Collaborative research is becoming the norm, as indicated by the increasing coauthorship of journal articles. Articles with authors in two or more countries have increased in number faster than any other segment of the S&E literature, indicating growing collaboration across national boundaries. In 1988, only 8% of the world's S&E articles had international coauthors; by 2007, this share had grown to 22%.
The United States rate of international collaboration is similar to that of Japan and China but lower than that of the EU, where explicit EU policies coupled with incentives stimulate international, and specifically intra-EU, collaboration (figure
An index of international collaboration corrects for the effects of unequal size of countries' research establishments. It summarizes regional and country coauthorship patterns, with values above "1" indicating higher-than-expected, and values below 1 indicating lower-than-expected, collaborations.
U.S. international collaborations measured by this bilateral index were widespread, were generally lower than expected, and remained mostly steady over the past decade (1998–2008). EU collaborations were equally widespread, were generally lower than expected for its large members, and increased measurably over the period, quite likely in response to explicit EU policies. Unlike the index values for established scientific nations, Asia's index values were substantially higher than expected.
In 2008, U.S. research collaborations were especially strong with Canada and Mexico in North America (1.18 and 1.03), with Israel (1.25), and with South Korea and Taiwan in Asia (1.23). U.S. collaborations with China, Japan, and India were above the U.S. average.
EU policies to increase intra-European research integration appear to be having their desired effect, as intra-EU collaboration index values increased substantially over the period, most of them above unity.
Intraregional collaborations are prevalent in Asia, where they have developed even without the integrating framework provided by the EU. Over the 10-year period, high levels of collaboration were evident between China and Japan, South Korea, Singapore, and Taiwan, whereas the rate of collaboration between China and India diminished noticeably. India, in turn, collaborated more with Japan, South Korea, Singapore, and Taiwan. The underlying index values suggest the genesis of an intra-Asian zone of scientific collaboration that has a counterpart in knowledge- and technology-intensive economic activities.