Large publishing consortia produce higher citation impact research but co-author contributions are hard to evaluate

TL;DR

This study analyzes large publishing consortia, revealing they produce higher-impact research, but evaluating individual author contributions remains challenging due to shared authorship and alphabetical ordering.

Contribution

Introduces a clustering method to identify large consortia and analyzes their citation impact and authorship patterns across disciplines.

Findings

88% of large consortia publish above average impact

Consortia research has nearly double the world average citation impact

Authorship often reflects infrastructure contributions rather than individual effort

Abstract

This paper introduces a simple agglomerative clustering method to identify large publishing consortia with at least 20 authors and 80% shared authorship between articles. Based on Scopus journal articles 1996-2018, under these criteria, nearly all (88%) of the large consortia published research with citation impact above the world average, with the exceptions being mainly the newer consortia for which average citation counts are unreliable. On average, consortium research had almost double (1.95) the world average citation impact on the log scale used (Mean Normalised Log Citation Score). At least partial alphabetical author ordering was the norm in most consortia. The 250 largest consortia were for nuclear physics and astronomy around expensive equipment, and for predominantly health-related issues in genomics, medicine, public health, microbiology and neuropsychology. For the health-related issues, except for the first and last few authors, authorship seem to primary indicate contributions to the shared project infrastructure necessary to gather the raw data. It is impossible for research evaluators to identify the contributions of individual authors in the huge alphabetical consortia of physics and astronomy, and problematic for the middle and end authors of health-related consortia. For small scale evaluations, authorship contribution statements could be used, when available.