The Forecast Demand Calculation is used to compute projected forecast demands of an inventory item by month. These forecasted quantities are then used by the Reorder Quantity Calculation batch jobs to determine the optimum quantity to reorder. If an order is placed too far in advance, the stock items will have to be stored in inventory before they are ready for use. This will lead to an increase in inventory costs. If an order is placed too late, the stock items may not arrive on time, thus causing stock outs. The Forecast Demand batch job takes the forecast month as a parameter, reads the Inventory table for eligible records, calculates the forecast for that month, and updates the forecast quantity for that stock item’s month on the Inventory table (INVNU). Finally, the process generates an Exception report.
Three methods are available to forecast demand: Manual, Seasonal and Non-seasonal.
Manual Forecasts - Enables users to perform a more detailed analysis of a Stock Item’s usage. Forecast will be calculated manually and not by forecast demand batch job.
Non-seasonal - After calculating the demand over a specified number of months, the average of those demands called Mean demand will be considered as the forecast demand.
Seasonal - The Mean Demand calculated as mentioned in the Non Seasonal method will be multiplied by the Seasonal Ratio to arrive at the Forecast Demand. The seasonal Ratio is calculated by comparing the Accounting period (corresponding to the forecast period) in the previous year with the rest of the previous year.
Forecast Demand is calculated in the following manner:
Calculate Total Demand and Mean Demand for each record
Calculate Seasonal Ratio if Forecast Method is Seasonal
Update the calculated Forecast Demand and Generate Exception Report