Wednesday, 13 February 2008

Journal Impact Factors

Journal Impact Factors provide a numeric measure of the 'quality' of journals using a simple calculation, the sum of published articles in the previous two years divided by the number of times articles in that journal have been cited in the current year. For example:


Number of articles in the Journal of Advanced Studies

2004 2005

20 + 20 = 40



Number of times articles the Journal of Advanced Studies published in 2004/5 have been cited by others in 2006

2004 2005

40 + 40 = 80



The Impact Factor is:

80/40 = 2.0

Impact Factors are calculated using data provided by the ISI Citation Indexes and presented in a separate database called the Journal Citation Reports. The Journal Citation Reports provide Impact Factors for individual titles and groups of tiles by subject in two databases Science and Social Sciences.

Impact Factors should be read with care.


  • Impact Factors are higher in the Sciences than the Social Sciences, Arts and Humanities. It is not appropriate to compare Impact Factors across disciplianry areas.

  • Newly created journal titles will not have Impact Factors in their first three years of publication.

  • Multi disciplinary areas of study are not well served by Impact Factors. Impact Factors favour established journals that fall within traditional disciplinary boundaries.

  • In some discipline areas, very few journal titles have Impact Factors compared with the total number of titles published, for example 'management' or 'business'. Journals with Impact Factors represent only a small amount of scholaly activity.



Although Impact Factors are crude in many ways, their wide acceptance means that they are a key measure of performance. Publishing in a journal title with an Impact Factor, or in a journal title that has a higher Impact Factor than other titles in the field is considered 'better'.


Links

Wikipedia article
Impacts Factors - essay by Dr. Eugene Garfield, Thompson ISI

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