The Impact Factor has had a long reign in academe. Beginning in 1975 as a byproduct of the Science Citation Index, it provided a unique, objective means of rating journals based on their citations and quickly became a standard measure of journal quality .
In December 2016, Elsevier launched a new journal metric, CiteScore, that takes direct aim at the hegemony of the Impact Factor, a product of Clarivate Analytics (formerly part of Thomson Reuters.) CiteScore is calculated from all citations recorded in Scopus in one year to content published in the last three years, divided by the number of items published