Ufuk Akcigit

Growth Through Heterogeneous Innovations

We study how exploration versus exploitation innovations impact economic growth through a tractable endogenous growth framework that contains multiple innovation sizes, multi-product firms, and entry/exit. Firms invest in exploration R&D to acquire new product lines and exploitation R&D to improve their existing product lines. We model and show empirically that exploration R&D does not scale as strongly with firm size as exploitation R&D. The resulting framework conforms to many regularities regarding innovation and growth differences across the firm size distribution. We also incorporate patent citations into our theoretical framework. The framework generates a simple test using patent citations that indicates that entrants and small firms have relatively higher growth spillover effects.

Innovation, Reallocation and Growth

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 network

Significance We describe the strength and importance of the innovation network that links patenting technology fields together. We quantify that technological advances spill out of individual fields and enrich the work of neighboring technologies, but these spillovers are also localized and not universal. Thus, innovation advances in one part of the network can significantly impact nearby disciplines but rarely those very far away. We verify the strength and stable importance of the innovation network by showing how past innovations can predict future innovations in other fields over 10-y horizons. This better understanding of how scientific progress occurs and how inventions build upon themselves is an important input to our depictions of the cumulative process of innovation and its economic growth consequences. 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 US 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 preexisting 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.

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

This paper introduces a model of endogenous growth 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 general equilibrium 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 R&D policies can accentuate the dynamic misallocation in the economy. We also find a strong complementarity between the property rights of basic research and the optimal funding of public research.

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

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 firms with different degrees of openness to disruption, we provide firm-level, patent level and cross-country 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 the age of the manager - 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, but we also show that once the effect of the sorting of young managers to firms that are more open to disruption is factored in, the (causal) impact of manager age on creative innovations is small.

Patent Value and Citations: Creative Destruction or Strategic Disruption?

Prior work suggests that more valuable patents are cited more and this view has become standard in the empirical innovation literature. Using an NPE-derived dataset with patent-specific revenues we find that the relationship of citations to value in fact forms an inverted-U, with fewer citations at the high end of value than in the middle. Since the value of patents is concentrated in those at the high end, this is a challenge to both the empirical literature and the intuition behind it. We attempt to explain this relationship with a simple model of innovation, allowing for both productive and strategic patents. We find evidence of greater use of strategic patents where it would be most expected: among corporations, in fields of rapid development, in more recent patents and where divisional and continuation applications are employed. These findings have important implications for our basic understanding of growth, innovation, and intellectual property policy.

Chapter 1 – What Do We Learn From Schumpeterian Growth Theory?

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.

THE ROLE OF INFORMATION IN INNOVATION AND COMPETITION

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 an information externality that leads to 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.

Optimal Capital Versus Labor Taxation with Innovation-Led Growth

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 pro.t-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.

Growth through Heterogeneous Innovations

We build a tractable growth model in which multiproduct incumbents invest in internal innovations to improve their existing products, while new entrants and incumbents invest in external innovations to acquire new product lines. External and internal innovations generate heterogeneous innovation qualities, and firm size affects innovation incentives. We analyze how different types of innovation contribute to economic growth and the role of the firm size distribution. Our model aligns with many observed empirical regularities, and we quantify our framework with Census Bureau and patent data for US firms. Internal innovation scales moderately faster with firm size than external innovation.