MECE, with examples
MECE stands for mutually exclusive, collectively exhaustive. It means splitting something into groups that don't overlap and together leave nothing out, so every item lands in exactly one group.
- MEMutually exclusive
- Mutually exclusive. No overlap. Each item fits in one group only.
- CECollectively exhaustive
- Collectively exhaustive. No gaps. Every item fits in some group.
The MECE test, worked
A clothing retailer's sales are down 10%. Where could the drop come from?
Not MECE
Prices, Competitors, The economy, Online shopping, Marketing
- Overlap.
- Competitors and online shopping both mean lost shoppers, and the economy drives all five.
- Gap.
- Nothing covers closed stores.
MECE
Sales = stores × shoppers per store × spend per shopper
Stores
How many are open
Shoppers per store
How many people buy
Spend per shopper
Price times items per visit
Where would it go?
Each cause from the first list now lands in exactly one bucket, and so does the one it missed.
- Three stores closed for a refit
- Stores
- A rival opened next door
- Shoppers per store
- Shoppers moved online
- Shoppers per store
- Shoppers trade down in a slow economy
- Spend per shopper
- Prices cut to clear stock
- Spend per shopper
Five ways to split anything MECE
Most MECE structures in a case use one of these.
1. A formula
Write the number as a sum or a product.
Profit = revenue − costs. Revenue = price × volume.
2. Steps in order
Follow the process from start to finish.
An online order: placed, picked, packed, shipped, delivered.
3. Segments on one dimension
Cut by one thing at a time, such as age, region or product.
Customers under 25, 25 to 44, and 45 and over.
4. Opposites
Use a pair that covers everything.
Internal or external, new customers or existing ones.
5. Time
Split by when it happens.
Before the sale, during it, after it.
MECE examples, before and after
Four lists that fail the test, and the fix.
A gym's customers
Students, young professionals, families, people trying to lose weight
Pick one dimension. By age: under 25, 25 to 44, 45 and over. Goals are a second, separate cut.
A factory's costs
Labor, overtime, materials, waste, energy
Labor, materials, energy and everything else. Overtime sits inside labor, waste inside materials.
Why a train line runs late
Old trains, bad weather, staff, signals, too many passengers
Follow the trip: delays at departure, between stations and at stops. Then ask what causes each one.
Ways to grow an app
Marketing, a better product, referrals, more features
Users × revenue per user. Users = new ones + kept ones. Each idea now has one place to go.
How interviewers test it
Three questions you can ask yourself first.
Where would this go?
Interviewers name a cause and ask which bucket it falls in. If it fits two, or none, the split needs work.
Is anything missing?
Read your top level back as one sentence. Sales come from stores, shoppers per store and spend per shopper. If the sentence is true, you are exhaustive.
Which do you start with?
MECE is not a reason to cover everything equally. Say which bucket you would test first and why.
Where MECE comes from
From McKinsey's interview with Barbara Minto and her own site, read October 15, 2026.
Barbara Minto
Minto, at McKinsey from 1963 to 1973, says the idea goes back to Aristotle but that she was the first to abbreviate it and apply it to groups of ideas. McKinsey says the term is now in daily use at the firm.
McKinsey alumni interviewThe Pyramid Principle
Her book's rule is the same idea applied to writing: ideas in a group must be logically alike, and the point above them must sum them up. The 1996 edition supersedes the 1987 book.
barbaraminto.comMcKinsey
A McKinsey consultant's post on its careers site describes an issue tree as breaking a problem into mutually exclusive and collectively exhaustive components.
McKinsey careers blog
Structure a case out loud
MECE is easy on paper and hard under pressure. Practice a case with an AI interviewer that asks for your structure, names causes for you to place and scores it.
Questions people ask
What does MECE stand for?
Mutually exclusive, collectively exhaustive. Mutually exclusive means the groups don't overlap. Collectively exhaustive means together they cover everything.
Who came up with MECE, and how do you say it?
Barbara Minto, at McKinsey in the 1960s and 1970s, named it, building on an idea she traces to Aristotle. At McKinsey it is usually "mee-see", while Minto says it as one syllable, "meece", rhyming with niece.
Does every case structure have to be MECE?
The top levels should be, because that is where overlaps double-count and gaps hide the answer. Deeper down, a short list of the likely causes is fine, as long as you say it is a shortlist.
Is an "other" bucket allowed?
Yes, at a low level, and it makes a list exhaustive by definition. Don't use it at the top. If most of the answer could sit in "other", the split is wrong.
What is the difference between MECE and an issue tree?
MECE is the rule for one split. An issue tree is a problem broken down level after level, each split following that rule.
Is MECE only for consulting?
No. It works for any list where overlaps or gaps cause trouble: a budget, a project plan, the sections of a report or the slides of a deck.
How do I practice MECE?
Take any number in the news, write it as a formula and split each part again. Then say the top level out loud in one sentence and have someone name causes for you to place.