Impact Factor Joined by Eigenfactor and H-Index

By Barbara Meyers Ford, President, Meyers Consulting Services

Earlier this year, Carl Bergstrom, an associate professor in the University of Washington Department of Biology, reported on an iterative ranking scheme that he and his colleagues developed. Called the Eigenfactor, this new metric ranks "journals much as Google ranks Web pages." At the Web site, Bergstrom and his team provide data for the nearly 8,000 titles in the Journal Citation Reports® along with about 110,000 other publications referenced by the JCR-covered serials. Bergstrom says they "use citations in the academic literature as tallied by JCR. By this approach, we aim to identity the most ‘influential’ journals, where a journal is considered to be influential if it is cited often by other influential journals" ("Eignefactor: Measuring the Value and Prestige of Scholarly Journals," College & Research Library News, May 2007, Vol. 68, No. 5).

Bergstrom explains that "while this might sound hopelessly circular, it is not: we can iteratively calculate the importance of each journal in the citation network by a simple mathematical algorithm" (see www.eigenfactor.org/methods.pdf). The focus is on the total influence of a journal. Thus, the Eigenfactor algorithm simulates how researchers follow citations as they more from journal to journal through references based on the frequency with which each journal is visited.

Jorge E. Hirsch, a physics professor at the University of California, San Diego, also devised "an alternative that appears to be a simpler and more reliable way to rank scientific output within a discipline than any now in use" ("Physicist proposes new way to rank scientific output," Physorg.com) Hirsch’s h-index—the "h" stands for "high citations"—may have some shortcomings. For instance, it is more applicable to researchers in the life and physical versus the social sciences, but it can be used as another measure to evaluate people’s contributions throughout their careers.

Hirsch's original paper, published in the Proceedings of the National Academy of Sciences in 2005, fully outlines his arguments and algorithms, which, if applied more widely, may be used to evaluate groups of researchers as well. He concludes that his index estimates "the importance, significance, and broad impact of a scientist’s cumulative research contributions." For a discussion of the h-index, see Wolfgang Glanzel, "On the Opportunities and Limitations of the H-Index," Science Focus, 2006, Vol. 1, No. 1, pp. 10-11.

Time will tell if either of these alternative metrics will someday replace the Impact Factor as the primary means of determining the quality of scholarly output and, consequently, the competitive ranking of scholarly journals in the marketplace. But their existence is clear evidence that some believe more reliable methods are needed.

Barbara Meyers Ford serves as editor in chief of SSP News. She is a founding member and past Board of Directors member of SSP and past president of the Council of Science Editors.