We study the implications for international relative prices of a simple Ricardian model of international trade with imperfect competition and variable markups, providing a tractable account of firm-level and aggregate prices. We show that both trade costs and imperfect competition with variable markups are needed to account for pricing-to-market at the firm and aggregate levels. We also show that international trade costs are essential, but pricing-to-market is not, to account for a high volatility of tradeable consumer prices relative to the overall CPI-based real-exchange rate.

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

Many view the period after the Second Industrial Revolution as a paradigm of a transition to a new economy following a technological revolution, including the Information Technology Revolution. We build a quantitative model of diffusion and growth during transitions to evaluate that view. With a learning process quantified by data on the life cycle of US manufacturing plants, the model accounts for the key features of the transition after the Second Industrial Revolution. But we find that features like those will occur in other transitions only if a large amount of knowledge about old technologies exists before the transition begins.

We analyze the effects of money injections on interest rates and exchange rates when agents must pay a Baumol‐Tobin‐style fixed cost to exchange bonds and money. Asset markets are endogenously segmented because this fixed cost leads agents to trade bonds and money infrequently. When the government injects money through an open market operation, only those agents that are currently trading absorb these injections. Through their impact on these agents’ consumption, these money injections affect real interest rates and real exchange rates. The model generates the observed negative relation between expected inflation and real interest rates as well as persistent liquidity effects in interest rates and volatile and persistent exchange rates.