Scholarly Publishing and Bibliometrics: Journal Rankings

Definition: The journal impact factor measures the importance of a journal by calculating the times its articles are cited.

How Impact Factor is Calculated: The calculation is based on a two-year period and involves dividing the number of times articles were cited by the number of articles that are citable.

Be Aware

Experts stress that there are limitations in using impact factors to evaluate a scholar's work. There are many reasons cited for not relying on impact factor alone to evaluate the output of a particular individual. Among these are the following:

• A single factor is not sufficient for evaluating of an author's work.

• Journal values are meaningless unless compared within the same discipline. Impact factors vary among disciplines.
  

• The impact factor was originally devised to show the impact of a specific journal, not a specific scholar. The quality and impact of the author's work may extend beyond the impact of a particular journal.

According to Jim Testa, a researcher for ThomsonReuters Scientific, the most widespread misuse of the Impact Factor is to evaluate the work of an individual author (instead of a journal). "To say that because a researcher is publishing in a certain journal, he or she is more influential or deserves more credit is not necessarily true. There are many other variables to consider" (interview 6/26/2008 in Thomson Reuters blog entry).

"Journal Citation Reports (JCR) offers a systematic, objective means to critically evaluate the world's leading journals, with quantifiable, statistical information based on citation data. By compiling articles' cited references, JCR helps to measure research influence and impact at the journal and category levels, and shows the relationship between citing and cited journals" (JCR website).

To use Journal Citation Reports, follow the steps below:

1. Open Journal Citation Reports.
2. Select either the Science or Social Sciences Edition and the Year.
3. Select an option to search for a specific journal, or to view a group of journals.
4. To search for a specific journal, you may search by Full or Abbreviated journal title, title word, or ISSN.
5. Click on the journal title to see Journal Information, Impact Factor, Immediacy Index, Cited Half-Life, Cited Journal Graph,etc.

For more information about Journal Citation Reports, click on the Information for New Users link located in the upper right hand corner of the database opening page, or view the Journal Citation Reports tutorial created by Thomson ISI.

The content on this page is borrowed with permission from the University of Michigan Library and the Arizona State University Library. You may access Michigan's Citation Analysis guide here and ASU's guide here.