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Evaluating the Importance of a Journal: The Impact Factor and Other Metrics

Benner, Rebecca S. MPS

doi: 10.1097/AOG.0b013e31823f2f6d

Ms. Benner is the director and managing editor of Obstetrics & Gynecology; e-mail:

Financial Disclosure The author did not report any potential conflicts of interest.

How do you keep a medical journal important and timely for readers, authors, and reviewers? At Obstetrics & Gynecology, the editors have compiled a set of philosophical goals aimed at producing a journal that has scientific integrity and that is evidence based, editorially independent, interesting and educational, and clinically relevant. These goals comprise our mission and govern editor decisions. The editors and staff also have some very practical objectives: to have a high impact factor, to consistently offer the fastest publication time, and to be user-friendly. The first two of these three objectives are measurable; the final objective is more subjective but nevertheless important.

The impact factor is a measure of how many citations the articles in a particular journal receive in any given year. It is released to journals in June of each year by Thomson Reuters as part of their Journal Citation Reports. The idea of the impact factor was proposed by Eugene Garfield, PhD, in 1955, in his discussion of a citation index for science: “… the system would provide a complete listing, for the publications covered, of all the original articles that had referred to the article in question. This would clearly be particularly useful in historical research, when one is trying to evaluate the significance of a particular work and its impact on the literature and thinking of the period. Such an ‘impact factor’ may be much more indicative than an absolute count of the number of a scientist's publications ….”1 Garfield went on to create the journal impact factor with Irving H. Sher2; today, the Journal Citation Reports analyze data from 10,196 titles.3

Per Garfield, “A journal's impact factor is based on two elements: the numerator, which is the number of cites in the current year to any items published in the journal in the previous 2 years; and the denominator, the number of substantive articles (source items) published in the same 2 years.”2 Obstetrics & Gynecology's 2010 impact factor is 4.392, based on the following equation: 2,855 (cites in 2010 to articles published in 2009 and 2008)/650 (number of articles published in 2009 and 2008)=4.392. This number, released yearly, helps us track where we rank in relation to other journals (see Fig. 1) and also gives us a sense of whether research published in Obstetrics & Gynecology is being read and referenced.

Timeliness in the publication process is another objective that we monitor closely. Our goal is to publish 80% of unsolicited, peer-reviewed manuscripts within 6 months. Case reports, which are published only twice yearly, are excluded from this calculation. In 2004, when we started monitoring our timing closely, only an average of 42% of articles published in that year completed the process from submission to publication within 6 months. This percentage gradually improved, however, to 50% in 2005, 71% in 2006, 77% in 2007, 86% in 2008, 83% in 2009, 87% in 2010, and 87% in 2011. Our reviewers, authors, and editors all participate in this effort: reviewers are given 14 days to complete their assignments, authors are given 30 days to revise their manuscripts, and editors are given 10 days to make decisions (both initial and final decision).

The third objective, user-friendliness, is not easy to measure. One way to gauge user-friendliness is through author, reviewer, and reader comments provided by e-mail, letter, or phone. Periodically, the journal sends out readership surveys as well. More and more, however, we are using the journal web site ( and social media to measure usage and monitor conversations about the journal. Web analytics allow the editors to track the number of visitors on the web site. We can also see from where these visitors are being referred, be it a news story,, Facebook, Twitter, or search engines such as PubMed or Google. Our Facebook page, launched in December 2009, has more than 3,000 “likes,” and our Twitter page, launched in September 2010, has more than 500 followers. We provide alerts and links to our content on, and the readers online are able to share this material easily on social media sites with colleagues and friends. Finally, the journal's accessibility on mobile devices and now—with this issue—on Apple's iPad also contribute to making the journal instantly and widely available.

As readers, your feedback and participation prompt improvements so that we can continue to strive to be the premier journal for obstetricians and gynecologists. Send your comments to; we want to hear from you.

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1. Garfield E. Citation indexes for science: a new dimension in documentation through association of ideas. Science 1955;122:108–11. Available at: Retrieved October 19, 2011.
2. Garfield E. The agony and the ecstasy—the history and meaning of the journal impact factor. Available at: Retrieved October 19, 2011.
3. Thomson Reuters. JCR 2010 data are now available. Available at Retrieved October 19, 2011.
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© 2012 The American College of Obstetricians and Gynecologists