The present paper explores the effect of trade liberalization on the level of productivity as well as the rate of productivity growth in an R&D-based model with heterogeneous firms. We introduce new and plausible features that are absent in existing studies. First, technical progress takes the...

We present a discrete-time version of an otherwise standard Schumpeterian growth model. Discrete time exhibits two important differences from continuous time. First, the probability of successful innovation cannot be homogeneous of degree one in inputs. A natural R&D analogue to constant returns...

This paper introduces quality innovations with endogenous sunk costs in a heterogeneous firm model of international trade and derives implications for the gravity equation. The model predicts that the effect of fixed costs on exports and on the share of exporters is lower in industries with a...

This chapter reviews and integrates much of what has been learned on the processes of technological evolution, their main features, and their effects on the evolution of industries. First, we map and integrate the various pieces of evidence concerning the nature and structure of technological...

Between 5000 BCE and 1800, the population of the world grew 120-fold despite constraints on the total amount of land available for production. This paper develops a model linking population growth to increasing productivity driven by random innovation and diffusion. People are endowed with a set...

Intellectual property rights are a recurrent source of tensions between developed and developing economies. This paper provides the first quantitative analysis of optimal patent policy in trading economies. We develop a new model of trade, growth and patenting in which patent protection affects...

This paper analyzes a dynamic, Ricardian model of international trade in which relative differences in technology are endogenously determined by investments in innovation by competitive firms. It considers the impact of these investments on trade patterns and the effect of trade patterns on...

We show a causal impact of immigration on innovation and dynamism in US counties. To identify the causal impact of immigration, we use 130 years of detailed data on migrations from foreign countries to US counties to isolate quasi-random variation in the ancestry composition of US counties that...

We study how frictions in learning others' technology, termed "imperfect technology spillovers," impact firm innovation strategies and the aggregate economy through changes in innovation composition. We develop an endogenous growth model that generates strategic innovation decisions, where...