Growth Through Heterogeneous Innovations
Executive Summary — Economists have long recognized that innovation is central to economic growth and development. But as a profession, economics is just beginning to model the many types of innovations that exist and the amazing heterogeneity in the firms that conduct research and development--from General Electric to Silicon Valley start-ups. This paper provides theoretical and empirical evidence surrounding how firm size influences the types of R&D undertaken, with particular focus on choices to pursue exploration R&D (capturing new product lines) versus exploitation R&D (refining current product lines internally). From the choices made by individual firms and new entrepreneurs, the model then builds to consider aggregate economic growth. Research was conducted by Ufuk Akcigit of the University of Pennsylvania and William R. Kerr of Harvard Business School. Key concepts include:
- Exploration R&D seeks to create new technologies and products for the company to build market leadership. Exploitation R&D focuses on improving existing product lines that the firm already owns, in order to build stronger profits.
- Large firms have many product lines and thus naturally engage in extensive exploitation R&D to improve their current technologies. Small firms and new start-ups have a comparative advantage for undertaking exploration R&D.
- Quantitative tests find that exploration R&D has had a greater spillover effect into economic growth than exploitation R&D in the United States over the last couple of decades. This illustrates one channel through which small, innovative businesses and start-ups can play an especially important role in economic growth.
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.