I first came across this term when I read the McKinsey way by Ethan Raisel. MECE (pronounced "me-see") stands for Mutually Exclusive and Collectively Exhaustive.
I later ran into the term again when I worked in the OD function of a fortune 100 technology firm, where MECE was used in training how to put forth ideas.
The basic tenet of the MECE principle is that when you present an analysis of a problem or issue it has to be analysed and decomposed so that the smaller issues are presented as
- Mutually Exclusive (each idea is distinct and separate; overlap represents muddled thinking) and
- Collectively Exhaustive (you've covered all the possibilities; you've thought of everything)
So next time you think about a business issue or problem can you present the data and analysis in a MECE format? The way that McKinsey consultants do? As the author says:
“MECE structures your thinking with maximum clarity…when you think you have determined the issues, take a hard look at them. Is each one a separate and distinct issue? If so, then your issue list is mutually exclusive. Does every aspect of the problem come under one (and only one) of these issues? If so, then your issues are collectively exhaustive,” Rasiel explains. MECE is a cardinal rule so much so that “every document (including internal memos), every presentation, every e-mail and voice mail produced by McKinsey-ite is supposed to be MECE.”. The McKinsey culture is mainly about “structure, structure, structure, MECE, MECE, MECE, MECE, hypothesis-driven, hypothesis-driven, hypothesis-driven,”