MECE stands for mutually exclusive and collectively exhaustive. The MECE principle was invented at McKinsey by Barbara Minto to be used for problem solving and logical problem structuring.
By the end of this article, you’ll understand the MECE principle and learn how you can apply it to consulting interviews to solve case interviews in a logical and structured way.
MECE Definition and Examples
The MECE principle is used to break down a concept, topic, or question into separate, smaller parts.
Let’s look at a simple MECE example by breaking down a question you likely face each day: what do you want to eat for dinner?
Most people try to answer this question by brainstorming and listing ideas that immediately come to mind:
- Do you want to eat Chinese food?
- Do you want to cook dinner instead?
- Do we want to order take out?
- Do you want to eat pasta?
- Do you want to eat sushi?
- Do you want to eat tacos?
This approach is highly unorganized and makes answering the question of where to eat difficult.
Instead a MECE approach to breaking down the question may look like the following:
There are two components to the MECE principle:
- Being mutually exclusive
- Being collectively exhaustive
Being mutually exclusive means that none of the different parts overlap with each other.
In this example, eating out and eating in are mutually exclusive. You cannot do both simultaneously, so you can only do one or the other.
Similarly, cooking dinner, ordering pickup, and ordering delivery are mutually exclusive under the category of eating in. You cannot do any of these simultaneously (unless you are planning to eat an enormous dinner!).
Being collectively exhaustive means that all of the different parts account for the entire whole with no ideas or possibilities missing.
In this example, eating out and eating in are collectively exhaustive. You will end up choosing one or the other because there are no other options or possibilities If you going to be eating dinner.
Similarly, cooking dinner, ordering pickup, and ordering delivery are collectively exhaustive under the category of eating in. You will end up choosing one or the other because there are no other options or possibilities.
Let’s look at another MECE example by looking at how we can segment the global population.
Example #1: If we break down the global population into dog-lovers and cat-lovers, is this MECE?
This segmentation is not mutually exclusive because many people are both dog-lovers and cat-lovers. Additionally, this segmentation is not collectively exhaustive because some people neither love dogs nor cats. Therefore, this segmentation is not MECE.
Example #2: If we break down the global population into age groups of 0-20 year-olds, 21-40 year-olds, 41-60 year-olds, and 61-80 year-olds, is this MECE?
This segmentation is mutually exclusive because each person can only fall under one of these age segments. However, this segmentation is not collectively exhaustive because it is missing people in the population over the age of 80. Therefore, this segmentation is not MECE.
Example #3: If we break down the global population into people over 160cm tall and people under 180cm tall, is this MECE?
This segmentation is not mutually exclusive because people between 160cm and 180cm would fall under both categories. This segmentation is collectively exhaustive because it covers all possible heights. Overall, this is not MECE.
Example #4: If we break down the global population into people that make less than $40,000, between $40,000 and $80,000 (inclusive), and over $80,000, is this MECE?
This segmentation is mutually exclusive because there is no overlap. If someone makes $40,000, they would fall in the second category. If someone makes $39,999.99, they would fall in the first category.
If someone makes $80,000, they would fall in the second category. If someone makes $80,000.01, they would fall in the third category.
This segmentation is collectively exhaustive because it covers all possible income levels.
Therefore, this segmentation is MECE because it is mutually exclusive and collectively exhaustive.
MECE Principle Importance
Why is the MECE principle important?
There are three primary reasons why being MECE is beneficial.
1. MECE frameworks are much more efficient. There is no duplication of work since all of the different parts are mutually exclusive from one another and do not overlap.
For example, in deciding what you want to eat for dinner, it would be inefficient for me to ask you if you wanted to order Chinese food if you had already told me that you did not want to order Asian food.
Since there is overlap between Chinese food and Asian food, asking both questions is a duplication of work.
2. MECE frameworks guarantee that you do not miss anything. Since the different parts are collectively exhaustive, no idea or possibility will be missing from the framework.
By using a MECE framework for deciding where to eat for dinner, you will have confidence that your answer is in the framework somewhere.
3. The MECE principle facilitates brainstorming. Most people approach problems by brainstorming a list of ideas and going through them. The MECE principle forces you to apply a clear structure to these ideas. This structure can help you generate both a higher quantity of ideas as well as a higher quality of ideas.
Five Ways to Make a Framework MECE
How do you make a framework MECE? There are five different strategies you can use:
- Two-Part MECE Frameworks
- MECE Math Frameworks
- Including “Other” to Make MECE
- Breaking Down Processes
- Breaking Down Stakeholders
Two-Part MECE Frameworks
The simplest way to make your framework MECE is to use a two-part framework that follows the structure of “X” and “Not X.”
For example, the following pairs of words are all MECE frameworks.
