CiteScore is essentially the average citations per document that a title receives over a three-year period and is highly similar to the existing and already controversial Journal Impact Factor (JIF). However, Citescore uses Scopus, the largest abstract and citation database of peer-reviewed literature. It covers almost twice as many journals as Web of Science, on which the next-leading abstract and citation data provider bases its metric. Moreover, unlike the JIF, which is available only to subscribers, CiteScore is free for anyone to view and analyse online. As a recent article in Nature describes, the significant difference between CiteScore and its closest competitor is that CiteScore counts all documents – including editorials, letters, and news items – as potentially citable. This key distinction results in some established high-impact journals, including Nature and Science, attaining a much lower citation score with CiteScore.
Both Clarivate Analytics, which bought the JIF and the Web of Science from Thomson Reuters earlier this year, and Elsevier, claim that their metrics are fully transparent with unbiased content coverage. However, it has been debated whether or not a publisher should be producing a journal metric at all.