Robust Counterfactual Predictions in Neoclassical Models of International Trade

经济学家和政策制定者依靠全球经济模型来预测贸易政策的变化（如进口关税）对生产、工资、就业和消费价格的影响。 这些模型受到限制，以便复制所观察到的过去的特征，但研究人员如何确切地施加这些限制是众所周知的困难，因此不可避免地不确定，并受到争议。 研究人员的目标是通过开发工具来解决这个问题，这些工具使模型和观察到的历史数据之间的联系尽可能简单，因为这些模型通常用于进行预测。因此，经济学家应该能够更有信心地回答有关国际贸易的关键政策问题。 考虑到在一般均衡环境中隔离准实验变化所固有的挑战，回答国际贸易中反事实问题的标准方法是依赖计算一般均衡模型。这个项目开发了一种新的方法来构建强大的，非参数的反事实预测使用CGE模型。 这项研究建立在新古典经济和减少交换经济之间的等价性，其中国家只是交易要素服务。这种等价性对于它的简化能力很重要。在缩减交换经济中，竞争均衡可以通过对缩减要素需求系统的分析来充分表征，该系统总结了所有代理人对要素服务的偏好。因此，对于一些反事实的问题，如贸易成本的统一变化对福利的影响，人们不需要完全了解各国和各行业的需求和生产函数，只需要知道不同国家的要素之间的可替代性。 因此，研究人员建议开发工具，并收集新的数据，旨在估计这种替代性。 其中一种办法将依赖于贸易要素含量的衡量。 第二种方法将依赖于使用观察到的数据来构建一般均衡福利变化的最佳非参数边界。

Economists and policy-makers rely on models of the global economy to predict the impact that changes in trade policy, such as import tariffs, will have on production, wages, employment, and consumer prices. These models are constrained so as to replicate features of the observed past, but how exactly a researcher imposes those constraints is notoriously difficult, and hence inevitably uncertain and subject to debate. The investigators aim to address this problem by developing tools that make the connection between model and observed historical data as simple as possible given the predictions that these models are commonly used to make. As a result, economists should be able to answer key policy questions concerning international trade with greater confidence. Given the challenges inherent in isolating quasi-experimental variation in general equilibrium settings, the standard approach to answering counterfactual questions in international trade is to rely on Computational General Equilibrium (CGE) models. This project develops a new way of constructing robust, nonparametric counterfactual predictions using CGE models. This research builds on the equivalence between neoclassical economies and reduced exchange economies in which countries simply trade factor services. This equivalence is important for its simplifying power. In a reduced exchange economy, competitive equilibria can be characterized fully by an analysis of the reduced factor demand system that summarizes all agents' preferences over factor services. Thus, for a number of counterfactual questions, like the welfare impact of uniform changes in trade costs, one does not need the complete knowledge of demand and production functions across countries and industries -- all one needs to know is the substitutability between factors from different countries. The investigators therefore propose to develop tools, and collect new data, aimed at estimating this substitutability. One such approach will rely on measures of the factor content of trade. A second approach will rely on using the observed data to construct the best possible nonparametric bounds on general equilibrium welfare changes.