Collaborative Research: Intertemporal Trade

在过去的半个世纪里，世界经济在许多方面变得更加一体化：国际贸易的增长速度远远快于世界产出。外国资产在投资组合中所占的份额越来越大。各国更多地依赖国际储蓄池来为投资和政府赤字融资。由于进出口数据很容易获得，可以在静态框架内进行分析，因此对第一种形式的一体化进行了最深入的分析。在以前的工作中，研究人员开发了一个国际贸易的量化一般均衡模型，该模型可以包含有关单个国家和分隔它们的地理壁垒的大量细节。由于涉及复杂的动态因素，对金融一体化的调查仍然要原始得多。模特只有两三个国家，他们的代表作非常程式化。因此，它们无法结合数据中显示的丰富多样性。这项研究建立了一个丰富的多国动态框架，将时间整合到研究人员在之前的工作中开发的静态框架中。这项研究包括三个部分。第一个指标包括贸易不平衡，以评估经常账户逆转对各国国内和跨国的汇率、福利和收入分配的影响。这项研究解决的一个关键政策问题是，美国经常账户赤字可能逆转将在美国和海外产生的影响。这一结果反映了(I)贸易商品组合的调整(广泛的边际)，(Ii)劳动力和其他生产要素在贸易活动和非贸易活动之间的流动，以及(Iii)地理位置在调整中的作用。在几乎没有调整能力的情况下，与实现经常账户再平衡相关的各国GDP的相对变化很大。由于不可贸易性的普遍性，汇率变化对生活水平的影响较为温和。第二部分介绍了跨期最大化。静态框架被扩展，以允许随着时间的推移以及各国之间在要素禀赋、技术和贸易壁垒方面的差异。各国之间会进行贸易，以适应冲击。但就地理壁垒所吸收的资源而言，这种贸易代价高昂。计算表明，静态重力模型所隐含的规模的贸易壁垒阻碍消费平滑的程度与数据中观察到的程度一致。第三个组成部分既考察消费，也考察投资。结果表明，地理障碍可以解释储蓄和投资的高相关性(但呈下降趋势)。这一分析有助于更深入地了解各国贸易收支长期波动的决定因素和后果。这项研究进一步提高了经济学家对一个动态的多国世界进行量化建模的能力。它连接了贸易流动的静态模型和动态开放经济宏观经济学两个文献。它制定的框架可用于解决国际经济政策中的许多关键问题。

Over the last half century the world economy has become more integrated in a number of dimensions: International trade has grown much faster than world output. Foreign assets constitute a growing share of portfolios. Countries rely more on international pools of saving to finance investment and government deficits. Because data on imports and exports are readily available and can be analyzed in a static framework, the first form of integration has been analyzed in greatest depth. In previous work the investigators developed a quantitative general equilibrium model of international trade that can incorporate substantial detail about individual countries and the geographic barriers that separate them. Because complex dynamic considerations are involved, investigation into financial integration remains much more primitive. Models have only two or three countries whose representation is very stylized. Hence they are incapable of incorporating the rich variety displayed in the data. This research builds a rich multicountry dynamic framework that integrates time into the static framework that the investigators developed in their previous work. The research has three components. The first incorporates trade imbalances to assess the impact of current account reversals on exchange rates, welfare, and income distribution within and across countries. A key policy question that the research addresses is the impact that a likely reversal of the U.S. current account deficit will have in the United States and abroad. The outcome reflects (i) adjustment in the set of goods that are traded (the extensive margin), (ii) the mobility of labor and other factors of production between traded and nontraded activities, and (iii) the role of geography in adjustment. With little ability to adjust, the relative GDP changes across countries associated with achieving current account rebalancing are large. Because of the pervasiveness of nontradability, the effect of exchange rate changes on standards of living is more modest. The second component introduces intertemporal maximization. The static framework is extended to allow for differences in factor endowments, technology, and trade barriers over time as well as across countries. Countries trade intertemporally to accommodate shocks. But this trade is costly in terms of the resources absorbed by geographic barriers. Calculations indicate that trade barriers of the magnitude implied by static gravity models impede consumption smoothing by amounts consistent with that observed in the data. The third component examines investment as well as consumption. Results indicate that geographic barriers can explain the high (but declining) correlation of savings and investment. The analysis provides a deeper understanding of the determinants and consequences of long-run swings in countries' trade balances. This research furthers economists' ability to model quantitatively a dynamic, multi-country world. It connects two literatures, the static modeling of trade flows and dynamic open-economy macroeconomics. The framework it develops can be used to address a host of key issues in international economic policy.