Once the historical data and the model parameters have been entered, with the OK button, the Forecast Module applies the underlying mathematical models to the data in order to generate forecasts for future periods, for the horizon defined in the cell Forecasting Horizon.
The displayed results are
•firstly, the historical data and the associated simulated forecasts, i.e. the forecasts that the model would have generated if applied to the past data. In addition to the graph, the three error criterions (based on this simulation for historical data) are given;
•secondly, the forecasts for the next periods (for the horizon defined in the cell Forecasting Horizon). In the Sales and Operations Plans, the forecasts are in general made on a monthly basis, while in this Sales Forecast Maintenance window the forecasts are usually made on a weekly basis.