MDX calculation has wrong order of precendence - ssas

Question

Im having an issue with an MDX query, and I think it boils down to the order of precedence between calculating an aggregate and a calculated member.
Let me start with the underlying data, which revolves around a valuation (which has a date, and some other data such as a member type, a scheme - and crucially for this question; a loading factor) and an associated value.
The data
Valuation Table
Id | Valuation Date | Member Type | Scheme | Loading Factor
=============================================================
1 | 2010-01-01 | TypeA | Scheme X | 0.02
2 | 2010-01-01 | TypeB | Scheme X | 0.02
3 | 2010-01-01 | TypeA | Scheme Y | 0.02
4 | 2010-01-01 | TypeB | Scheme Y | 0.02
ValuationValue table
ValuationId | Value
====================
1 | 1000.0
2 | 2000.0
3 | 3000.0
4 | 4000.0
This, when loaded into a cube has a Valuation dimension with attributes MemberType, Scheme and date. And a cube with Measure group ValuationValue containing Value measure, and a Valuation measure group containing Loading Factor like so:
Cube
-Measure Groups
- Valuation
|_Loading Factor
- ValuationValue
|_Value
- Dimensions
- Valuation
|_MemberType
|_Scheme
|_Date
The question
Loading factor is used to load the Value, think of it like a tax, so 0.02 means "Loading amount is 2% of the value". When returning Value from a query, I need to also calculate the amount to load this value by. A typical query might look like
SELECT
{
[Measures].[Value]
} ON 0,
[Valuation].[Scheme] ON 1
FROM Cube
This would return 2 rows, and as you can see by comparing to the data above it correctly sums across memberType:
Scheme | Value
=================
Scheme X | 3000.0
Scheme Y | 7000.0
Now, if I try to calculate my loading factor in that query, all goes wrong - i'll demonstrate. Given the following query:
WITH MEMBER [Measures].[Loading Value]
AS
(
[Measures].[Value] * [Measures].[Loading Factor]
)
SELECT
{
[Measures].[Value] ,
[Measures].[Loading Value]
} ON 0,
[Valuation].[Scheme] ON 1
FROM Cube
I get the result
Scheme | Value | Loading Value
=================================
Scheme X | 3000.0 | 120.0
Scheme Y | 7000.0 | 280.0
Basically, what is happening is that it is suming my Loading Factor and then multiplying that by the Sum of my values(The first row above should be 1000 * 0.02 + 2000 * 0.02 = 60. Instead it's calculating 3000 * 0.04 = 120).
This is of course a contrived example, my actual structure is a bit more complex - but I think this demonstrates the problem. I was under the impression that the calculated member in the example above should occur on a row-by-row basis, instead of at the end of an aggration of my Value measure.
Thanks for any replies.

Answer 1

Your [Measures].[Loading Factor] - How is that set, is it a SUM?
Calculated members are generally done as per the rows returned if I remember - Unless you specify otherwise.
If you want an example, take a look at the currency conversion wizard output - This does something similar using the LEAVES command - You will need to do this in the MDX script as a SCOPE'd command though.
Given your description, the code could be something like:
CREATE MEMBER [Measures].[Loading Value] AS NULL
Scope( { [Measures].[Loading Value] } );
Scope( Leaves([Valuation]) );
This = [Measures].[Value] * [Measures].[Loading Factor]
Format_String(This) = "#,##0.00;-#,##0.00";
End Scope;
End Scope;

Answer 2

I'm not sure I follow your example completely, but you might try using SOLVE_ORDER and SCOPE_ISOLATION to manipulate the order of the calculations.
For example,
WITH
MEMBER [Measures].[Custom Calculation] AS
'([Measures].[Sales Count] - [Measures].[Unit Returns])',
SOLVE_ORDER = 65535, SCOPE_ISOLATION = CUBE
SELECT
{[Measures].[Custom Calculation]} ON COLUMNS,
NON EMPTY [Time].[YQMD].[Day].AllMembers ON ROWS
FROM [Waremart]

Answer 3

Thes one turned out ot be REALLY easy.
WITH MEMBER [Measures].[Loading Value]
AS
(
[Measures].[Value] * [Measures].[Loading Factor]
)
WITH MEMBER [Measures].[Total Loading Value]
AS
SUM (
EXISTING [Valuation].[Id].[Id],
[Measures].[Loading Value]
)
SELECT
{
[Measures].[Value] ,
[Measures].[Measures].[Total Loading Value]
} ON 0,
[Valuation].[Scheme] ON 1
FROM Cube