Colleagues/ Major/Major New Studies Hot Off The Press /Gerry A Principal Component Analysis of 39 Scientific Impact Measures Bollen J, Van de Sompel H, Hagberg A, Chute R, 2009 A Principal Component Analysis of 39 Scientific Impact Measures. PLoS ONE 4(6): e6022. Background The impact of scientific publications has traditionally been expressed in terms of citation counts. However, scientific activity has moved online over the past decade. To better capture scientific impact in the digital era, a variety of new impact measures has been proposed on the basis of social network analysis and usage log data. Here we investigate how these new measures relate to each other, and how accurately and completely they express scientific impact. Methodology We performed a principal component analysis of the rankings produced by 39 existing and proposed measures of scholarly impact that were calculated on the basis of both citation and usage log data. Our results indicate that the notion of scientific impact is a multi-dimensional construct that can not be adequately measured by any single indicator, although some measures are more suitable than others. The commonly used citation Impact Factor is not positioned at the core of this construct, but at its periphery, and should thus be used with caution. Received: May 14, 2009; Accepted: May 26, 2009; Published: June 29, 2009 Excerpts and Links To Full Text Available From [ http://tinyurl.com/n2zjtr ] _____________________________________________________ Article-Level Metrics (At PLoS And Beyond) "Article-Level Metrics at PLoS" takes the view that readers need some way to measure, or at least indicate, the 'worth' (or 'impact' etc) of a journal article. With over a million articles published per year it's impossible to read everything & so filtering tools are needed. Some journals have been experimenting with providing data on online usage, but PLoS is going further than this. We are at the start of a program to provide citations, usage data, social bookmarking activity, media & blog coverage, commenting activity, 'star' ratings etc on all articles we publish. Links to The Full Presentation W/ Slides / Slide Notes / Audio / PDF And Related Items Available At [ http://tinyurl.com/qb7nf4 ] Enjoy ! /Gerry Gerry McKiernan Associate Professor Science and Technology Librarian Iowa State University Library Ames IA 50011 [log in to unmask] There Are No Answers, Only Solutions / Olde Irish Saying The Future is Already Here; It's Just Not Evenly Distributed / Attributed to William Gibson, SciFi Author; Coined 'Cyberspace' lis-e-resources is a UKSG list - http://www.uksg.org/serials UKSG groups also available on Facebook and LinkedIn