Disentangling non-linearities in the long- and short-run price relationships: An application to the U.S. hog/Pork supply chain

Increased concentration at the retail, food processing and farm input manufacturing levels has brought increased attention to patterns in retail-to-farm price spreads. Most studies documenting asymmetric price transmission focus on non-linear error correction processes, as opposed to the current study which analyzes potential non-linearities in the long-run relationship between the farm and retail prices. The null hypothesis of non-linearity in the long-run relationship between farm and retail prices in the U.S. hog/pork supply chain is rejected in favor of a Smooth Transition Cointegration (STC) framework. The STC framework predicts downward price stickiness in retail prices. The predicted residuals of the non-linear model are used to investigate whether it is possible to disentangle non-linearity in the long-run price relationship from non-linearity in the adjustment towards the long-run equilibrium. The results underline the importance of testing for linearity in the long-run price relationship before modeling non-linearity in short-run dynamics.