- Who am I?
- Introduction
- Disclaimer
- What is a case interview?
- Stages You’ll Experience
- Key Components of the Case
- Introduction
- Framework
- Estimations & Market Sizing
- Mental Math
- Brainstorming
- Chart Analysis
- Final Recommendation
- Case Etiquette
- How to Prepare
- Stage 1
- Stages 2 + 3
- General Advice
- Recommended Casebooks & Resources
- I’m happy to run a case with you!
Who am I?
I studied Finance at the University of Maryland, and most of my work experience was in startups - no fancy names here.
I didn’t go to an Ivy League School, have a 4.0 GPA, or run my school’s consulting club, and most people told me it’d be impossible to land a tier-1 strategy consulting job.
My application wouldn’t make it through the robots at PwC or Deloitte, so I didn’t even think McKinsey, Bain, or BCG were options.
And then - boom.
I got an email from Bain & Company to interview for their internship position - I was shocked.
I had a week to prep.
Long story short - I interviewed, didn’t make it to the second round, and was told to reapply the next time around.
When I reapplied, I knew I had to go big or go home.
Dozens of live cases.
Hundreds of math drills.
Hours on YouTube listening to the latest & greatest tips.
August 4th, 2022: “Hi Joe, it’s {Sarah} from Bain. We’re excited to offer you the role!”
Huge sigh of relief — I did it.
My only regret: I knew I could have done it better.
This is the casing guide I wish I had.
Introduction
Disclaimer
This guide is based on my personal experience in the consulting recruiting process and may not represent others’ casing strategies or experiences. The advice given here is my own and does not reflect the guidance of any of the firms mentioned. Additionally, this guide was written before my start at Bain and was not influenced by my experience or any knowledge collected at the firm.
What is a case interview?
To get a sense of your analytical and communication skills, top strategy companies and teams use case interviews where candidates are asked to structure and solve a business problem.
The interview can take anywhere from 20-40 minutes and varies based on firm.
Of the Big 3 (MBB), BCG and Bain tend to have a candidate-led approach, whereas, McKinsey takes on an interviewer-led approach.
Don’t sweat the differences too much, but basically candidate-led interviews let the candidate choose different paths to explore. It’s up to the candidate to ask for the right data.
In interviewer-led interviews, there is more structure to the case. This allows the firm to get to specific questions and test various skills (math, estimations, brainstorming, etc.).
With both styles, you must remain structured in your approach, accurate with your math, and creative with your ideas - the skills and preparation are the same across the board.
Stages You’ll Experience
I’ve prepped with a bunch of people and have found this to be true in them as well as myself.
You’ll likely experience 3 different stages in your casing journey:
- You’ll have no idea how to run a case.
- You’ll have the fundamentals down but still lost in the sauce.
- You’ll have a bird’s-eye view of the case and be able to drive it.
Stage 1
It’s important to get out of stage 1 as quickly as possible so you’re learning good habits and can get into learning the substance of the case.
I’ve cased with people who have done tons of prep but still didn’t know case etiquette or the key building blocks (we’ll talk about these below).
To get out as fast as possible, watch YouTube videos or videos from company websites. Here’s a good one from Bain:
Notice how the candidate takes time to structure thoughts, talks through math, and communicates clearly throughout the case.
Stage 2
Okay - now you have the fundamentals down no problem.
To get to a place where you are not lost you need to have a clear understanding of 2 things:
- The problem
- The data you need to make an informed decision
That’s all.
Part 1 is about knowing what you’re solving for.
Part 2 is about going step by step to collect key information.
At any point in the case, you need to understand how your current question (eg: calculate the market size of basketballs) helps you make an informed decision on the overarching case question (eg. should Baseballs Co. acquire Basketballs Co.).
Stage 3
At this point, you’ll be in a good position to refine & polish your skills. You’ll find faster ways to do math, better frameworks, and more creative solutions. You’ll learn which questions are the most powerful and how to stay organized throughout the case.
Let’s get you to Stage 3.
Key Components of the Case
These are the key components to a case, which we’ll get through in depth:
- Introduction
- Framework
- Estimations & Market Sizing
- Mental Math
- Chart Analysis
- Brainstorming
- Conclusion
The Introduction, Framework, and Conclusion will always fall in their current positions, the others will come up randomly as you dig through the framework and ask for data.
Introduction
Here’s how the introduction goes:
- Your interviewer will begin reading the case prompt.
- They will likely read a lot of information. Practice taking notes on only the most important details.
- You recap the prompt.
- Start with something like: “Just to make sure we’re on the same page” or “just to make sure I heard everything correctly.”
