International Collaboration and Citations

S&E research has become more global over the past decade—a trend evidenced cross-nationally (Glänzel and Schubert 2005; Luukkonen et al. 1993; Royal Society 2011). Researchers gather scientific expertise beyond their region, country, or economy’s borders through collaboration (coauthoring articles) and citation (referencing articles from other regions, countries, or economies). Measured at the region, country, or economy level, international collaboration and citation are strongly influenced by the size and the policies of the region, country, or economy. For example, some regions, countries, or economies provide preferential funding for cross-national research within a region through programs such as the European Commission’s Horizon Europe (European Commission 2021).

This section of the report examines trends in collaborations between researchers—as measured by coauthorships and citations—particularly among those involving international connections. In the sidebar Artificial Intelligence Publication Output and International Collaboration, this section also explores international collaboration in greater depth in the field of artificial intelligence using network analysis.

Researchers may collaborate for several reasons, including to develop a scientific relationship with another researcher or to gain access to costly or shared equipment. They may also work together to meet conditions attached to research funding that require international collaboration (Wagner 2018).

In general, national governments encourage international collaboration to achieve outcomes that exceed what they could achieve individually (although they may perceive risks in collaborating with regions, countries, or economies they regard as a potential threat). These positive outcomes include training a robust S&E workforce, partnering with researchers from developing countries, advancing domestic science excellence, increasing the impact of discoveries through better distribution of knowledge, strengthening scientific and diplomatic relations, and enhancing a sense of shared responsibility for future action (Lyons et al. 2016). Also, international collaborations increase the impact of research, as measured by citations (Chinchilla-Rodríguez, Sugimoto, and Larivière 2019; Narin, Stevens, and Whitlow 1991; Sugimoto et al. 2017). Domestic collaboration among researchers in the academic, government, and industry sectors also results in articles that receive higher citation rates when compared with articles from a single author or authors from only one sector (see the section Business Collaborations in Published Literature in Indicators 2022 report “Invention, Knowledge Transfer, and Innovation”).

International Collaboration Patterns

An article is classified as an international collaboration if at least two author organizations are located in different regions, countries, or economies, as determined by their addresses on the article. In 2022, the United States contributed to the largest number of articles involving international coauthorship (241,823 articles, representing 32% of all internationally coauthored articles) (Table SPBS-33). The most frequent coauthorship partners for the United States were China, the United Kingdom, Canada, and Germany (Table SPBS-35).

In 2022, the global rate of international collaboration was 23%, but these rates varied by region, country, or economy. Researchers in the United States collaborated with international partners on 40% of their articles in 2022 (Table SPBS-33). Of the top 15 largest producers, the regions, countries, or economies that had higher international collaboration rates than the United States included the United Kingdom (67%), Australia (63%), France (60%), and Canada (60%). Conversely, regions, countries, or economies with rates of international collaboration lower than the U.S. rate included China (19%), India (24%), and Russia (25%) (Figure PBS-12). Beyond the 15 largest producers of publications, the 2022 international collaboration rates varied—Saudi Arabia (80%), Switzerland (74%), and Belgium (73%) had higher collaboration rates than the United States, whereas Turkey (29%) and Brazil (38%) had lower collaboration rates, albeit still higher than those of China, India, and Russia (Table SPBS-33).

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International coauthorship of S&E publications for the 15 largest producing regions, countries, or economies of S&E publications: 2022

(Number of articles)
Region, country, or economy Domestic author(s) only International collaboration
China 789,084 182,305
United States 358,011 241,823
India 178,750 57,227
United Kingdom 62,783 127,771
Germany 76,940 98,072
Italy 63,424 65,078
Japan 87,053 41,128
Canada 45,421 67,144
France 42,253 65,140
Australia 38,831 66,095
Spain 46,513 53,721
Russia 74,020 24,260
South Korea 63,762 31,523
Brazil 51,667 31,235
Iran 47,164 25,379
Note(s):

Articles refer to publications from a selection of conference proceedings and peer-reviewed journals in S&E fields from Scopus. Articles are classified by their year of publication and are assigned to a region, country, or economy on the basis of the institutional address(es) of the author(s) listed in the article. Articles are credited on a whole count basis (i.e., each collaborating region, country, or economy is credited with one count). Articles without international coauthorship are counts of articles with one or more institutional addresses all within a single region, country, or economy, which include single-author articles and articles coauthored under the same institutional address. International articles are articles with institutional addresses from more than one region, country, or economy. The numbers of articles from the international collaboration and domestic author(s) only categories may not sum to the total article number because some coauthored publications have incomplete address information in the Scopus database. These publications often cannot be reliably identified as international or domestic collaborations. For this reason, they are not included in either subcategory but are still counted toward the total number of articles. For more detail, see Table SPBS-37.

