Are Technology Improvements Contractionary?
构建了衡量总体技术变化的指标，发现技术改进在短期内导致投入和投资大幅下降，产出变化不大，几年后投入和投资恢复正常且产出强劲上升。标准真实商业周期模型无法解释这一现象，而简单粘性价格模型与之吻合。
Yes. We construct a measure of aggregate technology change, controlling for aggregation effects, varying utilization of capital and labor, nonconstant returns, and imperfect competition. On impact, when technology improves, input use and nonresidential investment fall sharply. Output changes little. With a lag of several years, inputs and investment return to normal and output rises strongly. The standard one-sector real-business-cycle model is not consistent with this evidence. The evidence is consistent, however, with simple sticky-price models, which predict the results we find: when technology improves, inputs and investment generally fall in the short run, and output itself may also fall.