Li, Mingtang; (2024) Disruptive Innovation, Academic Impact, and Performance Dynamics in Scientific Careers. Doctoral thesis (Ph.D), UCL (University College London).

Text PhD Thesis Mingtang Li.pdf - Accepted Version Access restricted to UCL open access staff until 1 July 2025. Download (3MB)

Abstract

This thesis investigates the performance dynamics of scientific careers from the perspective of disruptive innovation. The primary motivation for this research arises from the prevalence of citations in research evaluations and its implications for both disruptive innovation and scientific careers. In the current research evaluation system, academic impact is usually operationalized through citation counts. Such practices incentivize researchers to pursue high productivity and to publish `safe' contributions in their careers, which stifles risk-taking, inhibits disruptive innovation, and proves detrimental to scientific development. In this research, disruptive innovation in science is quantified by the disruption score. This metric evaluates the extent to which a focal paper overshadows prior works cited in its bibliography and has demonstrated its effectiveness in measuring disruptive innovation across various publications in the science of science. Building on the disruption score, the thesis conducts three studies using datasets from Computer Science and Physics. These studies examine the evolution of career performance, the underlying mechanisms of disruptive innovation, and the tension between disruptions and citations. The thesis consists of three studies, summarized as follows: • Study 1 -- The Relationship between Disruptions and Citations. The first study analyzes correlations between disruption scores and citation counts. We show that in both publication and researcher datasets, highly disruptive papers tend to receive more citations than average, whereas highly cited papers are typically less disruptive. Our findings suggest that the two metrics capture distinct information, which substantiates the validity of the disruption score. • Study 2 -- Patterns in Disruption Peak Year. The second study examines the career milestone of disruptive innovation, defined as the most disruptive paper published by a researcher. We observe that this peak paper does not occur randomly in scientific careers. It is published during a peak year of disruption when other publications also exhibit high levels of disruption. Through a series of regression models, we find that the disruption level of the peak year is higher if preceded by a long period of focus and low productivity. These results are in stark contrast with the dynamics of impact, capturing the tension between disruptive innovation and academic impact in scientific careers. • Study 3 -- Dynamics of Disruptions and Citations in Scientific Careers. The third study investigates the yearly disruption and citation dynamics of researchers over a span of 20 years, focusing on the interaction between them. Our analysis indicates that disruption dynamics are characterized by the disruption peak year, whereas citation dynamics display an inverted V-shaped pattern in yearly citation levels. Despite these differing patterns, the two dynamics are largely independent of each other within the careers of researchers. The thesis presents the following contributions to science: • Underlying mechanisms of disruptive innovation. Our analysis of peak year disruption level indicates that truly disruptive research requires the accumulation of research experience and is typically preceded by long periods of concentration and low productivity. This contrasts with the dynamics of academic impact, which favor the pursuit of high productivity and incremental work in scientific careers. These results provide empirical evidence for scientific policy-making, supporting the development of more effective research evaluation standards to promote disruptive innovation. • Evolution of performance in scientific careers. This thesis examines the disruption and citation dynamics of researchers over a period of 20 years. In scientific careers, while the ability to attract citations improves over time, the capacity to disrupt is primarily marked by the most disruptive paper and the corresponding peak year. Intuitively, one might expect that an enhanced ability to attract citations would reflect an advanced capacity to disrupt. However, our findings suggest that this is not the case, as disruption and citation dynamics are largely independent within the careers of researchers. • Identification of high-quality research. Our studies suggest that academic impact and disruptive innovation are complementary dimensions for evaluating scientific contributions. In practice, a comprehensive research evaluation could incorporate both citation metrics and disruption scores, as papers and researchers excelling in both standards are more likely to be truly exceptional. • Comprehensive relationship between disruptions and citations. This thesis breaks down the correlation between disruption scores and citation counts at the level of both academic publications and scientific careers. This relationship not only reconciles the seemingly contradictory results in the literature but also establishes a solid foundation for future studies that integrate both disruption and citation analysis. • Pioneering the use of disruption scores in career analysis. While prior research relies heavily on citation counts and productivity to assess researchers' performance, this thesis is among the earliest to analyze scientific careers using the disruption score. Our work supports the effectiveness of disruption scores in career analysis. This methodological contribution provides a new perspective for evaluating the careers of researchers. Two papers based on Study 1 and Study 2 have been drafted and submitted for publication. The provisional titles of these papers are Breaking Down the Relationship between Academic Impact and Scientific Disruption and Quantifying the Dynamics of Peak Disruption in Scientific Careers.

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