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Why not use Journal Impact Factors?

Johannes Stegmann, Free University Berlin, University Clinic Benjamin Franklin, Medical Library,
D-12200 Berlin
Email: stegmann@ukbf.fu-berlin.de

Résumé: Pourquoi ne pas utiliser les facteurs d'impact des périodiques

L'article analyse la crise bibliométrique mentionnée dans un article publié récemment dans le Bulletin d'Information de l'AEIBS et considère l'image négative des facteurs d'impact qui y est représenté. Le potentiel d'une analyse bibliométrique poursuivie au-delà des seuls facteurs d'impact considérés est étudié.

Une variation apportée à la détermination des facteurs d'impact pourrait reposer sur un cadre d'analyse plus étendu dans le temps et sur l'établissement de facteurs d'impact pour des périodiques non compris dans les rapports de citation des périodiques est présentée.


Why not use Journal Impact Factors?


The "bibliometric crisis" mentioned in a feature article published recently in the EAHIL newsletter is analysed further with respect to the negative image of impact factors. The potential of bibliometric analysis beyond impact factors is noted. A variation of journal impact factors, based on wider time windows, and the construction of impact factors for journals not listed in the Journal Citation Reports is commentated.



In a recent article, Lazarev complains about librarians' increasingly sceptical attitude towards bibliometrics (1). Although it seems that there is a growing number of "bibliometrics papers" authored by libraries (see Figure 1; it might be worth mentioning that of the papers presented at the EAHIL conference in Utrecht also about 7 % deal with a bibliometric issue), the author is surely right mentioning "chaos in bibliometric terminology" (1, p. 18; 2) and the apparent predominance of electronic issues (1, p. 17). In addition, librarians might be prevented from bibliometric analyses due to further reasons. One of them, perhaps, is the obvious assumption shared by many people, that bibliometrics and impact factor usage are identical, the latter being inevitably associated with "research evaluation". Because evaluation of their own (or foreign) institutions hardly is a genuine goal of librarianship, and taken into account the negative image of impact factors, it is - along with patrons' objection to any kind of restrictions in journal acquisition - understandable that librarians are hesitant to applicate quantitative bibliometric analyses.


Citation analysis

However, bibliometrics is more than the mere application of impact factors. Bibliometrics -also in its narrower meaning of citation analysis - enables one to track science and to find out interrelationships between authors, journals, and subjects (see 3 and 4 for review). Bibliometrics thus might help librarians to contribute to a detailed analysis of the research activities of the institution they belong to. This can be achieved by searches (for institutional addresses and/or author names) in bibliographic databases and subsequent assignment of the individual papers retrieved to scientific subfields, followed by citation analysis including cocitation analysis and bibliographic coupling (3, p. 154-156).


Citation databases

At present, the citation databases (containing the references cited in the indexed articles) necessary for these purposes are supplied only by the Institute for Scientific Information (ISI). It has been suggested to build a freely available, web-based "universal citation database" (5), but this seems not to be a trivial task. For now, searching for cited references is restricted to the ISI databases (of course, manual searching is also possible). Relevant to biomedicine and health sciences are the databases SCISEARCH and SOCIAL SCISEARCH which are are offered by several vendors including DIMDI (Deutsches Institut fuer Medizinische Information und Dokumentation) as well as ISI itself through its Web of Science (6).


Journal impact factors

Although perhaps tired of discussing journal impact factors, librarians cannot disregard them because of an upward trend in usage of these journal measures by patrons. Journal impact factors, the underlying concept and the associated data published in the JCR have been the topic of numerous articles. In the EAHIL newsletter, too, impact factors and citation analysis have been extensively discussed (7, 8) as well as the relations between "use", "value" and "quality" of citations (8, p. 17).

Normally, journal impact factors are taken from the Journal Citation Reports (JCR), an ISI product published annually in two editions (science and social sciences) in print and on CD-ROM. The most recent science edition (1997) lists 4,963 journal titles with (amongst other data) their impact factors which has been calculated by dividing the number of cites (in ISI source journals) a journal received in 1997 to papers of any kind published in 1995 and 1996 by the number of research-relevant papers (articles, reviews, notes, but not editorials, letters, news items, meeting abstracts) published in 1995 and 1996 in the journal in question.

With respect to the three years time-window (publications in two years, cites in the third year), other periods are conceivable, e.g., in (9) the citation averages of five years (papers published and cited 1981-1985) are listed for more than 2,600 journals; today, these numbers might still be of some value. In a more recent paper, it was suggested to apply not only the "short term" but also a "longer term" impact factor to journal evaluation (10).


Constructed impact factors

It is also possible to calculate impact factors independently of the JCR by use of the citation databases mentioned above (11, 12, 13). This might be especially important for journals not listed in the JCR. The method to "construct" impact factors for non-JCR journals is described in detail in (13). In addition, the list of CIF (Constructed Impact Factor) journals will be made available via the world wide web (13). It must be emphasized, however, that the CIF list completely relies on the cited-references data collected in the ISI databases SCISEARCH and SOCIAL SCISEARCH. However, a future might be imaginable with (a) bibliographic database(s) which include(s) all cited references contained in non-JCR and non-ISI source journals. Those data could be used in addition to ISI's data for more thorough citation studies including impact factor calculations. Thus, why not use impact factors - in the future?

Figure 1: The percentage of library-authored papers with a bibliometric subject was calculated from the data retrieved by online searching at DIMDI in the databases SCISEARCH, SOCIAL SCISEARCH, MEDLINE, EMBASE, BIOSIS.

The search was restricted to libraries as authors by applying the search step:

FIND CS=(LIBRAR? OR BIBLIOT?) (CS: Corporated source; the "?" denotes end truncation).

The search was limited to bibliometric subjects by applying the terms (as keywords and free text):





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Osareh F. Bibliometrics, citation analysis and co-citation analysis: a review of literature II. Libri 1996;46(4):217-225.

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Schubert A, Glänzel W, Braun T. Scientometric datafiles. A comprehensive set of indicators on 2649 journals and 96 countries in all major science fields and subfields 1981-1985. Scientometrics 1989;16(1-6):3-478.

Moed HF, Van Leeuwen TN, Reedijk J. A new classification system to describe the ageing of scientific journals and their impact factors.
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Stegmann J. How to evaluate journal impact factors. Nature 1997;390:550.

Stegmann J. Building a list of journals with constructed impact factors. Journal of Documentation 1999;55(3):310-324.


Johannes Stegmann

Free University Berlin, University Clinic Benjamin Franklin, Medical Library, D-12200 Berlin

email: stegmann@ukbf.fu-berlin.de


back to ToC EAHIL Newsletter Nr. 47 (May 1999)


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