Nature Index: Research Metrics, Publications and Global Collaboration

The Nature Index is a database that tracks author affiliations and relationships with institutions. It measures contributions to research articles published in high-quality natural and health science journals selected for their reputation by an independent group of researchers.

Nature Index data provides absolute publication counts and fractional publication shares at institutional and national levels. These metrics offer an indication of high-quality research output and collaboration worldwide. The most recent 12 months of data are updated regularly and available under a Creative Commons license at natureindex.com. The database is compiled by Nature Portfolio.

Nature Index metrics

Count: Measuring research output

The Nature Index uses Count and Share to track research output. A country, region or institution receives a count of 1 for each paper with at least one author from that country, region or institution. This applies regardless of the number of authors on the article, meaning that the same paper can contribute to the count of multiple countries, regions or institutions.

Share: Measuring fractional contributions

To measure national, regional and institutional contributions without counting them more than once, the Nature Index uses Share. This fractional metric accounts for the proportion of authors associated with each country, region or institution.

The total number of shares available for each article is 1, divided among all authors on the assumption that each author contributed equally. For example, an article with 10 authors gives each author a share of 0.1. If an author is affiliated with multiple institutions, that author’s share is divided equally among those institutions. An institution’s total share is calculated by adding the shares of its affiliated authors.

The same process applies to countries and regions, although calculations are more complex because some institutions have overseas laboratories that contribute to the total of the host country or region.

Adjusted share

The adjusted share accounts for annual changes in the total number of articles published in Nature Index journals. It is calculated using the percentage difference between the total number of articles in the index in a given year and the number in the base year, then adjusting the share to the base-year level.

Bilateral collaboration score

The bilateral collaboration score (CS) between two institutions, A and B, is the sum of each institution’s share of papers contributed by both institutions. Bilateral collaborations can occur between any two institutions or countries or regions that co-author at least one paper in a journal tracked by the Nature Index.

Search Nature Index data and create reports

At natureindex.com, users can search for specific institutions or countries and create custom reports sorted by publication count or share.