Empirical evidence demonstrates that citations received by scholarly publications follow a pattern of preferential attachment, resulting in a power-law distribution. Such asymmetry has sparked significant debate regarding the use of citations for research evaluation. However, a consensus has yet to be established concerning the historical trends in citation concentration. Are citations becoming more concentrated in a small number of articles? Or have recent geopolitical and technical changes in science led to more decentralized distributions? This ongoing debate stems from a lack of technical clarity in measuring inequality. Given the variations in citation practices across disciplines and over time, it is crucial to account for multiple factors that can influence the findings. This article explores how reference-based and citation-based approaches, uncited articles, citation inflation, the expansion of bibliometric databases, disciplinary differences, and self-citations affect the evolution of citation concentration. Our results indicate a decreasing trend in citation concentration, primarily driven by a decline in uncited articles, which, in turn, can be attributed to the growing significance of Asia and Europe. On the whole, our findings clarify current debates on citation concentration and show that, contrary to a widely-held belief, citations are increasingly scattered.

中文翻译：

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未被引用文章的减少及其对被引集中度的影响

经验证据表明，学术出版物收到的引用遵循优先依恋模式，从而导致幂律分布。这种不对称性引发了关于使用引用进行研究评估的重大争论。然而，关于引用集中度的历史趋势尚未达成共识。引用是否越来越集中在少数文章中？或者最近科学领域的地缘政治和技术变化是否导致了更加分散的分布？这场持续的争论源于衡量不平等的技术清晰度的缺乏。鉴于不同学科和不同时间的引文实践存在差异，考虑到可能影响研究结果的多种因素至关重要。本文探讨了基于参考文献和基于引文的方法、未引用的文章、引文膨胀、文献计量数据库的扩展、学科差异和自引如何影响引文集中度的演变。我们的结果表明，引用集中度呈下降趋势，这主要是由于未引用文章的减少所致，而这反过来又可归因于亚洲和欧洲的重要性日益增强。总体而言，我们的研究结果澄清了当前关于引用集中度的争论，并表明，与广泛持有的观点相反，引用越来越分散。