Calculating a Sum Based on a List Criteria
It is a fairly easy task in PowerPivot to calculate a sum based on N criteria (after a learning curve). This can be accomplished by filtering your data before importing it in the PowerPivot window, selections made in the Pivot Table, or through some (relatively) simple DAX calculations.
However, if N gets too big, the task get much bigger. Now, imagine a table with thousands of customers and the task is to calculate a sum based on only 1000 of those customers. Conventional filtering does not provide a way to do this. Then, say that this list of customers changes from day to day. It would be nice to have a method to perform this calculation. There is!