It should be emphasized that in multi-step forecasts the model is estimated recursively in each step i using the observations until time m +i -1. Both one-step and multi-step forecasts are important in facilitating a short and long planning and decision making. They simulate the real-world forecasting environment in which data need to be projected for short and long periods [3]. มีค่า RMSE,MAE and MAPE ของ multi-step forecasts obtained are presented in Tables 2,3 and 4, ตามลำดับ