Synergizing Ventures

(w/ Emin Dinlersoz, Jeremy Greenwood, Veronika Penciakova)

Abstract: Venture capital and growth are examined both empirically and theoretically. Empirically, VC-backed startups have higher early growth rates and patenting levels than non-VC-backed ones. Venture capitalists increase a startup’s likelihood of reaching the right tails of the firm size and innovation distributions. Furthermore, outcomes are better for startups matched with more experienced venture capitalists. An endogenous growth model, where venture capitalists provide both expertise and financing for business startups, is constructed to match these facts. The presence of venture capital, the degree of assortative matching between startups and financiers, and the taxation of VC-backed startups matter significantly for growth.

Abstract: In this paper, we review the literature on declining business dynamism and its implications in the United States and propose a unifying theory to analyze the symptoms and the potential causes of this decline. We first highlight 10 pronounced stylized facts related to declining business dynamism documented in the literature and discuss some of the existing attempts to explain them. We then describe a theoretical framework of endogenous markups, innovation, and competition that can potentially speak to all of these facts jointly. We next explore some theoretical predictions of this framework, which are shaped by two interacting forces: a composition effect that determines the market concentration and an incentive effect that determines how firms respond to a given concentration in the economy. The results highlight that a decline in knowledge diffusion between frontier and laggard firms could be a significant driver of empirical trends observed in the data. This study emphasizes the potential of growth theory for the analysis of factors behind declining business dynamism and the need for further investigation in this direction.

What Happened to U.S. Business Dynamism?

(w/ Sina Ates)

NBER Working Paper #25756

Read more at: VoxEU, AEI, WCEG, l’Opinion, Frankfurter Allgemeine.
Watch an short interview at: VideoVOX.

Abstract: In the past several decades, the U.S. economy has witnessed a number of striking trends that indicate a rising market concentration and a slowdown in business dynamism. In this paper, we make an attempt to understand potential common forces behind these empirical regularities through the lens of a micro-founded general equilibrium model of endogenous firm dynamics. Importantly, the theoretical model captures the strategic behavior between competing firms, its effect on their innovation decisions, and the resulting ``best vs. the rest'' dynamics. We focus on four potential mechanisms that can potentially drive the observed changes and use the calibrated model to assess the relative importance of these channels. One particular exercise replicates the transitional dynamics of the U.S. economy through joint moves in all four channels and decomposes the contribution of each channel to the resulting trends. Our results highlight the dominant role of a decline in the intensity of knowledge diffusion from the frontier firms to the laggard ones in explaining the observed shifts. We conclude by presenting new evidence that corroborates a declining knowledge diffusion in the economy. We document higher concentration of patenting in the hands of firms with the largest stock and a changing nature of patents, especially in the post-2000 period, which suggests a heavy use of intellectual property protection by market leaders to limit the dissemination of knowledge. These findings present a potential avenue for future research on the drivers of declining knowledge diffusion.

The Patent Troll: Benign Middleman or Stick-Up Artist?

(w/ David Abrams, Gokhan Oz, and Jeremy Pearce)

NBER Working Paper #25713.

Abstract: How do non-practicing entities (“Patent Trolls”) impact innovation and technological progress? We employ unprecedented access to NPE-derived patent and financial data and a novel model to answer this question. We find that NPEs tend to acquire litigation-prone patents from small firms and acquire patents less core to the seller's business. When NPEs license patents, those that generate higher fees are closer to the licensee's business and more litigation-prone. Moreover, downstream innovation drops when patents are acquired by NPEs. Quantitatively, the overall impact of NPEs depends on the share of infringements that come from non-innovating producers.

Connecting to Power: Political Connections, Innovation, and Firm Dynamics

(w/ Salome Baslandze and Francesca Lotti)

NBER Working Paper #25136
CEPR Discussion Paper #13216
BFI Working Paper #2018-72

Read more at: The Economist, Harvard Business Review, BFI Research Brief, VoxEU.
Listen to a Podcast Interview at: VoxTalks.

