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What is the Schedule Performance Index?
The Schedule Performance Index is a key component to your project, and looking at the Variance of what we planned for our schedule versus what the schedule is actually ending up as when we’re tracking our project.
Using the Schedule Performance Index
The Schedule Performance Index itself measures how efficiently the project team is accomplishing that work and the way we calculate it is Earned Value (EV) divided by Planned Value (PV). This gives us a value of less than or greater than 1.
Now if we do end up with a value less than 1, this indicates that less work was completed than was planned, so we’re behind schedule. If we’ve got 0.8 for example, that’s less work than 1, which is what we had planned. If we had 1.2 then that might be more value delivered than was planned, and so we are ahead of schedule for what we’re delivering.
Let’s look at an example. Let’s say we’ve got a project budget at completion (BAC) of $10,000 and we’ve got 30 percent completed for delivering this product. And we had planned at this stage to be 40 percent completed. We’ve also spent (our Actual Cost) is $5,000 so far, so if you remember it is Earned Value which is our 30 percent of $10,000 ($3,000) divided by the Planned Value which is 40 percent of $10,000 ($4,000).
We’ve used nice round numbers so it’s a little bit easier to figure out than normal. You’ve got a EV divided by PV, or 30 percent of 10,000 which is $3,000 and we’ve got 40 percent of 10,000 which is $4,000, nice and easy. So three thousand divided by four thousand gives us 0.75, and if you remember if it’s minus one then we’re behind but if it’s greater than one then we are ahead of schedule, we have delivered more than what we expected.
And that is the idea of the Schedule Performance Index.
– David McLachlan