It sounds like EVM is the topic of the week on LinkedIn 😊 It prompts me to
raise awareness of one popular myth that pops up whenever EVM challenges are discussed.

👺 Myth: “Earned Schedule addresses EVM methodological time management problems”.

One of LI’s comments: “A good alternative to SPI is the Earned Schedule created by Walter Lipke, while SPI makes measurements the schedule deadline in money, earned schedule makes in time (i.e. days) much more reliable and understandable.”

No, it doesn’t! Earned Schedule addresses one problem, but others are so big that time forecast is still unreliable.

🔮 Addressed challenge:
The original EVM method is based on the assumption that the remaining part of the project will be performed as it was planned on time of baseline. Walter pointed out that current progress is a better proxy and offered a set of metrics to apply the new ‘TPI – Time Performance Index ‘ proxy.

It is the right idea that the performance factor has to be considered, so Earned Schedule is an excellent addition to EVM and is a better alternative to SPI. However, it does make forecasts reliable! It doesn’t show when the project is likely to be delivered!

There are other challenges that should not be ignored.

💣 Critical path.
We can’t apply the same principle to forecasting cost and time!

A dollar spent on a project will be added to the overall cost regardless of where it was spent. However, a day of delay may or may not impact the delivery date, depending on whether the delay was on a critical path.

The completion date depends on critical path activities, not all activities.
Both EVM and ES ignore this fact.

💣 Risk profile.
Let’s assume a project progressed ideally; all works performed as per the original plan but the probability of one risk is changed from low to high. It means that if the risk impacts activities that are likely to be on a critical path, the expected completion date is changed, but both SPI and TPI can’t show that.

💣 Project stages
Projects progress through different stages, meaning different activity types drive critical paths. Each stage has its unique uncertainties, challenges, and opportunities.

💡 There are no reasons to assume that previously materialised risks will materialise again for the same project!

Even worse, a project may accelerate delivery, pushing risks to later stages of the project. Rush (to initiate/design/develop/etc.) compromising maturity & quality may help with good performance but will likely cause delays during testing.

Due to the unique nature of projects, it is impossible to predict completion dates just by analysing past performance. It must be done by analysing the remaining work and risks. Performance is a complementary factor, not the base for such analysis.

Alex Lyaschenko

PMO | Portfolio Planning & Delivery | PMP | P3O Practitioner | AgilePM Practitioner | Six Sigma