JSM Impact Factor

2519 REPORT JSM Impact Factor Iain D. Craig, BSc (Hons) Wiley-Blackwell, 9600 Garsington Road, Oxford, OX4 2DQ, UK DOI: 10.1111/j.1743-6109.2008.01024.x The Institute for Science Information (ISI), now part of Thomson Reuters, released their Journal Citation Reports (JCR) at 12:30 pm EST on Thursday 17th June 2008. In an annual exercise that is taking on near comical proportions, publishers, and many other interested parties, sit pressing refresh on their web browsers at the appointed hour, eager to see the latest figures appear. Within minutes of the data becoming available, publishers were poring over the figures looking for the good news stories to promote. Wiley-Blackwell was no exception, publishing a press release [1] describing the success of its journal collection in passing the 900 figure mark in terms of journals with Impact Factors. Among the journals chosen to be individually highlighted in this press release was the Journal of Sexual Medicine (JSM), which has followed up on its maiden Impact Factor of 4.676 in JCR 2006 to post a value of 6.199 in JCR 2007, an increase of 33%, which elevates it to 2nd position (out of 55) in the JCR category of Urology & Nephrology. Only when the dust has settled and the feverish publishers have been put to bed could a more considered analysis of JSM’s performance be undertaken. The journal Impact Factor should be taken in context with the developments in the subject area as a whole. Is JSM a star in its own right or simply a boat being lifted by the rising tide? The median Impact Factor of the JCR category of Urology & Nephrology has risen from 1.1 to 1.9 over the period 1997–2007, equivalent to a yearly growth rate of 6.0%. Over the same time period, the annual growth in journals and articles published in this category (articles in this contect means original articles plus reviews) was 4.0% and 4.2%, respectively. JSM is growing far more rapidly than this, both in quality as measured by Impact Factor, and in publication output, with 40 articles and reviews published in volume 1(2004), rising to 199 by 2007. © 2008 International Society for Sexual Medicine The JCR category of Urology & Nephrology contains 55 journals encompassing both broad and niche publications. If we look at just those journals directly focussing on sexual medicine, only two, JSM, and the International Journal of Impotence Research, are listed in the category. There are relevant journals listed in other categories, including the Journal of Sex & Marital Therapy, which appears in the JCR categories of Clinical Psychology and Family Studies; Archives of Sexual Behaviour, which appears in the category of Clinical Psychology; and the Journal of Sex Research, which appears in the categories of Clinical Psychology and Multidisciplinary Social Sciences. Examining the subset of five journals mentioned above, only Archives of Sexual Behaviour, Journal of Sex & Marital Therapy, and Journal of Sex Research have been present over the period JCR 1997–2007. The International Journal of Impotence Research was first listed in JCR 1999, and JSM in JCR 2006. In 1997, only 87 articles were published across three journals, whereas in 2007, 412 articles were published across five journals, with JSM accounting for 199 of them. These figures would seem to demonstrate an increase in output, but what about quality? Between 1997 and 2007, the Impact Factor of Archives of Sexual Behaviour doubled from 1.2 to 2.4, and over the same period, the Impact Factor of Journal of Sex & Marital Therapy increased from 0.4 to 1.9. The International Journal of Impotence Research has fluctuated from 2 to 3 and back again, and the Journal of Sex Research has fluctuated between 0.9 and 1.4. Taken together, particularly with the increase in Impact Factor exhibited by JSM, there is an increasing quantity of research on sexual medicine taking place, in an increasing number of journals, and of increasing quality. However, the more articles that are published, the more opportunity they have to cite other J Sex Med 2008;5:2519–2521 2520 articles. What if the increase in citations that is driving the increases in Impact Factor is simply a natural phenomenon? A recent working paper [2] determined that between 1994 and 2005, the Impact Factors of ISI indexed journals have been increasing at an average rate of 2.6% per year. The authors sought to understand the growth in Impact Factors over time and explain its causes. They proposed four factors that could potentially explain the inflation: 1. An increase in the number of articles published, 2. An increase in the number of references per article, 3. An increase in the proportion of total citations to articles within the Impact Factor window, and 4. An increase in the fraction of cited articles that are in the indexed ISI literature. Of these, they determined that the largest contributing factor was the length of reference lists. As more and more references are inserted into articles, so the average Impact Factor of journals was observed to increase. Another important conclusion from this article was that the principal reason why Impact Factors vary so much between fields is the proportion of cited articles that are in the indexed ISI literature. “Those fields which cite heavily within the ISI data set, such as Molecular Biology or Medicine, buoy their own scores. Those fields which do not cite