Randol (Hongyu) Yao

Randol (Hongyu) Yao

PhD Candidate

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publications

The Geography of Science

(with Abhishek Nagaraj) The Economist, NBER Digest, CEPR VoxEU

Science has long been concentrated in the Western world, but the global research landscape is undergoing a profound reorganization. Using data on 44 million publications from 1980 to 2022, we document the geography of science in terms of who produces it, what it studies, and where it diffuses. The share of publications produced in the United States has fallen from 40% in 1980 to 15% in 2022, while China’s share has risen from near-zero to 32%. This pattern extends even to elite outlets, with China now producing over 35% of top-journal publications. Notably, this is driven not only by an expanding researcher base but also—to a large extent—by increases in individual productivity. This growth varies by fields: China leads in the Engineering and Physical Sciences (such as Chemistry), while the US retains its lead in Biomedical and Health Sciences. Moreover, China’s expanding leadership in scientific production has not translated into a commensurate shift in global diffusion and integration. Elite research remains disproportionately focused on US topics (40% of breakthrough publications), and citations to Chinese research disproportionately come from within China rather than from other regions, even for top-tier science. Similar to China, other middle- and low-income countries (including India, Russia, and Brazil) have also expanded output producing as much research as high-income European Union countries combined (about 21% overall) but they remain underrepresented in top-tier journals. Overall, our findings highlight both the democratization and fragmentation of global science, raising important questions about the future of the global scientific enterprise.

Diffusion of Knowledge in Traditional Medicine (with Joey Ryu)

Patent Exposure and the Diffusion of “Trapped Knowledge”

Valuable knowledge developed in one part of the world may remain trapped even when formally available because frictions prevent it from entering the consideration set of downstream users. This paper examines whether granting US patents to already-established foreign inventions can “untrap” this knowledge by increasing its effective exposure, making it more likely to be noticed, recognized as relevant, and seriously evaluated. Using difference-in-differences with an examiner leniency instrument, I find that US grants of foreign patents significantly increase both the intensity and reach of forward citations. Using a new measure of “trappedness,” I show that knowledge from historically more trapped countries and sectors experiences larger diffusion benefits after US grants. These findings highlight the historical role of the US as an influential platform of global knowledge diffusion.

AI evaluation may bias perceptions: The importance of context in interpreting academic writing (with Shang Wu)

talks

teaching