"Within the practice of Project cost Management, trends include the expansion of earned value management (EVM) to include the concept of earned schedule (ES).
ES is an extension to the theory and practice of EVM. Earned schedule theory replaces the schedule variance measures used in traditional EVM (earned value – planned value) with ES and actual time (AT). Using the alternate equation for calculating schedule variance ES – AT, if the amount of earned schedule is greater than 0, then the project is considered ahead of schedule. In other works, the project earned more than planned at a given point in time. The schedule performance index (SPI) using earned schedule metrics is ES/AT. This indicates the efficiency with which work is being accomplished. Earned schedule theory also provides formulas for forecasting the project completion date, using earned schedule, actual time and estimated duration."
PMI® PMBOK® Guide
6th Edition, pg. 233
The primary benefit of ES is that it’s parameters can be readily extracted from an IMS (Integrated Master Schedule) tool, if the IMS is set up properly. ES does not necessitate Resource or Financial data. If you couple the IMS tool with a complimentary integrated SRA (Schedule Risk Analysis) tool like Chrono™, then you have even greater ES capability.
Examples of ES Early Warning Indicators are provided below:
It is important to note that ES is no longer “Emerging”, it is now available from RTConfidence, Inc. And organizations can now effectively utilize this Disruptive “Best Practice” – doing so can significantly bolster competitiveness and overall business performance.