Abstract
Many of today’s societal challenges, such as climate change, biodiversity, and social inequality require responses that integrate insights from diverse disciplines. This recognition has led to efforts at individual, institutional, and country levels to encourage and conduct interdisciplinary research (IDR), i.e. research that integrates ideas from diverse disciplines, to overcome difficulties associated with bridging different research practices or other cultural aspects across these disciplines. Research on IDR, however, has not led to a coherent body of understanding on the concept of IDR, its measurement, and its factors. The objective of this thesis is to contribute to such an understanding.
This thesis first presents a synthesis of the conceptual definitions of IDR, based on which criteria are set for its measurement. We then use these to evaluate 21 measures of IDR, to then select one measure for our empirical analyses. Using a large, multidisciplinary dataset of publications, we validate this measure empirically by comparing it to others, by comparing it to manual assessments, by evaluating its sources of uncertainty and by quantifying this uncertainty through bootstrapping. Based on a review of reported factors of IDR in the literature, we focus on developing hypotheses that relate the IDR of research publications to various aspects of their respective author teams, including their size, specialisation variety, and the diversity of their knowledge base. Our regression analyses and robustness checks yielded no support for the common belief that larger teams publish research that is more interdisciplinary. Having a history of publishing IDR within the team members, however, was found to be a strong team-level factor of IDR.
In sum, this thesis contributes to the literature, a synthesized definition of IDR along with evaluation criteria for its measurement, a conceptual evaluation of various measures proposed in the literature, an empirical validation of one of the measures, and novel insights into the key team-level factors of IDR. The thesis provides recommendations for the application of the measures of IDR and the achievement of greater consistency in its measurement more generally and discusses the practical implications of its findings on the team-level factors of IDR.