The Journal Impact Factor is a metric representing the average citation counts of papers published in a journal over a two year period.
The JIF is an objective measure of overall quality of journals within a discipline. More prestigious journals have higher JIFs.
JIFs are released annually for journals indexed by Web of Science via Journal Citation Reports (JCR).
What can JCR provide?
Impact Factor—the ratio of the number of citations in the previous two years of the journal divided by the number of articles in those years = the average number of recent citations per article. Check against the library catalog both those journals identified as important, with the highest impact factors, as well as those journals with the weakest impact. See the H-Index, under Web of Science, as a companion or alternative to the Impact Factor.
Immediacy Index—the number of citations that year to articles published during the same year.
Cited Half-Life—the median age of articles in the journal that were cited by other journals during the year.
Journal Citing Half-Life—the median age of the articles that are cited by the articles published in that same year.
Number of articles published in a given year or span of years.
How often articles in a journal refer to articles previously published in that journal.
How often articles in a journal refer to articles previously published in other journals.
Number of citations from articles published in a journal in a given year or span of years to that journal and other journals.
The frequency with which articles published in a journal during each of the most recent ten years were cited by specific journals during the year.
The most frequented cited journals.
Citation and article counts, which measure the frequency of which scholars use individual journals.
The largest journals in a subfield.
almost all of the journals are in English
and are published in Western Europe and the U.S.
not all areas of study—especially within the humanities and social sciences—are represented,
while others are under-represented in terms of their journals
working papers are not included
data is included from journals that publish original research as well as from review journals' review articles, each of which have very different citation patterns and behavior
negative citations give false weight to the measurement of impact