Abstract: Do political connections affect firm dynamics, innovation, and creative destruction? We study Italian firms and their workers to answer this question. Our analysis uses a brand-new dataset, spanning the period from 1993 to 2014, where we merge: (i) firm-level balance sheet data; (ii) social security data on the universe of workers; (iii) patent data from the European Patent Office; (iv) the national registry of local politicians; and (v) detailed data on local elections in Italy. We find that firm-level political connections are widespread, especially among large firms, and that industries with a larger share of politically connected firms feature worse firm dynamics. We identify a leadership paradox: When compared to their competitors, market leaders are much more likely to be politically connected, but much less likely to innovate. In addition, political connections relate to a higher rate of survival, as well as growth in employment and revenue, but not in productivity -- a result that we also confirm using a regression discontinuity design. We build a firm dynamics model, where we allow firms to invest in innovation and/or political connection to advance their productivity and to overcome certain market frictions. Our model highlights a new interaction between static gains and dynamic losses from rent-seeking in aggregate productivity.

Taxation and Innovation in the 20th Century

(w/ John Grigsby, Tom Nicholas, and Stefanie Stantcheva)

NBER Working Paper #24982.

 Revise and Resubmit, Quarterly Journal of Economics.

Abstract: This paper studies the effect of corporate and personal taxes on innovation in the United States over the twentieth century. We use three new datasets: a panel of the universe of inventors who patent since 1920; a dataset of the employment, location and patents of firms active in R&D since 1921; and a historical state-level corporate tax database since 1900, which we link to an existing database on state-level personal income taxes. Our analysis focuses on the impact of taxes on individual inventors and firms (the micro level) and on states over time (the macro level). We propose several identification strategies, all of which yield consistent results: i) OLS with fixed effects, including inventor and state-times-year fixed effects, which make use of differences between tax brackets within a state-year cell and which absorb heterogeneity and contemporaneous changes in economic conditions; ii) an instrumental variable approach, which predicts changes in an individual or firm's total tax rate with changes in the federal tax rate only; iii) a border county strategy, which exploits tax variation across neighboring counties in different states. We find that taxes matter for innovation: higher personal and corporate income taxes negatively affect the quantity, quality, and location of inventive activity at the macro and micro levels. At the macro level, cross-state spillovers or business-stealing from one state to another are important, but do not account for all of the effect. Agglomeration effects from local innovation clusters tend to weaken responsiveness to taxation. Corporate inventors respond more strongly to taxes than their non-corporate counterparts.

Dancing with the Stars: Innovation through Interactions

(w/ Santiago Caicedo, Ernest Miguelez, Stefanie Stantcheva,  and Valerio Sterzi)

NBER Working Paper #24466.

Revise and Resubmit, Econometrica.

Abstract: An inventor's own knowledge is a key input in the innovation process. This knowledge can be built by interacting with and learning from others. This paper uses a new large-scale panel dataset on European inventors matched to their employers and patents. We document key empirical facts on inventors' productivity over the life cycle, inventors' research teams, and interactions with other inventors. Among others, most patents are the result of collaborative work. Interactions with better inventors are very strongly correlated with higher subsequent productivity. These facts motivate the main ingredients of our new innovation-led endogenous growth model, in which innovations are produced by heterogeneous research teams of inventors using inventor knowledge. The evolution of an inventor's knowledge is explained through the lens of a diffusion model in which inventors can learn in two ways: By interacting with others at an endogenously chosen rate; and from an external, age-dependent source that captures alternative learning channels, such as learning-by-doing. Thus, our knowledge diffusion model nests inside the innovation-based endogenous growth model. We estimate the model, which fits the data very closely, and use it to perform several policy exercises, such as quantifying the large importance of interactions for growth, studying the effects of reducing interaction costs (e.g., through IT or infrastructure), and comparing the learning and innovation processes of different countries.

