Did you notice a jump in the Journal Citations Report Impact Factor for one of your favorite journals this year? If so, good catch!
Journal Impact Factor calculations depend on the calendar year of publication. For journals that still publish in print, Clarivate traditionally used the print publication date to determine the year of publication. However, in the past 20 years, various models of online publication (early view, advance access, accepted articles) have been introduced. Typically, these online articles are citable with a stable DOI, weeks to months before they appear in a print issue, but have not been counted in the Journal Impact Factor until their print publication date.
For 2021, Clarivate has changed the game. Early Access citations with a publication date of 2020 are included in the numerator of the Journal Impact Factor equation. Journals that have a backlog of articles online waiting on print publication will receive a Journal Impact Factor bump from this change. The playing field will level again by 2022. There are indications that this model may affect some journals disproportionately.
What does this mean for authors and researchers? While Journal Impact Factor is still a good metric, you may want to consider other metrics as well while the Journal Impact Factor data fluctuations work their way out of the system. You can view our Journal Metrics information on the Publication Metrics Guide.