The article discusses how import tariffs on farm products do not fully show the distortions in agricultural markets. It suggests that to understand these distortions, we need to look at various policies affecting agriculture, like taxes, subsidies, and restrictions. The researchers analyzed data from China between 1981 and 2005 to estimate support to farmers and used a model to see the global effects of these distortions in 2004. They found that non-agricultural policies also impact agricultural markets in developing countries.