Abstract: We examine the golden age of U.S. innovation by undertaking a major data collection exercise linking inventors from historical U.S. patents to Federal Censuses between 1880 and 1940 and to regional economic aggregates. We provide a theoretical framework to motivate the micro and macro-level stylized facts we uncover in the data. We show that inventors were highly educated and that father's income and education were important intergenerational transmission channels. Inventors tended to migrate to places that were conducive to innovation and they were positively selected through exit early in their careers. New inventors received more patent citations than incumbent inventors, suggesting a cycle of creative destruction. The financial returns to technological development were high. At the macro-level we identify a strong relationship between patented inventions and long-run economic growth, and use an instrumental variables approach exploiting an historical shift in innovation activity during World War II to show that this relationship could be causal. Finally, we document a U-shaped relationship between top income inequality and innovation, yet innovative places tended to be more socially mobile. Our new data help to address important questions related to innovation and long-run growth dynamics.

Innovation and Trade Policy in a Globalized World

(w/ Sina Ates and Giammario Impullitti)

NBER Working Paper #24543

Read more at: The Atlantic, VoxEU, Chicago Booth Review.

Abstract: How do import tariffs and R&D subsidies help domestic firms compete globally? How do these policies affect aggregate growth and economic welfare? To answer these questions, we build a dynamic general equilibrium growth model where firm innovation endogenously determines the dynamics of technology, and, therefore, market leadership and trade flows, in a world with two large open economies at different stages of development. Firms’ R&D decisions are driven by (i) the defensive innovation motive, (ii) the expansionary innovation motive, and (iii) technology spillovers. The theoretical investigation illustrates that, statically, globalization (defined as reduced trade barriers) has ambiguous effects on welfare, while, dynamically, intensified globalization boosts domestic innovation through induced international competition. Accounting for transitional dynamics, we use our model for policy evaluation and compute optimal policies over different time horizons. The model suggests that the introduction of the Research and Experimentation Tax Credit in 1981 proves to be an effective policy response to foreign competition, generating substantial welfare gains in the long run. A counterfactual exercise shows that increasing tariffs as an alternative policy response improves domestic welfare only when the policymaker cares about the very short run, and only when introduced unilaterally. Tariffs generate large welfare losses in the medium and long run, or when there is retaliation by the foreign economy. Protectionist measures generate large dynamic losses by distorting the impact of openness on innovation incentives and productivity growth. Finally, our model predicts that a more globalized world entails less government intervention, thanks to innovation-stimulating effects of intensified international competition.

Economic Growth: The Past, the Present, and the Future

Commemorative Essay in "The Past, Present, and Future of Economics: A Celebration of the 125 Year Anniversary of the JPE and Chicago Economics," Edited by John List and Harald Uhlig.

Journal of Political Economy, 2017, 125(6): 1736-47.

Abstract: What are the roles of human capital, fertility,  ideas, basic science, and public policy for growth? These are just some of the important questions that were posed by many highly influential studies featured in the issues of the Journal of Political Economy over the years.  In this paper, I revisit some of those  seminal J.P.E. papers in the field of economic growth, briefly describe some of the more recent contributions, and end with some thoughts about the future direction of the field.

The Social Origins and IQ of Inventors

(w/ Philippe Aghion, Ari Hyytinen and Otto Toivanen)

NBER Working Paper #24110

CEPR Discussion Paper #12496

Read more at: Project Syndicate, Harvard Business Review, VoxEU, The Economist.

Abstract: In this paper we merge three datasets - individual income data, patenting data, and IQ data - to analyze the determinants of an individual's probability of inventing. We find that: (i) parental income is positively associated with the probability of inventing, yet the estimated impact of parental income is greatly diminished once parental socioeconomic status, parental education, and the individual's IQ are controlled for; (ii) IQ has both a direct effect on the probability of inventing and an indirect impact through education; the impact of IQ is robust to controlling for unobserved family characteristics by focusing on potential inventors with brothers close in age; and the effect of IQ is larger for inventors than for medical doctors or lawyers; (iii) social family interactions also matter, as shown by looking at biological versus non-biological parents; (iv) there is a positive and significant interaction effect between IQ and father income.

On the Returns to Invention within Firms: Evidence from Finland

(w/ Philippe Aghion, Ari Hyytinen and Otto Toivanen)

American Economic Association Papers and Proceedings, 2018, 108: 208-212.