heavily within the ISI data set such as Computer Science or Mathematics have correspondingly lower scores.” Impact Factors need to be compared only between journals of similar subject and scope, otherwise, variation in the number and patterns of citations render such a comparison useless. While the differences in coverage between different subjects had been well known for decades, this knowledge has largely been academic, as the source for any citation analysis has almost exclusively been ISI’s citation indexes, collectively known as Web of Science. In recent years, new sources of citation information have emerged to provide a viable alternative to Web of Science. Perhaps the most fully featured alternative is Scopus [3], which covers approximately 15,000 journals across the majority of subject areas. While Scopus and its owner, Elsevier, have yet to create a journal ranking metric to compete directly with the Impact Factor, data originating from Scopus has been used to create such an indicator—the SCimago Journal Rank Indicator J Sex Med 2008;5:2519–2521 Craig [4] (SJR). There is an interesting parallel between the SJR and the EigenFactor [5], which is a citation metric based on ISI data, although not published under the ISI brand. Both the EigenFactor and the SJR rely on rather complex mathematics to weight citations according to the importance of the citing journal. So a citation from two journals at different ends of the quality spectrum will be treated very differently from each other, whereas with the Impact Factor, citations are treated equally irrespective of the citing source they originate from. Returning to JSM, where this editorial began, JSM’s performance in terms of its SJR appears to be as strong as its Impact Factor performance, with the journal ranked 4th from 56 in the Urology category. It is interesting to note that JSM’s SJR value of 0.515 is about 40 times smaller than the highest SJR recorded in the overall dataset, that of Annual Review of Immunology with a value of 20.893. When a similar comparison is performed for the Impact factor, comparing JSM’s value of 6.199 to that of CA—A Cancer Journal for Clinicians—with a value of 69.026, the difference is only of the order of 11 times. What is important to remember when examining these different metrics is the underlying subject coverage. Subject coverage within the ISI indexes is heterogeneous, and it is safe to assume that Scopus will have areas that are better covered than others. It is relatively simple (at least for those with access to the raw citation data) to determine the levels of coverage in both the ISI or Scopus datasets, but for other citation indexes such as GoogleScholar [6], it is currently impossible to make a precise determination. Before one concludes anything about the performance of journals across different ranking systems, one should first look at the levels of coverage of that subject area, to see whether a fair comparison can be made. Both the ISI and Scopus citation universes are selective in their journal coverage, and so the Impact Factor/EigenFactor and the SJR will reflect this selectivity. ISI made a decision to add JSM to their universe and this decision in itself indicates that they see an increase in research in this area and that JSM’s inclusion will enhance their products for researchers. This is a powerful vindication of the field of sexual medicine. For individual journals like JSM, whether they perform better or worse in one system or another should only be of marginal significance. A good 2521 JSM Impact Factor example of when Impact Factor chasing can have unintended consequences is the current vogue for increasing the publication of review articles, in the belief that the additional citations that these items tend to accumulate will be a fast track to a higher Impact Factor. With so many journals adopting this scenario these days, there are more review articles than ever before, reviewing smaller and smaller bundles of original articles, so diminishing the overall utility of the review. Journals are defined not by their rankings, but by the communities that they serve. When journals chase high rankings, in whatever system, they are departing from this fundamental definition. Corresponding Author: Iain D. Craig, BSc (Hons), Wiley-Blackwell, 9600 Garsington Road, Oxford, OX4 2DQ, UK. Tel: 01865 476301; Fax: 01865 471301; E-mail: [email protected] Conflict of Interest: None declared. References 1 Blackwell Publishing. Wiley-Blackwell’s Portfolio Now Includes over 900 Journals with Impact Factors. 24 June 2008. Available at: http://www. blackwellpublishing.com/press/pressitem.asp?ref= 1797 (accessed 4 September 2008). 2 Althouse BM, West JD, Bergstrom TC, Bergstrom CT. Differences in Impact Factor Across Fields and Over Time. 23 April 2008. Available at: http:// repositories.cdlib.org/ucsbecon/dwp/2008-4-23 (accessed 4 September 2008). 3 Elsevier. Scopus Info – Scopus Overview – What is it? 2008. Available at: http://www.info.scopus.com/ about (accessed 4 September 2008). 4 SCImago Research Group. Scimago Journal & Country Rank. 2008. Available at: http://www. scimagojr.com (accessed 4 September 2008). 5 Bergstrom C. 2008. Available at: http://www. eigenfactor.org (accessed 4 September 2008). 6 Google. Google Scholar. 2008. Available at: http:// scholar.google.co.uk (accessed 4 September 2008). J Sex Med 2008;5:2519–2521