The History Correction page enables you to review and adjust the parameters specified for the management of demand history correction. It also enables you to review the history correction impact in unit terms resulting from both system and manual correction at a product, customer, and period level.
Before you start
The page provides context selector fields that enable you to specify a product and customer. Select the required options from the list at the top right of the page, or manually enter the required value using the search function.
Parameters
The parameters are used to propose history correction through an outlier detection process. The display shows variances between demand and system-corrected history by significance. The page helps you focus on variances by exception for review and correction as required. The charts enable you to review the impact of history correction, displaying unit volume, percentage value impacts of automated correction, manual correction, and final correction.
Parameters are normally set by a system administrator at a global level, and are displayed in the Effective Parameters card. They apply to all product customer combinations. However, you can override the parameter values locally, for a product and customer combination, by setting values in the Edit Parameters card:
| Parameters | Values |
| Correct From | Specifies the baseline for correction. With From Mean or From Trend Line, the values are calculated using periodic data starting from the product’s effective date and ending with the last effective period:
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| Outlier Magnitude | Specifies the number of standard deviations from the mean (or standard errors from the trend line) that determine an outlier. A value of 2 highlights data points more than two standard deviations from the mean (or standard errors from the trendline) as outliers. |
| Correct What | Specifies what correction is applied to the outlier's history:
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| Correct To | Determines the value to which an outlier is corrected:
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| Period by Period | Determines the value to which an outlier is corrected:
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Note: When adjusting parameters for a product and customer combination, the changes are not applied globally.
The History Correction Statistics Summary chart displays the values below:
- C-Var (Mean): Standard Deviation divided by the Mean of pure history value.
- C-Var (Trend): Standard Error divided by the Mean of the Trendline.
- C-Var (Residual): The difference between the Standard Deviation and Predicted values.
Note: A minimum of two years of demand history is required to detect trend seasonality. An alert displays in the Alert card if there is insufficient history.
The View Settings display the values below:
| Parameter | Value |
| View years History | Enter the number of years of demand history to display (default setting is -1). |
| View Period Type |
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Select the Effective Only (Refresh) option to only include products selected for planning. See D1030 - Product Effectivity for more information.
The History Correction chart visualizes the impact of history correction, with a clear view of history before and after correction.
| Parameter | Value |
| Chained History (U) | Displays the sum of the Selected History (U) and Inherited History (U) values. |
| Mean (U) | Displays the mean of pure history. |
| Trend (U) | Displays the mean of the trendline. |
| Trend Seasonal (U) | Displays the mean of the trend seasonal trendline. |
| Upper Limit | Displays the value of the Outlier Magnitude, which controls the number of standard deviations from the mean that determine an outlier. Values exceeding the upper limit are automatically corrected if "Spikes" or "Both" is specified in the Correct What parameter. |
| Lower Limit | Displays the value of the Outlier Magnitude, which controls the number of standard deviations from the mean that determine an outlier. Any values exceeding the lower limit are automatically corrected if "Dip" or "Both" is specified in the Correct What parameter. |
| Corrected History (U) | Displays the applied history correction value. |
The Outliers Table (Refresh) table displays the values below:
| Parameter | Value |
| Chained History (U) | Displays the sum of the Selected History (U) and Inherited History (U) values. |
| Period by Period | If Period by Period correction is enabled, you can select the periods to correct. |
The History Corrrection table displays the values below:
| Parameter | Value |
| Chained History (U) | Displays the sum of the Selected History (U) and Inherited History (U) values. |
| Period by Period | If Period by Period correction is enabled, you can select the periods to correct. |
| System Corrected History (U) | Displays the applied history correction value. |
| Manual Correction (U) | Specify a value to manually override the System Corrected History (U). |
| Corrected History (U) | Displays the default System Corrected History (U) unless you have entered a Manual Correction (U) value. |
| Comments | A text field allowing you to enter comments specific to the product and history correction process step. |