These frameworks are mutually exclusive because there is no overlap between “X” and “Not X.” Additionally, these frameworks are also collectively exhaustive because all ideas and possibilities must be either “X” or “Not X” by definition.
These two-part MECE frameworks are simple and quick to develop. This MECE strategy is most commonly used when trying to brainstorm a long list of ideas.
For example, if you are brainstorming barriers to entry in a market, you could use this MECE strategy to develop the following framework.
This strategy guarantees that your framework is MECE.
MECE Math Frameworks
Using math formulas are also a quick way to develop MECE frameworks. This MECE strategy is most commonly used when trying to identify ways to improve a particular metric.
For example, if you are trying to identify how to increase profits for a company, you could use this MECE strategy.
We know the following basic formulas for profit:
- Profit = Revenue – Costs
- Revenue = Quantity * Price
- Costs = Variable Costs + Fixed Costs
Therefore, your MECE framework could look like the following.
All of the different parts of this framework are mutually exclusive because each part makes up the formula for profit. Additionally, this framework is collectively exhaustive because it includes all of the different terms in the profit formula.
Including “Other” to Make MECE
Sometimes, it can be difficult to brainstorm all ideas or possibilities that are collectively exhaustive. In these cases, focus on identifying the largest and most relevant parts of the whole and then add “Other” into your framework to make it collectively exhaustive.
For example, let’s say that you are trying to brainstorm all of the different products and services that Apple sells.
You may brainstorm the following different Apple products and services:
This list is likely not collectively exhaustive because we are probably missing a few smaller products or services that Apple sells.
To make this list collectively exhaustive, we can add “Other” to it.
The rationale is that as long as we have listed the major products and services, the smaller products and services that make up a small percentage of total revenues can be grouped into “Other.”
You should try not to use this strategy too much, but it is an easy way to make your framework more MECE if you are struggling with developing a MECE structure.
Breaking Down Processes
When dealing with business situations that involve improving processes, an easy way to create a MECE framework is to break the process down into separate, distinct components.
This approach can help you systematically go through each component to identify issues or opportunities for improvement.
For example, let’s say that you are trying to determine how to improve how Amazon fulfills orders to customers in order to decrease delivery time. You can decompose this process into the following components:
- Take the customer order information from the website
- Determine the right warehouses to ship from
- Select and package the right products
- Ship the products to large distribution centers
- Determine which local delivery vehicle and route the products should be transported through
- Deliver the products to the customer’s doorstep
This MECE framework ensures that you are not missing any steps in the process and that you are not assessing the same step twice.
Breaking Down Stakeholders
When dealing with business situations that involve many different stakeholders, an easy way to create a MECE framework is to identify all of the major groups of stakeholders.
This approach can help you systematically go through each stakeholder to identify strategies to target each group.
For example, let’s say that you are working with a real estate developer that is trying to get approval to build a new port in the city to facilitate the transportation of goods.
In order to develop a strategy to get approval, you can identify the major stakeholders involved:
- City government officials
- Shipping companies
- Labor unions
- Financial institutions
- Environmental groups
This MECE framework ensures that you cover the major stakeholder groups and that you do not mix different stakeholder groups together.
Being MECE in Consulting Case Interviews
There are many different case interviews and business situations in which creating a MECE framework is incredibly difficult.
For example, how would you create MECE frameworks for the following?
- Deciding whether to enter a market
- Deciding whether to launch a new product
- Deciding whether to acquire a company
- Deciding how to price a product
Read this ultimate guide to case interview frameworks to learn how to create robust and tailored frameworks for each of these cases.
In short, during interviews, it is unreasonable to expect anyone to create 100% mutually exclusive, collectively exhaustive frameworks to every case or question. In interviews, you are under a lot of pressure and likely only have a few minutes to develop a framework.
Even McKinsey, BCG, and Bain consultants cannot create a framework that is 100% MECE every single time.
Rest assured that as long as your framework is 80% MECE or more, that is likely a far better framework than most interview candidates.
Therefore, focus on these three points when making MECE frameworks.
1. Check that you are being mutually exclusive: It is easier to be mutually exclusive than to be collectively exhaustive. Therefore, do a quick check to make sure that none of the areas in your framework have significant overlap.
2. Focus on the biggest and most important areas: Generating a collectively exhaustive list of ideas can be difficult. In these situations, focus on including areas that collectively make up 80% or more of the whole. You can categorize and group everything else as “Other” and justify this by saying that the other areas are much smaller and less relevant than the major areas you have identified.
3. Ensure your framework areas are highly relevant: It is better to have a non-MECE framework in which every area is highly relevant to the case than to have a MECE framework in which no area is relevant to the case. Your framework can be 100% MECE, but if it is inappropriate for the case or business situation, it is useless.
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