- Then repeat back some key details to show you understand the problem.
- Do not read your notes word for word. The more conversational you can make this, the better.
- Do not ask questions in the middle of your recap.
- Ask clarifying questions
- Now you can ask 2-4 clarifying questions which typically fall into 3 categories:
- Definitions
- These are words you don’t understand - don’t be afraid to ask!
- Business Operations
- How does this business work? Examples:
- “How does this business make money?”
- “Do they sell B2B or B2C?”
- Parameters
- Here you can ask about the goal. Examples:
- “Is there a specific revenue target in mind?”
- “Are there any time constraints?”
- When you’re done asking clarifying questions, take a moment to structure your approach.
- Proper etiquette here is to say: “Can I take a moment to structure my thoughts?”
Framework
Now the framework.
This is an extremely nuanced part of the case that I will not go into advanced detail on.
A framework (or structure) is your blueprint for solving the case question. It should contain 2-5 high-level buckets with specific questions under each. Here is an example:
Developing the framework is important because it sets the foundation for the rest of the case. Now, I’ll dissect the high-level buckets and bullet points.
High-Level Buckets
You’ll often hear that consulting frameworks need to be MECE (mutually-exclusive, collectively-exhaustive).
This means that the categories must be all-encompassing (collectively-exhaustive) but not overlapping (mutually-exclusive).
Why is this important? Because consultants will think of these categories as workstreams and look to divide them among members of their team. You don’t want to be missing key information, and you don’t want team-members to be doing repetitive work either.
I love this video from Crafting Cases on the 5 Ways To Be MECE:
Bullet Points
Once you’ve outlined your high-level buckets, start to jot down key data you need to make an informed decision.
Here are a few examples:
- Market
- What is the size of the market?
- What is the growth rate?
- Who are the competitors & how is market share segmented?
- Profitability
- Revenues
- What is the average price?
- How many units are sold?
- Costs
- What are total fixed costs?
- What are total variable costs?
The closer these questions are to numbers, the better. And be ready to answer, “why do you want to know that?”
Estimations & Market Sizing
Estimations can often be (but are not always) market sizing questions. The purpose of the question is to see how you think thoroughly and analytically through an ambiguous problem. It is not about getting the right answer - it’s about walking through your approach methodically and accurately.
There are 2-types of approaches: Top-down and bottom-up. 99% of the time you should use top-down, starting with a general population and narrowing down to your desired number.
An example of a market sizing question is: how big is the market for basketballs?
Here’s the step by step:
- Clarify the scope
- As you can tell, the question is pretty broad. You’ll want to start by asking any clarifying questions. Examples:
- “Are we only calculating the market size in the US?”
- “Are we looking at only adult-sized basketballs, or mini basketballs too?”
- “Should our final number be in units or revenue?”
- Outline your approach
- This is where I often tripped up. Before diving into the math you need to outline your approach. Do not do this: “So there are 330M people in the US, then we need the number of adults, so I’ll do this equation….” Do this instead:
- The market size of basketballs in the US equals the quantity of basketballs sold in a given year times the price of a basketball (price x quantity). First, let’s get the quantity:
- First we need the total US Population.
- Then we need to get to only males.
- Then we need to get the number of adult males.
- Then we’ll need the percentage of adult males who play basketball.
- Then we’ll need the percentage of those who would actually own a basketball. (*Think about parks & courts - there’s often just 1 basketball for 10 people)
- Once we have the amount of people in the US who own a basketball, we’ll need to understand the replacement rate. How often does someone replace a basketball?
- Once we have the volume, we can multiply it by the average price to get the total market size in revenue.
- Get the numbers
- There are 2 ways you’ll get the numbers you need:
- You ask for the number, and your interviewer gives it to you.
- You are asked to estimate the number.
- Bring in real life examples to create reasonable estimations:
- Not all men play sports, and there are a bunch of different sports available in the US like baseball, soccer, football, etc. Assuming only 50% of men play sports, I’d use 10% given the popularity of basketball in the US. How does that sound?
- Plug in the numbers
- Now it’s just simple math. Complete your calculation based on the approach you’ve outlined. Be sure to keep track of your math & corresponding labels as you go along. Organization is key. Here are two tips for staying organized:
- Label intermediate values - what does this number represent?
- Use different colored pens/markers
For the sake of this problem we will calculate the total annual revenue of adult, men’s basketballs in the US.
Mental Math
Mental math is a core piece of the case interview and can often trip candidates up. I have a bunch of tips on this but rocketblocks.me does a better job by offering tips, tricks, and drills.