Abstract: In this paper we merge individual income data, firm-level data, patenting data and IQ data in Finland over the period 1988-2012 to analyze the returns to invention for inventors and their co-workers or stakeholders within the same firm. We find that: (i) inventors collect only 8% of the total private return from invention; (ii) entrepreneurs get over 44% of the total gains; (iii) bluecollar workers get about 26% of the gains and the rest goes to whitecollar workers. Moreover, entrepreneurs start with significant negative returns prior to the patent application, but their returns subsequently become highly positive.

Immigration and the Rise of American Ingenuity

(w/ John Grigsby and Tom Nicholas)

American Economic Review, Papers and Proceedings, 2017, 107(5): 327-331.

Read more at: The Atlantic, Harvard Business Review, VoxEU, NBER Digest, BizEd Magazine, Les Echos

Abstract: We build on the analysis in Akcigit, Grigsby, Nicholas (2017) by using US patent and Census data to examine the relationship between immigration and innovation. We construct a measure of foreign born expertise and show that technology areas where immigrant inventors were prevalent between 1880 and 1940 experienced more patenting and citations between 1940 and 2000. The contribution of immigrant inventors to US innovation was substantial. We also show that immigrant inventors were more productive than native born inventors; however they received significantly lower levels of labor income. The immigrant inventor wage-gap cannot be explained by differentials in productivity.

Optimal Taxation and R&D Policies

(w/ Douglas Hanley and Stefanie Stantcheva)

NBER Working Paper #22908

Revise and Resubmit, Econometrica.

Abstract: We study the optimal design of R&D policies and corporate taxation as a dynamic mechanism design with externalities using the tools of public economics. Firms are heterogeneous in their research productivity, i.e., in the efficiency with which they convert a given set of R&D inputs into successful innovations. There are non-internalized technology spillovers across firms, but the asymmetric information about firms' research productivity prevents the first best solution. We characterize the optimal policies for firms of different sizes and ages. We highlight that key parameters for these policies are i) the relative complementarities between observable R&D investments, unobservable R&D inputs, and firm productivity, and ii) the dispersion and persistence of firm productivity. We estimate our model using firm-level data matched to patent data and quantify the optimal policies. Simpler innovation policies, such as linear R&D subsidies and linear profit taxes, lead to large revenue losses relative to the optimal mechanism. Our formulas and theoretical and numerical methods are more broadly applicable to the provision of firm incentives in dynamic settings with asymmetric information and spillovers.

Back to Basics: Basic Research Spillovers, Innovation Policy and Growth

(w/ Douglas Hanley and Nicolas Serrano-Velarde)

CEPR Discussion Paper #11707

Revise and Resubmit, Review of Economic Studies

Abstract: This paper introduces a general equilibrium model of endogenous technical change through basic and applied research. Basic research differs from applied research in the nature and the magnitude of the generated spillovers. We propose a novel way of empirically identifying these spillovers and embed them in a framework with private firms and a public research sector. After characterizing the equilibrium, we estimate our model using micro-level data on research expenditures by French firms. Our key finding is that standard innovation policies (e.g., uniform R&D tax credits) can accentuate the dynamic misallocation in the economy by oversubsidizing applied research. Policies geared towards public basic research and its transmission to the private sector are significantly welfare improving.

Lack of Selection and Limits to Delegation: Firm Dynamics in Developing Countries

(w/ Harun Alp and Michael Peters)

NBER Working Paper #21905

Revise and Resubmit, American Economic Review.

Abstract: Managerial delegation is essential for firm growth. While firms in poor countries often shun outside managers and instead recruit among family members, the pattern is quite the opposite for firms in rich countries. In this paper, we ask whether these differences in managerial delegation have important aggregate effects. We construct a model of firm growth where entrepreneurs have fixed-time endowments to run their daily operations. As firms grow larger, the need to delegate decision-making authority increases. Firms in poor countries might therefore decide to remain small if delegating managerial tasks is difficult. We calibrate the model to firm-level data from the U.S. and India. We show that the model is quantitatively consistent with the experimental micro evidence on managerial efficiency and firm growth reported in Bloom et al (2013). Our quantitative analysis shows that the low efficiency of delegation in India can account for 5% of productivity and 15% of income differences between the U.S. and India in steady state. We also show that such inefficient delegation possibilities reduce the size of Indian firms, but would cause substantially more harm for U.S. firms. This is because there are important complementarities between the ease of delegation and other factors affecting firm growth.

