Forecast vs Actuals variance

[Levi Turner]

Hi All,

I would like to calculate the variance between our production forecast and actual production as it comes in.

I managed to view this as a percentage using this

[ALLOC_GAS_VOL] / sum([Production Forecast]) OVER ([sTART_DATETIME])

However, I cannot calculate the volume difference on a daily basis

[ALLOC_GAS_VOL] - Sum([Production Forecast]) OVER ([sTART_DATETIME])

I tried this but it doesn't seem to work.

Any ideas out there

Thanks in advance