Nature Index: Metrics, Count, Share and Collaboration Scores

The Nature Index is a database that tracks author affiliations and relationships with research 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 and fractional measures of research output at institutional and national levels. These metrics offer an indicator of high-quality research and collaboration worldwide. The most recent 12 months of data are updated regularly and available under a Creative Commons licence at natureindex.com. The database is compiled by Nature Portfolio.

Nature Index metrics

Nature Index uses two primary measures to track research output: Count and Share.

Nature Index Count

A country, region or institution receives a Count of 1 for each paper with at least one author affiliated with that country, region or institution. The number of authors on an article does not affect its Count. As a result, the same paper can contribute to the Count of multiple countries, regions or institutions.

Nature Index Share

Nature Index uses Share, a fractional measure, to show national, regional and institutional contributions to research papers without counting the same contribution more than once. Each article has a total of 1 available share, divided equally among its authors.

For example, in an article with 10 authors, each author receives a share of 0.1. If an author is affiliated with multiple institutions, that author’s share is divided equally between those institutions. An institution’s total Share is calculated by adding the shares of all its affiliated authors.

The same process is used to calculate country and regional Shares. However, the calculation is more complex when institutions have overseas laboratories that contribute to the total of the host country or region.

Adjusted Share

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 published 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 from 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.

NatureIndex.com

At natureindex.com, users can search for specific institutions or countries and create reports ranked by Count or Share.