Opening the box: Comparing EU and US scientific output by scientific field

Recent reports suggest that, during the 1990s, the EU15 overcame the US in scientific output. This paper provides a comprehensive comparative analysis of the evolution of the EU 15 and US scientific output and impact throughout the 1990s, looking at publications and impact trends by scientific field. Results show that changes in scientific production for the two blocks are driven by particular scientific fields which grew or declined at a fast rate during the decade. Throughout this period, the EU 15 had eight fields of science, corresponding to a 13% of the total papers published, growing at a rate faster than 10% in relation to world average, while the US had only four fast growing fields, representing 6% of its total output. The situation was exactly reversed for the decline, with the US having more than doubled the number of scientific fields when compared to the EU 15 declining at a rate faster than 10%. Despite this recent trend, the US maintains a distant leadership in impact across all scientific fields. A detailed analysis of the EU 15 countries shows some convergence in terms of outputs and impact, but considerable differences among countries remain. These reflect the evolution, not only of their science, technology and higher education systems, but also their integration in the international science system. (C) 2007 Elsevier Inc. All rights reserved.