Use Impact Factors wisely

I've received a few enquiries regarding the Impact Factor (IF) of certain journals.

Lets first start with what IF is:


IF was devised in 1955 to help select journals for the Science Citation Index and
"it is a measure of the frequency with which the "average article" in a journal has been cited in a particular year or period.

The annual JCR impact factor is a ratio between citations and recent citable items published. Thus, the impact factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years.

The impact factor is useful in clarifying the significance of absolute (or total) citation frequencies. It eliminates some of the bias of such counts which favor large journals over small ones, or frequently issued journals over less frequently issued ones, and of older journals over newer ones. Particularly in the latter case such journals have a larger citable body of literature than smaller or younger journals.

All things being equal, the larger the number of previously published articles, the more often a journal will be cited." ISI Impact Factor

But the IF is NOT a way to assess the usefulness of a journal and should not be misused:

“the impact factor should not be used without careful attention to the many phenomena that influence citation rates, as for example the average number of references cited in the average article. The impact factor should be used with informed peer review. In the case of academic evaluation for tenure it is sometimes inappropriate to use the impact of the source journal to estimate the expected frequency of a recently published article. Again, the impact factor should be used with informed peer review. Citation frequencies for individual articles are quite varied." ISI Impact Factor



For step-by-step instructions on how to search for a journals IF, click and download the presentation Journal Citation/Impact factors.