Examining the role of co-first authorship in scientific collaboration: a quantitative study

As collaboration prevails in academia, the convention of overemphasizing the first author while neglecting other contributors has become problematic, leading to the emergence of co-first authorship. In this study, we identified papers with co-first authors (CFAs) using author contribution declarations from 96,264 papers in PLOS journals published between 2018 and 2022, then conducted a quantitative analysis to examine the role of co-first authorship in collaborative research via informetric methods. The results showed that (1) though CFAs usually claim to have equal contributions, those listed ahead typically contribute more, e.g. our calculations show that the contribution index of the first CFA is 2.55 times greater than that of the second CFA; (2) authors declared as CFA in 2nd, 3rd, 4th, and 5th positions typically contribute more than those in the same positions who were not declared as CFA; (3) co-first authorship is associated with increased collaboration, as evidenced by a higher average number of authors per publication (7.41 for CFA papers compared to 6.36 for non-CFA papers), and a greater intensity of contributions and collaboration among leading authors. Our study lays the groundwork for further exploration of co-first authorship and its effects on collaboration, while providing valuable insights for research administrators to enhance evaluation practices and foster scientific collaboration.