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Res Integr Peer Rev. 2017 Nov 3;2:18. doi: 10.1186/s41073-017-0042-y. eCollection 2017.

Percentage-based Author Contribution Index: a universal measure of author contribution to scientific articles.

Author information

1Institut de Recherche sur la Biologie de l'Insecte (IRBI) - UMR 7261 CNRS / Université de Tours, Parc Grandmont, 37200 Tours, France.
2Applied Molecular Solutions Research Group, Environmental and Animal Sciences, Unitec Institute of Technology, Private Bag 92025, Victoria Street West, Auckland, 1142 New Zealand.
Japan Agency for Marine-Earth Science and Technology, Yokohama Institute for Earth Sciences, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001 Japan.
4Bio-Protection Research Centre, Lincoln University, P. O. Box 85084, Christchurch, 7647 New Zealand.
5Department of Evolutionary Biology, Ecology and Environmental Sciences, and Biodiversity Research Institute (IRBio), University of Barcelona, Avd. Diagonal, 643, 08028 Barcelona, Spain.
6Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark.
7Department of Entomology, The University of Georgia, Coastal Plain Experimental Station, 2360 Rainwater Rd, Tifton, GA 31793 USA.



Deciphering the amount of work provided by different co-authors of a scientific paper has been a recurrent problem in science. Despite the myriad of metrics available, the scientific community still largely relies on the position in the list of authors to evaluate contributions, a metric that attributes subjective and unfounded credit to co-authors. We propose an easy to apply, universally comparable and fair metric to measure and report co-authors contribution in the scientific literature.


The proposed Author Contribution Index (ACI) is based on contribution percentages provided by the authors, preferably at the time of submission. Researchers can use ACI to compare the contributions of different authors, describe the contribution profile of a particular researcher or analyse how contribution changes through time. We provide such an analysis based on contribution percentages provided by 97 scientists from the field of ecology who voluntarily responded to an online anonymous survey.


ACI is simple to understand and to implement because it is based solely on percentage contributions and the number of co-authors. It provides a continuous score that reflects the contribution of one author as compared to the average contribution of all other authors. For example, ACI(i) = 3, means that author i contributed three times more than what the other authors contributed on average. Our analysis comprised 836 papers published in 2014-2016 and revealed patterns of ACI values that relate to career advancement.


There are many examples of author contribution indices that have been proposed but none has really been adopted by scientific journals. Many of the proposed solutions are either too complicated, not accurate enough or not comparable across articles, authors and disciplines. The author contribution index presented here addresses these three major issues and has the potential to contribute to more transparency in the science literature. If adopted by scientific journals, it could provide job seekers, recruiters and evaluating bodies with a tool to gather information that is essential to them and cannot be easily and accurately obtained otherwise. We also suggest that scientists use the index regardless of whether it is implemented by journals or not.


Author contribution; Co-authorship; Publication metric; Scientific integrity

Conflict of interest statement

Application for human ethics were granted by the Unitec Research Ethics Committee (UREC) (application number: 2016-1062) and the University of Georgia Institutional Review Board (IRB) (application number: STUDY00004056). Our online survey was anonymous and included the following sentence: ‘By answering you agree that the data you provide is used for the above-mentioned analysis and subsequent publication’.Not applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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