Hi
I did once something which I guess is similar to your problem.
My task was to set up a rolling forecast model where each month the forecast values should be replaced by actual values but to allow a comparison between the actuals and the latest forecast for a specific month.
My solution was:
Set up within the data cube one "Category"-Dimension which contains the elements "Actual", "Forecast" and "Rolling Forecast". "Actual" and "Forecast" are for input of the values, "Rolling forecast" will be taken from the "Actual" or "Forecast" element, depending on which period we have.
Therefore I set up a new cube with only the "Category" and "Time" dimension plus a new dimension (called "Basics") with only one element "ActualTick".
If then the specific period shall be calculated from Actual there is a "1" in the data cell, otherwise it is blank.
The values in the data cube for rolling forecast are then simply calculated by a rule like:
['Rolling Forecast'] = N:IF(PALO.DATA("Database_name","Basics","ActualTick",!'Time') >= 1,['Actual'],['Forecast'])
This would allow also other categories like variance Forecast - Actual or different Forecast versions like good, median, bad....
That's it and it works fine for me.
There might be other solutions and further ideas are welcome.
Greetz
Lars