Impact Factor (IF) and CiteScore are the most popular journal metrics for evaluating the impact of scholarly journals. Eugene Garfield, the founder of the Institute of Scientific Information (ISI) in Philadelphia, created the IF.1 In 1975, Thomson Reuters (now Clarivate Analytics) began calculating and publishing IF every year in the Journal Citation Reports (JCR). The average number of citations received by papers published in a journal during the previous 2 years each year is determined by IF. Editorials, letters, and news items are not considered citable items for IF, but original research articles and reviews are. For example, if a journal received 500 citations in 2024 to articles published in 2022 and 2023, and it published 100 citable articles in those 2 years, its IF for 2024 would be: 500 / 100 = 5. This means that, on average, papers published in 2022 and 2023 received 5 citations each in 2024. Year 2024 IF is published in 2025, and it cannot be calculated until all the publications have been processed by the indexing agency. It started out as a tool to assist libraries in choosing those journals to buy, but it now has a significant impact on the scientific community, influencing choices about where to publish. CiteScore is an alternative journal metric introduced by Elsevier in December 2016 as an alternative to JCR IF and is based on data from Scopus, one of the largest abstract and citation databases.2 CiteScore determines the average number of citations received for each document published over a 4-year period in a journal. CiteScore, using this methodology, was initially made available in June 2020. By dividing the total number of documents published over the preceding 4 years (Years B-1 to B-4) by the number of citations received in that year (Year B), one can determine the CiteScore for that year. For example, if a journal received 1,200 citations in 2024 for documents published between 2020 and 2023, and it published 300 documents during that period, its CiteScore for 2024 would be calculated as 1,200 divided by 300, resulting in a CiteScore of 4.0. All document types, including articles, reviews, conference papers, editorials, letters, and notes, are regarded as citations for CiteScore. CiteScore was calculated for the previous 3 years, divided by the total number of citable items, prior to 2020. The differences between IF and CiteScore are summarized below.Despite their widespread use, both IF and CiteScore face criticism. IF’s 2-year window may not capture the long-term impact of publications, especially in slow-moving disciplines like the humanities. Web of Science and Scopus do not index all journals equally, leading to potential regional, and language bias. Different fields have different citation behavior. For instance, medical journals generally receive more citations than mathematics journals. Relying solely on IF or CiteScore to judge the quality of individual articles or researchers may be flawed. These metrics reflect journal performance, not the impact of individual works. Journals also may adopt strategies like publishing more review articles (which are cited more often) or engaging in citation stacking. Both Clarivate and Elsevier have taken steps to make their metrics more transparent and comprehensive. From 2023 onwards, Clarivate has started to include all document types (not just citable items) in the denominator for IF calculations, aligning it closer to CiteScore’s approach. Scopus (Elsevier) offers a CiteScore tracker, updated monthly to show the journal’s evolving performance throughout the year. Additionally, several complementary metrics have been developed to address the shortcomings of CiteScore and IF. The h-index evaluates an author’s or journal’s productivity as well as the impact of their citations.3 Eigenfactor Score: Assigns citation weights according to the citing journal’s influence.4 As determined by Scopus data, SCImago Journal Rank (SJR) takes into consideration both the quantity of citations and the standing of the citing journals.5 Altmetrics: Calculates the impact a publication has on online channels, such as news outlets, policy documents, and social media.6 Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Borkar et al. (Wed,) studied this question.