Calculating Schedule Deviation in MPP

Schedule Deviation = (Finish-Baseline Finish) / (Baseline Finish-Baseline Start + 1)
Create 3 custom number fields.
Numerator : Number1 Field = ProjDateDiff([Baseline Finish],[Finish])/[Minutes Per Day]
Denominator : Number2 Field = ProjDateDiff([Baseline Start],[Baseline Finish])/[Minutes Per Day]+1
Schedule Deviation ( N/D*100 ): Number3 Field = IIf([Number2]<>0,[Number1]/[Number2]*100,0)