Tax Simplicity and Heterogeneous Learning

(w/ Philippe Aghion, Matthieu Lequien, Stefanie Stantcheva)

NBER Working Paper #24049.

Read more at: Washington Post

Abstract. We study how strongly individuals respond to tax simplicity and how they learn about the complexities of the tax system.  We focus on the self-employed, who can more easily adjust to tax incentives and whose responses directly stem from their own understanding of the tax system. We use new French tax returns data from 1994 to 2012. France serves as a good quasi-laboratory: it has three fiscal regimes -- or modes of taxation-- for the self-employed, which differ in their monetary tax incentives and in their tax simplicity. Two key features are that, first, these regimes are subject to eligibility thresholds; we find large excess masses (bunching) right below the latter. Second, the regimes impact different agents heterogeneously and have changed extensively over time. Taken together, these two key elements give us measures of tax responses (the bunching) as well as the variation needed to jointly estimate a value of tax simplicity and taxable income elasticities. They also give us an opportunity to study how individuals learn about and respond over time to changing policy parameters.
We estimate a large value for tax simplicity of up to 650 euros per year per individual depending on the regime and activity. We also find sizable costs of tax complexity; agents are not immediately able to understand what the right regime choice is, leave significant money on the table, and learn over time. The cost of complexity is "regressive" in that it affects mostly the uneducated, low income, and low skill agents.
Agents who can be viewed as more informed and knowledgable (e.g., the more educated or high-skilled) are more likely to make the correct regime choice and to learn faster.

Growth through Heterogeneous Innovations

(w/ William Kerr)

Journal of Political Economy, 2018, 126(4): 1374-1443.

Abstract:  We study how external versus internal innovations promote economic growth through a tractable endogenous growth framework with multiple innovation sizes, multi-product firms, and entry/exit. Firms invest in external R&D to acquire new product lines and in internal R&D to improve their existing product lines. A baseline model derives the theoretical implications of weaker scaling for external R&D versus internal R&D, and the resulting predictions align with observed empirical regularities for innovative firms. Quantifying a generalized model for the recent U.S. economy using matched Census Bureau and patent data, we observe a modest departure for external R&D from perfect scaling frameworks.

Taxation and the International Mobility of Inventors

(w/ Salome Baslandze and Stefanie Stantcheva)

American Economic Review, 2016, 106(10): 2930-81.

Read more at: The Wall Street Journal, The Telegraph, The Washington Post, The Telegraph (Comment), VoxEU, NBER Digest, Microeconomic Insights.

Abstract: This paper studies the effect of top tax rates on inventors' mobility across OECD countries since 1977. We put special emphasis on "superstar'' inventors, those with the most and most valuable patents. We use data on inventors from the United States Patent Office to track inventors' locations over time and combine it with international effective top tax rate data. We construct a detailed set of proxies for inventors' counterfactual incomes in each possible destination country including, among others, measures of patent quality and technological fit with each potential destination. We find that superstar top 1% inventors are significantly affected by top taxes rates when deciding on where to locate. The elasticity of domestic inventors to the net-of-tax rate is 0.04, while the elasticity of foreign inventors is 1.3. The elasticities to top net-of-tax rates decline as one moves down the quality distribution of inventors. Inventors who have worked in multinational companies are more likely to take advantage of tax differentials. On the other hand, if the company of an inventor has a higher share of its research activity in a given country, the inventor is less sensitive to the tax rate in that country. We perform extensive robustness checks, including using an alternative dataset based on European Patent Office filings.

Innovation Network

(w/ Daron Acemoglu and William Kerr)

Proceedings of the National Academy of Sciences, 2016, 113(41): 11483–11488.

