Policymakers are increasingly relying on computable general equilibrium (CGE) models to provide economy-wide impacts of trade agreements; however, these assessments often make the simplifying assumption of complete bilateral tariff elimination. But agreements typically involve partial tariff elimination for sensitive sectors—which are often differentiated at the tariff line. As such, applying a uniform tariff reduction in a CGE sector that encompasses many products could introduce bias. We propose a tariff line approach for modelling exemptions for sensitive goods in CGE models with the aim of reducing this bias. This approach is tested for the Canada–EU trade agreement, and systematically compared to standard approaches to bilateral trade liberalisation in CGE analysis. We find that more common approaches might systematically overestimate trade and welfare impacts by neglecting partial liberalisation in selected sectors and/or not considering substitution across tariff lines.

中文翻译：

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一切都在细节中：在关税线处建模贸易协定的双边方法

政策制定者越来越依赖于可计算的一般均衡 (CGE) 模型来提供贸易协定对整个经济的影响；然而，这些评估往往简化了完全消除双边关税的假设。但协议通常涉及敏感部门的部分关税取消——这些部门通常在关税细目上有所区别。因此，在包含许多产品的 CGE 部门中应用统一的关税削减可能会引入偏见。我们提出了一种关税线方法，用于在 CGE 模型中对敏感商品的豁免建模，目的是减少这种偏差。这种方法已针对加拿大-欧盟贸易协定进行了测试，并与 CGE 分析中双边贸易自由化的标准方法进行了系统比较。