What is "impact factor"?
Impact factor is a measure of the frequency with which the "average article" published in a given scholarly journal has been cited in a particular year or period and is often used to measure or describe the importance of a particular journal to its field. The Thomson-Reuters (formerly Institute for Scientific Information (ISI)) ranks, evaluates, and compares journals within subject categories and publishes the results in Journal Citation Reports . The new rankings come out in the Spring, for the previous year's journals. Three years worth of data are required to calculate a Journal Impact Factor.
The formula to determine the 2008 impact factor for a journal would be calculated as follows:
A = the number of times articles published in the journal during 2006-7 were cited by other
journals during 2008
B = the number of articles or reviews that were published in the journal during 2006-7
2008 Impact factor for a journal = A/B
How to find a journal's impact factor or relative importance
From the library homepage, search " Journal Citation Reports" in the easy search box.
The grey box directly under your search results should read, "Your search Journal Citation Reports matched a journal/magazine/database title(s)."
The next screen will list " Thomson."
Click on the link that says " THOMSON REUTERS DATABASES"
Select the Science or Social Science Edition, select a year, and choose to view a group of journals, search for a specific journal, or view all journals. You may view a group of journals by Subject Category (such as Agricultural Engineering, Astronomy, or Biology), by Publisher, or by Country/Territory.
Impact factors have a huge, but controversial, influence on the way published scientific research is perceived and evaluated. Numerous criticisms have been made of the system:
- Journal impact factors depend on the research field: high impact factors are likely in journals covering large areas of basic research and less likely in more subject-specific journals.
- Although Journal Citation Reports includes some non-English journals, the index is heavily skewed toward English-language journals, leaving out important international sources.
- Researchers may be more likely to pursue fashionable topics that have a higher likelihood of being published in a high-impact journal than to follow important avenues that may not be the as popular.
Alternative ways of ranking journals
and mapping scientific knowledge
- The Eigenfactor algorithm ranks journals much as Google ranks websites .
Australian Research Councilhas undertaken
the project of developing journal rankings
- 20,712 unique peer reviewed journals have been included in the ERA 2010 Journal List.
- Register to attend our workshop "Understanding Impact: Impact Factor and Other Bibliometrics" or view our libguide
- Monastersky, R. (2005). The number that's devouring science. The Chronicle of Higher Education, 52(8), A12. Available at: http://chronicle.com/free/v52/i08/08a01201.htm
- Lange, L. L. (2002). The impact factor as a phantom; is there a self-fulfilling prophecy effect of impact? Journal of Documentation, 58(2), 175-184. Available at: http://www.emeraldinsight.com/10.1108/00220410210425449