How Impact Factor is Calculated?
The calculation is based on a two-year period and involves dividing the number of times articles were cited by the number of articles that are citable.
Calculation of 2010 IF of a journal:
A = the number of times articles published in 2008 and 2009 were cited by indexed journals during 2010.
B = the total number of "citable items" published in 2008 and 2009.
A/B = 2010 impact factor.
An Impact Factor of 1.0
means that, on average, the articles published one or two year ago have been cited one time. An Impact Factor of 2.5
means that, on average, the articles published one or two year ago have been cited two and a half times. Citing articles
may be from the same journal; most citing articles are from different journals.
The Impact Factor (IF) graph reflects only the citations retrieved from the International Science Index