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”).

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).^{​Regions, countries, or economies contributing less than 1% of all internationally coauthored publications in 2020 were not included in the analysis.Regions, countries, or economies contributing less than 1% of all internationally coauthored publications in 2020 were not included in the analysis.}

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).^{​The total international collaboration rate differs from the rate of co-publications of individual regions, countries, or economies. Individual scores use whole counting, in which each region, country, or economy with an institutional address on the publication receives 1 point. Therefore, the basis count for individual regions, countries, or economies will be larger than the number of publications that have authors with institutional addresses from two or more regions, countries, or economies, which is the basis for computing the total international collaboration rate.The total international collaboration rate differs from the rate of co-publications of individual regions, countries, or economies. Individual scores use whole counting, in which each region, country, or economy with an institutional address on the publication receives 1 point. Therefore, the basis count for individual regions, countries, or economies will be larger than the number of publications that have authors with institutional addresses from two or more regions, countries, or economies, which is the basis for computing the total international collaboration rate.} 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%).

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.

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).