Impact Factors

Published on
July 29, 2005

Whether deserved or not great value is attached to the Impact Factor of journals, but what do they mean? The Impact Factor is a sort of appreciation of a journal, based on the number of times that articles from that journal are cited over a given period of time. The assumption being that if articles in the journals are often cited it indicates that it is a good quality journal. In order to prevent large journals being preferred to smaller ones, account is taken of the number of published articles in the same period. The Impact Factor is calculated as follows (for example Nature with as IF 30,979)

Impact Factor 2003 for the journal Nature:
The number of times in 2003 that articles from 2001 plus 2002 were cited = 56,629
The number of articles appearing in Nature in 2001 plus 2002 = 1,828
Impact Factor = 55,629/1,828 = 30,979

The Impact Factor of journals can be found in the Journal Citation Reports of ISI: select ISI Journal Citation Reports from the list.

Warning: There is often the tendency to judge researchers on the basis of the Impact Factors of the journals in which they publish. This is absolutely not advisable. For responsible assessment of both the research and the researcher many more factors should be taken into consideration. The Library can advise and assist you in this matter.

    (newsletter 6-2005)