El factor de impacto

The impact factor was created in 1960 by Irving H. Sher and Eugene Garfield, and is published annually in the Journal of Citation Report (JCR) of the Thomson Reuters Institute, which offers a range of tools for its assessment. It is a measure of the average number of times published papers are cited up to two years after publication. Thus the impact factor 2009 for a journal is equal to A/B, where A is the number of times articles published in 2007-2008 were cited in indexed journals during 2009, and B the number of articles published in 2007-2008.