Adaptive vs. predictive

There are two ways of going about anything:

• Predictive: You think about every aspect of the output upfront, design it carefully, and then build it. Think of sending a rover to Mars or building a bridge; that’s the only reasonable way you can go about them.
• Adaptive: We can’t predict everything when the way output works depends massively on the acceptance of the end users, which is mainly a problem for software applications. In that case, instead of trying to predict everything, which we know doesn’t work well, we can create an environment in which we can build subsets of the output, have end-user representatives work with it, collect direct and indirect feedback from their work, and use that to decide how to proceed in each consecutive step.

Adaptive methods are commonly called Agile. The Agile community usually calls predictive systems waterfall and traditional, but we don’t refer to them as such in the PMBOK Guide, because those words can have a negative connotation. Both approaches are valid, though, and each works well for a specific type of output.