How is the Schedule Performance Index (SPI) calculated?

The Schedule Performance Index (SPI) is a key performance measure used in project management to assess how efficiently a project is progressing in terms of the planned schedule. It is calculated by comparing the earned value (EV) of the work actually completed to the planned value (PV) of the work that was supposed to be completed by that point in time.

Using the formula EV ÷ PV, the SPI indicates how well the project is adhering to its schedule. If the SPI is equal to 1, it means the project is on schedule. An SPI greater than 1 signifies that the project is ahead of schedule, while an SPI less than 1 indicates that the project is behind schedule. This calculation helps project managers make informed decisions regarding scheduling, resource allocation, and project timelines.

Understanding this metric is crucial for effective project tracking and is a fundamental concept within the field of Earned Value Management (EVM). The correct calculation relates earned value directly to planned value, providing clear insight into schedule performance.