Checklist are not an efficient tool to choose between “Waterfall” ​ or “Agile” ​

The Stacey Complexity Matrix

The most frequent answer to “When should we use Waterfall or be Agile?” is almost always revolving around a version of the Stacey Matrix, like the one directly below:

Do you know what to do? (Requirement axis)

Do you know how to do it? (Technology axis)

If you can answer both question by ‘yes’, then you are really lucky and there is no real necessity to use Agile methods. It is also more likely that you could perform the work without using any management methods at all — you’d just need to do it!

Being Human as the biggest issue

Big developments are often complex endeavors done by big teams, and as soon as you are dealing with people, nothing is black or white anymore. Having this in mind, a more realistic way to phrase the two questions on the Stacey Matrix would be to put a bigger emphasis on the human side of it:

How confident are you that you know what to do?

How confident are you that you know how to do it?

It is indeed very important to understand that we try to appreciate our feelings about a risk/cause relationship and that human-beings are terrible at doing so in an accurate and reliable manner. That’s why poker is a game for much of us, we have an access our chances of winning based on the current situation and we get it wrong most of the time, making the game exciting to play.

People are terrible at assessing risks and certainties due to all the Cognitive Bias we are subject to.

The Checklist Mirage

The normal temptation would be to remove the emotional part from the equation by defining a hard criteria-based checklist; but it should also be clear to you that each organization will need to define a specific checklist covering its context but also the bias that are driving its members.

Checklist are carrying the bias of an organization and can’t/shouldn’t be reused.

Clearly, an organization that is biased toward innovation will create a checklist that will minimize the impact of risks or uncertainties — which will lead to a lot of challenging developments being run as super safe waterfall projects (and vice-versa a lot of classical projects might be rolled using Scrum or Fake Agile, and might end up in a very bad place).

Human Interactions over Tools and Processes

The best way to take an informed decision on how to run a new development effort is to reduce its complexity and to do so in a comprehensive way. Luckily, this is something that human beings are doing surprisingly well: Breaking down complex developments into simpler tasks was the basis on the industrial revolution — lead notably by Taylor and Ford — and it is still the basis of any good Project Management.


Agile is the goal of reducing the cost of changes in an organization, which makes its methods useful in complex environment. In more certain context, traditional methods are more likely to be successful and in full anarchy, nothing will ever save you.

  • How confident are you that you know what to do? (Requirement axis)
  • How confident are you that you know how to do it? (Technology axis)




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Baptiste Grand

Baptiste Grand


I’m an Agile Coach that wants to inspire you to seek happiness in your work and your life, by changing the way we do stuff.