The Impact of Production Externality on Intra-Industry Reallocations and Aggregate Industry Productivity

[[abstract]]本文提供一些理論架構描述產業在生產上的正向外部性對個別廠商生產的影響，進而討論它如何造成產業資源配置及整體產業生產力的變動。首先，我們利用獨佔性競爭模型分析產業內及跨產業的外部性分別影響廠商的邊際生產力及生產之固定成本的情況下之各種總和效果。當外部性影響邊際生產力時，產業的廠商數並不會改變，但個別生產力提高會提升總和生產力，經濟體系的總體福利因此改善。當外部性影響廠商生產之固定成本時，個別廠商的產量維持固定，但廠商數增加，此促使總和生產力增加，經濟體系的福利也因而提升。最後，我們分析產業內廠商生產力異質，且個別廠商為產業內的獨佔廠商時，產業的外部性對總體生產力的影響。外部性影響廠商存活於產業內的門檻，而造成產業內廠商數的變動，整體生產力因個別廠商生產力提高及廠商數的增加而向上提升。[[abstract]]This article provides some theoretical frameworks to depict the impact of the positive externalities on individual manufacturer that are sourced from industrial production, and then discuss how the externalities can make industries’ productions reallocate and boost their productivities. First, we apply the model established by Dixit and Stiglitz (1977) to analyze what the effects of Intra-industry externalities and Inter-industry externalities on the aggregate and individual productions are in the cases in which they affect individual firms’ marginal productivity and its fixed costs of production. When the externalities affect the marginal productivity of individual firm, the number of manufacturers in industry remains the same, but the aggregate productivities of industry increase and hence the welfare of the economy is improved. When the externalities affect the individual firms’ fixed costs of production, individual firm’s output maintains a constant, but the number of industrial manufacturers is increased. This promotes aggregate productivity and benefits the welfare of economy. Finally, we analyze how the impact of externalities on the overall productivity of industry in the case where firms have heterogeneous productivities and individual manufacturer is a monopolistic firm. Externalities affect the threshold that to survive in a market an individual firm has its productivity surpass, induce a change in the number of firms that exist within an industry, and lifts the overall productivity of industry.[[note]]碩