The Life Cycle of Products: Evidence and Implications
研究发现单个产品的销售额在产品生命周期中持续下降，产品因面临来自竞争企业和本企业新产品的竞争而迅速过时。构建的动态模型揭示了创新与过时的循环，对量化经济增长和创新政策的影响有重要意义。
We document that sales of individual products decline steadily throughout most of the product life cycle. Products quickly become obsolete as they face competition from newer products sold by competing firms and the same firm. We build a dynamic model that highlights an innovation-obsolescence cycle, where firms need to introduce new products to grow; otherwise, their portfolios become obsolete as rivals introduce their own new products. By introducing new products, however, firms accelerate the decline of their own existing products, further depressing their sales. This mechanism has sizable implications for quantifying economic growth and the impact of innovation policies.