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Research Department - IRCCS Policlinico San Matteo - Pavia

THE ELECTRONIC EDITION OF SCIENTIFIC JOURNALS MAY INFLUENCE THE DETERMINATION OF THEIR OWN IMPACT FACTOR?. Moreno Curti, Vanna Pistotti*, Gabriellla Gabutti, Andrea Zeccato, Carmine Tinelli, Catherine Klersy. Research Department - IRCCS Policlinico San Matteo - Pavia

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Research Department - IRCCS Policlinico San Matteo - Pavia

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  1. THE ELECTRONIC EDITION OF SCIENTIFIC JOURNALS MAY INFLUENCE THE DETERMINATION OF THEIR OWN IMPACT FACTOR? Moreno Curti, Vanna Pistotti*, Gabriellla Gabutti, Andrea Zeccato, Carmine Tinelli, Catherine Klersy Research Department - IRCCS Policlinico San Matteo - Pavia *G.A.Pfeiffer Memorial Library - Istituto M.Negri - Milano

  2. The Impact Factor (IF) The value of IF was derived from the Journal Citation Report Science Edition (JCR), a yearly publication of the ISI (Institute for Scientific Information, Philadelphia). For each year the impact factor is given by the ratio of the number of citations of the journal over one year (e.g. in 1999) to the number of articles published by the same journal in the two years before (e.g. in 1997-1998)

  3. The Impact Factor (IF) The impact factor is an indicator of the journal's quality based on the overall citations of the papers published in the journal over a certain time lapse. An impact factor score is attributed to the 5500 and more scientific journals indexed by the Science Citation Index.

  4. The Impact Factor (IF) Impact Factor is the "presentation card" of each scientific journal, an indicator of its quality, which is based on the acknowledgement of its value by the scientific community through citations.

  5. The development of the electronic editions of scientific journals and the rapid spread of scientific information might modify the bibliographic citation pattern in scientific papers. This in turn, could influence the IF score and the “quality” of the journal.

  6. the authors - will assess the changes in the impact factor over the last few years of a large number of journals;- they will verify whether the presence of the electronic version of the journal is associated with the value of the impact factor score.

  7. This was a retrospective longitudinal study • The journals included in the study were those ranking among the first 20 of each of the following subject categories in jcr - year 1998: • 1) cardiac and cardiovascular system; • 2) medicine, general & internal; • 3) medicine, research & experimental; • 4) multidisciplinary sciences; • 5) othorinolaryngology (orl); • 6) surgery; • 7) hematology; • 8) transplantation.

  8. Note: • “Transplantation” includes only 12 journals, thus a total of 152 journals were evaluated, corresponding to 139 titles.

  9. The availability of the journal on the Internet (1) years considered (1995 to 2000), assessed transversally between December 2000 and January 2001. The presence of table of contents (TOC), abstract, full text and free full text were evaluated.

  10. The availability of the journal on the Internet (2) Google.com was utilized as a search engine, the rationale being its widespread use and good power. Both title of the journal and ISSN were considered for the search strategy. Only sites with free access were included, where no subscription to journal or package of full text journals was required to enter the site

  11. Data sampling • The first project did not succeed (London EAHIL 2000), where a questionnaire was sent to the Editors. A low response rate was obtained. Items included questions on Internet availability and year of first publication. • For the second project (Alghero 2001), information for years 1996-2000, was transversally obtained from the Internet in December 2000 and January 2001, together with longitudinal data on the Impact Factor from SCI.

  12. Statistical analysis (1) • Descriptive statistics (journals and internet) • Changes in the impact factor over the years were modeled by means of a Linear regresssion model: • A) impact factor and time • B) impact factor and time accounting for the effect of subject categories • C) impact factor and time assessed within each subject category

  13. Statistical analysis (2) • Changes in the impact factor and presence of the journal in Internet in terms of TOC, abstract, full text and free full text was fitted by a series of a Linear regresssion model.

  14. Results: journals and Internet • 118/139 journals (85%) had the TOC on the Internet • 107 (77%) had the abstract • 97 (70%) had the full text • 33 (24%) had the free full text

  15. Results: impact factor Median impact factor for all the considered journals. Regression analysis p=0.0022

  16. Subject category was demonstrated to be an independent predictor of the impact factor score. Moreover changes over years were different among categories (interaction present). Thus separate models for time were fitted within each subject category, that elicited significant changes (p<0.05) in all fields but for the multidisciplinary sciences category

  17. Results: internet and impact factor Higher impact factors were observed when the journal had an electronic version.

  18. Results: internet and impact factor univariate multivariate analysis analysis TOC p=0,0005 p=0,002 Abstracts p=0,0002 p=0,002 Full text p<0,0001 p=0,001 Free full text p=0,0025 p=0,02

  19. Results: internet and impact factor Findings in each category tend to reflect the general behavior illustrated above. They show higher values of the impact factors in the presence full text on the internet (but for surgery and orl) and an increase of the number of available journals over years. The degree of variability observed could mainly be attributed to the low sample size obtained, when considering subgroups.

  20. Discussion (1) In this paper we have shown an increase of the availability of journals on the Internet in terms of TOC, abstract, full text and free full text. A significant growth of the impact factor is observed over these years, that climbs from 1.65 to 2.35. We show the impact factor to increase differently according to the subject categories. This is to be related to the high variability of this index across subject fields and within subjects’ fields.

  21. Discussion (2) Garfield in 1996 denies the influence of circulation of information and impact factor (Garfield E. Fortnightly Review: How can impact factors be improved? BMJ 1996;313:411-3.). Our data demonstrate higher values of the impact factor in the presence of the journal on the Internet. This is true for TOC, abstract, full text and free full text, at univariate analysis and after controlling for the confounding effect of year and subject category

  22. Discussion (3) • No definite answer can be given right now, as we could only transversally assess the availability of journals on the Internet. However the curve for “Internet yes” stays all the time above that for “Internet no”.

  23. Study limitation • The main study limitation is related to the design that allowed longitudinal assessment of the impact factor through the JCR but only a transversal assessment of the Internet availability: this particular information was not collected prospectively year by year.

  24. Medline (1) • for Toc and abstracts, PubMed (and some commercial databases) already allowed to search the Internet for the literature, full text availability might represent a real change. • Actually PubMed was and is used to search by means of keywords, with a particular problem in mind.

  25. Medline (2) • The electronic version of journal seems to more and more replace the printed version in the continuous education of the medical researcher, where a global approach to bibliographic information is used. Both ways of referring to literature complement each other.

  26. Conclusions (1) • The impact factor has been used for years to evaluate journals quality. • It has been used by librarians to identify journals to purchase and • by researchers to identify journals where to submit their articles. • In many research and academic settings, the impact factor is also used to fund research based on the evaluation of the quality of the several groups of researchers.

  27. Conclusions (2) The impact factor has been widely criticized for a series of pitfalls in its calculation, as • choice articles included in the denominator; • choice of journals included in the source; • length of impact factor window; • choice of type of article included in the numerator; • use of negative citations. • Moreover the use and misuse of impact factor for evaluation of the single researcher or group or comparison across different specialties has been reported.

  28. Conclusions (3) • One further limitation of this indicator appears from our work, where impact factor values would be related to the amount of circulation of the information through the Internet.

  29. Conclusions (4) • Thus, it is particularly relevant to be aware of the appropriate use of the impact factor and to understand its limitations.

  30. Conclusions (5) • Possibly this could be a temporary limitation, that could disappear when all journals will be able to offer the electronic version on their Website and the Net will be available to all medical researchers. • In that case we could expect levels of impact factors to undergo a general increase, related to the higher number of citations.

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