Definition: A measure of the frequency with which the "average article" in a journal has been cited in a particular year or period. Clarivate Analytics
Calculation for a journal's 2017 journal impact factor:
Caveat: Only journals in the sciences and social sciences that meet Clarivate Analytics' standards for inclusion in the Web of Science Core Collection are assigned impact factors. Impact factors are not computed for journals in the humanities.
Ongoing Debate: Currently impact factors are the most widely known way to rank journals, however, they are controversial. Some people believe that impact factors do not accurately reflect the impact of a journal or article.
(Hate journal impact factors? New study gives you one more reason, Science July 6, 2016)
Definition: CiteScore is the number of citations received by a journal in one year to documents published in the three previous years, divided by the number of documents indexed in Scopus published in those same three years. Scopus
Available from: Scopus Journal Metrics
Definition: Ranking based on incoming citations for a journal with more weight given to citations from significant and larger journals
Further information: Eigenfactor: Detailed Methods (2007)
Definition: Journals are classified into two main categories (NAT and INT) and two sub-categories (INT1 and INT2) based on their audience, distribution and reach.
Available from: The European Science Foundation
Definition: A measure of the average influence of each of a journals' articles over the first five years after publication.
Definition: A measure of scientific influence of scholarly journals that accounts for both the number of citations received by a journal and the importance or prestige of the journals where such citations come from. Factors considered for SJR journal rankings include:
Definition: A metric that accounts for field-specific differences in citation practices. It enables direct comparison of journals in different subject fields. Additional information from Leiden University.
Definition: The Journal Citation Indicator "represents the relative citation impact of a given paper as the ratio of citations compared to a global baseline. A value of 1.0 represents world average, with values higher than 1.0 denoting higher-than-average citation impact (2.0 being twice the average) and lower than 1.0 indicating less than average" . (Introducing the Journal Citation Indicator, May, 2021)
The Journal Citation Indicator calculation controls for different fields, document types (articles, reviews, etc.) and year of publication. It is calculated for all journals indexed in the Web of Science Core Collection using the most current three years of data.. This metric is similar to the SNIP (Source Normalized Impact Per Paper) metric.
Definition: The h-index of a publication is the largest number h such that at least h articles in that publication were cited at least h times each. For example, a journal with a h-index of 20 has published 20 articles that have been cited 20 or more times.
Definition: Mathematical Citation Quotient (MCQ) for a given year is defined as the number of times the items published in the journal in the previous five years were cited by items in reference lists of journals published in the given year, divided by the number of articles the journal published in that same five-year period.