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Background documentation  Forecast Parameters  Locate the document in its SAP Library structure

Maintenance of the following parameters is optional or mandatory, depending on which model you select. The following table shows which parameters are required for which model.

Forecast parameters Dependent on the Forecast Model

Specified model/model to be tested

Mandatory parameters

Constant models:

  

First-order exponential smoothing model

Alpha factor

First-order exponential smoothing model with optimization of the smoothing factors


(none)

Moving average model

Number of historical values

Weighted moving average model

Weighting group

   

Trend models:

  

First-order exponential smoothing model

Alpha and beta factors

Second-order exponential smoothing model

Alpha factor

Second-order exponential smoothing model with optimization of the smoothing factors

  
   

Seasonal model:
Winters' method


Alpha and gamma factors
Periods per season

   

Seasonal trend model:
First-order exponential smoothing model


Alpha, beta, and gamma factors
Periods per season

Weighting Group

You only have to maintain this field if you selected the forecast model "weighted moving average". This key specifies how many historical values are included in the forecast and how these values are weighted in the forecast calculation.

Periods per Seasonal Cycle

You only have to specify the number of periods per season if you have selected the seasonal model or if you want the system to carry out a seasonal test.

The system uses the following factors for exponential smoothing, depending on the model. Thus, for example, only the alpha and the delta factors are required for the constant model, whereas all the smoothing factors are required for the seasonal trend model.

Alpha Factor

The system uses the alpha factor to smooth the basic value. If you do not specify an alpha factor, the system will automatically use the predefined alpha factor 0.2.

Beta Factor

The system uses the beta factor to smooth the trend value. If you do not specify a beta factor, the system will automatically use the predefined beta factor 0.1.

Gamma Factor

The system uses the gamma factor to smooth the seasonal index. If you do not specify a gamma factor, the system will automatically use the predefined gamma factor 0.3.

Delta Factor

The system uses the delta factor 0.3 to smooth the absolute mean.

See also:

Model Initialization