Systematic knowledge on citation cartels of scientific journals is surprisingly scarce. We have little knowledge about the phenomenon itself, about how often cartels occur, and about where to draw the line between acceptable and unacceptable between-journal citation behavior. With this blogpost, we wish to open up the floor for further scrutiny of journal citation cartels. Our aim is to arrive at a better conceptual and empirical understanding of the phenomenon – and we would like your help with this.
In its latest Journal Citation Reports, published last week, Thomson Reuters suppressed the citation statistics of 18 journals that display ‘anomalous citation patterns’. As explained here, 16 journals were suppressed because of abnormal numbers of self-citations, and two were removed because of citation stacking.
Unlike journal self-citations, citation stacking implies a connection between at least two journals. It refers to the phenomenon of one journal giving a very large number of citations to recent articles in another journal. Citation stacking does not always need to indicate the existence of a journal citation cartel. In principle, a journal can have legitimate reasons for giving a large number of citations to another journal. We therefore reserve the term ‘citation cartel’ for situations in which an individual or group of individuals affiliated with different journals (as authors, editors, et cetera) act with the intent to influence citation statistics of one or more of these journals.
Last year Thomson Reuters suppressed the citation statistics of ten journals because of citation stacking, and as already mentioned, this year the statistics of two journals (Applied Clinical Informatics and Methods of Information in Medicine) were suppressed. In 2013, Thomson Reuters’ algorithm for identifying citation stacking led to the detection of a Brazilian citation cartel. Earlier a citation cartel involving a number of medical journals was revealed by Phil Davis, and recently a case of citation stacking by three Romanian physics journals was identified by Petr Heneberg.
Apart from the above-mentioned cases, little seems to be known about citation stacking and the existence of journal citation cartels. For this reason, we recently decided to perform a systematic scan of papers in the Web of Science database in order to identify articles that may play a role in journal citation cartels. Our analysis is still ongoing, but we already found a few cases that we would like to share. These cases are summarized in the table below.
Asia Pacific Journal of Tourism Research
Journal of Travel & Tourism Marketing
Leung, Au, & Law (2015)
Hoc Nang Fong, Au, & Law (2015)
Methods of Information in Medicine
Applied Clinical Informatics
Lehmann & Haux (2014)
Lehmann & Gundlapalli (2015)
Haux & Lehmann (2014)
Chinese Journal of Catalysis
Archives of Toxicology
Stewart & Marchan (2012)
Cadenas, Marchan, et al. (2012)
Let us look more closely at the first two cases listed above. In the first case, the article published in the Asia Pacific Journal of Tourism Research contains 161 references (out of 172) to the Journal of Travel & Tourism Marketing, which also published an article with 130 references (out of 161) to the Asia Pacific Journal of Tourism Research. Both papers are co-authored by Rob Law, the managing editor of one of the journals and an editorial board member of the other.
The second case involves a set of three papers, two of them published in Methods of Information in Medicine and the third one in Applied Clinical Informatics. This case also involves editorial board members. More precisely, Applied Clinical Informatics has Christoph Ulrich Lehmann as editor-in-chief and Reinhold Haux and Adi V. Gundlapalli as editorial board members. Lehmann (editorial board member) and Haux (senior consulting editor) are also both on the editorial board of Methods of Information in Medicine. We note that the journals involved in this second case have been suppressed by Thomson Reuters in this year’s Journal Citation Reports because of citation stacking. This indicates a certain convergence between Thomson Reuters’ method for detecting abnormal citation patterns and our own.
In each of the above cases, there is a reciprocal relationship between a pair of journals, with one or more articles in one journal citing heavily to the other journal and the other way around. Many more examples can be given of articles in one journal citing heavily to a specific other journal, but our preliminary analysis suggests that reciprocal relationships similar to the ones listed above are relatively rare.
Trying to conclude whether articles have been published with the specific intent to increase the citation statistics of a cited journal, and in particular the journal’s impact factor, is perhaps a slippery slope. And even if the idea of increasing a journal’s impact factor has played a role in the publication of an article, one could still debate how this should be judged from an ethical perspective. For the moment, we would like to get a better empirical understanding of citation stacking and the related phenomenon of citation cartels. A large-scale analysis of citation data is one approach to obtain such an understanding, but more subtle ways in which citation cartels could potentially operate may go unnoticed in such an analysis. Therefore, we also would like to benefit from the knowledge and the experiences of the readers of this blog post. Sharing your knowledge on citation cartels may help to obtain a more refined picture of the phenomenon of citation cartels, and it may support us in improving our algorithms for detecting suspicious citation behavior.
If you have any information on citation cartels, we would be very grateful if you could share this information with us. This can be done by responding to this blog post or, if you prefer to share your information privately, by contacting us by e-mail. We will collect and analyze all information we receive, and we plan to publish the results either in a follow-up blog post or as part of a scientific paper.
Postscript (June 24th, 2016): It has been suggested to us that it may have been more appropriate to anonymize the cases discussed in this blog post. We have chosen not to anonymize the cases because we feel that discussions on citation stacking and citation cartels benefit from everyone having full access to all relevant information. However, we very much welcome a discussion on the pros and cons of anonymization. We would like to emphasize that we have tried not to make any assumptions about authors’ intent in this blog post. We have contacted the authors of the papers mentioned above to inform them about the publication of the blog post, and we have invited them to share their views by responding to the blog post.
Postscript (July 19th, 2016): The title of this blog post has been changed from ‘What do we know about journal citation cartels? Some evidence and a call for information’ into ‘What do we know about journal citation cartels? A call for information’. The original title gave the incorrect impression that our blog post provides evidence of journal citation cartels. The evidence that we provide is about citation stacking, not necessarily about citation cartels.