MECE Framework

I used to believe the GMAT was all about mastering test-taking techniques. After years of teaching, I’m convinced it’s fundamentally a test of logical reasoning, crucial for business school success. Of course, strong English reading comprehension plays a role too, since business schools operate in an English-speaking world. That’s why at A2GMAT, we focus on developing logical thinking rather than just teaching shortcuts.

For many people (myself included at the time), “logical reasoning training” is a rather abstract concept. It’s even more abstract than “how to save your first million” or “how to learn English.” At least you know that working at a convenience store can help you save money, and enrolling in an English cram school can help you practice English. But how do you train “logical reasoning”? Where do you even start? It’s surprisingly hard to find specialized training for thinking skills. So, what can we do? Should we just accept we weren’t born smart enough? Or ask for a do-over?

Here’s a practice method I find most effective: ask yourself three types of questions and then answer them.

Type 1:

• Under what circumstances do people cry? List all unique answers you can think of.
• How can one scam a person over the phone? List all unique methods you can think of.

To tackle these, you need to brainstorm thoroughly and jot down every possible scenario. You’ll quickly see that grouping by broad categories makes the process much more efficient. For instance:

• When alone, what makes someone cry? Breakups, failing exams, losing a job, death of loved ones…
• When with someone else, what makes someone cry? Arguments, breakups, watching sad movies…
• When with more than two people, what makes someone cry? Attending a funeral, watching sad movies…

Without categorization, you’ll either miss situations or list repetitive ones. After writing everything down, remove duplicates. This process itself is a foundational step in logical thinking: clarifying all the factors involved. It’s also the basis for McKinsey’s MECE (Mutually Exclusive Collectively Exhaustive) analysis method.

Just like how Dustin, when consulting students on their study plans, always starts by asking a barrage of questions:

When do you plan to go abroad? How much preparation time do you have each day? Is your work flexible? What is your target score? When is the school’s deadline? What is your daily routine? What are your study habits? What is your family’s attitude? How many times have you taken the test this year? How much budget and energy do you have left for preparation? …

In practice, you’d mentally sort these conditions into “adjustable” and “non-adjustable.” For example, if your family insists you go abroad this year and you’ve already taken the test three times with a deadline three months away, the “non-adjustable factors” are fixed: you have two more attempts within three months. Then, you’d re-evaluate the “adjustable factors.” Maybe you need to sleep less to prepare more. If a work project demands your attention, you might have to study less, adjust your preparation method, and perhaps even lower your target score…

Type 2:

• Without looking up any data, how would you estimate the total number of times the word “幹” (a common expletive in Mandarin) is spoken in Taiwan per day?
• Without looking up any data, how would you estimate the number of cigarette packs sold daily at all 7-Eleven stores in Taiwan?

This stage builds on the categorization skill from Type 1, introducing the need to make assumptions. Using the categorization approach, we can divide Taiwan’s population by age: 0-10, 11-20, 21-30, 31-40, and so on. Then, estimate the proportion of the population in each age group. Given the declining birth rate, you might estimate 0-10 year olds are 5%, 11-20 year olds are 10%, and those over 65 are 30% due to an aging population. Next, assume the average daily frequency each age group uses the expletive. For instance, 0-10 year olds might say it 0 times on average, while 11-20 year olds, being more rebellious, might say it 5-10 times a day. During this process, you’ll uncover overlooked factors like education level or regional cultural differences. You might then subdivide further: 11-20 year olds with education versus without education, and estimate proportions and averages. Finally, you’d calculate a weighted average. Notice how these questions mirror consulting firm or Google interview questions? They’re testing your ability to “categorize and enumerate factors” and “make assumptions.” This ability to categorize and the courage to make assumptions are vital for the third type of problem.

Type 3:

• I opened a bookstore, but sales are dismal. How can I improve sales?
• He looks very tired. Did he just recover from a serious illness a few days ago?

At this point, Type 3 questions closely resemble GMAT Critical Reasoning (CR). After the “categorization and enumeration” and “assumption making” from the first two types, you’ll naturally develop a Standard Operating Procedure (SOP) for approaching them. For the bookstore example: Under what circumstances do people buy books? Categorize and enumerate:

Supply side – Book pricing, book quality, bookstore location…
Demand side – Interest in books, sufficient disposable income, reading habits, awareness of the book/store.

Make assumptions:

What is a reasonable price for a book? Is the current pricing reasonable?
What constitutes good book quality? Is the current quality good?
What kind of bookstore location attracts people? How many people are in this area currently?

You’ve now acquired fundamental critical thinking methods applicable to GMAT problems and even future business school case studies. Don’t jump straight into GMAT questions. Practice with everyday scenarios first. Only through real-life application can you become proficient and tackle seemingly complex problems.

Here’s a little secret:

Interviews for consulting firms or Silicon Valley tech/startup companies often include “out-of-the-box” questions. People outside these fields often hear, “It’s not about whether your answer is correct, but about the logic and structure of your process.” This vague advice isn’t very helpful. (If I were that logical, would I be worried?)

Now, I’ll use a practical example to show what an effective answer looks like.

Example: “How many trains does the Taipei Metro Corporation own in total?”

1. Mental thought process: What are trains used for?
2. Start with “Mutually Exclusive Collectively Exhaustive” categorization: “In Operation,” “Undergoing Maintenance,” “In Reserve for Contingencies.”
3. Next, analyze variables for each category:
   • A. In Operation: You can estimate the number of trains on a line by dividing the “round trip time” by the “peak headway.” Summing across all lines gives the total number in operation.
   • B. & C. “Undergoing Maintenance,” “In Reserve for Contingencies”: This requires knowledge of internal policies. We can reference foreign practices or consult the Taipei Metro directly. Estimate these as XX% and YY% respectively.
4. Organize this into a coherent presentation for the recruiter. Use reasonable estimates for unclear data:

Ans.

The Metro system’s trains are primarily used for operation, maintenance, and reserve support. Let’s estimate for each of the five Taipei Metro lines: The Bannan Line’s round trip takes about 2.5 hours. During peak hours, the headway is around 2 minutes. So, roughly 75 trains operate on the Bannan Line at any given time during peak hours. For the Tamsui Line… Additionally, the Taipei Metro’s maintenance ratio is estimated at 20%, meaning 20% of trains are undergoing routine maintenance. Finally, the corporation needs reserve trains for major events or emergencies. We estimate this reserve at 15%. Therefore, we divide the number of normally operating trains by (100% – 20% – 15%) = 65%. Based on this, I estimate the Taipei Metro owns approximately xx trains.

Recruiter: (Appreciative nod)

This answer is a good start, but not fully comprehensive:

• It doesn’t yet account for factors like train dwell time at terminals or switching between depots. However, it effectively demonstrates your analytical and logical thinking.
• There are multiple ways to estimate. For example, you could calculate “normal operation” based on driver schedules and availability (though is it easier than using headway and travel time?).
• The exact data might vary significantly from reality. But the focus isn’t on precision; it’s on whether your analytical factors are essential.

(This is precisely why the Quantitative section includes Data Sufficiency questions!)

Finally, here’s a little secret: The most frustrating thing for me over the years has been people using only GMAT questions as their sole practice material for developing reading and logical reasoning skills. It’s like trying to fly before you can walk, leading to awkwardness and inefficiency. These are skills that should be applied in everyday thinking! Scoring high on the GMAT doesn’t mean you’re exceptionally intelligent; it simply means you’ve used your brain a bit more than 80% of people in your daily life.