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 2007 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
2007 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 a workshop.
- Or, if you can't attend a workshop, download the presentation: (Powerpoint) or (PDF).
- 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