The model specification procedure facilitated the identification of the equation that best simulates the data generating process. The output indicates that for the Producer’s Price (PP) model, the coefficients associated to the constant (fl0) and the trend parameter (น2) are significant at the 1% level, suggesting that adding these two variables to the equation significantly improves the explanatory power of the restricted model. Such a result is confirmed by the F-test statistic (21.63), which is highly superior to the critical value of F (1.252) at the 1% level (6.74).