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.

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.

What quantitative lessons can we learn from models of endogenous technical change through innovative investments by firms for the impact of changes in the economic environment on the dynamics of aggregate productivity in the short, medium, and long run? We present a unifying model that nests a number of canonical models in the literature and characterize their positive implications for the transitional dynamics of aggregate productivity and their welfare implications in terms of two sufficient statistics. We review the current state of measurement of these two sufficient statistics and discuss the range of positive and normative quantitative implications of our model for a wide array of counterfactual experiments, including the link between a decline in the entry rate of new firms and a slowdown in the growth of aggregate productivity given that measurement. We conclude with a summary of the lessons learned from our analysis to help direct future research aimed at building models of endogenous productivity growth useful for quantitative analysis.

We examine the quantitative impact of policy-induced changes in innovative investment by firms on growth in aggregate productivity and output in a model that nests several of the canonical models in the literature. We isolate two statistics, the impact elasticity of aggregate productivity growth with respect to an increase in aggregate innovative investment and the degree of intertemporal knowledge spillovers in research, that play a key role in shaping the model’s predicted dynamic response of aggregate productivity, output, and welfare to a policy-induced change in the innovation intensity of the economy. Given estimates of these statistics, we find that there is only modest scope for increasing aggregate productivity and output over a 20-year horizon with uniform subsidies to firms’ investments in innovation of a reasonable magnitude, but the welfare gains from such a subsidy may be substantial.