On the skewness of journal self-citations and publisher self-citations: Cues for discussion from a case study

This paper takes the cue from the case of a retracted paper, cited both by the retraction notice and by an article published later in the same journal. This led to analysis and discussion on the skewness of citations in the journal Sustainability and within Multidisciplinary Digital Publishing Institute (MDPI) journals, particularly investigating self-citations at journal and publisher levels. I analysed articles published by Sustainability in 2015 and found that self-citations are higher than expected under a uniform probability distribution. Self-citations in this journal make a 36% difference to the journal's impact factor. This research raises the question of what citation patterns can be expected as normal, and where the boundary between normal and anomaly lies. I suggest the issue deserves further investigation because self-citations have several implications, ranging from impact factors to visibility and influence of scientific journals.