Agriculture trade restrictiveness in Canada: How important are the cross effects?

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 multicommodity 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.