SCIENCE & ENGINEERING INDICATORS

The 28 nations that make up the EU collectively have the highest output of S&E publications globally. China’s S&E publication output ranks next, followed by the United States. The citation impact of China’s publications is rising rapidly, although it is currently lower than that of the United States and the EU. With respect to industrial output between 2003 and 2018, the U.S. share of worldwide value-added output declined for R&D-intensive industries even though the U.S. level of output rose.

R&D produces new knowledge. The EU, China, United States, India, Japan, and South Korea together produce more than 70% of the worldwide refereed S&E publications (Figure 21). As with the worldwide trends for degrees awarded and R&D spending, the output of peer-reviewed S&E publications in recent years has grown more rapidly in middle-income countries, especially China, than in high-income countries, including the United States (see Glossary for definitions). China’s S&E publication output has risen nearly tenfold since 2000, and as a result, China’s output in terms of absolute quantity now exceeds that of the United States.

As measured by publication output, the subject-matter emphasis of scientific research varies across countries and regions. Among the largest producers in 2018, the United States and the EU each produced more biomedical and health sciences articles than did China. However, China surpassed the United States and the EU individually in the production of engineering articles and now produces more than twice as many engineering articles as the United States.

Publications receiving more citations generally have more impact on a particular scientific discipline. The relative impact of an economy’s S&E research can be compared through the representation of its articles among the world’s top 1% of cited articles, normalized to account for the size of each country’s pool of S&E publications. This normalized value is referred to as an index and is similar to a standardized score. For example, if a country’s global share of top articles is the same as its global share of all publication output, the index is 1.0. The U.S. index was 1.9 in 2016, meaning that its share of the top 1% of cited articles was about twice the size of its share of total S&E articles (Figure 22). Between 2000 and 2016, the EU index of highly cited articles grew from 1.0 to 1.3 while China’s index more than doubled, from 0.4 to 1.1, indicating rising impact from both areas.

U.S. research capacity, as well as that of other nations, is enhanced through connection with researchers around the world. The proportion of worldwide articles produced with international collaboration—that is, by authors from least two countries—has grown from 14% in 2000 to 23% in 2018. Most of the large producers of S&E scholarly articles in 2018 were highly collaborative (Figure 23): the UK (62%), Australia (60%), France (59%), Canada (56%), Germany (53%), Spain (53%), and Italy (50%) have relatively high international collaboration rates. In 2018, 39% of U.S. articles were developed through international collaboration, up from 19% in 2000. U.S. authors collaborated most frequently with authors from China (about 26% of U.S. internationally coauthored articles in 2018). Since 2000, international collaboration grew for most of the top 15 largest producers of S&E articles.

Knowledge and technology intensity within an industry can be measured in several ways, including an industry’s employment of highly skilled workers and its R&D intensity. Using R&D intensity as a measure, the most R&D-intensive industries globally are manufacturing of aircraft; pharmaceuticals; computer, electronic, and optical products; computer software publishing; and scientific R&D. In these industries, global value-added output in 2018 was more than $3.2 trillion. Between 2003 and 2018, U.S. output increased from about $570 billion to $1.04 trillion, while the U.S. global share declined from 38% to 32%. Over this period, the EU’s and Japan’s global shares declined, whereas China’s share rose rapidly (Figure 24). The collective share for several other Asian countries and economies rose more moderately.

Industries with lower but still appreciable levels of R&D intensity include chemicals (excluding pharmaceuticals), transportation equipment (excluding aircraft), electrical and other machinery and equipment, information technology services, and scientific instruments. In these medium-high R&D-intensive industries, global output in 2018 was nearly $5.8 trillion. Although U.S. output increased from about $600 billion to $1.25 trillion between 2003 and 2018, its global share decreased slightly (Figure 25). China, starting from a low base in 2003, now produces 26% of the global output. The EU and Japan saw declining shares.

Many knowledge- and technology-intensive industries depend on powerful computers, known as supercomputers. They are one contributor to S&T capacity, including the capacity for developing artificial intelligence (AI) technologies. China is building its supercomputing capacity from a low base; its share of the worldwide 100 most powerful computers rose from 5% to 9% between 2010 and 2019. The United States had the largest share in 2019 (37%). However, the U.S. share has declined since 2010 (43%).