Impact factor and other citation measures: counting what matters Moderated by Maria Ekstrand Presented by Valda Vinson and Nathan Ford

Washington D.C., USA, July 2012www.aids2012.org The Impact Factor at Science Valda Vinson Science AIDS 2012 July 25, 2012

Washington D.C., USA, July 2012www.aids2012.org Defining the Impact Factor 2011 IF= Total citations/total number of citable items –Citations = the number of times articles published in were cited in indexed journals during 2011 –Citable items = Primarily articles and reviews, published in ; typically not editorials and letters-to-the-Editor (rule of >15 citations) note that the 2011 impact factor was actually published in 2012, because it could not be calculated until all of the 2011 publications had been received So a journal that is cited once, on average, for each article published has an IF of 1

Washington D.C., USA, July 2012www.aids2012.org How is the IF used? As a way to measure the importance or prestige of a journal As a way to establish the success of individual scientists Science’s view is the IF is an imperfect tool to measure the success of either of these factors

Washington D.C., USA, July 2012www.aids2012.org Problems with the IF: Science’s perspective The IF varies from field to field 1061: “An integrated genomic analysis of human glioblastoma Multiforme” vs. 328: “Optical images of an exosolar Planet 25 light-years from Earth” Biology vs. Physical Sciences split IF of Annual Reviews of Immunology vs. Science, Nature and Cell The IF of a journal does NOT reflect the worth of any individual paper published in that journal. A large fraction of the IF is made up by a relatively small percentage of papers: Acta Crystallographica Section A rose from in 2008 to in 2009 because 1 paper received 6600 citations A paper in a lower impact journal may be much more important than one in a high impact journal: Original Th17 papers were published in Nature Immunology (1564 citations)

Washington D.C., USA, July 2012www.aids2012.org Problems with the IF: Science’s perspective Journals can manipulate their IF Science 335, 542 (2012). Many journal editors appear to strategically target authors and papers to pressure them into citing the editors' journals. The Impact Factor distorts the process of science. An obesity-associated gut microbiome with increased capacity for energy Nature 444, 1027 (2006) Controversial/topical papers Rational Design of Envelope Identifies Broadly Neutralizing Human Monoclonal Antibodies to HIV-1 Science 329, 856 (2010). Total cites: 172

Washington D.C., USA, July 2012www.aids2012.org How does Science use the IF? Our goal is to publish the best papers in all disciplines IF is one (imperfect) way to measure the impact of a paper Important to remember IF is relative to a given field and some papers take a while to show their impact