International knowledge spillover through co-inventors: An empirical study using Chinese assignees' patent data

摘要

Knowledge spillover is a widespread phenomenon among main economic entities of the world. Most of prior studies adopt patent citation data to indicate the traces of knowledge flows. However, patent citation is a noisy indicator in reflecting technology diffusion and has limitation in identifying knowledge flows induced by personal contacts. In this paper, we propose a method for the construction of international knowledge spillover networks by incorporating patent citations with co-inventors information so as to detect the change of network structure induced by social ties of co-inventors and reflect both explicit and tacit knowledge diffusions across national frontiers. We apply the proposed method to a sample of power system related patents granted to Chinese assignees by USPTO during 2000-2007. Our results confirm that patent citation is not an adequate indicator of knowledge flows since it reflects very few knowledge exchanging channel. However, co-invented relationships which provide trace of tacit knowledge flows can complement the patent citation data to produce a fuller picture of international knowledge spillover. The incorporation of co-inventors data helps produce a Sino-American spillover network with a structure changed from extremely loose to loosely-tied in whole but cohesive locally. The cohesive subgroups contribute much to knowledge spillover from U.S. to China and dissipate internally among Chinese firms.