Earned Schedule

Posted on December 1, 2009 by

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The project manager’s tool of Earned Value Management (EVM) is extended through Earned Schedule which draws a distinction between schedule performance measured in terms of currency and schedule performance measured in terms of time. EVM typically uses units of currency as a means of tracking schedule performance. For example, in EVM, Schedule Variance (SV) is how close to schedule the project is in terms of cost. It is calculated as Earned Value (EV) – Planned Value (PV). It simply examines the difference between the value in currency of the work actually accomplished and the value in currency of the work we had planned on accomplishing at this point of time. The Schedule Performance Index (SPI) conveys this same information in terms of a ratio. It is calculated as EV / PV.

Earned Schedule makes the distinction between schedule performance based on currency versus time. SV and SPI as described above are denoted by SV($) and SPI($). When tracking schedule performance based on time rather than currency, the notations used are SV(t) and SPI(t). SV(t) is calculated as Earned Schedule(ES) – Actual Time(AT); and SPI(t) is calculated as ES / AT. The concept is the same, but time has replaced currency. To review additional notations, see http://www.earnedschedule.com/Terminology.shtml.