Read more at: VoxEU

Abstract: Technological progress builds upon itself, with the expansion of invention in one domain propelling future work in linked fields. Our analysis uses 1.8 million U.S. patents and their citation properties to map the innovation network and its strength. Past innovation network structures are calculated using citation patterns across technology classes during 1975--1994. The interaction of this pre-existing network structure with patent growth in upstream technology fields has strong predictive power on future innovation after 1995. This pattern is consistent with the idea that when there is more past upstream innovation for a particular technology class to build on, then that technology class innovates more.

Creative Destruction and Subjective Wellbeing

(w/ Philippe Aghion, Angus Deaton and Alexandra Roulet)

American Economic Review, 2016, 106(12): 3869-3897.

(Click here for the Online Appendix)

Read more at: American Economic Association.

Abstract: In this paper we analyze the relationship between turnover-driven growth and subjective wellbeing. Our model of innovation-led growth and unemployment predicts that: (i) the effect of creative destruction on expected individual welfare should be unambiguously positive if we control for unemployment, less so if we do not; (ii) job creation has a positive and job destruction has a negative impact on wellbeing; (iii) job destruction has a less negative impact in US Metropolitan Statistical Areas (MSA) within states with more generous unemployment insurance policies; (iv) job creation has a more positive effect on individuals that are more forward-looking. The empirical analysis using cross-sectional MSA-level and individual-level data provides empirical support to these predictions.

Transition to Clean Technology

(w/ Daron Acemoglu, Douglas Hanley and William Kerr)

Journal of Political Economy, 2016, 124(1): 52-104.

Read more at: VoxEU

Abstract: We develop a microeconomic model of endogenous growth where clean and dirty technologies compete in production and innovation -in the sense that research can be directed to either clean or dirty technologies. If dirty technologies are more advanced to start with, the potential transition to clean technology can be difficult both because clean research must climb several steps to catch up with dirty technology and because this gap discourages research effort directed towards clean technologies. Carbon taxes and research subsidies may nonetheless encourage production and innovation in clean technologies, though the transition will typically be slow. We characterize certain general properties of the transition path from dirty to clean technology. We then estimate the model using a combination of regression analysis on the relationship between R&D and patents, and simulated method of moments using microdata on employment, production, R&D, firm growth, entry and exit from the US energy sector. The model's quantitative implications match a range of moments not targeted in the estimation quite well. We then characterize the optimal policy path implied by the model and our estimates. Optimal policy heavily relies on research subsidies as well as carbon taxes. We use the model to evaluate the welfare consequences of a range of alternative policy structures. For example, just relying on carbon taxes or delaying intervention both have significant welfare costs -though their implications for medium run temperature increases are quite different.

Abstract:  An endogenous growth model is developed where each period firms invest in researching and developing new ideas. An idea increases a firm's productivity. By how much depends on how central the idea is to a firm's activity. Ideas can be bought and sold on a market for patents. A firm can sell an idea that is not relevant to its business or buy one if it fails to innovate. The developed model is matched up with stylized facts about the market for patents in the U.S. The analysis attempts to gauge how efficiency in the patent market affects growth.

Innovation, Reallocation and Growth

(w/ Daron Acemoglu, Harun Alp, Nicholas Bloom and William Kerr)

CEPR Discussion Paper #12449
NBER Working Paper #18993

American Economic Review, 2018, 108(11): 3450-3491.

Read more at: BFI Research Highlights

Abstract: We build a model of firm-level innovation, productivity growth and reallocation featuring endogenous entry and exit. A new and central economic force is the selection between high- and low-type firms, which differ in terms of their innovative capacity. We estimate the parameters of the model using US Census micro data on firm-level output, R&D and patenting. The model provides a good fit to the dynamics of firm entry and exit, output and R&D. Taxing the continued operation of incumbents can lead to sizable gains (of the order of 1.4% improvement in welfare) by encouraging exit of less productive firms and freeing up skilled labor to be used for R&D by high-type incumbents. Subsidies to the R&D of incumbents do not achieve this objective because they encourage the survival and expansion of low-type firms.

