One of the most foundational ideas in consulting problem solving is “MECE.” If you have been around current or former strategy consultants, you’ve probably heard someone say this, typically pronounced “mee-see.”

MECE is an acronym for the phrase Mutually Exclusive, Collectively Exhaustive. Put simply, it is a principle that will help you sharpen your thinking and simplify complex ideas into something that can be easily understood.

MECE is made up of two parts. First, “mutually exclusive” is a concept from probability theory that says two events cannot occur at the same time. For example, if you roll a six-sided die, the outcomes of a six or a three are mutually exclusive. When applied to information, mutually exclusive ideas would be distinctly separate and not overlapping.

Second, “collectively exhaustive” means that the set of ideas is inclusive of all possible options. Going back to the six-sided dice example, the set {1,2,3,4,5,6} is mutually exclusive AND collectively exhaustive.

Combining these two elements will enable you to take a large amount of information and simplify it into multiple groups of separate and distinct ideas.

First, A Quick History of MECE

The concept of MECE was brought into the world by Barbara Minto, who worked at McKinsey in the 1960s and 1970s. She is notable for being the first female MBA that McKinsey hired and even more importantly, creating a framework for thinking and problem solving that most modern consulting firms adopted and use to this day.

After being hired at McKinsey, she noticed that people around her struggled to write clearly and simply. In her book, The Pyramid Principle: Logic in Writing and Thinking, she says that the advice people were getting was to “write more clearly.”

This seemed like bad advice:

“The problem was the thinking, not the language,” (Minto) says. “People were starting to write without working out their thinking in advance. But how does one go about figuring out one’s thinking in advance?”

The other interesting fact around MECE is how it is pronounced. If you walk into any consulting firm today, you will find that people pronounce it “mee-cee.”

The concept required the groups of ideas to be MECE—divided pieces that were mutually exclusive of each other and collectively exhaustive in terms of the whole. The term is now in daily use at the Firm today. We usually say it “Mee-cee”, but Barbara pronounces it with one syllable, meece, rhyming with “niece” or “Greece.”

The interview quotes Minto who gives us her stance on the issue:

“I invented it, so I get to say it how to pronounce it,” she says.

A Simple Way To Think About MECE From A Trip To The Grocery Story

Let’s walk through a simple way to use MECE, a list of nine items

can you remember a list of items from the grocery store?

Quickly look through the list for about 10 seconds and try to remember the list.

Now close your eyes and try to remember as many of the words as possible.

Really…close your eyes. Come on, just try it!

Not that easy, right?

Using MECE as our guide, we take the list and try to create mutually exclusive groups. We might end up with the following three groups:

  • Bakery Items: Bread, Muffin, Bagel
  • Frozen Food: Popsicles, Ice Cream, Fish Sticks
  • Fresh Fruit: Strawberry, Banana, Grapes

Within the context of our list, the three groups we identified are distinctly different and separate. They are mutually exclusive. Additionally, our grouping covers all nine items in the original list, so the grouping is “collectively exhaustive” as well.

This grouping is called synthesis – taking detailed information and summarizing it into a higher level category.

What is the point of doing all of this anyway? Why not just keep the list of nine items?

The answer is that the information will be much more memorable and persuasive to an audience you communicate your message to. Remembering three things is easier than nine.

Similarly, in a business presentation, the CEO will not want a list of 25 specific actions to take. Instead, he’ll want to know “I need to focus on improving working capital and improving culture.” These will be what he will remember and will trigger him to dive deeper into the specifics at a later date.

Putting It In Practice

Here are some scenarios where you can use MECE:

  • Simplifying a long list of data or information into a smaller set of ideas
  • Breaking down a problem statement into a MECE set of hypotheses
  • Breaking down a list of information into groups
  • Simplifying an article with many different sections into a smaller number of high-level themes
  • Using the pyramid principle to structure an argument
  • Creating an executive summary or TL;DR takeaway of something
  • Sorting a long PowerPoint presentation into clear and distinct sections
  • Breaking down a project into separate “workstreams”
  • Creating a menu of service offerings for your consulting or service business

Remember, MECE Is Not Law Of The Land

MECE is an ideal not a law. When grouping or simplifying some of your ideas it can help you assess whether or not you are actually clarifying information or making it more confusing.

It is a means to the end of improving your writing or thinking, not an end in itself. Many people get caught up optimizing for MECE rather than using it to improve what you are trying to do.

When used in teams, it can be even more powerful as people with a common understanding of a framework can help each other create something well beyond what any one person could come up with.

Want to Practice MECE? I run a course, Think Like A Strategy Consultant, that will walk you through detailed examples of MECE, explain how it fits in with the consulting process, show some of the common mistakes people make trying to use it, and you assignments so you can practice

Do you have a toolkit for business problem solving? I created Think Like a Strategy Consultant as an online course to make the tools of strategy consultants accessible to driven professionals, executives, and consultants. This course teaches you how to synthesize information into compelling insights, structure your information in ways that help you solve problems, and develop presentations that resonate at the C-Level. Click here to learn more or if you are interested in getting started now, enroll in the self-paced version ($497) or hands-on coaching version ($997). Both versions include lifetime access and all future updates.