.
Causal Claims in Economics. Joint with Thiemo Fetzer.
View Paper. Open-Access Data. Twitter Thread (v1, v2), Summary and Method Guide.
Coverage: The Economist, Marginal Revolution (v1, v2), Noahpinion, World Bank, VoxEU (1, 2), VoxDev, Australian Treasury, Nada es Gratis
Data and Code on Github. Highlights at www.causal.claims
As economics scales, a key bottleneck is representing what papers claim in a comparable, aggregable form. We introduce evidence-annotated claim graphs that map each paper into a directed network of standardized economic concepts (nodes) and stated relationships (edges), with each edge labeled by evidentiary basis, including whether it is supported by causal inference designs or by non-causal evidence. Using a structured multi-stage AI workflow, we construct claim graphs for 44,852 economics papers from 1980--2023. The share of causal edges rises from 7.7% in 1990 to 31.7% in 2020. Measures of causal narrative structure and causal novelty are positively associated with top-five publication and long-run citations, whereas non-causal counterparts are weakly related or negative.
Politicized Scientists: Credibility Cost of Political Expression on Twitter. Joint with Eleonora Alabrese and Franceso Capozza
Access: Paper , Twitter Thread.
Coverage: Times Higher Education (article, op-ed), TheAmericanSaga, University of Bath, Italian media (Nadaesgratis, A Fuoco, iL Post)
As social media becomes prominent within academia, we examine its reputational costs for academics. Analyzing Twitter posts from 98,000 scientists (2016–22), we uncover substantial political expression. Online experiments with 6,000 U.S. respondents and 135 journalists, rating synthetic academic profiles with different political affiliations, reveal that politically neutral scientists are seen as the most credible. Strikingly, political expressions result in monotonic penalties: Stronger posts reduce perceived credibility of scientists and their research and audience engagement more, particularly among oppositely aligned respondents. Two surveys with scientists highlight their awareness to penalties, their perceived benefits, and a consensus on limiting political expression outside their expertise.
AI-Generated Production Networks: Measurement and Applications to Global Trade. Joint with Thiemo Fetzer, Peter John Lambert, Bennet Feld.
Access: Paper. Website. Twitter Thread.
Coverage: VoxEU, Interview by SCMP, The Ecologist
Interactive Website (aipnet.io) includes open data on input-output links between 5000 HS products.
This paper leverages generative AI to build a network structure over 5,000 product nodes, where directed edges represent input-output relationships in production. We layout a two-step ‘build-prune’ approach using an ensemble of prompt-tuned generative AI classifications. The ’build’ step provides an initial distribution of edge predictions, the ‘prune’ step then re-evaluates all edges. With our AI-generated Production Network (AIPNET) in toe, we document a host of shifts in the network position of products and countries during the 21st century. Finally, we study production network spillovers using the natural experiment presented by the 2017 blockade of Qatar. We find strong evidence of such spill-overs, suggestive of on-shoring of critical production. This descriptive and causal evidence demonstrates some of the many research possibilities opened up by our granular measurement of product linkages, including studies of on-shoring, industrial policy, and other recent shifts in global trade.
Simple contagion drives population-scale platform migration. Joint with Dorian Quelle, Frederic Denker and Alexandre Bovet
Access: Paper. Best Student Paper at NetSciSci2025
Coverage: Cybernews, Aporia Magazine
Social media platforms mediate professional communication, political expression, and community formation, making the rare instances when users collectively abandon an incumbent platform particularly consequential. Strong network effects raise switching costs and strengthen incumbents' positions, making coordinated exit difficult. Here we link 276,431 scholars on Twitter/X to their respective new profiles among the universe of all 16.7 million Bluesky accounts, tracked from January 2023 to December 2024, using a scalable, high-precision cross-platform matching pipeline. Exploiting exogenous variation from Brazil's court-ordered suspension of Twitter/X and a dynamic matching design, we show that adoption is peer-driven, treatment effects are short-lived and dose-dependent, and contagion is simple, not complex. Three patterns characterize adoption and retention. Adoption concentrates among users deeply embedded in Twitter's social graph. Public political expression predicts migration, consistent with homophilous inflows into a largely left-of-center Bluesky information space. Early reconnection with prior contacts predicts longer tenure and engagement. Our findings provide the first population-scale causal evidence of peer influence in a social media platform migration by exploiting exogenous exposure variation in a natural experiment and using daily dynamic matching. Rather than the complex contagion mechanism often emphasized in the literature, contagion is predominantly simple. Our findings recast migration as a multi-homing strategy that insures against governance uncertainty and show that users who quickly reconnect with prior contacts remain active longer on Bluesky.
(How) Do Health Shocks Reallocate Research Direction? Joint with Hongyu Zhou and Thiemo Fetzer
Access: Paper
We examine whether research systems reallocate scientific effort as health needs change. We assemble a global disease-location panel for 204 countries and territories (1990-2021) by linking disease-specific publication output to disease burden in the same place and year. Using large language models, we extract diseases from article text, map them into a standardized disease classification, and classify research funders by type. Empirically, we estimate how publication output co-moves with disease burden within countries and diseases over time, and we use event-study difference-in-differences designs that exploit plausibly exogenous variation from the timing of outbreak alerts. We find that responsiveness to endemic burden has increased over time but remains highly uneven across locations; outbreak alerts trigger rapid, statistically significant research surges that have strengthened in recent years; and funding composition is strongly associated with adjustment dynamics, with philanthropic and government-supported research contributing disproportionately to responsiveness growth in lower-income settings.
AI health advice accuracy varies across languages and contexts. Joint with Thiemo Fetzer
Access: Paper
Using basic health statements authorized by UK and EU registers and ~9,100 journalist-vetted public-health assertions on topics such as abortion, COVID-19 and politics from sources ranging from peer-reviewed journals and government advisories to social media and news across the political spectrum, we benchmark seven leading large language models in 21 languages. We find that, despite high accuracy on English-centric textbook claims, performance falls in multiple non-European languages and fluctuates by topic and source. This highlights the urgency of comprehensive multilingual, domain-aware validation before deploying AI in global health communication.
What Should Economics Ask Next?
Conspiratorial Thinking Joint with Thomas Graeber and Christopher Roth
Measuring Missing Innovation Joint with Peter Lambert, Ralf Martin and Denis Medvedev
Cross-Border Enforcement and Product Innovation
Self-Censorship of International Academics on Social Media Joint with Vitor Melo and Patrick Warren
Creativity in Science Joint with Soumitra Shukla
Stories We Tell About Science Joint with Thiemo Fetzer
A Global Task-Skill Atlas of AI Exposure Joint with Jasmin Baier and Tommaso Crosta
Voices in the Air: The Origins of Competition Policy Joint with Thiemo Fetzer, Joel Kariel, Luke McWatters, Jakob Schneebacher
Mapping Bob Dylan’s Mind
Aeon Magazine. Access: essay, technical paper, Thread on Twitter/Bluesky
Coverage: Financial Times
For six decades, Bob Dylan has challenged listeners with songs that reward interpretation. Critics and fans have long pored over his words, treating them as literary texts worthy of a slow, devotional reading, line by line, image by image. In 2016, Dylan even won the Nobel Prize in Literature. As the Swedish Academy put it, the prize honoured him for ‘having created new poetic expressions within the great American song tradition’. But what more might we discover if, instead of a human scholar, we asked an artificial intelligence to sift through every word Dylan ever wrote? What patterns, connections or evolution in Dylan’s massive body of lyrics might reveal themselves to a machine’s analysis, and what could that tell us about the man and his music?