Table 5-27
Citation of S&E literature in U.S. patents relative to share of scientific literature, by selected major publishing region or country/economy and field: 2004
(Relative citation index)
Field United States European Union-15 Japan East Asia-4
All fields 1.208 0.784 0.851 0.578
Clinical medicine 1.102 0.816 0.716 0.424
Biomedical research 1.242 0.744 0.590 0.363
Chemistry 2.128 1.619 1.326 0.906
Physics 1.249 0.603 1.333 0.873
Engineering/technology 1.158 0.791 0.993 0.590

NOTES: Relative citation index is frequency of citation of major publishing region/country/economy's scientific literature by U.S. patents, adjusted for its world share of published S&E literature. Citations of country/economy's own literature are excluded. Index of 1.00 indicates region/country/economy's share of cited literature equals its world share of scientific literature. Index >1.00 or <1.00 indicates region cited relatively more/less frequently than indicated by its share of world S&E literature. Citations are references to U.S. S&E articles in journals indexed and tracked by Science Citation Index (SCI) and Social Sciences Citation Index (SSCI). Citation counts based on 6-year window with 2-year lag, (e.g., citations for 2002 are references in U.S. patents issued in 2002 to articles published in 1995–2000). Scientific field determined by ipIQ's classification of journal. Engineering/technology includes computer sciences.

SOURCES: Thomson ISI, SCI and SSCI,; ipIQ, Inc.; and National Science Foundation, Division of Science Resources Statistics, special tabulations.

Science and Engineering Indicators 2006