A recent analysis of scientific publication and patent citation networks by Park et al. (Nature, 2023) suggests that publications and patents are becoming less disruptive over time. Here we show that the reported decrease in disruptiveness is an artifact of systematic shifts in the structure of citation networks unrelated to innovation system capacity. Instead, the decline is attributable to 'citation inflation', an unavoidable characteristic of real citation networks that manifests as a systematic time-dependent bias and renders cross-temporal analysis challenging. One driver of citation inflation is the ever-increasing lengths of reference lists over time, which in turn increases the density of links in citation networks, and causes the disruption index to converge to 0. A second driver is attributable to shifts in the construction of reference lists, which is increasingly impacted by self-citations that increase in the rate of triadic closure in citation networks, and thus confounds efforts to measure disruption, which is itself a measure of triadic closure. Combined, these two systematic shifts render the disruption index temporally biased, and unsuitable for cross-temporal analysis. The impact of this systematic bias further stymies efforts to correlate disruption to other measures that are also time-dependent, such as team size and citation counts. In order to demonstrate this fundamental measurement problem, we present three complementary lines of critique (deductive, empirical and computational modeling), and also make available an ensemble of synthetic citation networks that can be used to test alternative citation-based indices for systematic bias.

翻译：帕克等人（《自然》，2023）近期对科学出版物与专利引文网络的分析表明，出版物与专利的颠覆性随时间推移逐渐减弱。本研究证明，这种看似下降的颠覆性实则是与创新系统能力无关的引文网络结构系统性偏移造成的人为假象。该下降趋势实际源于"引文膨胀"——真实引文网络固有的系统时间依赖性偏差特征，该特性使跨时间分析面临挑战。引文膨胀的成因之一在于参考文献列表长度随时间持续增长，这直接导致引文网络连接密度增加，并使颠覆性指数趋近于零。第二重驱动因素来自参考文献列表构建方式的转变：自引比例上升加剧了引文网络中的三元闭包形成速率，从而干扰了本为三元闭包测度的颠覆性评估。两重系统性偏移的共同作用，使得颠覆性指数存在时间偏差，不适用于跨时间分析。该系统性偏差进一步阻碍了将颠覆性与团队规模、引文数量等其他时间依赖性指标进行相关性研究的尝试。为揭示这一根本测量问题，我们提出演绎论证、实证分析与计算建模三类互补性批判路径，并公开一套可检验其他基于引文的指数系统性偏差的合成引文网络集成。