As PMs and EVM staff we need to focus on priorities. Here's a related thought.

A Boeing 777 pilot wrote in Flying Magazine: "What defines us competent pilots is our ability to establish a priority for each management task. That ability keeps the proverbial blue side up (sky) especially when non-normal circumstances occur."

Are your priorities in keeping the "blue side" up on your projects?

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At the AACE Annual Meeting Steven Wageman, CCC, EVP, PSP provided a presentation and a formal paper discussing the relationship between EVM and Critical Path Method (CPM). When we establish our project schedule we find a critical path that determines the project completion data. Activities on this path must complete in sequence and on time for our project to complete per the schedule. But activities off the critical path do not have this demanding requirement. These non-critical paths and activities have float. They have attributes of early start, early finish, late start, and late finish. So they can start late and as long as they finish by the late finish date the critical path is not impacted. Yet most scheduling software default settings schedule these activities to start as early as possible (early start date).

So when we establish our PMB using this schedule it is biased (shifted left) by the use of early start and early finish dates, even though we can miss these dates and not impact the project schedule. So a project that is executing the critical path perfectly, but delaying the non-critical work toward the late start/late finish date generates a schedule variance. Should it? Should we have an alternate PMB reflecting the late start/finish dates of non-critical work?

Wageman illustrates this as two PMBs, one shifted to downward from the normal PMB thus representing less PV planned at any point in time due to later influence of the non-critical activities.

He claims that as long as the EV is between the left and right values the project may be performing as planned. A review of the critical path is needed to determine if the project end date has shifted. He recommends that an "average" PMB using the higher and lower PV be charted and used as a reference point for PV.

His Earned Value Float Ratio Index (EVFRI) provides an index from EVM data. It shows how much of the float has been consumed. For example a value of 0.4 shows more than ½ of the available float has been used 0.6. Negative values show that all float has been used and we're in trouble. Values greater than 1.0 indicate an early project completion.

EVFRI = (EV-PV late)/ (PV early - PV late)

If you want to know more or request the paper contact Steve.

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