Bucketing of forecast is done differently in the Demand/Forecasting side of the application versus the Purchasing/Replenishment side of the application.
So, the resulting weekly rollups (buckets) of demand you see between Forecast Analysis and Order Schedule will be slightly different, even though the monthly total for your forecast will be the same.
The main difference between the two is that with a demand forecast split we consider all calendar days in a particular month, versus only work days with a replenishment forecast split. We will use the example below of an item with 1666 units of forecast for the month of March, and 1323 units in the month of April to dive into the calculations.
Forecast Analysis weekly split (Demand forecast)
Here is the forecast analysis weekly split for this item-site:
Since this is the monthly demand forecast, the daily split is obtained using calendar days instead of work days.
Daily demand forecast for every day in March: (1666/31) = 53.74 per day. For April's daily demand forecast: (1323/30) = 44.1
For the weeks of 3/2, 3/9, 3/16 and 3/23, we come up with the weekly demand forecast by multiplying daily demand forecast * 7 = 53.74 * 7 = 376.18 (rounding to 376)
For the week of 3/30, we have 2 days in march and 5 days in April. We will take the Daily demand forecast in march * 2 + Daily demand forecast in April * 5 = 53.74*2 + 44.1*5 = 107.5 + 220.5 = 328
In order to reconcile and make sure that the monthly sum of the weeks adds up on the Forecast analysis and matches forecast manager:
Add 3/1 daily demand forecast + Weekly forecast for 3/2,3/9,3/16,3/23 + 3/30 daily demand forecast + 3/31 daily demand forecast = 53.74 + 376 + 376 + 376 + 376+ 53.74 + 53.74 = 1665.22 (rounding to 1666)
Order Schedule Weekly Split (Replenishment Forecast)
Here is the order schedule weekly split for this item-site:
Here is the order schedule daily split for this item-site:
Since this is the replenishment forecast, the daily split is obtained by using work days instead of calendar days.
Daily replenishment forecast for every day in March: (1666/21) = 79.3. For April's daily replenishment forecast: (1323/22) =60.1
For the weeks of 3/2, 3/9, 3/16, 3/23, the weekly replenishment forecast is obtained by multiplying daily replenishment forecast * 5 = 396.5 (rounding to 397)
For the week of 3/30 we have 1 work day in March and 4 work days in April. We will add: Daily replenishment forecast for March + (4* Daily replenishment forecast for April) = 79.3 + (60.1*4) = 319.7 (rounding to 320)
In order to reconcile and make sure that the monthly sum of the weeks adds up on the Order schedule and matches forecast manager:
Weekly replenishment forecast for 3/2, 3/9, 3/16, 3/23 + 3/31 Daily replenishment forecast = 396.5 + 396.5 + 396.5 + 396.5 + 79.3 = 1665.3 (rounding to 1666)