Brainstorming
Any time you’re asked “do you have any ideas on…?” - you’re being asked a brainstorming question.
You want to show 2 things in your answer:
- Structured thinking
- Creativity
Refer to the 5 ways to be MECE above for creating great brainstorming structures quickly.
Chart Analysis
Sometimes you’ll be shown charts in your case interview. Your goal is to drive insights from the chart to ultimately make a recommendation.
Crafting Cases does an excellent job outlining the approach to chart interpretation:
To sum up the above:
- Understand what you’re looking at
- Chart title
- Axis titles
- Account for details
- What scale are these numbers in?
- What do the colors represent?
- What does the key tell you?
- Read through the data
- What do you see in the data?
- Drive Insights
- What sticks out?
- Why does that matter?
- How does that connect to the case objective?
Some like to ask for 30 seconds to take notes; I personally like to talk through what I see on the chart to show the interviewer how I think - both work.
Final Recommendation
Your conclusion needs to be clear, concise, and backed by data. This means that throughout the case, you should be marking important numbers that you want to refer back to in your final recommendation.
Your final recommendation should be structured accordingly:
- Your Answer
- Data to back up your answer
- Risks with your recommendation
- Next steps
Here’s what this looks like in practice:
- We recommend that Baseballs Co does acquire Basketballs Co.
- We’ve done an initial analysis and estimate the basketball market to be $500M, and Basketballs Co has a strong presence with 20% market share. Additionally, we expect the basketball market to grow 5% annually for the next 5 years.
- Some risks we’ve identified with this acquisition are around brand integration, as Baseballs Co seems like a brand focused on baseballs. One idea we’ve had to combat this is to create an umbrella company like “Sports Co” that owns both companies but operates them under separate brands.
- Next steps are to get more information from the target company to discover any other operational risks. If all goes well, we can move forward with negotiating the deal terms and making the acquisition.
Key points
- Start with your answer.
- Bring up relevant data points that you’ve discovered in the case. This can look like market size, expected profits, increased revenues, etc.
- Mention some of the brainstorming questions that you’ve explored - they often address risks of a certain strategy and can be used in the Risks section of your conclusion.
Case Etiquette
Throughout this guide, I have mentioned the details of the case interview at each step. Here are a few tips for making a great impression throughout the interview.
- Your interviewer will be asking themself this question throughout your case: can I put this person in front of a client? This means that you need to be super confident & poised throughout the interview.
- Smiling is important. After doing a bunch of cases, you might feel like a casing robot. Many will know how to do cases, but personality will set apart the great from the good.
- You will likely trip up at some points - that’s totally okay. Be open to feedback during the case and stay resilient.
- Practice succint communication & avoid rambling.
How to Prepare
As mentioned earlier in this guide, there are 3 stages most experience in their case prep:
- You’ll have no idea how to run a case.
- You’ll have the fundamentals down but still lost in the sauce.
- You’ll have a bird’s-eye view of the case and be able to drive it.
Stage 1
By the time you finish this guide you should be close to getting out of stage 1. Here’s what I would focus on in this stage:
- Videos of live cases
- Introduction to the case interview guides (including this)
- 2-3 practice cases with a friend
After this, you should clearly identify your weak points and understand how to navigate through a case. That brings us to Stages 2 + 3.
Stages 2 + 3
You’ve indetified your weaknesses are you’re able to see what went wrong in your practice cases. Here are a few ways to practice:
- Drills
- Doing only full cases will make it hard to focus on your weaknesses. Do drills in the building blocks of a case to make sure you’re hitting the certain performance level.
- Find drills on Rocketblocks or pull them out of full cases from the casebooks below.
- Full cases
- Do these with people who can give constructive feedback and know how to deliver a case.
General Advice
How much time should you spend?
My case prep followed a rough schedule:
- 2-3 cases per week
- 2-3 hours of drills/week
- For 10 weeks.
Who should you prepare with?
Prep with people who are going through the process or who are experts at giving cases. You’ll waste a lot of time working with people who are unable to properly give a case or provide meaningful feedback.
Recommended Casebooks & Resources
I loved the Crafting Cases free course which covers the key building blocks of a case. It’s free, and you can find it here: craftingcases.com
Rocketblocks.me is a great resource for drills on frameworks and math. They walk through a bunch of different tips & tricks I’ve found extremely helpful.
I’m happy to run a case with you!
I’m fortunate enough to have had a strong support network around me through my recruiting process and would love to pay it forward.
If you feel I could be of help in any way, please reach out on LinkedIn!