Who Captures Knowledge Spillovers? Academic Mobility and the Geography of Scientific Inequality

In this Academic Research Seminar, Frank van der Wouden will present his paper, co-authored by Zixuan Zhang, “Who Captures Knowledge Spillovers? Academic Mobility and the Geography of Scientific Inequality.”

Speaker: Frank van der Wouden, Assistant Professor of Economic Geography and Innovation Studies

Authors: Frank van der Wouden and Zixuan Zhang

Paper Abstract: Does physical proximity still shape the flow of scientific ideas? And if it does, who captures the spillovers? Using a matched panel of 52,878 scholars tracked through OpenAlex from 1975 to 2024, we estimate a heterogeneity-robust staggered difference-in-differences model with Coarsening Exact Matching on pre-move productivity and networks. When a scholar relocates, the destination city’s share of their new-audience citations rises by 6.6 percentage points (SE = 0.002; p < 10⁻¹⁶). The probability that any previously unconnected local researcher cites them jumps by 24 percentage points. The effect is immediate, persistent and survives a large number of robustness checks. Three findings stand out. First, co-location redirects rather than creates scholarly attention. Total new-audience citations do not rise, while non-destination citations fall. Second, the citation boost also happens to papers the scholar had already written before moving (+0.24 pp; p < 10⁻⁵). This suggests that pure talent sorting is not driving this effect, since what is on the page cannot change with the scholar’s address. Third, the effect is markedly larger where the destination hosts more scholars in the mover’s own subfield and in elite academic hubs (ATT = 0.088 in Top-40 cities vs. 0.047 elsewhere). These findings have implications for academic recruitment and science policy. Hiring functions as a mechanism through which local communities gain access to a scholar’s existing knowledge. The returns do not depend on recruiting only the most elite. Yet, because top academic hubs both capture larger spillovers per hire and absorb most mobile scholars, the current pattern of academic hiring may deepen the gap between leading and peripheral cities.

Speaker Bio: Professor Frank van der Wouden is an Assistant Professor of Economic Geography and Innovation Studies at The University of Hong Kong. His work uses large-scale patent, publication and mobility data to uncover how innovation travels across cities, teams and individuals. He holds a PhD from UCLA and did a post-doctoral training at the Kellogg School of Management at Northwestern University.”

Whether attending in person or virtually, please register in advance.

The Growth Lab’s Research Seminar series is a weekly seminar that brings together researchers from across the academic spectrum who share an interest in growth and development.