This dissertation consists of three chapters studying topics in innovation, diffusion and economic growth. The first chapter studies the creativity of innovations filed in US patents. The second chapter studies the diffusion of disruptive technologies. The third chapter develops a measure of knowledge diffusion across borders and emphasizes the role of immigration, trade and FDI.
In the first chapter, I study the divergence between falling aggregate TFP growth and rising number of new patents filed. I offer an explanation for this puzzling divergence: the creativity embodied in US patents has dropped dramatically over time. To separate creative from derivative patents, I develop a novel, text-based, measure of patent creativity: the share of two-word combinations that did not appear in previous patents. I show that only creative and not derivative patents are associated with significant improvements in firm level productivity and stock market valuations. Using the measure, I show that younger inventors on average file more creative patents. To estimate the effect of changing US demographics on aggregate creativity and productivity growth, I build a growth model with endogenous creation and adoption of technologies. In this model, falling population growth explains 42% of the observed decline in patent creativity, 32% of the slowdown in productivity growth, and 15% of the increase in derivative patenting.
In the second chapter, I (along with my coauthors Nick Bloom, Tarek Hassan, Josh Lerner, Marcela Mello and Ahmed Tahoun) identify phrases associated with novel technologies using textual analysis of patents, job postings, and earnings calls, enabling us to identify key stylized facts on the diffusion of jobs relating to new technologies. First, the development of disruptive technologies is geographically concentrated, more so even than overall patenting. 53% of disruptive technologies come from just two U.S. locations, Silicon Valley and the North-East corridor. Second, as the technologies mature and the number of new related jobs grows, hiring spreads geographically. But this process is very slow, taking around 50 years to disperse fully. Third, while initial hiring is concentrated in high-skilled jobs, over time the mean skill level in new positions declines, driven by the reduced importance of positions associated with research, development, and production of technologies.
In the third chapter, I develop a new measure to identify international knowledge diffusion. Using this measure, I provide empirical evidence to highlight drivers, benefits and frictions of knowledge diffusion. First, I show that knowledge diffusion is embodied in migrants, trade and foreign direct investment. Second, knowledge diffusion from advanced countries is associated with higher firm value and higher productivity. Third, vast majority of variation in my measure is at the firm level, not at the country or the sector level. This suggests a role of firm-level frictions in diffusion of knowledge across countries.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/49080 |
| Date | 16 July 2024 |
| Creators | Kalyani, Aakash |
| Contributors | Hassan, Tarek A., Restrepo, Pascual |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution-NonCommercial-NoDerivatives 4.0 International, http://creativecommons.org/licenses/by-nc-nd/4.0/ |
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