The results of the unit root tests (Table 3) indicate that for the pp and WP variables there is insufficient evidence to reject the null hypothesis of unit roots at the 5% level. Considering that the PP and WP are nonstationary series integrated of the same order, a Johansen Trace Test was used to determine if the variables are long-run cointegrated. The results of the Johansen’s Test (Table 4) indicate that there is strong evidence to reject the null hypothesis of non-cointegration between WP and pp, suggesting the existence of a long-run single cointegration relationship between wholesalers’ and producers’ prices.