What is MECE?

Two tests for any grouping

Mutually exclusive means each item belongs in exactly one group, so no fact is counted twice and no argument is made twice under different headings. Collectively exhaustive means the groups together cover the whole question, so nothing important falls between them. A breakdown of costs into fixed and variable passes both tests, because every cost is one or the other and every cost is included. A breakdown of customers into small businesses, retailers and online shops fails the first test, because one customer can be all three. MECE is not a formula for the right answer; it is a check that the structure of an answer is sound.

Where the term comes from

Barbara Minto, who joined McKinsey in 1963 as its first female MBA professional hire and worked there until 1973, developed the Minto Pyramid Principle while editing consultants' reports. In an interview for McKinsey's alumni news, she explains that the pyramid required groups of ideas to be MECE, divided pieces that were mutually exclusive of each other and collectively exhaustive in terms of the whole. She credits the underlying idea to Aristotle, saying she was the first to abbreviate it and apply it to analysing groups of ideas. The firm pronounces it mee see; Minto herself says it as one syllable, rhyming with niece.

How MECE is used in decks

In analysis, MECE shapes issue trees: a question is split into sub questions that do not overlap and together cover the question, then each is split again. In a deck, the same structure becomes the storyline. The top level points are the sections, each supported by slides whose points do not repeat each other. On a single slide, MECE governs any grouping: the pillars of a strategy, the categories in a chart legend, the causes on a fishbone diagram, the columns of a comparison. Checking a slide for overlap and gaps before presenting catches many of the questions an audience would otherwise ask.

Common mistakes

The first is an other category so large it hides the real structure. The second is mixing dimensions, such as grouping customers partly by size and partly by industry, which guarantees overlap. The third is pursuing exhaustiveness so far that a slide lists twelve trivial categories; in practice, collectively exhaustive means covering what matters, with a small remainder named honestly. The fourth is treating MECE as the analysis itself, when a tidy structure can still contain wrong facts. The fifth is groupings that are MECE in theory but not in the data, such as categories whose boundaries nobody can apply consistently.

MECE and the rule of three

Consultants often combine MECE with small groups: two to five items at each level of a breakdown, so the audience can hold them in mind. That sometimes means reorganising a long list into a few higher level groups, each of which then contains the detail. Both habits push toward the same result, a structure that is easy to follow and hard to poke holes in. A practical way to test a grouping before a meeting is to take ten real items, such as ten customers, ten costs or ten causes, and try to place each one. If any item fits two groups, the groups overlap; if any fits none, there is a gap. Ten minutes with real examples finds problems that staring at category names never will.

Where it shows up in the product

Several slide roles here suit MECE structures. Framework has 22 templates for models and grids, tree has 10 for hierarchies, and matrix slots include a two by two quadrant, a three by three grid and a SWOT, each of which imposes a grouping that still has to be filled carefully. Pillars suits parallel groups that are all true at once. The lessons learned example on this site uses a fishbone slide that sorts the causes of a six week delay into data, process, vendor, people and governance. Nothing in the builder checks a grouping for overlap or gaps, so apply the two tests yourself after generating.

Questions people ask