Aggregate implications of innovation policy

In this paper we present a tractable model of innovating firms and the aggregate economy that we use to assess quantitatively the link between the responses of firms to changes in innovation policy and the impact of those policy changes on aggregate output and welfare. We show that, to a first-order approximation, a wide range of policy changes have a long-run impact in direct proportion to the fiscal expenditures on those policies, and that to evaluate the aggregate impact of a policy change, there is no need to calculate changes in firms' decisions in response to these policy changes. ; We use these results to compare the relative magnitudes of the impact on aggregates in the long run of three innovation policies in the United States: the Research and Experimentation Tax Credit, federal expenditure on R&D, and the corporate profits tax. We argue that the corporate profits tax is a relatively important policy through its negative effects on innovation and physical capital accumulation. We also use a calibrated version of our model to examine the absolute magnitude of the impact of these policies on aggregates. We show that, depending on the magnitude of spillovers, it is possible for changes in innovation policies to have very large impact on aggregates in the long run. However, over a 15-year horizon, the impact of changes in innovation policies on aggregate output is not very sensitive to the magnitude of spillovers. ; On the basis of these results we conclude that, while it is possible to make comparisons about the relative importance of different policies and sharp predictions about their aggregate impact in the medium term, it is very difficult to shed much light on the implications of innovation policies for long-run aggregate outcomes and welfare in the absence of direct quantitative evidence on the magnitude of spillovers.

The transition to a new economy after the Second Industrial Revolution

During the Second Industrial Revolution, 1860–1900, many new technologies, including electricity, were invented. After this revolution, however, several decades passed before these new technologies diffused and measured productivity growth increased. We build a quantitative model of technology diffusion which we use to study this transition to a new economy. We show that the model implies both slow diffusion and a delay in growth similar to that in the data. Our model casts doubt, however, on the conjecture that this experience is a useful parallel for understanding the productivity paradox following the Information Technology Revolution.

Innovation, firm dynamics, and international trade

We present a general equilibrium model of the response of firms' decisions to operate, innovate, and engage in international trade to a change in the marginal cost of international trade. We find that, although a change in trade costs can have a substantial impact on heterogeneous firms' exit, export, and process innovation decisions, the impact of changes in these decisions on welfare is largely offset by the response of product innovation. Our results suggest that microeconomic evidence on firms' responses to changes in international trade costs may not be informative about the implications of changes in these trade costs for aggregate welfare.

Pricing-to-market, trade costs, and international relative prices

International relative prices across industrialized countries show large and systematic deviations from relative purchasing power parity. We embed a model of imperfect competition and variable markups in a quantitative model of international trade. We find that when our model is parameterized to match salient features of the data on international trade and market structure in the US, it can reproduce deviations from relative purchasing power parity similar to those observed in the data because firms choose to price-to-market. We then examine how pricing-to-market depends on the presence of international trade costs and various features of market structure.Purchasing power parity

The Transition to a New Economy After the Second Industrial Revolution

During the Second Industrial Revolution, 1860-1900, many new technologies, including electricity, were invented. These inventions launched a transition to a new economy, a period of about 70 years of ongoing, rapid technical change. After this revolution began, however, several decades passed before measured productivity growth increased. This delay is paradoxical from the point of view of the standard growth model. Historians hypothesize that this delay was due to the slow diffusion of new technologies among manufacturing plants together with the ongoing learning in plants after the new technologies had been adopted. The slow diffusion is thought to be due to manufacturers' reluctance to abandon their accumulated expertise with old technologies, which were embodied in the design of existing plants. Motivated by these hypotheses, we build a quantitative model of technology diffusion which we use to study this transition to a new economy. We show that it implies both slow diffusion and a delay in growth similar to that in the data.

Models of energy use: putty-putty vs. putty-clay

Energy use is inelastic in time-series data, but elastic in international cross-section data. Two models of energy use reproduce these elasticities: a putty-putty model with adjustment costs developed by Pindyck and Rotemberg (1983) and a putty-clay model. In the Pindyck-Rotemberg model, capital and energy are highly complementary in both the short run and the long run. In the putty-clay model, capital and energy are complementary in the short run, but substitutable in the long run. We highlight the differences in the cross-section implications of the models by considering the effect of an energy tax on output in both models. In the putty-putty model, an energy tax that doubles the price of energy leads to a fall in output in the long run of 33%. In contrast, the same tax in the putty-clay model leads to a fall in output of only 5.3%.Power resources

Models of Energy Use: Putty-Putty versus Putty-Clay

In this paper, we build a version of the putty-clay model in which there is a large variety of types of capital goods which are combined with energy in different fixed proportions. Our principal contribution is to establish easily checked conditions under which the problem of solving for the equilibrium of the model economy reduces to a dynamic programming problem with only two endogenous state variables, regardless of the number of different types of capital goods that are allowed. In appropriate applications, this result allows us to avoid the 'curse of dimensionality' that typically plagues attempts to analyze the dynamics of economies with a wide variety of capital goods and binding non-negativity constraints on investment. We apply these results to study the equilibrium dynamics of value-added, investment, wages, and energy use in a simple model of energy use with putty-clay capital.