The hottest citation
The article at the top of the spires lists of the most-cited articles in high-energy physics is, as always, the Review of Particle Physics (RPP), a compendium of experimental data and reviews put out by the Particle Data Group. This highly useful work is cited whenever the author of a paper refers to standard experimental results, and it gets more than 1000 citations every year.
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| Source: spires |
Just as physicists often look at spires' lists as a measure of which papers are ''hot" at a given moment, librarians and journal publishers, in evaluating journals, look at something called the impact factor. It's based on the number of articles published in a journal in a two-year span and the number of citations those articles received in the following year. Impact factors, like other ranking systems based on article citations, may be pilloried as useless or vaunted as convenient measures of quality. In reality they are somewhere in between, and the RPP provides a good example of some subtle effects.
The RPP is run in one of the major particle physics journals every two years, although it isn't submitted, reviewed, or edited like a typical journal article. Because the RPP gets more than 1000 citations a year, any journal in which it appears in gets a big but temporary lift in its impact factor.
In Physics Letters B, for example, 10% of the 10,000 citations received in 2005 were to the RPP. The resulting boost in impact factor from 4.5 to 5 was based on nothing more than the Particle Data Group's decision to publish the review in the journal that year. For this reason, among others, the group rotates the publication of the book among several journals, and the RPP effect, while pronounced in each year, does get spread around. In 2003 and 2004 the Physical Review D impact factor was boosted by about 5% due to the RPP, in 2005 and 2006 Physics Letters B saw a 10% rise, and for 2007 and 2008, we can expect the Journal of Physics G to see a near doubling of its impact factor due to the RPP.
While physicists generally nod their heads in agreement when they see the RPP at the top of spires' lists, confirming that the Particle Data Group's efforts are quite useful, journal publishers and librarians who don't know about the RPP may wonder at the strange cycle of bumps in impact factors for the journals of particle physics.
Travis Brooks, SLAC
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