By their very nature, citation cartels are difficult to detect. Unlike self-citation, which can be spotted when there are high levels of references to other papers published in the same journal, cartels work by influencing incoming citations from other journals.
In 2012, I reported on the first case of a citation cartel involving four biomedical journals. Later that year, Thomson Reuters suspended three of the four titles from receiving an Impact Factor. In 2014, they suspended six business journals for similar behavior.
This year, Thomson Reuters suspended Applied Clinical Informatics (ACI) for its role in distorting the citation performance of Methods of Information in Medicine (MIM). Both journals are published by Schattauer Publishers in Germany. According to the notice, 39% of 2015 citations to MIM came from ACI. More importantly, 86% of these citations were directed to the previous two years of publication — the years that count toward the journal’s Impact Factor.
