I have written a couple of posts now (here and here) about the new PMBOK v4 guide due out soon. One of the new graphs included helps describe how project characteristics change over the project life time.
The top blue line of the graph is used to illustrate how Stakeholder Influence, Risk and Uncertainty start off high and then reduce as the project progresses. The Escalating orange line illustrates how the Cost of Changes increase dramatically over the project timeline.
Quite a lot has already been written on flattening the Cost of Change curve within agile, so I will leave that for now and focus first on the top line.
Before discussing ideas such as how ongoing business input in, for example, prioritization of the remaining work prolongs their ability to influence the project, we should take a moment to understand the PMBOK audience. The PMBOK is not just for software projects, or IT projects, it is an industry agnostic guide relevant to construction, engineering, and manufacturing among other disciplines.
As a general guide, I think these curves make sense, especially outside of software projects. The ability to influence does decline rapidly once designs are committed and construction begins. Likewise, Risks and Uncertainty also reduce generally later in the project once technical obstacles have been overcome.
Software though is different, actually I would hazard a guess that every industry is different really, however software is the one that I know about. Software exhibits a characteristic known as “Extreme Modifiability” meaning we can make many changes, even late in the lifecycle and still be successful. While it would be difficult to move a bridge 3 miles upstream when it was 75% complete; we could choose to move validation logic from the presentation layer, to a middle tier, or a database trigger late into a project.