What is Impact Factor?

The impact factor, often abbreviated IF, is a measure reflecting the average number of citations to articles published in science and social science journals. It is frequently used as a proxy for the relative importance of a journal within its field, with journals with higher impact factors deemed to be more important than those with lower ones. The impact factor was devised by Eugene Garfield, the founder of the Institute for Scientific Information (ISI), now part of Thomson Reuters. Impact factors are calculated yearly for those journals that are indexed in Thomson Reuters Journal Citation Reports.

Key Points :

• The only quantitative way of ranking a journal
• A quantitative measure of the frequency with which the "average article" published in a given scholarly journal has been cited in a particular year or period.
• Is used in citation analysis
• It is calculated each year by the Institute for Scientific Information (ISI) for those journals which it tracks, and are published in the Journal Citation Report.
• Impact Factors have a huge, but controversial, influence on the way published scientific research is perceived and evaluated

Calculation of Impact Factor

The impact factor for a journal is calculated based on a three-year period, and can be considered to be the average number of times published papers are cited up to two years after publication. For example, the 2007 impact factor for a journal would be calculated as follows:

              A = the number of times articles published in 2005-6 were cited in indexed journals during 2007

              B = the number of articles, reviews, proceedings or notes published in 2005-6 

             2007 impact factor = A/B

• (note that the 2007 impact factor was actually published in 2008, because it could not be calculated until all of the 2007 publications had been received.)

Available in citation database such as ISI, Scopus, MyAIS