Journal Impact Factors

Journal Citation Reports is an analytical tool produced by commercial publisher Thomson Reuters. It enables the user to determine if a particular journal has an official impact factor. A journal impact factor is a number calculated by dividing the total number of citations received by a particular journal in a one year period, by the number of citable articles published by that journal in the previous two years.

For example the 2010 impact factor of a journal would be determined as follows:

       # of citations received by the journal in 2010 to articles published in 2008 and 2009
                  # of citable articles published by the journal in 2008 and 2009

The higher the impact factor, the greater the perceived importance of that journal within the field. Only journals index by Journal Citation Reports (JCR) will have an official impact factor.

Thomson Reuters cautions users not to rely solely on JCR for journal evaluation, citing factors such as language, journal history, format, publication schedule and subject specialty to consider.

Further information is available from JCR