Publication Output by Geography and Scientific Field

Output by Geography, S&E Field, and Sector

Worldwide S&E publication output totaled 3.3 million articles in 2023, based on entries in the Scopus database.^{​Publication output includes only those indexed in the Scopus database. The publication output discussion uses fractional counting, which credits coauthored publications according to the collaborating institutions or regions, countries, or economies based on the proportion of their participating authors. Country assignments refer to the institutional address of authors, with partial credit given for each international coauthorship. As part of the data analysis, filters were employed on the raw Scopus S&E publication data to remove publications with questionable quality, which appear in what are sometimes called predatory journals (NSB Indicators 2018: Bibliometric Data Filters).} In 2023, four countries each produced more than 100,000 articles: China, the United States, India, and Germany. Together, they accounted for over 50% of the worldwide total in 2023 (Table DISC-12).^{​The proportion of output attributable to the large producers is consistent whether using fractional counting, as in Figure DISC-22 and Table DISC-12, or whole counting, as in Table SDISC-21. There is a slight difference between the United States and China when looking at the whole-counting total production numbers. Using whole counting for 2023, the United States had 568,973 articles, whereas China had 1,003,473. A whole-counting measure allocates one full count to each region, country, or economy with an author contributing to the article; in fractional counting, each region, country, or economy receives a proportion of the count based on the number of authors from that region, country, or economy. For example, if an article had four authors—two from the United States, one from China, and one from Brazil—the fractional scores would be half for the United States, a quarter for China, and a quarter for Brazil. The use of whole counting or fractional counting to tally the publication output of countries can change the calculated publication count based on the degree to which a country is involved in international collaborations.} The majority of the growth in worldwide annual publication output from 2.2 million in 2014 to 3.3 million in 2023 was driven by authors from two countries: China (51% of additional publications during that period) and India (13%) (Figure DISC-22). Articles from the United States and the EU-27 grew modestly from 2014 to 2023, but both have since decreased from their peak years in 2021. Publications from the United Kingdom and Japan decreased since 2021.

The distribution of publications by field of science across geographies may indicate research priorities and capabilities. Globally, health sciences represented 23% of all publications in 2023, the highest output of any field (Figure DISC-23). Other fields with large numbers of publications included engineering (17% of publications in 2023), computer and information sciences (13%), and biological and biomedical sciences (12%). Among top producers, authors in three regions, countries, or economies had their highest concentration of publications in health sciences in 2023: the United States (36% of its total publications), Japan (32%), and the EU-27 (25%). Meanwhile, authors from China had the most publications in engineering (26%), and authors from India had the most publications in computer and information sciences (28%).

Within the United States, the fastest-growing scientific fields from 2010 to 2023 were psychology (up 30%), social sciences (up 27%), and health sciences (up 23%) (Figure DISC-24). Meanwhile, fields with the largest decreases in U.S. publications included physics (down 35% from 2010 to 2023), materials science (down 26%), and geosciences, atmospheric sciences, and ocean sciences (down 17%).

Research can be conducted in different sectors—such as academia, business, or government—with publication output serving as an indicator for resulting discoveries and collaboration. While students, faculty, and other academic staff may be more incentivized to produce peer-reviewed articles than authors from the business sector (Hicks 1995; Simeth and Raffo 2013), companies do benefit from publications by their scientists and engineers (Rotolo et al. 2022) resulting from their R&D activities (see section U.S. Business R&D), along with other research outputs such as patenting and licensing (see Indicators 2026 report “Translation to Impact: U.S. and Global Science, Technology, and Innovation Output” [NSB forthcoming]). In the United States, the overall number of publications with business sector authors decreased from 2008 (58,346 articles) to 2023 (51,293). At the same time, an increasing share of articles with business sector authors were published collaboratively with authors outside the business sector. Coauthorship with colleagues from U.S. academic institutions produced the highest business publications output in 2023 (28,956), followed by collaboration with foreign (21,306) and U.S. government institutions (6,509) (Figure DISC-25).

Impact of Published Research

In addition to the total production of articles, indicators gauging the significance of published articles help assess the vitality and competitiveness of the U.S. S&E enterprise. Generally, authors of scientific articles cite previously published articles that influenced or informed their own research (Merton 1973; Tahamtan and Bornmann 2018). Thus, when an article is cited by many other articles, it is deemed to have scientific impact (Garfield 1973). Articles may accumulate citations over time, and although most scientific articles garner few or no citations, a small share receives hundreds or thousands of citations (Van Noorden, Maher, and Nuzzo 2014). Counting the citations earned by an article at least 2 years after publication provides sufficient time for high-impact articles to receive a distinguishing number of citations, although only articles published in the same field and the same year may be compared (Wang 2012). For this reason, the most recent available year for HCA-rated indicators is 2022.

