Innovation Networks and Innovation Policy

We study the optimal allocation of R&D resources in an endogenous growth model with an innovation network, through which one sector's past innovations may benefit other sectors' future innovations. First, we provide closed-form sufficient statistics for the optimal path of R&D resource allocation, and we show that planners valuing long-term growth should allocate more R&D toward key sectors that are upstream in the innovation network. Second, we extend to an open-economy setting and illustrate an incentive for countries to free-ride on fundamental technologies: an economy more reliant on foreign knowledge spillovers has less incentive to direct resources toward innovation-upstream sectors, leading to cross-country differences in unilaterally optimal R&D allocations across sectors. Third, we build the global innovation network based on over 30 million global patents and establish its empirical importance for knowledge spillovers. Fourth, we apply the model to evaluate R&D allocations across countries and time. Adopting optimal R&D allocations can generate substantial welfare improvements across the globe. For the United States, R&D misallocation accounts for about 0.68 percentage points of missing annual growth since the 2000s