Nov 02, 2014 9:38 AM
Replying to Kenneth Fung
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As per the PMBOK Guide “Earned Value (EV) is the value of work performed expressed in terms of the approved budget assigned to that work for an activity or WBS Component.”, "Measure of work performed expressed in terms of budget authorized for that work. "How much work was actually done?" If the work is 100% completed the value of work performed is equal to the approved budget assigned to that work.
SPI is often used at the Project Level. By using SPI at project level, the EV is the sum of all work that is started and performed at a point in time. PV is the sum of all approved budget of all the work that is started as of a point in time. It is used for performance measurement of a project.
SPI at the work package level is less meaningful. Since no work can finish before it starts (not logical). This would means that the Planned start date is wrong and should be amended. Please NOTE that the schedule baseline the PV should be / can be updated.
However, I believe SPI should be evaluated at the activity or WBS level, as different curve behaviours cancel each other out at the project level. For example,
Engineering (front-loaded) is late → SPI = 0.5
Installation (back-loaded) hasn’t started → SPI = 1.2
At project level: They cancel each other out → Project SPI ≈ 1 Management sees green. Reality is red
