Does the productivity J-curve exist in Japan?-Empirical studies based on the multiple q theory

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).