The Nature Index is a database of author affiliations and institutional relationships. The index tracks contributions to research articles published in 82 high-quality natural science journals, chosen by an independent group of researchers.
The Nature Index provides absolute and fractional counts of article publication at the institutional and national level and, as such, is an indicator of global high-quality research output and collaboration. Data in the Nature Index are updated regularly, with the most recent 12 months made available under a Creative Commons licence at natureindex.com. The database is compiled by Nature Research.
Nature Index metrics
The Nature Index uses article count (AC) and Fractional Count (FC) to track research output. A country/region or an institution is given an AC of 1 for each article that has at least one author from that country/region or institution. This is the case regardless of the number of authors an article has, and it means that the same article can contribute to the AC of multiple countries/regions or institutions.
To glean a country’s, a region’s or an institution’s contribution to an article, and to ensure they are not counted more than once, the Nature Index uses fractional count (FC), which takes into account the share of authorship on each article. The total FC available per article is 1, which is shared among all authors under the assumption that each contributed equally. For instance, an article with 10 authors means that each author receives an FC of 0.1. For authors who are affiliated with more than one institution, the author’s FC is then split equally between each institution. The total FC for an institution is calculated by summing the FC for individual affiliated authors. The process is similar for countries/regions, although complicated by the fact that some institutions have overseas labs that will be counted towards host country/region totals.
Nature Index 2019 Collaboration and big science is based on the Nature Index database, covering articles published during the period 1 January 2015 to 31 December 2018.
The tables rank institutions by their fractional counts in the journals tracked by the index. Article counts are also shown. The table rankings are for high affiliation articles only, meaning articles with authors from 10 or more separate principal institutions. The three fields of research designated in the supplement as big science were defined using FoR codes from the Dimensions database from Digital Science.