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 Springer Nature.
Nature Index metrics
The Nature Index provides several metrics to track research output and collaboration. These include article count, fractional count and multilateral and bilateral collaboration scores.
The simplest is the article count (AC). 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.
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.
Two metrics measure collaboration. The multilateral collaboration score (MCS) is an indicator of collaboration between multiple institutions and can be calculated for an individual institution or a group of institutions. MCS takes account of the number of collaborating institutions on a given article, so it can be added across multiple institutions, always resulting in a total FC of 1 for each article.
The bilateral collaboration score (CS) between two institutions A+B is the sum of each of their FCs on the papers to which both have contributed. A bilateral collaboration can be between any two institutions or countries/regions co-authoring at least one article in the journals tracked by the Nature Index.
Nature Index 2018 China is based on data from natureindex.com, covering articles published during six years from 1 January 2012 to 31 December 2017 at the country level, and articles from 1 January 2015 to 31 December 2017 at the institution level. Most analyses within the supplement use FC as the primary metric.
The tables rank the top institutions by their FC from 2015 to 2017, overall and according to each of the four broad areas of the natural sciences covered by the Nature Index. Article counts are also included. For the large umbrella organisations, Chinese Academy of Sciences and Chinese Academy of Agricultural Sciences, output has been broken down into their subsidiary institutions.