Analyzing a global sample of 4 million authors and 26 million scientific papers: The top 1% most-cited scientists have increased their cumulative citation shares from 14 to 21% between 2000 and 2015

Global citation inequality is on the rise. Mathias Wullum Nielsen and Jens Peter Andersen. Proceedings of the National Academy of Sciences, February 16, 2021 118 (7) e2012208118; https://doi.org/10.1073/pnas.2012208118

Significance: By analyzing a global sample of 4 million authors and 26 million scientific papers, this study finds that the top 1% most-cited scientists have increased their cumulative citation shares from 14 to 21% between 2000 and 2015 and that the Gini coefficient for citation imbalance has risen from 0.65 to 0.70. The growing citation concentration should be understood in the context of diverging trends in publication and collaboration activities for the top 1% compared to the “ordinary scientist.” Our study raises intriguing questions about how rising inequalities will shape the evolution of science.

Abstract: Citations are important building blocks for status and success in science. We used a linked dataset of more than 4 million authors and 26 million scientific papers to quantify trends in cumulative citation inequality and concentration at the author level. Our analysis, which spans 15 y and 118 scientific disciplines, suggests that a small stratum of elite scientists accrues increasing citation shares and that citation inequality is on the rise across the natural sciences, medical sciences, and agricultural sciences. The rise in citation concentration has coincided with a general inclination toward more collaboration. While increasing collaboration and full-count publication rates go hand in hand for the top 1% most cited, ordinary scientists are engaging in more and larger collaborations over time, but publishing slightly less. Moreover, fractionalized publication rates are generally on the decline, but the top 1% most cited have seen larger increases in coauthored papers and smaller relative decreases in fractional-count publication rates than scientists in the lower percentiles of the citation distribution. Taken together, these trends have enabled the top 1% to extend its share of fractional- and full-count publications and citations. Further analysis shows that top-cited scientists increasingly reside in high-ranking universities in western Europe and Australasia, while the United States has seen a slight decline in elite concentration. Our findings align with recent evidence suggesting intensified international competition and widening author-level disparities in science.

Keywords: scientific elitescitationsinequalitysciencesociology of science