  The purpose of citation indexes and metrics is intended to be a measure for
scientific innovation and quality for researchers, journals, and institutions.
However, those metrics are often prone to abuse and manipulation by excessive
and unethical self-citations induced by authors, reviewers, editors, or
journals. Identifying whether there are or not legitimate reasons for
self-citations is normally determined during the review process, where the
participating parts may have intrinsic incentives, rendering the legitimacy of
self-citations, after publication, questionable. In this paper, we conduct a
large-scale analysis of journal self-citations while taking into consideration
the similarity between a publication and its references. Specifically, we look
into PubMed Central articles published since 1990 and compute similarities of
article-reference pairs using sentence embeddings. We examine journal
self-citations with an aim to distinguish between justifiable and unethical
self-citations.
