CiteScore and Impact factor
CiteScore is a new review metric launched by Elsevier in 2016 as an alternative to Impact Factor, a product of Clarivate Analytics (formerly part of Thomson Reuters). Both companies already have competing bibliographic citation databases in Scopus (Elsevier) and the Web of Science (Clarivate Analytics).
Launched as an offshoot of the Science Citation Index, it provided a distinctive way of rating journals based on their citations, and quickly became the mantra for journal quality!
The impact factor is obtained from Journal Citation Reports (JCR) from Clarivate Analytics.
As the impact factor is derived from journals indexed in the Web of Science - another product of Clarivate Analytics, other journals cannot have an impact factor.
Elsevier launched CiteScore to compete with the impact factor. You can freely access it on the Scopus Journal Metrics website. At the same time, JCR is a paid subscription.
For Elsevier, CiteScore is calculated from the list of Scopus journals, which is much larger than the Web of Science list.
Verification of the impact factor of Scopus indexed journals
Scopus no longer uses the Thomson-Reuters impact factor. They introduced the new metric from the journal CiteScore last December. This is a new metric calculated as
CiteScore = Number of citations in 2019 / (number of documents from 2016 to 2018)
The CiteScore usually gives a number greater than the impact factor.