According to the PMBOK Guide, specifically within the Control Costs process of Project Cost Management, the To-Complete Performance Index (TCPI) is a specialized metric used to determine the efficiency required for the remaining work.
* Definition: The TCPI is a measure of the cost performance that must be achieved with the remaining resources to meet a specific management goal, such as the Budget at Completion (BAC) or the Estimate at Completion (EAC).
* The Formula: It is calculated as the ratio of the " cost to finish the outstanding work " to the " remaining budget. "
* To meet the BAC:
$$TCPI = \frac{BAC - EV}{BAC - AC}$$
* To meet the EAC:
$$TCPI = \frac{BAC - EV}{EAC - AC}$$
* Interpretation:
* If TCPI > 1.0: The remaining work must be performed more efficiently than originally planned to stay within the budget (harder to achieve).
* If TCPI < 1.0: The remaining work can be performed less efficiently than originally planned while still meeting the goal (easier to achieve).
* Purpose: It provides the project manager with a " reality check. " If the calculated TCPI is significantly higher than the current Cost Performance Index (CPI), the project goal may be unrealistic.
Comparison with other options:
* A. Budget at Completion (BAC): This is the total planned budget for the project. It is a static figure used in the TCPI calculation, not the ratio of remaining work to remaining funds.
* B. Earned Value Management (EVM): This is the overarching methodology that combines scope, schedule, and resource measurements. TCPI is a specific tool within the EVM framework.
* D. Cost Performance Index (CPI): This measures the cost efficiency of work already performed (
$$CPI = \frac{EV}{AC}$$
). While TCPI looks forward at what efficiency is required, CPI looks backward at what efficiency has been achieved.