Source(s):

National Center for Science and Engineering Statistics; Science-Metrix; Elsevier, Scopus abstract and citation database, accessed April 2023.

Science and Engineering Indicators

The percentage of worldwide S&E articles produced with international collaboration has grown over time, increasing from 19% in 2012 to 23% in 2022 (Table SPBS-33). Each region, country, or economy leading in publications showed increases in international collaboration rates (Figure PBS-13). United Kingdom researchers had international coauthors on 37% of their articles in 2003, a percentage that had increased to 67% by 2022. Similarly, Germany’s international collaboration rate increased from 39% to 56% over the same period. The United States and Japan both saw notable increases in international collaborations between 2003 and 2022 (from 23% to 40% and from 19% to 32%, respectively), whereas there was less change in the rates for China (from 15% to 19%) and India (from 19% to 24%).

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Selected leading region, countries, or economies with publications with international coauthors: 2003–22

(Percent of articles)
Year United Kingdom Germany United States Japan India China
2003 36.7 39.0 23.0 18.7 18.7 15.4
2004 38.6 40.1 23.4 19.3 19.0 13.9
2005 39.6 40.5 23.8 19.4 18.9 12.4
2006 40.3 41.2 24.8 20.1 19.0 12.6
2007 41.5 42.4 25.8 20.7 18.5 12.9
2008 43.1 42.2 26.5 21.2 18.1 13.0
2009 44.5 43.7 27.8 21.7 18.3 13.3
2010 45.9 44.5 28.6 22.1 18.4 13.9
2011 47.5 45.4 29.5 22.5 17.8 15.0
2012 49.1 46.1 31.0 23.6 17.7 16.3
2013 51.6 47.5 32.5 24.3 18.3 17.6
2014 53.7 48.2 33.9 25.0 18.1 18.4
2015 55.7 49.7 35.2 26.2 18.2 19.7
2016 57.6 50.2 36.5 27.5 18.3 20.5
2017 59.4 50.9 37.4 28.2 18.8 21.5
2018 61.4 52.3 38.7 29.7 18.7 22.0
2019 62.5 52.7 39.2 30.5 20.5 21.9
2020 64.5 54.7 39.7 32.6 21.7 21.7
2021 65.7 54.8 39.6 31.4 22.9 20.0
2022 66.6 55.8 39.9 31.8 24.2 18.7
Note(s):

Articles refer to publications from a selection of journals and conference proceedings in S&E from Scopus. Articles are classified by their year of publication and are assigned to a region, country, or economy on the basis of the institutional address(es) of the author(s) listed in the article. Articles are credited on a whole count basis (i.e., each collaborating region, country, or economy is credited with one count). Articles with international institutions are counts of articles with institutional addresses from more than one region, country, or economy. For additional countries, see Table SPBS-33.

Source(s):

National Center for Science and Engineering Statistics; Science-Metrix; Elsevier, Scopus abstract and citation database, accessed April 2023.

Science and Engineering Indicators

Over time, the top collaborators of the United States have changed. In 2004, the United Kingdom accounted for 13% of articles that the United States coauthored internationally—the highest percentage of any partner region, country, or economy (Figure PBS-14). By 2022, China had become the largest collaborator with the United States, with 24% of internationally coauthored U.S. articles having a Chinese coauthor, although this represents a slight decline from 26% in 2020. Meanwhile, the percentage of U.S. internationally coauthored articles with the United Kingdom increased slightly over this period to 14% in 2022.

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U.S. international S&E publications with coauthor(s) from the United Kingdom and Asian countries: Selected years, 2004–22

(Percent of articles)
Publication year China United Kingdom Japan South Korea India
2004 7.0 12.9 9.1 4.5 2.4
2006 8.7 12.7 8.6 5.0 2.6
2008 11.2 12.8 7.6 5.0 2.8
2010 14.1 12.7 6.7 5.3 3.0
2012 16.5 12.6 6.3 5.6 3.3
2014 19.7 13.0 5.5 5.2 3.4
2016 22.6 13.5 5.5 4.9 3.5
2018 25.6 13.4 5.4 4.5 3.8
2020 26.3 13.7 5.4 4.5 4.1
2022 24.2 14.2 5.3 4.7 5.6
Note(s):

Articles refer to publications from a selection of conference proceedings and peer-reviewed journals in S&E fields from Scopus. Articles are classified by their year of publication and are assigned to a region, country, or economy on the basis of the institutional address(es) of the author(s) listed in the article. Articles are credited on a whole count basis (i.e., each collaborating region, country, or economy is credited with one count). Articles with international institutions are counts of articles with institutional addresses from more than one region, country, or economy. For more detail, see Table SPBS-36.

