Definition: A measure of the frequency with which the "average article" in a journal has been cited in a particular year or period.
Calculation for a journal's 2019 journal impact factor:
Number of citations received by the journal in 2019 to articles published in 2017 and 2018. (example 500)
Number of citable articles published by the journal in 2017, 2018 (example 50)
The journal's 2019 impact factor is 10.
Available from: Journal Citation Reports. We do not have a subscription. But technically it can be calculated from the Web of Science (WOS) citation data OR through a Publication Name search in WOS.
Limitations: 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.
Chapman CA et al. 2019 Games academics play and their consequences: how authorship, h-index and journal impact factors are shaping the future of academia. Proc. R. Soc. B 286: 20192047. http://dx.doi.org/10.1098/rspb.2019.2047
How to look up Impact Factor of a journal in the Web of Science.
Follow instructions in the attached document.
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: 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:
Available from: SJR