We specified a two-step single equation ECM to assess the dynamics of the relationship between the different price series. The ECM allowed นร to capture the short-term effect that a shock in the independent variables has on the dependent variable and the speed at which the system will adjust to the new equilibrium after the shock. The result of the Granger causality test indicates that in the setting of a ECM, the series WP should be on the left-hand side.