How do agricultural policy restrictions on global trade and welfare differ across commodities?

For decades the world's agricultural markets have been highly distorted by government policies, but differently for different commodities such that a ranking of weighted average nominal rates of assistance across countries can be misleading as an indicator of the trade or welfare effects of policies affecting global markets. This article develops two theory-based indicators, drawing on the recent literature on trade restrictiveness indexes. It estimates those indicators for each of 28 key agricultural commodities from 1960 to 2004,based on a sample of 75 countries that together account for more than three-quarters of the world's production of those agricultural commodities.