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 Historical Forecasts

Use

The system calculates the forecast for the number of periods that you specified in the forecast profile in the Forecast Periods field, and saves the result. If the system then recalculates the standard deviation one period later, it in turn calculates the forecast for this number of periods and saves the result. However, in doing so, the system overwrites the forecast for all periods apart from the first period of the previous calculation. This means that you can no longer access the forecast results previously calculated.

However, if a location has a replenishment lead time of more than one period, for example, you may also need the results of the previous forecast calculation to plan exactly. The system therefore records all calculated forecast results as historical forecasts in the above operation.

The following figure shows the overwrite operation and the recording of historical forecasts:

Features

Display Historical Forecasts

You can see historical forecasts for a combination of location product and key figure, for example Forecast: Demand , on the SAP Easy Access screen under Start of the navigation path Advanced Planning and Optimization Next navigation step Service Parts Planning (SPP) Next navigation step Planning Next navigation step Forecasting Next navigation step Historical Forecasts End of the navigation path .

On this screen, the system displays the following information for each location product:

  • Forecast strategy that the system used to calculate the historical forecast

  • Number of periods that the system uses to calculate the standard deviation

    You have specified this number in the forecast profile for this location product on the Model Parameter tab page.

  • Offset forecast creation

    You have specified this time offset in the forecast profile on the General tab page.

  • Historical forecasts

    In the Key Figures column, you see the periods in which the system created the forecasts. Here, the system displays the number of periods it used to calculate the standard deviation.

    In the next columns you see the forecasts for each period as of the creation period. A value is stored as green for each column. A value stored green is always the forecast value that the system calculated for each period before the number of periods defined in the Offset Forecast Creation field.

    In the last row, the system takes the green stored value for each period. This means that in the last row you see the composite historical forecast for a location product.

Recalculation of Forecast in the Past

If you select a different forecast model for a location product manually, or if the system selects a different forecast model during automatic model selection , the system only has historical forecasts for this location product that it had calculated according to the previous forecast model. Historical forecasts calculated according to the new forecast model are not available at first.

However, for each location product that has a change of forecast model, the system sets the Forecast Model Change trigger (SPP_FCSTMODEL_CHANGE). If you need historical forecasts for these location products according to the new forecast model, you can schedule the SPP: Recalculation of Forecast in Past (SPP_RECALC_HISTFCST)planning service in a planning profile of the Planning Service Manager (PSM).

Note Note

For this planning service, you must choose the method Lo c.Prod. for Recalc. of Fcst in Past ( SPP_LOCPROD_FCSTRECALC) as the method for package creation.

For more information about scheduling a planning service in the PSM, see Using the Planning Service for Service Parts Planning .

End of the note.

In the package creation method Loc.Prod. for Recalc. of Fcst in Past , the PSM only considers location products that correspond to the selection for which the Forecast Model Change trigger is set.For each of these location products, the system goes back in the past over the whole demand history and, depending on the model, the initialization period. Starting from this point in time, the SPP: Recalculation of Forecast in Past planning service calculates the forecast for the location product for each period according to the changed forecast model. This means that the planning service calculates the forecast in the past for a location product for which the forecast model has changed, and displays the results of this recalculation as a historical forecast.

Note Note

For the Leading-Indicator-Based Forecast the system does not save any historical forecasts and does not recalculate the historical forecast.

End of the note.