Optimal combination of patent instruments in a cumulative-innovation growth model
Review of Economic Dynamics · 2026 · Davin Chor、Edwin L.‐C. Lai
中文摘要
我们构建了一个关于累积创新与增长的易于处理的一般均衡模型,以研究三种专利工具的最优组合:防止未来渐进式创新的可专利性要求、防止当期模仿的专利宽度,以及决定专利有效期限的专利长度。新思想严格建立在前沿技术之上,生产率改进的幅度则从随机分布中抽取。模型具有正的知识外溢,我们讨论了在何种情况下,相对于社会计划者基准,市场均衡会导致研发投资不足。我们以解析方式刻画了每种专利工具如何影响研发激励,并进一步证明:在福利最大化组合中,可专利性要求与专利宽度均被设定在严格低于研发最大化组合的水平。将模型校准至总量数据后,福利最大化的工具组合表现为较大的专利宽度、较长的专利期限,但适中的可专利性要求。定量分析表明,这些专利政策可带来可观的福利收益,同时凸显了拥有多种专利工具的重要性。
Abstract
We develop a tractable general equilibrium model of cumulative innovation and growth to study the optimal combinations of three patent instruments: a patentability requirement to protect against future incremental innovation, a patent breadth to protect against current imitation, and the patent length governing the duration of its validity. New ideas strictly build upon frontier technologies, with the size of productivity improvements drawn from a stochastic distribution. The model features positive knowledge spillovers, and we discuss when this leads to under-investment in R&D in the market equilibrium relative to the social planner’s benchmark. We characterize analytically how each patent instrument affects research incentives, and further establish that the patentability requirement and patent breadth in the welfare-maximizing combination are each set at a strictly lower level than in the R&D-maximizing combination. Calibrating the model to aggregate data, the welfare-maximizing combination of instruments features a large patent breadth, a long patent duration, but a modest patentability requirement. The quantitative analysis points to sizeable welfare gains from these patent policies, while highlighting the importance of having multiple patent instruments.