Agility is often thought of in terms of “fixing” the ills of the sequential, step-wise, plan-driven methods that have come to be known as “Waterfall”.  So the question begs, just what is wrong with waterfall?

The short answer is nothing is wrong with waterfall methods.  We’ve all done good work using these methods and I expect that we will all do more good work with them as well.

Let’s look a little deeper though.  In his book Agile & Iterative Development; A Manager’s Guide, Craig Larman describes two broad categories of projects:

  • Predictive - You can define all the work for the project upfront, put a plan and schedule together to do that work, and then execute that plan with reasonable confidence that things won’t change much beyond the normal rigors of running a project.
  • Inventive - The project has a high degree of uncertainty and change and you cannot derive estimates or schedules from previous similar projects. As work on the project is completed, you learn more about what is required and the resources and effort needed to deliver it and adjust accordingly.

Waterfall techniques address predictive projects very well.  Because the work is well-known is it possible to set the correct path for the project and then use traditional waterfall methods to maintain that path. That is what these techniques are all about.  Change is acceptable but only after some rigorous validation that it is the best thing for the project.

Agility on the other hand is best suited for inventive projects. Because the work required is not well-known, these techniques focus on the expected business value.  Change is not only acceptable, it is expected as we learn more about the business objectives and the work required to achieve them.  As a result these methods readily adapt to change in a receptive, but disciplined manner.

So while there is nothing wrong with waterfall methods, what is wrong  is mis-applying them to an inventive project.

As professional project managers we have an obligation to recognize (and help our stakeholders recognize) where our project falls in the predictive-inventive spectrum and adopt the project management methods that offer us the best chance for success.

Waterfall and Agility are both valuable toolsets.  Every project manager should have both in his or her tool belt and know when and how to use them.