Mutually Exclusive and Collectively Exhaustive lists are a very profound way to look at the lists way make both consciously and unknowingly.

The idea is that whenever you create a list, you make sure that:

• The items in the list do not overlap
• The items in the list cover the complete subject they the list they are part of is about
• The level of abstraction of the items is the same

We tend to make lists with overlapping items to make sure we cover every bit of a subject. We also tend to cover some areas of a subject with finer grainer topics (typically because we know more details about the area).

So we end up with a list with items that can be visualized as follows:

MECE on the other hand forces us to come up with clearer items, that can be visualized as follows:

MECE is a mindset-tool from the McKinsey toolbox and is really powerful, as it will make presenting subjects much more digestible to your audience; you will have a clear story to tell, covering the subject area precisely and without ugly overlaps. In turn, you audience will therefor better understand what you are bringing.