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The United States remains the most scientifically productive region in the world — but only just. The member states of the European Union (EU) are about to take the number one spot, suggesting that Western Europe has regained its position as the world's leading producer of scientific knowledge.

At the same time, however, the quality of US science, at least as measured by the rate at which US papers are cited by other researchers, remains substantially higher than that of its main economic competitors, with the United Kingdom coming second, Germany third and France fourth.

These conclusions are based on analysis by the Institute for Scientific Information (ISI) in Philadelphia, and published in the May/June issue of ISI's ScienceWatch. They are based on citation statistics covering 102 subfields representing all areas of science, as well as the social sciences and humanities.

ISI's analysis reveals that between 1981 and 1996 the proportion of such papers with at least one author from the United States fell from 40.5 per cent to 36.5 per cent, with a particularly marked fall since 1991. In contrast, the proportion with at least one author coming from a member state of the EU increased from 30.5 to 36.2 per cent.

Europe's figures were, admittedly, bolstered by the fact that the number of countries belonging to the union rose from 10 to 15 during this period. The decline in the US lead also reflects the fact that the Asia-Pacific region increased its output significantly during this period — from 12.8 to 18.8 per cent of the total — as did Latin America.

But the new EU members are relatively small science-producers. The overall trend (see chart, right) indicates that, measured at least in terms of the quantity of scientific output, Europe has regained a role that it occupied from the scientific revolution of the seventeenth century up to the end of the Second World War.

In terms of scientific impact, measured by the number of citations to each of the papers published in the 102 specialist journals, Switzerland maintains the top ranking which it held in the previous comparative analysis, carried out by ISI in 1991. The Netherlands, Denmark and Sweden also remain in the top five — a reflection of the traditional high quality of the science in these relatively small countries.

Among the larger countries, however, the United States remains ahead, recording an average 5.03 citations to each of its 1,239,188 published papers. “Although the United States has lost some of its world share of papers the overall strength of US science as measured by citation impact seems to be holding steady,” comments ISI. The institute argues that the new figures appear to belie “grim predictions” about the state of US science at the time of the 1991 survey.

In terms of the relative strengths of different geographic regions in different scientific fields, the ISI analysis shows that the EU had a considerably higher-than-average citation rate in geological/petroleum/mining engineering, agriculture/agronomy, metallurgy and nuclear engineering.

Table 1 Products of scientific papers, 1992-96
Full size table