Things to Think About Before Carrying out the MRP Forecast

Before you can carry out the forecast for an article, the following prerequisites must be fulfilled:

• You must have maintained the forecast parameters in the article master.

• You must have determined the period for which the system is to carry out the forecast. You do this by defining the period indicator in the article master. For each article, the forecast can be carried out on either a daily, weekly, or monthly basis, or alternatively, according to accounting period.

• You must already have determined how the system is to select the forecast model. This can either be done manually by the RP controller or automatically by the system. In the case of automatic model selection, you must make sure that the required number of historical values are available; the number required varies depending on the forecast model selected.

• If no historical values were entered when creating the article master, you must carry out manual model initialization.

For a more detailed description of these prerequisites, see Overview

Before carrying out the forecast, you also have the possibility of revising an article's historical values which are normally automatically updated by the system during withdrawal postings. On the one hand, you can achieve this by doing one of the following;

• manually changing the values in the article master by means of the correction values

• correcting the weighting factor for the historical values in customizing - for the weighted moving average model.

On the other hand, you can reduce the number of periods to be taken into consideration by limiting the number of historical values in the article master. This means that not all of the historical values are used for the forecast, and instead, only the number of values that you enter.

If a structural interruption appears in the time series of past values stored in the article master record, and if for the next forecast you only want the system to take those values into account which lie after the interruption, then you do this by entering the appropriate number of past time periods in the Historical values field.

Consumption values not determined by the SAP System can be maintained directly with the following exception.

Consumption values for the period in which the article was created as well as in the previous period. These periods can only be influenced by consumption postings for the respective period.