Forecast Parameters 

Maintenance of the following parameters is optional or mandatory, depending on how you carry out model selection and which model you choose; that is, the forecast parameters are dependent on the forecast model. Which parameters are required for which model is shown in the table below.

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


-

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 following factors are used by the system, depending on the model, for exponential smoothing. 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 alpha factor set in the profile. In the standard SAP profile, this is the 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 beta factor set in the profile. In the standard SAP profile, this is the 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 gamma factor set in the profile. In the standard SAP profile, this is the factor 0.3.

Delta factor

The system uses the delta factor 0.3 in every forecast model to smooth the mean absolute deviation.