Estimating Policy Effects on Spatial Market Efficiency: An Extension to the Parity Bounds Model
扩展了平价边界模型，用于估计营销政策变化对市场空间效率的动态调整路径，并应用于埃塞俄比亚玉米和小麦市场，发现改革对多数市场效率影响不大。
The standard parity bounds model (PBM) is extended to allow for dynamic shifts in regime probabilities in response to changes in marketing policy. The approach allows estimation of the length of the adjustment period and a statistical test for no policy effects. The extended PBM is applied to maize and wheat markets in Ethiopia. Evidence of a dynamic adjustment path is found and grain marketing reforms are found to have improved spatial efficiency in a few markets, worsened it in a few others, but generally to have had little effect on the spatial efficiency of Ethiopian grain markets.