We've recently discovered that a former WFP has been adding shrinkage to workload FTE incorrectly in long term budget forecasts. In short, they were adding the shrinkage to the workload FTE using the formula FTE*(1+% fraction) which left us with a 'supposed' required FTE but after further investigation we found when subtracting the shrinkage from this required FTE (assuming your forecast ended up being your actual) you were left with a number lower than forecast workload FTE as it was subtracting a % from the new whole number. I loosely understand what's happening here but wondering if anyone can explain in a little more details so I can confidently explain to MGMT what's been going on and why our revised budget forecast FTE is higher than previous. Any maths whiz that can better explain would be greatly appreciated.
PS please note in case you are wondering that after adding shrinkage we are also adding a factor for occupancy (target 90%) and schedule efficiency (10% inneficiency) which also wasn't done previously and again contributed to the higher than previous forecasts.