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Research Article
Distributional differences of the impact factor in the sciences versus the social sciences: An analysis of the probabilistic structure of the 2005 journal citation reports
Article first published online: 16 APR 2008
DOI: 10.1002/asi.20810
© 2008 ASIS&T
Issue
Journal of the American Society for Information Science and Technology
Volume 59, Issue 9, pages 1366–1382, July 2008
Additional Information
How to Cite
Bensman, S. J. (2008), Distributional differences of the impact factor in the sciences versus the social sciences: An analysis of the probabilistic structure of the 2005 journal citation reports. J. Am. Soc. Inf. Sci., 59: 1366–1382. doi: 10.1002/asi.20810
Publication History
- Issue published online: 9 JUN 2008
- Article first published online: 16 APR 2008
- Manuscript Accepted: 3 DEC 2007
- Manuscript Revised: 2 OCT 2007
- Manuscript Received: 18 JUL 2007
- Abstract
- Article
- References
- Cited By
Abstract
This paper examines the probability structure of the 2005 Science Citation Index (SCI) and Social Sciences Citation Index (SSCI) Journal Citation Reports (JCR) by analyzing the Impact Factor distributions of their journals. The distribution of the SCI journals corresponded with a distribution generally modeled by the negative binomial distribution, whereas the SSCI distribution fit the Poisson distribution modeling random, rare events. Both Impact Factor distributions were positively skewed—the SCI much more so than the SSCI—indicating excess variance. One of the causes of this excess variance was that the journals highest in the Impact Factor in both JCRs tended to class in subject categories well funded by the National Institutes of Health. The main reason for the SCI Impact Factor distribution being more skewed than the SSCI one was that review journals defining disciplinary paradigms play a much more important role in the sciences than in the social sciences.