Case Interview Fundamental Case Interview MECE

MECE, pronounced “mee see", is a concept commonly used in top consulting firms such as McKinsey, BCG or Bain. Case Interview MECE framework shapes how consultants in the MBB approach their client’s problems and figure out an effective and comprehensive solution. If you intend to be a part of a consulting firm, don’t miss this article on Case Interview MECE!

A quick glance

  1. What is MECE
  2. What are the principles for MECE
  3. How can it be applied in Case Interview

1. What is MECE?

MECE is a method of segmenting information into elements that are “mutually exclusive” and “collectively exhaustive”. In other words, elements should not overlap each other and exhaust all related aspects.

Mutually Exclusive

Mutually exclusive aims at avoiding overlapping. You need to make sure that your divided elements share no common parts.

Collectively Exhaustive

Collectively exhaustive means all possible options have been considered without leaving any alternatives untouched. 

See our video above for a more detailed explanation!

2. What are the principles for MECE?

Before applying MECE framework into your case interview, there are some best principles that make MECE easier for you. 

No.1: Small pieces of a set should not overlap.

In other words, small pieces of a set should mutually exclusive as we have mentioned in previous part.

Let's take a look at how to break customer groups in In & Out Restaurants.

Here is an example of a not-mutually-exclusive approach: 

  • Walk-in customers
  • Male customers

This framework is not mutually exclusive as there is an overlapping part of two elements. You should notice that some male customers can be walking-in. 

And this is an example of mutually exclusive approach: 

  • Walk-in customers
  • Online customers

This approach is ME as it corresponds different customers based on how they come to the restaurant, in which no elements are dependent on each other.

However, you should be careful because some common parts are difficult to recognize. Always ask the question: “Are there instances when my breakdown can overlap?” 

No.2: The sum of small parts should equal to the big group.

In order to be collectively exhaustive, the add-up of small parts should represent the whole. Again, we will utilize our previous example to illustrate.

If we only segment students in undergraduate school into walk-in customers and online customers, we have not included all elements because there may be drive-through and other types of customer.​

No.3: Small elements should parallel each other.

The small group of MECE classification should be on the same level. Let's come back to our example on breaking down the customers of In & Out Restaurants.

We divided customers coming to In & Out Restaurants based on where they live: 

  • California 
  • Las Vegas area
  • Salt Lake city area

Though the division above is mutually exclusive and collectively exhaustive, it is still not MECE. California as a state is bigger than Las Vegas area as a metropolitan area, and we cannot make comparison between two categories when in need. So be consistent! 

No.4: Follow the rule of magic three.

It is not compulsory to always follow the magic three, however, optimal number of bullets, ideas and elements is always three as it is more memorable and intuitive. It is acceptable if you break down the problem into two or four aspects.

3. How can it be applied in real
Case Interview

A – When drawing new Issue tree. 

This helps you stay on track when finding the Root-cause without getting lost in all the details of the case.

B – In structuring and delivering your pitches

Being MECE in your speech shows that you are a structured and organized person – just the one that the consulting firm is looking for!

Want to learn more? Check out our article on Case Interview Concepts or join millions of others on our Case Interview End-to-end Secret Program. You can also subscribe to our newsletter or our YouTube channel for updated content on your management consulting needs!

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