A new approach for main path analysis: Decay in knowledge diffusion

Main path analysis is a powerful tool for extracting the backbones of a directed network and has been applied widely in bibliometric studies. In contrast to the no-decay assumption in the traditional approach, this study proposes a novel technique by assuming that the strength of knowledge decays when knowledge contained in one document is passed on to another document down the citation chain. We propose three decay models, arithmetic decay, geometric decay, and harmonic decay, along with their theoretical properties. In general, results of the proposed decay models depend largely on the local structure of a citation network as opposed to the global structure in the traditional approach. Thus, the significance of citation links and the associated documents that are overemphasized by the global structure in the traditional no-decay approach is treated more properly. For example, the traditional approach commonly assigns high value to documents that heavily reference others, such as review articles. Specifically in the geometric and harmonic decay models, only truly significant review articles will be included in the resulting main paths. We demonstrate this new approach and its properties through the DNA literature citation network.