A trade restrictiveness index (TRI) aggregates an entire protection structure into a single uniform measure that is consistent with trade theory and reflects the extent of policy interventions on trade or welfare. Although there are several variants of a TRI, all approaches aggregate protective measures using weights that depend on import demand and export supply elasticities; some studies ignore cross‐price effects while others account for them. This study measures the degree of bias introduced by ignoring cross effects. It provides a practical approach to account for demand‐ and supply‐side cross‐price effects in a multi‐commodity TRI setting. This approach is illustrated with a case study of distortions in the Canadian crop and livestock sector. Domestic demand and supply cross effects are approximated using a “constant differences of elasticities of substitution” functional form. On average, over the period 1996–2016, we find that cross‐price effects do make a difference, and that including them makes the TRI 27% higher than an approach which ignores them. Furthermore, both TRI approaches produce indices that are higher and more variable than the OECD's percentage Producer Support Estimate (PSE) that measures policy transfers as a share of gross farm receipts. The fundamental differences between a TRI and PSE% is driven by market price support for milk.

中文翻译：

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加拿大的农产品贸易限制：交叉影响有多重要？

贸易限制指数（TRI）将整个保护结构汇总为一个统一的量度，该量度与贸易理论相一致，并反映了对贸易或福利的政策干预程度。尽管TRI有多种变体，但所有方法都使用取决于进口需求和出口供应弹性的权重来汇总保护措施。一些研究忽略了交叉价格效应，而另一些则说明了交叉价格效应。这项研究通过忽略交叉效应来衡量引入的偏差程度。它提供了一种解决多商品TRI环境中需求和供应方交叉价格影响的实用方法。以加拿大农作物和畜牧业扭曲的案例研究为例说明了这种方法。国内需求和供应的交叉影响可以使用“替代弹性的恒定差异”功能形式。平均而言，在1996年至2016年期间，我们发现交叉价格效应确实有所作为，而且包括交叉价格效应在内的TRI价格比忽略它们的方法高出27％。此外，这两种TRI方法产生的指数都比经合组织的生产者支持估算百分比（PSE）高，且该变量将政策转移量作为农业总收入的一部分进行衡量。TRI和PSE％之间的根本差异是由牛奶的市场价格支持所驱动。