An Impact Factor (IF) provides a quantitative assessment of a journal's influence or impact. According to Thomson Reuters, the Journal Impact Factor is the frequency with which the “average article” in a journal has been cited in a particular year. A journal’s Impact Factor is determined by dividing the number of citations in the JCR year by the total number of articles published in the two previous years.
[The formula is n=number in the subject category
n-rank/n-1 x 100 =percentile]
A Journal Impact Factor of 4.0 means that, on average, the articles published in that journal within the past three years have been cited four times. There must be at least two years of data in order to calculate the Impact Factor.
Using Impact Factors (IF) Wisely:
A researcher should not depend entirely on JCR data to evaluate a journal because:
· IF only includes journals indexed by Thomson Reuters Scientific (ISI).
· IF does not evaluate individual researchers.
· Journals can only be compared within the same discipline. Citation results vary widely across disciplines.
· The number of articles found in journals include both research and review articles. "Citation counts in JCR do not distinguish between citations to letters, reviews, or original research articles, even though only original research and review articles are used in IF calculations."
· Title changes or changes in format of a journal affects the IF.
Go to the Journal Citation Reports database. Choose a year, and select "View a group of journals by Subject Category" using the button to the left.
Select "View Journal Data - sort by Journal Title."
A Journal Summary List of economics journals appears. Change the sort option to Impact Factor.
View a journal's information based on the sort selection. The journal in the Economics category with the highest Impact Factor (IF) is the Journal of Economic Literature. Its basic data is provided below.