Through the analysis of citation references, Journal Citation Reports (JCR®) measures research influence and impact at the journal and category levels and shows the relationship between citing and cited journals. It is based on Web of Science data using the Science Citation Index Expanded and the Social Science Citation Index.
Note: the JCR impact factor should not be the only tool used by researchers to assess the usefulness of a journal. It is recommended that it be used together with informed peer review.
Journal Impact Factor (IF)
The Impact Factor is the average number of citations to papers in a journal in one year, from articles published in any Thomson Reuters listed journal during the previous two years.
* articles include research articles, review articles, substantial notes. Items such as editorials, letters, news items, and meeting abstracts are not counted.
An Eigenfactor Score is the number of current year citations to citable items from the previous five years, similar to the pagerank algorithm used by Google.
Article Influence™ Score
The Article Influence™ Score determines the average influence of a journal's articles over the first five years after publication, calculated as the journal's Eigenfactor Score divided by the number of articles published by the journal.