Collaborative Research: Obsolescence of Durable Goods and Aggregate Fluctuations

在技术革新率高的市场中，陈旧过时是耐用品贬值的主要原因。 由于许多技术创新都包含在新的耐用品中，因此耐用品的过时建模对于我们理解宏观经济至关重要。 考虑耐久性的主要方式是指数物理折旧。 陈旧过时在两个重要方面不同于实物折旧。 首先，过时不是一个连续的过程。 新产品的开发是昂贵的，这就是为什么新产品只是周期性地推出。 例如，每年都会出现新的汽车型号，新一代英特尔处理器平均每三年出现一次。 因此，新型号的周期性到来使过时离散。 第二，随着过时，来自商品的服务流由其技术时代定义。 计算机因为不能运行最新的软件而变得过时。 当最新的车型到达时，新车库存会大幅打折，这表明过时在汽车中也很重要。 由于耐用品即使从未使用也会老化，因此延迟购买新型号的消费者将享受较低的服务流程。因此，过时给消费者一个激励，以协调他们的更换决定与新的模式介绍。 这种关于过时的思考方式以前没有得到充分的探讨，但它可能对宏观经济波动的模式产生深远的影响。 本项目研究一类具有耐用品过时的动态经济。 它看起来像一个一般均衡模型，具有竞争性的耐用品生产，以及耐用品市场的模型与战略生产者。

Obsolescence is the major reason for depreciation of durables in markets with high rates of technological innovation. Since much of the technological innovation is incorporated in new durables, modeling obsolescence of durable goods is vital for our understanding of the macroeconomy. The dominant way of thinking about durability is in terms of exponential physical depreciation. Obsolescence is different from physical depreciation in two important respects. First, obsolescence is not a continuous process. Development of new products is costly, which is why new goods are introduced only periodically. For example, new car models appear every year, and new generations of Intel processors appear on average, every three years. Thus periodic arrival of new models makes obsolescence discrete. Second, with obsolescence, the service flow from the good is defined by its technological age. Computers become obsolete because they cannot run the latest software. New car inventory is heavily discounted when the latest models arrive, suggesting that obsolescence is important in cars as well. Since durables age even if never used, consumers who purchase a new model with a delay will enjoy a lower service flow. Thus obsolescence gives consumers an incentive to coordinate their replacement decisions with new model introductions. This way of thinking about obsolescence has not been fully explored before, yet it may have profound effects on the patterns of macroeconomic fluctuations. This project studies a class of dynamic economies with durable goods subject to obsolescence. It looks a general equilibrium models with competitive production of durable goods as well as models of durable good markets with strategic producers.