Using SSAS 2005/2008 as PowerPivot Data Source: Calculated Members
A general problem of any cube is the way PowerPivot handles calculated members. From a technical point of view, it is absolutely correct that PowerPivot imports the result of a calculated member evaluated at the granularity of the query result. However, from the user point of view, it is not pretty clear why importing a calculated member it imports a value and not the formula. If your users are used to browse cubes, and because calculated member are defined at the cube level and not on the client side, users often don’t see the difference between a “native” measure and a calculated one. For example, if a calculated member shows the value of an indicator (for example, the ratio of sales per phone call), when a user imports that indicator in PowerPivot for Country, City, Year, Month, Day and Product, he will see a wrong number looking at this indicator browsing data and selecting only the total per Year, without a Month/Day detail.