According to PMBOK, SPI>1 means ahead of schedule, SPI=1 means on schedule, and SPI<1 means behind schedule. But I was looking on some projects on the Internet and they were indeed on schedule, but their SPI was lower than 1. How is that possible?

I'm a PM Student, not profissional yet.

2 Answers 2


It is not possible. Folks are reporting on time and ignoring the metrics because they can't cope with bad news.

Thinking about this a little more, I'd like to add this:

SPI, as with the other EV indices, are as the name suggests: indicators. As with all predictors, EV has predictive validity issues, i.e., nothing is 100% perfect. So while an SPI can show under performance, there may be other indicators that suggest better performance and, putting them all together, you would draw your conclusion of where you are in your schedule. You also have to remember that SPI is a lagging indicator. That plays into your analysis.

Nevertheless, if I had an SPI that was less than zero, I'd be hard pressed to conclude that I am on time except if I lost confidence in the EV reporting. But that would also mean that I am flying blind with all the risks therein.

  • My answer assumes a reasonably performing EV capability. Mar 31, 2016 at 20:11


We can only assume here without reference to the case you saw.

We can assume a few things:

1: They may be referring to a sprint(s) in the over all project being ahead of schedule (If the project has iterative components.)

2: They are reporting incorrectly, taking into account only project components that the stakeholders really care about.

3: Many more possibilities without knowing more.

Can you provide reference to where you saw this project case?

  • Welcome! I don't think references will help much beyond public shaming, and that is not the goal. Your answer is on-spot, and the question is about the theory, not on a specific project.
    – Mindwin
    Apr 4, 2016 at 19:57
  • Thank you! My intention was not to publicly shame, but to find more detail about the project in question. He does mention an actual project with this number, as such we can gain insight from both theory AND real world examples.
    – JSolano
    Apr 5, 2016 at 21:08

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