(20 May 2021) The recent announcement made by Clarivate says,
“By normalizing for different fields of research and their widely varying rates of publication and citation, the Journal Citation Indicator provides a single journal-level metric that can be easily interpreted and compared across disciplines. The Journal Citation Indicator will be calculated for all journals in the Web of Science Core Collection™ – including those that do not have a Journal Impact Factor (JIF)™ – and published in the 2021 JCR in June.”
Citations serve as an immediate, valid marker of research influence and significance, reflecting the judgments that researchers themselves make when acknowledging important work. Nevertheless, citations must be considered carefully and in context. For validity in assessing the impact of published research, citation analysis must control for such variables as subject field, document type and year of publication.
The new Journal Citation Indicator meets this requirement for journal evaluation, providing a single number that accounts for the specific characteristics of different fields and their publications. Although the calculations behind the Journal Citation Indicator are complex, requiring considerable computing power, the end result is simple: a single value that is easy to interpret and compare, complementing current journal metrics and further supporting responsible use.
In its calculation for a given journal, the Journal Citation Indicator harnesses another Clarivate measure: Category Normalized Citation Impact (CNCI), a metric found in the analytic and benchmarking tool InCites™. The value of the Journal Citation Indicator is the mean CNCI for all articles and reviews published in a journal in the preceding three years. (For example, for the 2020 Journal Citation Indicator value, the years under analysis are 2017, 2018 and 2019.)
As in the CNCI measurement, the Journal Citation Indicator calculation controls for different fields, document types (articles, reviews, etc.) and year of publication. The resulting number represents the relative citation impact of a given paper as the ratio of citations compared to a global baseline. A value of 1.0 represents world average, with values higher than 1.0 denoting higher-than-average citation impact (2.0 being twice the average) and lower than 1.0 indicating less than average.
In essence, the Journal Citation Indicator provides a field-normalized measure of citation impact where a value of 1.0 means that, across the journal, published papers received a number of citations equal to the average citation count in that subject category.
Here’s the full announcement by Martin Szomszor, Director of Institute for Scientific Information, Clarivate.
