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

Recent reports suggest that, during the 1990s, the EU15 overcame the US as the world largest scientific producing block. In this paper we perform a comprehensive comparative analysis of the evolution of the EU15 and US scientific output and impact throughout the 1990s looking at publications and impact trends by scientific field. Results show that changes of scientific production between the two blocks are associated with a set of scientific fields which grew or declined at a fast rate in the decade. During this period, the EU15 had eight fields of science growing above 10% in relation to the average of the world, corresponding to a 13% of the total papers published, while the US had only four fast growing fields, representing 6% of total output. The situation was exactly reverse for the decline, with the US having more than double the number of scientific fields and relative weight declining above 10% compared to the EU15. Despite this change, the US maintains a distant leadership in impact across all scientific fields. A detailed analysis of the EU15 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.