Innovation and Top Income Inequality

(w/ Philippe Aghion, Antonin Bergeaud, Richard Blundell, and David Hemous)

(Click here for the Online Appendix)

NBER Working Paper #21247

Read more at: VoxEU, US News

Review of Economic Studies, 2019, 86(1): 1-45.

Abstract: In this paper we use cross-state panel and cross-US commuting-zone data to look at the relationship between innovation, top income inequality and social mobility. We find positive correlations between measures of innovation and top income inequality. We also show that the correlations between innovation and broad measures of inequality are not significant. Next, using instrumental variable analysis, we argue that these correlations at least partly reflect a causality from innovation to top income shares. Finally, we show that innovation, particularly by new entrants, is positively associated with social mobility, but less so in local areas with more intense lobbying activities.

The Role of Information in Innovation and Competition

(w/ Qingmin Liu)

(Click here for the Online Appendix)

Journal of the European Economic Association, 2016, 14(4): 828-870.

Abstract:  Innovation is typically a trial-and-error process. While some research paths lead to the innovation sought, others result in dead ends. Because firms benefit from their competitors working in the wrong direction, they do not reveal their dead-end findings. Time and resources are wasted on projects that other firms have already found to be fruitless. This is a major problem, particularly in industries that rely heavily on trial-and-error research. We offer a simple model with two firms and two research lines to study this prevalent problem. We characterize the equilibrium in a decentralized environment that necessarily entails significant efficiency losses due to wasteful dead-end replication and a flight to safety -an early abandonment of the risky project. We show that different types of firms follow different innovation strategies and create different kinds of welfare losses. In an extension of the core model, we also study a centralized mechanism whereby firms are incentivized to disclose their actions and share their private information in a timely manner.

Networks and the Macroeconomy: An Empirical Exploration

(w/ Daron Acemoglu and William Kerr)

NBER Macro Annual 2015, ed. by Martin Eichenbaum and Jonathan Parker, 2016, Vol 30: 276-335.

Read more at: Bloomberg

Abstract: The propagation of macroeconomic shocks through input-output and geographic networks can be a powerful driver of macroeconomic fluctuations. We first exposit that in the presence of Cobb-Douglas production functions and consumer preferences, there is a specific pattern of economic transmission whereby demand-side shocks propagate upstream (to input supplying industries) and supply-side shocks propagate downstream (to customer industries) and that there is a tight relationship between the direct impact of a shock and the magnitudes of the downstream and the upstream indirect effects. We then investigate the short-run propagation of four different types of industry-level shocks: two demand-side ones (the exogenous component of the variation in industry imports from China and changes in federal spending) and two supply-side ones (TFP shocks and variation in knowledge/ideas coming from foreign patenting). In each case, we find substantial propagation of these shocks through the input-output network, with a pattern broadly consistent with theory. Quantitatively, the network-based propagation is larger than the direct effects of the shocks, sometimes by severalfold. We also show quantitatively large effects from the geographic network, capturing the fact that the local propagation of a shock to an industry will fall more heavily on other industries that tend to collocate with it across local markets. Our results suggest that the transmission of various different types of shocks through economic networks and industry interlinkages could have first-order implications for the macroeconomy.

Young, Restless, and Creative: Openness to Disruption and Creative Innovations

(w/ Daron Acemoglu and Murat Alp Celik)

NBER Working Paper #19894

Revise and Resubmit, AEJ: Macro.


Abstract: This paper argues that openness to new, unconventional and disruptive ideas has a first-order impact on creative innovations -innovations that break new ground in terms of knowledge creation. After presenting a motivating model focusing on the choice between incremental and radical innovation, and on how managers of different ages and human capital are sorted across different types of firms, we provide cross-country, firm-level and patent-level evidence consistent with this pattern. Our measures of creative innovations proxy for innovation quality (average number of citations per patent) and creativity (fraction of superstar innovators, the likelihood of a very high number of citations, and generality of patents). Our main proxy for openness to disruption is manager age. This variable is based on the idea that only companies or societies open to such disruption will allow the young to rise up within the hierarchy. Using this proxy at the firm, patent and country level, we present robust evidence that openness to disruption is associated with more creative innovations.

