Optimal Adoption of Complementary Technologies
当生产过程需要两种高度互补的投入时，传统观点认为企业应同时升级它们。但本文表明，若升级每种投入有固定成本，企业可能在不同时间异步升级，这有助于解释工厂生产力随年龄增长、投资波动等现象。
When a production process requires two extremely complementary inputs, conventional wisdom holds that a firm would always upgrade them simultaneously. We show, however, that if upgrading each input involves a fixed cost, the firm may upgrade them at different dates, “asynchronously.” This insight helps us understand why productivity rises with the age of a plant, why investment in structures is more spiked than equipment investment, and why plants have spare capacity. The bigger point of the paper is that complementarity does not necessarily imply comovement—not even for a single decision maker.