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Monday, June 05, 2006

Manipulating Journal Impact Factors

In today's Wall Street Journal (online subscription required) Sharon Begley provides a rare look into the world of academic journal rankings. She describes some of the ways that scientific journals manipulate their "impact factors".

For those of you who aren't academics, an "impact factor" is a measure of the importance or relevance of the research published in the journal. The "impact factor" was created in 1950 by Eugene Garfield, and is calculated yearly by ISI, a Thomson company. The calculation is pretty simple (at least now that everything's computerized). As an example, to calculate the 2005 impact factor for the Journal of Financial Economics (a top finance journal), ISI would calculate the number of times a 2003 or 2004 JFE article was cited in any journal in the ISI database. This number is then divided by the number of articles JFE published in those two years to get the 2005 JFE impact factor.

Impact factors are important both for "bragging rights" and for economic reasons. Since they measure the extent to which researchers think that the journal's articles are important, they are one of the major determinants of a journal's ranking. Publishing in a top-ranked journal can have a major impact on an academic's career. Particularly in the world of academic finance, this can have a significant financial impact as well, since it allows them to move up the pecking order of institutions. Even if an academic makes a lateral move, the mobility is important: if they stay at their given institution, they invariably suffer salary compression. Publishing in high-ranked journal gives academics mobility, which keeps their salaries marked to the market.
Impact factors are also important to the journal for other economics-driven reasons. Libraries use them as a major input to determine which journals they subscribe to. Since a library's subscription in some cases can run $10,000, the benefits of a higher impact feature are pretty clear - a small increase in a journal's impact factor could mean many thousands of additional dollars in subscription revenues..

The article mentions the most common tricks journal editors use to boost impact factors, and they're not limited to scientific journals. One is to ask authors to include additional citations to other pieces in the journal. I've seen this tactic used several times (both on my pieces and on those of colleagues). Typically, once a piece is either accepted or in the "last round", the editor might "suggest" other articles in the same journal which might possibly be cited. In one case, the editor gave a colleague of mine a list of eight possible citations (which would have increased the total citations in the author's bibliography by almost 50%). However, this doesn't happen as much as you'd think, because I use my bibliography as one of the criteria I use in deciding which journal to submit a piece to: if I cite a good number of articles from a particular journal, it's probably a good fit for the piece.

The other strategy journals use to pump up their impact factors is to publish "reviews." Since these types of articles have extensive bibliographies, they almost automatically increase citation counts. They also tend to get cited themselves often, which further raises impact factors.

Note: For a little more information on impact factors, here's a recent Chronicle of Higher Education piece on the topic, and here's the Wikipedia entry on the topic.

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