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  • NATURE INDEX

A guide to the Nature Index

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 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 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.

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 2021 Materials Science supplement is based on the Nature Index database, covering the research articles published between 1 January 2015 and 31 December 2020. The data are drawn from a subset of 27 journals in the Nature Index that excludes journals in areas unrelated to materials science. The 27 journals were searched via the Dimensions from Digital Science database to extract materials-science articles, using both keyword and fields of research (FOR) searches. It is noted that the assignment of articles to FORs in Dimensions has changed in some cases since the Nature Index 2019 Materials Science supplement.

As part of the material-science topics analysis, keyword searches using title and abstract were performed in the Dimensions database for each trending topic. The number of articles returned from each Dimensions search was tallied and aggregated into two groups: Dimension articles and NI collection. The Dimensions articles contain all returned publications that were identified as ‘article’ in the publication type. The NI collection contains articles tracked by the Nature Index journals (82 in total) and is not only restricted to the subset of the Nature Index articles identified as materials-science-related (that is, those extracted using both keyword and fields of research from the 27 Nature Index journals).

The topics and the equivalent keyword-search-terms using the Dimensions web-interface are as follows:

high-entropy alloys: ‘high entropy alloy’

water electrolysis: hydrogen AND energy AND ‘water electrolysis’

soft robotics: ‘soft robotics’

solid-state batteries: ‘solid state batteries’

nano immuno-engineering: (immunoengineer* OR immunotherap*) AND nano*

It is noted that the above search terms were chosen after considering different keyword combinations for each trending topic. The results presented in the supplement do not include all articles under each trending topic. Rather, the articles returned here are those with a strong focus on the trending topics, as the selected keywords were found in the title and abstract search option when using Dimensions as a data source.

The proportion of articles related to each topic is shown as a percentage of the topic total for the period 2015–20, with the topic article counts in 2015 and 2020 shown in text in the plots.

Two materials science tables are provided, based on the results computed using articles extracted from keyword and fields of research from the 27 Nature Index journals. One table shows the leading institutions ranked by their article share (Share) in materials science in 2020. Also listed are each institution's number of materials-science articles in 2020 (Count 2020), proportion of article Share in materials science relative to total Share (Materials science%), and percentage of internationally collaborative articles in materials science (International articles%).

The other table shows the top 50 rising institutions ranked by change in article Share (Share) in materials science from 2019 to 2020. Also listed are each institution’s Shares in materials science in both years, and percentage change in Share in materials science over the same period.

doi: https://doi.org/10.1038/d41586-021-01794-2

This article is part of Nature Index 2021 Materials science, an editorially independent supplement. Advertisers have no influence over the content.

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