Brynjolfsson, Rock, and Syverson (2021) argued that the standard TFP growth is low during an investment boom for new technology such as the IT revolution. As the new capital is operated and productivity improves, the shape of the movements in the standard productivity growth resembles a J-curve. However, when costs associated with investment for new technology are recognized as intangible investment - which is not counted in the conventional value added –, the revised TFP growth including these unmeasured intangibles show different movements from the standard TFP growth. Following Brynjolfsson, Rock, and Syverson (2021), we examine the gap between the standard TFP growth and the revised TFP growth. According to their theory, unmeasured intangibles are estimated by the gap between the shadow value and the price of investment goods. We obtain this shadow value of investment through an estimated parameter in each asset using listed firm-level data and revise the standard TFP growth rate. In the case of all industries, the standard TFP growth is overestimated in most years in the late 1990s and the 2000s, because the growth in intangible investment associated with measured investment is lower than measured capital accumulation rate. When we focus on the IT-intensive industries, we find the productivity J-curve in the late 1990s, at the early stage of the IT revolution, as indicated by Brynjolfsson, Rock and Syverson (2021).

Brynjolfsson，Rock和Syverson（2021）认为，在IT革命等新技术的投资热潮期间，标准的TFP增长率较低。随着新资本的运营和生产率的提高，标准生产率增长中的运动形状类似于J曲线。但是，当将与新技术投资相关的成本确认为无形投资时（不计入传统增加值中），修订后的TFP增长（包括这些未计量的无形资产）显示出与标准TFP增长不同的变化。继Brynjolfsson，Rock和Syverson（2021）之后，我们研究了标准TFP增长与修正TFP增长之间的差距。根据他们的理论，未计量的无形资产是通过影子价值与投资商品价格之间的差距来估算的。我们使用列出的公司级数据通过每种资产的估计参数来获得此投资的影子值，并修改标准TFP增长率。就所有行业而言，在1990年代末和2000年代的大多数年份中，标准全要素生产率的增长都被高估了，因为与可衡量的投资相关的无形投资的增长低于可衡量的资本积累率。当我们专注于IT密集型行业时，我们发现在1990年代末期，即IT革命的早期阶段，生产率曲线呈J曲线，正如Brynjolfsson，Rock和Syverson（2021）所指出的那样。因为与计量投资相关的无形投资的增长低于计量资本积累率。当我们专注于IT密集型行业时，我们发现在1990年代末期，即IT革命的早期阶段，生产率曲线呈J曲线，正如Brynjolfsson，Rock和Syverson（2021）所指出的那样。因为与计量投资相关的无形投资的增长低于计量资本积累率。当我们专注于IT密集型行业时，我们发现在1990年代末期，即IT革命的早期阶段，生产率曲线呈J曲线，正如Brynjolfsson，Rock和Syverson（2021）所指出的那样。