Page History: Weighted Usage Calculation
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    Page Revision: 05/03/2011 10:21 AM
The Formula:  (((Units1 sold/Month1 days) * Month1 weight) + ((Units2 sold/Month2 days) * Month2 weight) + ((Units3 sold/Month3 days) * Month3 weight) + ….. ) / (Month1 weight + Month2 weight +Month3 weight + …..) 
Scenario:  Creating a PO on December 8th using a weighted month calculation for the months of October, November and partial December.
Part number sales history:  October = 14 units, November = 16 units and December = 7 Units.
Example 1:Weights used as “1” in all three months.
October daily usage:  14 units divided by 31 days = daily usage of .4516
November daily usage:  16 units divided by 30 days = daily usage of .5333
December daily usage:  7 units divided by 8 days = daily usage of .8750 
Next multiple each month’s daily usage calculation by the weight assigned to that month.  In this case all were weighted as a value of 1 so no multiplier is needed.
Last step is to add all the month’s usage calculations together and divide that value by the total of all weights used.
(.4516 + .5333 + .8750) divided by 3 (total weight) = Average daily Usage of .620.
Example 2:  Only difference is the weight given each month.
Weights:  October = 3, November = 3 and December = 1
October daily usage:  14 units divided by 31 days = daily usage of .4516   Multiplied by weight of 3 = 1.3548
November daily usage:  16 units divided by 30 days = daily usage of .5333   Multiplied by weight of 3 = 1.5999
December daily usage:  7 units divided by 8 days = daily usage of .8750   Multiplied by weight of 1 = .8750
(1.358 + 1.5999 + .8750) divided by 7 (total weight) = Average daily usage of .5476 
4.06521
4.7997