When you calculate forecast, you can account for the difference between the actual number of working days per period (in the Active forecast file) and the average number of working days per period (in the IC control file). This is accomplished by calculating a workday index for each item/warehouse record per forecast period. The index is then used to apply workday adjustments when the forecast is calculated. See section Workday index calculation for a description of how the index calculation is performed.
Note: The calculated workday adjustment can be used with the forecast methods exponential smoothing and moving average, but not with forecast copy.
Workday adjustment setup
The following sections describe the data that must be set up before you can activate the workday adjustment.
Calendar ID table
This file is used to create the actual number of working days per forecast period in the Forecast file. The number of actual working days can differ from period to period. Define the actual workdays by setting Work day to YES. Then, click Create calendar to create the calendar and update the number of actual workdays in the Active forecast file.
IC control file
Define the normal number of working days in the IC control file by completing the following fields:
- Workdays/week
- Enter the normal number of working days per week. Valid numbers are 1 through 7.
- Note: This field becomes protected once the system generates data in the Forecast file.
- Workdays/month
- Enter the normal number of working days per month. Valid numbers are 1 through 31.
- Note: This field becomes protected once the system generates data in the Forecast file.
- Workdays/period
- This field is automatically calculated from the Forecast period type, the No of periods/year, the workdays/week, and the workdays/month. The resulting value is the average number of working days per period. The actual number of days per period is displayed in the Active forecast file.
- Note: This average value is used when calculating forecast.
Item file
Complete Adjust workdays to indicate that the forecast should be adjusted according to the workday index.
Workday index calculation
The workday index is calculated from the actual number of working days for any single forecast period and the average number of working days per period. This index is used in the forecast calculation to apply workday adjustment effects on demand and forecast.
There are 6 periods per year and the actual number of workdays per period are as follows:
| Period | Actual number of workdays |
|---|---|
| 1 | 44 |
| 2 | 3 |
| 3 | 42 |
| 4 | 46 |
| 5 | 40 |
| 6 | 34 |
- Workday index = number of actual days per period/normal days per period
If the average number of workdays is 42, (as shown in the Workdays/period field in the IC control file) the following workday indices apply:
| Period | Actual days | Normal days | Workday index |
|---|---|---|---|
| 1 | 44 | 42 | 1.04762 |
| 2 | 3 | 42 | 0.85714 |
| 3 | 42 | 42 | 1.00000 |
| 4 | 46 | 42 | 1.09524 |
| 5 | 40 | 42 | 0.95238 |
| 6 | 34 | 42 | 0.80952 |
The workday index is used in two steps in the calculation:
- The indices are used to remove the workday effect from all historical demand data, making it normalised data. The forecast calculation is performed on the normalised data, yielding a normalised forecast.
- Finally, the workday index for the current forecast period is applied to the normalised forecast to get a forecast including the workday adjustment.
Enquiries and printouts
- Calendar ID table enquiry
- Active forecast period enquiry
- Forecast enquiry
No of workdays displays the actual number of workdays for this period, retrieved from the Active forecast file. Adjust workdays indicates if you have stated in the Item file that the workdays should be adjusted. - IC control file enquiry
- Item file enquiry
- Calendar IDs printout
- IC control file printout