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贸易模型、贸易弹性与贸易利得

Trade models, trade elasticities, and the gains from trade
Journal of International Economics · 2026 · Ina Simonovska、Michael E. Waugh

中文摘要

我们考察五个国际贸易模型, 它们属于这样一类模型: 其中贸易弹性与国内贸易份额构成自给自足福利成本的充分统计量。其中三个为固定品种模型, 其特征是微观层面调整边际递增: 分别为阿明顿 (Armington) 模型、李嘉图 (Ricardian) 模型及其可变加成对应版本。另两个为具有垄断竞争特征的内生品种模型: 克鲁格曼 (Krugman) 模型与梅里茨 (Melitz) 模型的版本。对于这三个固定品种模型, 我们从理论上证明: 尽管三者蕴含相同的从贸易弹性到福利的映射, 但它们所蕴含的从贸易弹性到同一商品跨国价格缺口之可观测次序统计量的映射却各不相同。这一结果意味着, 若选取控制贸易弹性的参数以匹配数据中相同的次序统计量, 将对各模型测算的自给自足福利成本产生不同程度的影响。我们对全部五个模型量化了这些差异。

Abstract

We consider five models of international trade that belong to the class of models in which the trade elasticity and domestic trade share are sufficient statistics for the welfare cost of autarky. Three are fixed-variety models featuring increasing micro-level margins of adjustment: versions of the Armington model, the Ricardian model, and its variable-markup counterpart. Two are endogenous-variety models featuring monopolistic competition: versions of the Krugman model and the Melitz model. For the three fixed-variety models, we show theoretically that, although they imply the same mapping from the trade elasticity to welfare, they imply different mappings from the trade elasticity to observed order statistics of price gaps of identical goods across countries. This result implies that choosing the parameter that governs the elasticity of trade to match the same order statistics in the data differentially impacts each model’s measured welfare cost of autarky. We quantify these differences for all five models.
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