H-index remains one of the key quantitative indicators used to assess a researcher when applying for a position, submitting grant proposals, or undergoing academic evaluation. There are numerous strategies for raising it, including self-citation. However, many researchers deliberately avoid referencing their own previous work, believing that it will look like manipulation of their metrics. How justified are these concerns, and how does self-citation really affect the h-index? Let's examine this in the article below.
What is self-citation, and how does it affect the h-index?
Self-citation – is when an author references their own previously published work in a new scientific paper. This practice is fairly common, since research rarely starts from scratch, and researchers usually build on results they obtained in earlier work. The rate is measured as a percentage of the total number of references in a paper, and the approximate threshold generally considered acceptable is 12%.
To understand the relationship between the h-index and self-citation, it is worth looking at the underlying logic of this indicator. H-index is built on the number of publications and the citations they receive, and self-citation is, in essence, just another citation that the author adds by their own hand.
When a researcher references their own earlier paper in a new one, they thereby increase the citation count of that earlier paper by one. Since the h-index depends directly on how many citations each publication accumulates, such an action can, in theory, bring a paper closer to the conditions needed for the indicator to grow.
In practice, however, this effect is usually limited. One or two self-citations are rarely able to significantly change the h-index, especially if a researcher has a large body of publications and has already accumulated a substantial number of citations from other authors. In such a case, a few additional references make almost no difference against the overall picture. The effect becomes more significant, however, at the early stages of a research career, when overall citation numbers are still low. In this situation, every individual reference to a paper, including self-citation, has a more noticeable impact on the final figure.
Possible consequences of excessive self-citation
Because isolated self-citations cannot instantly raise the h-index, some researchers try to compensate for this with quantity, and start overusing the practice, adding more references to their own work than is justified by the content. However, excessive and inappropriate self-referencing can harm a researcher far more than it benefits them through formally higher influence metrics. How exactly?
- Loss of trust. The author's reputation suffers first and foremost. The academic community may interpret unjustified references to one's own work as an attempt to artificially boost one's metrics and standing within the academic environment. This, in turn, calls the researcher's honesty and integrity into question.
- Decline in the quality of the work. Some authors overuse self-citation to such an extent that they fail to sufficiently account for the work of colleagues in the same field. As a result, the paper loses novelty and relevance, since it lacks the integration of other research that could have broadened its context.
- Breach of academic integrity. If self-citation is used to manipulate metrics or to mask a study's weak novelty, this is classified as a breach of research ethics.
- Rejection by the editorial board. The level of self-citation is one of the parameters checked during peer review. If it appears unjustifiably high, editors and reviewers may begin to doubt the paper's scientific novelty and the author's academic integrity, which risks the paper being rejected for publication.
When is self-citation appropriate, and should it be avoided?
The negative consequences described above relate specifically to overuse, not to the practice itself. Referencing one's own previous work is entirely justified in several cases. First, when another study by the author is necessary for understanding the new paper, and the topic cannot be fully addressed without it. Second, when it adds depth and context to the topic through relevant data. And finally, when the new article is a direct continuation or development of the previous one, and the reference is needed to correctly show this connection and avoid self-plagiarism.
So the question is not whether to use self-citation, but how to do so competently and appropriately. What needs to be taken into account: Self-citation within approximately 12% of the total number of references usually raises no questions and is in line with average field-specific norms. Every self-citation should be checked for substantive necessity (whether the reader genuinely needs this reference, not just the author). Self-citations should not be added merely to pad the statistics, since reviewers and editors easily recognise this practice, and it is more likely to raise suspicions of manipulation than to add weight to the work.
In conclusion, self-citation as a practice can significantly ease a researcher's task of writing new papers, as it allows them to logically build on their own previous work without describing already-known methods or results all over again. At the same time, its effect on the h-index generally remains moderate. Early in a research career, when the number of citations is still small, self-citation can have a somewhat more noticeable effect on the indicator. However, as the number of publications and citations grows, this effect becomes progressively less pronounced.
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