This argument is supported in the report by a number of case studies that illustrate that, although macro-economic policy reforms have had positive effects on agriculture in some parts of Africa, the overall impact of the reforms has been slower and less dramatic than could have been expected. The main reason for the reforms' restricted impact is that the constraints to achieving sustainable agricultural productivity and increasing yields lie both on and off the farm. Hence, in many cases, transportation, trade, and macroeconomic policies have stronger effects on farmer and trader incentives than do agricultural sector policies, a point that underscores the need for better policy coordination across ministries. Strategies should therefore focus on transforming the weak points along the food system as a whole, and avoid too narrow a focus on farming.