Articles in the top 1% of all published articles in a given year and field are designated as highly cited articles (HCAs). For each geographic location (region, country, or economy), the proportion of HCAs relative to its total publication output is called its HCA share, and this indicator of scientific impact relative to total publication is comparable across different-sized producers. An HCA share above 1.00 means that more than 1% of the country’s articles achieved HCA status, indicating that the country’s published research has disproportionately higher impact given the overall number of articles its researchers produce.^{​In mathematical terms, a region, country, or economy’s HCA ratio (the share of the articles ranked in the highest 1% based on citations) is computed as follows: Sx = HCAx / Ax, where Sx is the share of output from country x in the top 1% most-cited articles, HCAx is the number of articles from country x that are among the top 1% of most-cited articles, and Ax is the total number of articles from country x with a relative citation (RC) score. HCAx and Ax are based on whole counting. The RC score is a normalized citation score assigned to a publication and is used to rank articles into the top 1%. The RC score takes into consideration the citation behavior between fields and years of publication. Based on the observation that distinct differences in the citation rates of articles appear 2 years or more after publication, the HCA ratio is calculated with a time lag of at least 2 years (meaning that in 2024, the HCA ratios were calculated based on publications issued in 2022).}

In 2022, 1.7% of peer-reviewed publications with U.S. authors were on the HCA list, showing that authors from the United States generate a disproportionate share of influential articles (Figure DISC-26). The HCA share for the United States had stayed above 1.9% in each year from 2008 through 2017 but has steadily declined since 2014. As of 2022, the U.S. HCA share stands at its lowest level throughout the period from 2006 to 2022. In contrast, China’s HCA share has increased in each year from 2006 to 2022, rising from 0.4% in 2006 to 1.3% in 2022 (Figure DISC-26). The disparity in HCA shares between the United States and China has decreased steadily since 2008. Given that China produced more scientific articles than the United States in 2022, this convergence appears to represent a consistent increase in the scientific impact of publications with Chinese authors that is not outpaced by its overall publication growth (Table SDISC-6). The collective HCA share for the EU-27 has stayed at or above 1.2% since 2011 (Figure DISC-26). The HCA share for Japan, another major contributor to the world’s scientific literature, has tended to lag behind the overall global HCA share. Japan’s HCA share reached its highest level (1.1%) in 2022. India’s HCA now exceeds the global HCA share, reaching 1.1% in 2022.

The HCA share of each country also varies between fields, reflecting research specializations or differences in the country’s prominence in particular research fields or topics. In the United States, the HCA shares of 2022 publications in all selected fields also exceeded the baseline 1% HCA share (Figure DISC-27). In particular, 2.2% of materials science, 1.9% of physics, 1.8% of health science, 1.8% of biological and biomedical sciences, and 1.8% of computer and information sciences publications authored in the United States were HCAs in those respective fields.^{​The unrounded HCA share of U.S. health science articles in 2023 was 1.8499%.} Further, this was a higher HCA share in each of these fields compared to China, the EU-27, Japan, and India. The HCA shares of U.S.-authored publications in each selected field peaked between 2014 and 2019, whereas the HCA shares of publications by Chinese authors reached their highest level in 2020 or later (Table SDISC-53–Table SDISC-68). For HCAs in engineering, in 2022, the United States (1.3%) and China (1.3%) had similar shares of the top articles in that field. The HCA shares of chemistry publications in China (1.5%) and the United States (1.4%) were also close. In 2022, for authors based in China, the top scientific field by impact was the social sciences, in which 3.3% of social sciences publications were HCAs, which was higher than the social sciences HCA share for the United States, EU-27, Japan, and India.

International Collaboration in Published Research

International collaborations can build a robust S&E workforce, increase scientific capabilities and cooperation (Lyons et al. 2016), including in emerging and critical technologies (see sidebar Biotechnology R&D and Publications Output, and see sidebar Semiconductor Research Publication Output and International Collaboration at the end of this section). An article is classified as an international collaboration if at least two authors are located in different countries, as determined by their organizational affiliation on the article. 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). S&E research has become more global—a trend evidenced cross-nationally (Glänzel and Schubert 2005; Luukkonen et al. 1993; Royal Society 2011; Wagner, Park, and Leydesdorff 2015).

In 2023, researchers in the United States contributed to the largest number of articles involving international coauthorship (225,565 articles, representing 32% of all internationally coauthored articles) (Figure DISC-28; Table SDISC-69). The most frequent partners for the United States were China, the United Kingdom, Canada, and Germany (Table SDISC-71). Elsewhere, the percentage of worldwide S&E articles produced with international collaboration has grown over time, increasing from 19% in 2012 to 22% in 2023 (Table SDISC-69).^{​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 geographic location with an institutional address on the publication receives 1 point. Therefore, the 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 DISC-29). United Kingdom researchers had international coauthors on 32% of their articles in 2002 and on 68% of their articles in 2023. Similarly, Germany’s international collaboration rate increased from 35% to 56% over the same period. The United States and Japan both saw notable increases in international collaborations between 2003 and 2022 (from 20% to 40% and from 16% to 32%, respectively), whereas there were smaller increases for India (from 16% to 23%) and China (from 13% to 17%). China is the only selected country that shows a decrease in international collaboration since its peak in 2018 (22%). 

Over time, the top countries with authors collaborating with U.S. researchers have changed. In 2003, partnerships with authors in the United Kingdom accounted for 12% of articles coauthored with U.S. collaborators—the highest percentage of any partner region, country, or economy (Figure DISC-30; Table SDISC-71). By 2009, China had overtaken the United Kingdom as the origin of the greatest percentage of coauthors with U.S. researchers and has remained in first place since that time. The increasing share of global publications from authors in China over the same period may have contributed to this increase in collaboration. In 2023, 23% of internationally coauthored U.S. articles have a Chinese coauthor, although this represents a decline from 27% in 2019. Meanwhile, the percentage of U.S. internationally coauthored articles with the United Kingdom increased slightly over this period to 15% in 2023. Since 2019, authors from India (from 4% to 6%) passed those from Japan (steady at 5%) and South Korea (from 4% to 5%) in collaborations with U.S. partners.