Almost two weeks late, here are some NBER abstracts that caught my eye:

The Two Crises of International Economics – In this essay, we argue that key assumptions in international macroeconomic theory, though useful for understanding the economic relationships among developed countries, have been pushed beyond their competence to include relationships between developed economies and emerging markets. The Achilles heel of this extended development model is the assumption that threats to deprive the debtor countries of gains from trade provide incentives for poor countries to repay more than trivial amounts of international debt. Replacing this assumption with the idea that collateral is required to support gross international capital flows suggests that the pattern of current account balances seen in recent years is a sustainable equilibrium.

Zeros, Quality and Space: Trade Theory and Trade Evidence – Product-level data on bilateral U.S. exports exhibit two strong patterns. First, most potential export flows are not present, and the incidence of these “export zeros” is strongly correlated with distance and importing country size. Second, export unit values are positively related to distance. We show that every well-known multi-good general equilibrium trade model is inconsistent with at least some of these facts. We also offer direct statistical evidence of the importance of trade costs in explaining zeros, using the long-term decline in the relative cost of air shipment to identify a difference-in-differences estimator. To match these facts, we propose a new version of the heterogeneous-firms trade model pioneered by Melitz (2003). In our model, high quality firms are the most competitive, with heterogeneous quality increasing with firms’ heterogeneous cost.

Trade Growth under the African Growth and Opportunity Act – This paper explores whether one of the most important U.S. policies towards Africa of the past few decades achieved its desired result. In 2000, the United States dropped trade restrictions on a broad list of products through the African Growth and Opportunity Act (AGOA). Since the Act was applied to both countries and products, we estimate the impact with a triple difference-in-differences estimation, controlling for both country and product-level import surges at the time of onset. This approach allows us to better address the “endogeneity of policy” critique of standard difference-in-differences estimation than if either a country or a product-level analysis was performed separately. Despite the fact that the AGOA product list as chosen to not include “import-sensitive” products, and despite the general challenges of transaction costs in African countries, we find that AGOA has a large and robust impact on apparel imports into the U.S., as well as on the agricultural and manufactured products covered by AGOA. These import responses grew over time and were the largest in product categories where the tariffs removed were large. AGOA did not result in a decrease in exports to Europe in these product categories, suggesting that the U.S.-AGOA imports were not merely diverted from elsewhere. We discuss how the effects vary across countries and the implications of these findings for aggregate export volumes.