What does the Schedule Performance Index (SPI) measure?

The Schedule Performance Index (SPI) measures the efficiency of schedule progress by comparing the earned value (EV) to the planned value (PV), which reflects how efficiently work is being completed relative to the project's schedule baseline.

B. Total float is unrelated to SPI; it measures scheduling flexibility, not efficiency.
C. Resource utilization variance doesn't directly relate to schedule efficiency as described by SPI.
D. SPI focuses on overall progress, not just critical activities.

1. PMI. (2017). A Guide to the Project Management Body of Knowledge (PMBOK® Guide), 6th Edition. Section 7.4.1.2.

2. Kerzner, H. (2017). Project Management: A Systems Approach to Planning, Scheduling, and Controlling, 12th Edition. Chapter 23, pp. 584-589.

3. Mulcahy, R. (2018). Creating a Winning Project Portfolio. Gower Publishing. DOI: https://doi.org/10.4324/9781351227519.

4. Oracle. (2020). Oracle Primavera P6 Enterprise Project Portfolio Management. Documentation on Performance Index metrics.

5. PM Solutions. (2015). Managing Project Performance. Section on Performance Metrics.