Product Differentiation in International Trade

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This thesis is concerned with the role of product quality in explaining observed price and trade patterns. The first chapter introduces the topic, summarizes the main findings of the dissertation and contrasts them to other results in the literature. The second chapter develops a tractable general equilibrium model that includes quality differentiation among heterogeneous firms. The theory explicitly demonstrates how heterogeneity in a single exogenous parameter, productivity, can produce dispersion in product quality and price. The framework predicts that relatively productive firms will choose to produce high quality varieties. This finding accords well with the observation that the unit value of exported varieties increases with exporter's income, capital- and skill- abundance. The model is used to analyze how international trade policy and quality differentiation interact to shape patterns of production and trade flows. In particular, the model predicts a positive relationship between product quality and export status at the firm level and that trade liberalization decreases the average quality of a country's exports.

The third chapter evaluates the importance of vertical product differentiation in explaining price and export status patterns observed in microdata on U.S. manufacturing plants. The main difficulty in exploring the impact of vertical product differentiation is that product quality is not directly observable. The analysis tackles the problem from two angles. First, the chapter develops a novel empirical strategy to obtain a proxy for quality, which is then used to evaluate important conditional correlations. The results show that both quality and productivity are important determinants of price and export status pattern. Second, the simulated method of moments is used to obtain structural estimates of the parameters of the model and to assess the importance of quality differentiation. The estimates suggest that quality differentiation plays an important role in explaining the variation in price, size and export status across U.S. manufacturing plants.

The fourth chapter briefly concludes by summarizing the main findings and suggesting avenues for future research. Overall the analysis presented in this dissertation implies that vertical product differentiation, or quality, plays an important role in explaining dispersion in producer output price and export status.