This is part 4 of our 4-part on MECE thinking — part 1, part 2, part 3, and part 4.

We’ve talked a few times about being mutually exclusive and collectively exhaustive (or MECE) in our thinking:

First, we've seen how being MECE in our thinking helps ensure that we leave no overlaps (ME) and no gaps (CE). Then we looked at ways to be more MECE. And we’ve also addressed the fundamental issue of MECE thinking in problem solving: Our actual intent is seldom finding answers that are truly mutually exclusive but rather independent, because being ME requires a preclusion that isn't necessarily desirable. This resulted in introducing the idea that we should aim at finding ideas that are ICE (independent and collectively exhaustive) rather than MECE.

I teach graduate students and executives to be better at solving complex problems, and this differentiation between MECE and ICE thinking can sometimes be difficult to grasp. So let's get back to it.

In short, 
make the structure of your question map MECE and the nodes, the actual answers to the question, ICE. Let me explain.

Your question map should have MECE branches. Consider the poster child of all question maps, the profitability map, below.

[IMAGE MISSING: Screen-Shot-2019-11-24-at-16.50.34-1024x603.png]
Good question maps have a MECE structure.Forcing the branches to be truly ME is good because it prevents redundancies: If you have included an idea in, say, the “revenues” branch, then it won't appear in the “costs” one. However, the answers (that is, the nodes of the map) are not ME: Maybe you can improve your profitability by increasing your revenues from returning clients and by also decreasing your variables costs. Pursuing one solution does not preclude you from also pursuing the other (assuming you have the resources to do both). These ideas are independent (i.e., one does not require the help of another to be a logically valid answer to the question).

And this is fine, this is what you want: an efficient map (a map without redundancies) leading to a set of elements several of which might be an answer to your question.

For some problems, making your answers independent will also force them to be mutually exclusive. In the example below, assuming that you are traveling only once from NYC to London and that whichever means of transportation you choose takes you the entire way, traveling by plane, say, precludes you from also traveling by boat.

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In the "going from NYC to London" problem, nodes are both independent and actually mutually exclusive.

But this is a characteristic of the problem rather than a property of your solution, so you should not worry about it.

In the end, 
the structure of your map is MECE. The ideas/nodes are ICE and sometimes MECE.

References

Chevallier, A. (2016). Strategic Thinking in Complex Problem Solving. Oxford, UK, Oxford University Press.Davis, Ian, David Keeling, Paul Schreier and Ashley Williams. “The Mckinsey Approach to Problem Solving.” McKinsey Staff Paper, no. 66 (2007): 27.Eppler, Martin J. “Toward a Pragmatic Taxonomy of Knowledge Maps: Classification Principles, Sample Typologies, and Application Examples.” In Information Visualization, 2006. IV 2006. Tenth International Conference on, 195-204: IEEE, 2006.Gardner, Howard. Frames of mind: The theory of multiple intelligences. Basic books, 1985.Kazancioglu, Emre, Ken Platts and Pete Caldwell. “Visualization and Visual Modelling for Strategic Analysis and Problem-Solving.” In Information Visualisation, 2005. Proceedings. Ninth International Conference on, 61-69: IEEE, 2005.van Gelder, T. (2010). "What is MECE, and is it MECE?". Retrieved October 4, 2014, from https://timvangelder.com/2010/06/04/what-is-mece-and-is-it-mece/.