Clarivate, the company that calculates Journal Impact Factors based on citations to articles, didn’t publish the metric for 17 journals this year due to suspected citation manipulation. That’s a substantial increase from last year, when only four were excluded. 

Clarivate suppressed nearly twice as many journals in 2020, when it penalized 33 for self-citation. The company suppressed 10 in 2021, and three the following year. In an email to Retraction Watch, a spokesperson said journals are suppressed from the report due to "anomalous citation behavior, including where there is evidence of excessive journal self-citation and/or citation stacking (which involves two or more journals). We do not presume a motive or accuse these journals of wrongdoing." 

The editors of many of the blocked journals are conducting their own research on the comments provided by Clarivate. Some consider the cited citations to be valid, some review articles with a high number of citations for possible retraction due to citation manipulation. Blocked journals remain in the Web of Science core collection until a final decision is made.