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The Nature Index is a database of author affiliations and institutional relationships. The index tracks contributions to research articles published in high-quality natural-science and health-science journals, chosen based on reputation 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 Portfolio.

Nature Index metrics

The Nature Index uses Count and Share to track research output. A country/territory or an institution is given a Count of 1 for each article that has at least one author from that country/territory 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 Count of multiple countries/territories or institutions.

To glean a country’s, territory’s, region’s or an institution’s contribution to an article, and to ensure that they are not counted more than once, the Nature Index uses Share, a fractional count that takes into account the share of authorship on each article. The total Share 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 a Share of 0.1. For authors who are affiliated with more than one institution, the author’s Share is split equally between each institution. The total Share for an institution is calculated by summing the Share for individual affiliated authors. The process is similar for countries/territories, although complicated by the fact that some institutions have overseas labs that will be counted towards host country/territory totals.

Adjusted Share accounts for the small annual variation in the total number of articles in the Nature Index journals. It is arrived at by calculating the percentage difference in the total number of articles in the Index in a given year relative to the number of articles in a base year and adjusting Share values to the base year levels.

The bilateral collaboration score (CS) between two institutions A+B is the sum of each of their Shares on the papers to which both have contributed. A bilateral collaboration can be between any two institutions or countries/territories co-authoring at least one article in the journals tracked by the Nature Index.

NATUREINDEX.COM

natureindex.com users can search for specific institutions or countries and generate their own reports, ordered by Count or Share.

Each query will return a profile page that lists the country or institution’s recent outputs, from which it is possible to drill down for more information. Articles can be displayed by journal, and then by article. Research outputs are organized by subject area. The pages list the institution or country’s/territory’s top collaborators, as well as its relationship with other organizations. Users can track an institution’s performance over time, create their own indexes and export table data.

This supplement

The Nature Index 2023 North–south collaboration supplement is based on the Nature Index database and the Dimensions database from Digital Science. It includes Nature Index articles in 82 selected natural-science journals published between 2015 and 2022, and Dimensions articles from the same period.

Global-north and global-south countries were defined using the World Bank’s country classifications, which divide economies into four income groupings: low, lower middle, upper middle and high. South countries refer to those from the low and lower middle-income groupings and north countries are those in the upper middle and high-income groupings. Income classifications set on 1 July 2023 for the fiscal year 2024 were used for the supplement.

Nature Index and Dimension articles with affiliations from both north and south countries formed two data sets for the supplement, one for each database.

The tables in this supplement show leading institutions and countries/territories in each database, as well as the leading institutional north–south collaborations in different subjects in the Nature Index.