Source(s):

National Center for Science and Engineering Statistics; Science-Metrix; Elsevier, Scopus abstract and citation database, accessed April 2023.

Science and Engineering Indicators

The U.S.-China collaboration on publications has benefited not only both countries but also global science through the amount of published research collaborations, funding agency support from the United States and China, and roles of collaborators on publications (Lee and Haupt 2020). The rapid growth in U.S.-China collaborations coincided with China’s growing scientific and technological capabilities, such as rising R&D spending and university degree awards (see Indicators 2022 report “Higher Education in Science and Engineering)—both of which may be contributing factors to the U.S.-China collaboration pattern.

Rates of U.S. collaboration with other Asian regions, countries, or economies have also changed over time. From 2004 to 2022, the percentage of U.S. internationally coauthored articles with Japan decreased (from 9.1% to 5.3%), whereas the share coauthored with India increased (from 2.4% to 5.6%). The share of U.S. international collaborations involving South Korea grew between 2004 and 2012 (from 4.5% to 5.6%), then declined through 2022 (from 5.6% to 4.7%) as South Korea increased its partnerships with other Asian regions, countries, or economies (Figure PBS-14; Table SPBS-35). Meanwhile, there was little change from 2003 to 2022 in the U.S. coauthorship percentages with Canada (12% in 2022) and with European regions, countries, or economies such as the United Kingdom (14% in 2022) and Germany (11% in 2022) (Table SPBS-35).

Normalizing international collaborations by a region, country, or economy’s publication output enables comparison independent of its size. For example, the international collaboration index (ICI), adapted from He (2009), is obtained by dividing a region’s, country’s, or economy’s share of collaboration with a partner by the partner’s overall share of international collaborations with all regions, countries, or economies. An ICI value of 1.0 shows that the level of coauthorship between two regions, countries, or economies is proportional to the partners’ overall rates of international coauthorship. ICI values above 1.0 indicate more extensive ties between two regions, countries, or economies, whereas values below 1.0 indicate weaker ties. In 2022, the United States had ICI values above 1.0 with Canada (1.3), South Korea (1.1), and Brazil (1.1). ICI values between the United States and most other major research-producing regions, countries, or economies increased between 2003 and 2022, except for South Korea (from 1.3 to 1.1), India (from 0.9 to 0.7), and Saudi Arabia (from 0.6 to 0.4) (Figure PBS-15).

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Relative international collaboration index of selected large-producing regions, countries, or economies with the United States: 2003 and 2022

(Relative international collaboration index)
Region, country, or economy 2003 2022
Canada 1.14 1.32
South Korea 1.27 1.13
Brazil 0.88 1.06
China 0.84 1.00
Switzerland 0.71 0.99
Japan 0.92 0.97
Netherlands 0.66 0.91
Germany 0.68 0.87
United Kingdom 0.69 0.84
Italy 0.71 0.83
France 0.58 0.80
Australia 0.74 0.80
Spain 0.62 0.75
India 0.86 0.73
Saudi Arabia 0.57 0.39
Note(s):

Article counts for computing the index refer to publications from a selection of conference proceedings and peer-reviewed journals in S&E fields from Scopus. Articles are classified by their year of publication and are assigned to a region, country, or economy on the basis of the institutional address(es) of the author(s) listed in the article. Articles are credited on a whole count basis (i.e., each collaborating region, country, or economy is credited with one count). Regions, countries, or economies that have contributed to less than 1% of all internationally coauthored articles in 2022 are omitted. The index of collaboration is calculated as follows: ICxy = (Cxy / Cx) / (Cy / Cw), where ICxy is the index of collaboration between country x and country y, Cxy is the number of publications coauthored between country x and country y, Cx is the total number of international coauthorships by country x, Cy is the total number of international coauthorships by country y, and Cw is the total number of international coauthorships in the database. For additional regions, countries, or economies, see Table SPBS-38.

Source(s):

National Center for Science and Engineering Statistics; Science-Metrix; Elsevier, Scopus abstract and citation database, accessed April 2023.

Science and Engineering Indicators

Artificial Intelligence Publication Output and International Collaboration