Per capita income in the richest countries of the world exceeds that in the poorest countries by more than a factor of 50. What explains these enormous differences? This paper returns to several old ideas in development economics and proposes that linkages, complementarity, and superstar effects are at the heart of the explanation. First, linkages between firms through intermediate goods deliver a multiplier similar to the one associated with capital accumulation in a neoclassical growth model. Because the intermediate goods ’ share of revenue is about 1/2, this multiplier is substantial. Second, just as a chain is only as strong as its weakest link, problems at any point in a production chain can reduce output substantially if inputs enter production in a complementary fashion. Finally, the high elasticity of substitution associated with final consumption delivers a superstar effect: GDP depends disproportionately on the highest levels of productivity in the economy. This paper builds a model with links across sectors, complementary inputs, and highly substitutable consumption, and shows that it can easily generate 50-fold aggregate income differences.

Per capita income in the richest countries of the world exceeds that in the poorest countries by more than a factor of 50. What explains these enormous differences? This paper returns to two old ideas in development economics and proposes that complementarity and linkages are at the heart of the explanation. First, just as a chain is only as strong as its weakest link, problems at any point in a production chain can reduce output substantially if inputs enter production in a complementary fashion. Second, linkages between firms through intermediate goods deliver a multiplier similar to the one associated with capital accumulation in a neoclassical growth model. Because the intermediate goods ’ share of revenue is about 1/2, this multiplier is substantial. The paper builds a model with complementary inputs and links across sectors and shows that it can easily generate 50-fold aggregate income differences.

ABSTRACT ———————————————————————————————————— Quantitative results from a large class of structural gravity models of international trade depend critically on a single parameter governing the elasticity of trade with respect to trade frictions. We provide a new method to estimate this elasticity and illustrate the merits of our approach relative to the estimation strategy of Eaton and Kortum (2002). We employ this method on data for 123 developed and developing countries for the year 2004 using new disaggregate price and trade flow data. Our benchmark estimate for all countries is approximately 4.5, nearly 50 percent lower than the alternative estimation strategy would suggest. This difference implies a doubling of the measured welfare costs of autarky across a large class of widely used trade models.

Using an industry-level dataset of production and trade spanning 75 countries and 5 decades, and a fully specified multi-sector Ricardian model, we estimate productivities at the sector level and examine how they evolve over time in both developed and developing countries. We find that in both country groups, comparative advantage has become weaker: productivity grew systematically faster in sectors that were initially at the greater comparative disadvantage. The global welfare implications of this phenomenon are significant. Relative to the counterfactual scenario in which an individual country’s comparative advantage remained the same as in the 1960s, and technology in all sectors grew at the same country-specific average rate, welfare today is 1.9 % lower for the median country. The welfare impact varies greatly across countries,

Empirical studies find a strong positive relationship between a country’s per-capita income and price level of final tradable goods. Among alternative explanations of this observation, I focus on variable mark-ups by firms. Mark-ups that vary with destinations ’ incomes are evident from a clothing manufacturer’s online catalogue featuring unit prices of identical goods sold in 28 countries. Such price discrimination on the basis of income suggests that firms exploit lower price elasticity of demand for identical goods in richer countries. In order to capture that, I introduce non-homothetic preferences in a model of trade with product differentiation and heterogeneity in firm productivity. The model helps bring theory and data closer along a key dimension: it generates positively related prices and incomes, while preserving desirable features of firm behavior and trade flows of existing frameworks. Quantitatively, the model suggests that variable mark-ups can account for at least a half of the observed positive relationship between prices of tradables and income across a large sample of countries.

ABSTRACT ———————————————————————————————————— Quantitative results from a large class of structural gravity models of international trade depend critically on a single parameter governing the elasticity of trade with respect to trade frictions. We provide a new method to estimate this elasticity and illustrate the merits of our approach relative to the estimation strategy of Eaton and Kortum (2002). We employ this method on data for 123 developed and developing countries for the year 2004 using new disaggregate price and trade flow data. Our benchmark estimate for all countries is approximately 4.5, nearly 50 percent lower than the alternative estimation strategy would suggest, but within the range of existing estimates obtained using a variety of data. This difference implies a doubling of the measured welfare costs of autarky across a large class of widely used trade models.

It is costly to acquire information about markets in other places, especially in developing countries. In this paper, I examine the effect of such information frictions on trade. I embed a process where heterogeneous producers sequentially search across regions to determine where to sell their produce into a perfect competition Ricardian trade model. Information frictions explain the empirical failure of price arbitrage and provide new insight into how market conditions affect trade flows. Using a data set I assemble on regional agricultural trade in the Philippines, I show that observed trade flows and prices suggest the presence of substantial information frictions. I then structurally estimate the model to disentangle information frictions from transportation costs. I find that (1) estimated transportation costs are half as large as those implied by complete information models and more consistent with observed freight costs; and (2) the vast majority (93 percent) of the “gravity ” relationship between trade flows and distance can be attributed to information

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The world is comprised of N countries, indexed by n and i. There are J tradeable sectors, plus one nontradeable sector J + 1. Utility over these sectors in country n is given by J∑

Models in which growth is driven by innovation naturally lead to scale effects. These scale effects result in the counterfactual prediction that larger countries should be much richer than smaller ones. We explore and quantify two candidates to solve the puzzle: First, countries are not fully isolated from each other; and second, countries are not fully integrated domestically. To such end, we build a quantitative model of trade and multinational production (MP) with frictions to move goods and ideas not only across, but also within countries. The calibrated model goes a long way to resolve the puzzle. The existence of domestic frictions, rather than openness to trade and MP, is what allows the extended model to come close to matching the data.