1. Copyright 2006 Thomson Corporation 1 Citation Analysis: Some Historical, Sociological And Philosophical Considerations Henry Small, Chief Scientist and Director Nancy Bayers, Manager Research Services Group Thomson Scientific Colloque de l’Académie des Sciences, 14-15 Mai 2007 Evaluation des Publications Scientifiques

2. Copyright 2006 Thomson Corporation 2 Reference or Citation? reference citation “It is impossible to separate them without losing the rays of light that they send back one to the other” (17 th author)

3. Copyright 2006 Thomson Corporation 3 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 The Web of Science Story Science Citation Index SciSearch Social Sciences Citation Index SCI-CD ISI Web of Knowledge Century of Science Arts & Humanities Citation Index Web of Science: v3 v4 v5 v6 v7

4. Copyright 2006 Thomson Corporation 4 Authors referenced in works of Aristotle AuthorReferences Aristotle121 Plato120 Homer100 Empedocles97 Anaxagoras64 Democritus55 Euripides51 Socrates43 Pythagoras39

5. Copyright 2006 Thomson Corporation 5 17 th Century – Newton and the Principia 100 references to 50 authors Philosophical Transactions – the changing nature of citations embedded references footnotes endnotes 18 th Century – Lavoisier and the Traité 160 references to 60 authors Darwin and the Origin 750 references to books and articles

6. Copyright 2006 Thomson Corporation 6 Authors referenced by Einstein 1902 - 1909 AuthorReferences Einstein32 Planck15 Boltzmann4 Lenard4 Stark4 Kirchhoff4 Lorentz4

7. Copyright 2006 Thomson Corporation 7

8. 8 2005 2004 2003 Impact Factor All Previous Years 2006 Immediacy Index Cited ½ Life Source paper – published in 2005 Cited reference – to item published in 2005 Cited reference to item – published in 2003 or 2004 Citations

9. Copyright 2006 Thomson Corporation 9 Percent of mean citations accounted for by top papers

10. Copyright 2006 Thomson Corporation 10 Individual paper metrics 69 Cites: Total citation count for selected paper. 225 Cites2: 2nd generation cite count based on total citations received by the citing articles. 8.3 Expected Citation Rate: An average rate of citation for all the papers of that document type (articles, reviews, letters, etc.), in that journal, for that selected year. A journal-level metric. 8 Ratio: Ratio of expected to actual cites Earth Sciences: Field: Subject area for the journal in which the paper appeared. 0.229%: Percentile position of the paper based on citations in the same field. A field-level metric.

11. Copyright 2006 Thomson Corporation 11 Group of papers metrics: Iceland National Citation Report 2330 Total # papers and total # cites: combined numbers for the set 4.6 Mean times cited: Total cites divided by total papers. 1 Median times cited: Midpoint for citations 41 H-Index: Number of papers (N) in a given dataset having N or more citations. 1.3 C-Index: Sum of all actual citations divided by sum of all expected citations. 57.4 Average Percentile: average of the field percentile measures which are based on field and year of publication 0.03 Disciplinarity: reflects the level of multidisciplinarity in a set of papers, ranging from 0 to 1, where the lower the number, the greater the multidisciplinarity. (Herfindal Index)

12. Copyright 2006 Thomson Corporation 12 Identifying Research Fronts by Co-citation Links 123 citing paper co-cited papers citation

13. Copyright 2006 Thomson Corporation 13 2004 cluster of organic thin film transistors rubrene single crystals ink jet printing, displays pentacene thiophenes n-type

14. Copyright 2006 Thomson Corporation 14 Unity of science? Pathway from social science to astrophysics Source: H. Small, A passage through science, Library Trends, 1999.

15. Copyright 2006 Thomson Corporation 15 URLs www.in-cites.com www.esi-topics.com www.sciencewatch.com

16. Merci! Henry Small henry.small@thomson.com Nancy K. Bayers nancy.bayers@thomson.com henry.small@thomson.com nancy.bayers@thomson.com