Ace the AACE PSP Certification 2026 – Master Your Planning & Scheduling Power!

The Schedule Performance Index (SPI) is the most appropriate measurement for determining whether a project is delayed relative to its schedule. SPI is a key performance indicator in project management that measures the efficiency of time utilization on a project. It is calculated by dividing the Earned Value (EV) by the Planned Value (PV).

When the SPI is equal to 1, it indicates that the project is exactly on schedule. An SPI greater than 1 suggests that the project is ahead of schedule, while an SPI less than 1 indicates that the project is behind schedule. This makes SPI a direct measure of schedule performance, allowing project managers to assess whether they are on track and to make informed decisions about resource allocation and project adjustments.

In contrast, while the Cost Performance Index (CPI) measures cost efficiency, the Estimated Costs (EC) reflect anticipated spending, and Actual Costs (AC) show how much money has been spent to date, none of these metrics provide direct insight into the scheduling aspect of project performance. Thus, the SPI is clearly the appropriate choice for assessing schedule delays.