Patent Value and Citations: Creative Destruction or Strategic Disruption?

(w/ David S. Abrams and Jillian Grennan)

NBER Working Paper #19647

Abstract:  Prior work suggests that more valuable patents are cited more. Using novel revenue data from a large non-practicing entity, we find that the relationship between citations and value forms an inverted-U, with fewer citations at the high end of value than in the middle. We explain the inverted-U with a model of innovation that has productive and strategic patents. Empirically, we observe more strategic patents where the model predicts: among inventors in fields of rapid development and where divisional applications are employed. These findings have important implications for our understanding of growth, innovation, intellectual property policy, and patent valuation.

What Do We Learn from Schumpeterian Growth Theory?

(w/ Philippe Aghion and Peter Howitt)

in Handbook of Economic Growth, ed. by P. Aghion and S. N. Durlauf, 2014, Vol.2: 515-563.

Abstract: Schumpeterian growth theory has operationalized Schumpeter's notion of creative destruction by developing models based on this concept. These models shed light on several aspects of the growth process that could not be properly addressed by alternative theories. In this survey, we focus on four important aspects, namely: (i) the role of competition and market structure; (ii) firm dynamics; (iii) the relationship between growth and development with the notion of appropriate growth institutions; and (iv) the emergence and impact of long-term technological waves. In each case Schumpeterian growth theory delivers predictions that distinguish it from other growth models and which can be tested using micro data.

Optimal Capital Versus Labor Taxation with Innovation-Led Growth

(w/ Philippe Aghion and Jesus Fernandez-Villaverde)

NBER Working Paper #19086

Abstract: Chamley (1986) and Judd (1985) showed that, in a standard neoclassical growth model with capital accumulation and infinitely lived agents, either taxing or subsidizing capital cannot be optimal in the steady state. In this paper, we introduce innovation-led growth into the Chamley-Judd framework, using a Schumpeterian growth model where productivity-enhancing innovations result from profit-motivated R&D investment. Our main result is that, for a given required trend of public expenditure, a zero tax/subsidy on capital becomes suboptimal. In particular, the higher the level of public expenditure and the income elasticity of labor supply, the less should capital income be subsidized and the more it should be taxed. Not taxing capital implies that labor must be taxed at a higher rate. This in turn has a detrimental effect on labor supply and therefore on the market size for innovation. At the same time, for a given labor supply, taxing capital also reduces innovation incentives, so that for low levels of public expenditure and/or labor supply elasticity it becomes optimal to subsidize capital income.

Intellectual Property Rights Policy, Competition and Innovation

(w/ Daron Acemoglu)

Journal of the European Economic Association, 2012, 10(1): 1-42.

(Click for the Online Appendix)

Abstract: To what extent and in what form should the intellectual property rights (IPR) of innovators be protected? Should a company with a large technology lead over its rivals receive the same IPR protection as a company with a more limited advantage? The analysis of these questions necessitates a dynamic framework for the study of the interactions between IPR and competition, in particular to understand the impact of such policies on future incentives. In this paper, we develop such a framework. The economy consists of many industries and firms engaged in cumulative (step-by-step) innovation. IPR policy regulates whether followers in an industry can copy (or license or build upon) the technology of the leader. With full patent protection, followers can catch up to the leader in their industry only by making the same innovation(s) themselves (or by full licensing). We prove the existence of a steady-state equilibrium in a baseline environment and characterize some of its properties. We then quantitatively investigate the implications of different types of IPR policy on the equilibrium growth rate and welfare. The most important result from this exercise is that full patent protection is not optimal (welfare maximizing); instead, optimal policy involves state-dependent IPR protection, providing greater protection to technology leaders that are further ahead than those that are close to their followers. This form of the optimal policy results from the impact of policy on dynamic incentives, in particular from a form of trickle-down effect: providing greater protection to firms that are further ahead of their followers than a certain threshold increases the R&D incentives also for all technology leaders that are less advanced than this threshold.