Tracing policy diffusion: Identifying main paths in policy citation networks

Citation-based main path analysis (MPA) has been widely applied to identify developmental trajectories of science and technology, while rarely used to detect paths of policy diffusion. Compared with scientific publications and patents, policy documents show some distinct characteristics, such as citation relationships with different legal validity, which could be considered to improve the policy citation analysis. To this end, this study formally constructs a policy citation network based on a plethora of citing/cited links embedded in the textual content of policy documents and proposes a preference-adjusted main path analysis (PMPA) approach to track historical routes of policy diffusion. PMPA incorporates two kinds of policy citation preferences, including validity bias and time bias. An evidence analysis from China's new energy policies (NEPs) is implemented to show the efficacy of the proposed approach. The results unveil that the preference-adjusted main path approach can capture more important policies and more informative main paths of policy diffusion than the original MPA. Moreover, our research can yield in-depth insight into the evolutionary process of policy diffusion and provide guidance for policy-makers and industry decision-makers to formulate practical policy-making.