Abstract
Impact Factor, the pre-eminent performance metric for medical journals, has been criticized for failing to capture the true impact of articles; for favoring methodology papers; for being unduly influenced by statistical outliers; and for examining a period of time too short to capture an article’s long-term importance. Also, in the era of search engines, where readers need not skim through journals to find information, Impact Factor’s emphasis on citation efficiency may be misplaced. A better metric would consider the total number of citations to all papers published by the journal (not just the recent ones), and would not be decremented by the total number of papers published. We propose a metric embodying these principles, “Content Factor”, and examine its performance among leading medical and orthopaedic surgery journals. To remedy Impact Factor’s emphasis on recent citations, Content Factor considers the total number of citations, regardless of the year in which the cited paper was published. To correct for Impact Factor’s emphasis on efficiency, no denominator is employed. Content Factor is thus the total number of citations in a given year to all of the papers previously published in the journal. We found that Content Factor and Impact Factor are poorly correlated. We further surveyed 75 experienced orthopaedic authors and measured their perceptions of the “importance” of various orthopaedic surgery journals. The correlation between the importance score and the Impact Factor was only 0.08; the correlation between the importance score and Content Factor was 0.56. Accordingly, Content Factor better reflects a journal’s “importance”. In sum, while Content Factor cannot be defended as the lone metric of merit, to the extent that performance data informs journal evaluations, Content Factor– an easily obtained and intuitively appealing metric of the journal’s knowledge contribution, not subject to gaming– can be a useful adjunct.
Highlights
Impact Factor, conceived by Garfield [1] and promulgated by Thomson Reuters’s Journal Citation Reports, is the pre-eminent performance metric for medical journals
We consider the Content Factors for the leading medical and orthopaedic surgery journals and we address the differences between Content Factor and Impact Factor especially as they relate to the perceived importance of the journal
The Content Factor is reported in kilo-cites to present units comparable in magnitude to those typically reported for Impact Factor
Summary
Impact Factor, conceived by Garfield [1] and promulgated by Thomson Reuters’s Journal Citation Reports, is the pre-eminent performance metric for medical journals. The Impact Factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years’’ [2] by the total number of such source items. The 2010 Impact Factor for the journal CA: A Cancer Journal for Clinicians was 94.33, the highest among all scientific journals. This number is calculated by noting that 19 source items were published in 2008 and 23 items in 2009 and in turn the journal’s 2008 and 2009 material was cited a total of 3,962 times in 2010 (3,962/42 = 94.33). One criticism centers on that citations fail to capture ‘‘how well read and discussed the journal is outside the core scientific community or whether it influences health policy’’ [3]. (For example, the 2008 JAMA articles by Barack Obama [4] and John McCain [5] on health care reform have been cited only ten times as of this writing.) Further, because citations do not follow a normal distribution, Impact Factor can be ‘‘influenced by a small minority of [a journal’s] papers’’ [6]: for example, the impact factor for CA-A CANCER JOURNAL FOR
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
