Cost Performance Index indicated the current performance. Whereas the To-Complete Performance Index (TCPI) indicates the required performance.
The cost performance index is calculated by taking the Earned Value and dividing it by the Actual Cost.
CPI = EV / AC
If the original budget is not modified and the CPI value is less than 1.0 (poor performance), then the TCPI value must be great than 1.0, which means that we need to improve performance. This means that due we need to get more than $1 of performance for every dollar spend.
Let’s say you project sponsors wants to know the CPI that you need need to perform at to meet the original budget. What do you do?