Case Interview: all you need to know (and how to prepare) | MyConsultingCoach

Case Interview: A comprehensive guide

What is a case interview?

Case interviews are simply word problems based on real client projects on which the interviewers themselves have worked. The interviewer will be assessing you on several areas that characterise a good consultant, that can be summarised in your ability to solve problems and translate solutions into actionable insights for clients.

Case interview format

You will have to complete between 4 and 6 interviews divided in two rounds before landing an offer, with each interview lasting approximately 50-60 minutes. Here’s the typical interview breakdown:

  1. First 15-30 minutes: Fit Interview, assessing your motivation to be a consultant in that specific firm and your leadership and teamwork traits. Learn more about the fit interview on our fit interview article.

  2. Next 30-40 minutes: Case Interview

  3. Last 5 minutes: Fit Interview, again. This time it’s about your questions for the interviewer.

Both the Case and Fit interviews plays a crucial role in the finial hiring decision. There is no “average” between case and fit interviews: if your performance is not up to scratch in either of the two you will not be able to move on to the next interview round or get an offer.

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Difference between first and second round interviews

Despite interviews in the first and second round follow the same format, seniority of the interviewer, time pressure (with usually three interviews in a row) and value at stake make the second round potentially one of the most challenging moments of your working life. There are three key differences between the two rounds:

  1. Time pressure: the Final Round tests your ability to perform under pressure, with 3 interviews in a row and often very small breaks between them

  2. Focus: Since interviewers in the Second Round tend to be more senior (usually partners with 12+ years experience), they will be more interested in your personality and ability to handle challenges independently. Some partners will literally drill down into your experiences and achievements to the extreme. They want to understand how you react to challenges and your ability to identify and learn from past mistakes.

  3. Psychological pressure: while interviews in the first round are usually more focused on simply cracking the case, second round interviewers often use the "bad cop" strategy to test the way candidates react to challenges and uncertainty.

Frame the Airline Case Study

Is there a difference between McKinsey and other firms?

Most cases test your ability to crack a broad problem, with a case prompt often going like: "How much would you pay for a banking licence in Ireland?". You, as a candidate are expected to identify your path to solve it (structure), leveraging your interviewer to collect the data and test your assumptions.

But McKinsey interviews, especially in the first rounds are slightly different, with the interviewer controlling the pace of the conversation much more than in another case interviews. Easentially your interviewer will ask you a set of pre-determined questions, regardless of what your initial structure is. You will have to understand the problem, come up with a mini structure, ask for additional data (if necessary) and come to the conclusion that answers the question.

Essentially interviewer led cases are big cases with lots of mini-cases within them. The method you have to follow is basically the same as in the standard (or the candidate led cases), the main difference being that instead of solving one big case you are solving several mini cases.

Case interview topics

Several self-proclaimed consulting gurus made fortunes out of creating long laundry lists of case types and selling a ready-made recipe for each of them. The truth is simpler: cases are extremely varied but they are usually built around few common topics:

  • Estimates, i.e. being able to combine the “guess factor” and the quantitative factor to come up with reasonable estimates of unknown facts.

Example: How many bank branches are there in Italy?

  • Business analysis, i.e. understanding how a business makes money, what is its value proposition to its (existing and potential) customers and how it compares/competes with other players. Several cases will include elements of market entry, new product development, pricing that broadly fall into this category.

Example: Should we export our peanuts butter to Tunisia?

  • Profitability, i.e. understanding the key drivers that enable a business to make (or lose) money: revenue and cost base (e.g. is it a fixed cost-business like an airline or a variable cost business like a grocery?).

Example: Despite steady growth in customer flow, Walfort supermarkets has seen its profitability declining over the last year. What is the reason of such decline?

As a matter of fact, each case will include a one or more the three above common topics.

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Skills required in a consulting interview?

In Cases there is no right or wrong answer, what really matters is the way you think the problem through, how confident you are with your conclusions and how quick you are with back of the envelope arithmetic. If you visit McKinsey, Bain and BCG website pages on case interview, you will find that the three firms look for very similar traits. Broadly speaking, your interviewer will be evaluating you across 5 areas:

One: Probing mind

Showing intellectual curiosity by asking relevant and insightful questions that show critical thinking and a proactive nature. For instance, if we are told that revenues for a leading supermarket chain have been declining over the last 10 years, a successful candidate would ask:

We know revenues have declined. This could be due to price or volume. Do we know how they changed over the same period?
instead of a laundry list of questions such as:

  • Did customers change their preferences?

  • Which segment has shown the decline in volume?

  • Is there a price war in the industry?

Two: Structure

Structuring means creating a framework, i.e. a series of clear consecutive steps in order to get to a solution to the problem. The focus of a framework (and of the whole case in general) is not on the solution itself but rather on how to get there.

This is the trickiest part of the case interview and the main reason for candidates failing the case interview. Millions were made by selling books describing 10 or 12 standardised frameworks, which were said to be the passkey to solve virtually any case on earth. Unfortunately this approach simply does not work, for a few reasons. First Consultants are not naïve enough to hire people who are just good at memorizing 12 schemes, second because you are expected to think exactly in the same way a real consultant would do in a real case. And, since no consultant uses pre-packaged frameworks in real projects (feel free to ask all your friends in consulting), do you think they expect you to use them in an interview which is set to represent as closely as possible their work?

This is why we created the Problem-driven Structure. As ex-consultants, we aim to teach candidates what real consultants do in real projects, i.e. crafting a tailored framework for every case. The key pieces of your structure should be:

  • Proper understanding of the objective of the case. Ask yourself: "What is the single crucial piece of advice that the client absolutely needs?"

  • Identification of the drivers: Ask yourself: "What are the key forces that play a role in defining the outcome?"

At first sight this concept looks pretty intuitive. However this is a radically different from the typical one-size-fits-all framework approach, trying to force-fit a random framework into a case. Let’s understand why with a simple case question.

Our client is PharmaCorp, a Dutch pharma company specialized in researching, developing, and selling “small molecule” drugs. This class of drugs represents the vast majority of drugs today, including aspirin and blood-pressure medications. PharmaCorp is interested in entering a new, growing segment of drugs called “bionics”. These are complex molecules that can treat conditions not addressable by traditional drugs. R&D for Bionics is vastly different from small molecule R&D. PharmaCorp wants to jumpstart its biologicals program by acquiring BioHealth, a leading bionics startup from the Silicon Valley with a promising drug pipeline. Should PharmaCorp acquire BioHealth?

Check out the difference between the standard framework-based approach and our Problem-driven Structure.

Three: Problem solving

You’ll be tested on your ability to identifying problems and drivers, isolating causes and effects, demonstrating creativity and prioritising issues. In particular, the interviewer will look for the following skills:

  • Prioritising: Can you tell a relevant from an irrelevant fact?

  • Connecting the dots: Can you connect new facts and evidence to the big picture?

  • Establishing conclusions: Can you establish the right conclusions without rushing to conclude facts not supported by evidence?

Four: Numerical agility

In case interviews, you are expected to be quick and confident with (precise and approximated) numbers. This translates into:

  • Performing simple calculations quickly: essential to solve cases quickly and impress the clients with quick estimates and preliminary conclusions)

  • Analysing data: extract data from graphs and charts, elaborate it and draw insightful conclusions.

  • Solving business problems: translate a real world case to a math problem and solve it.

Five: Communication

As in the real consulting life, coming up with the best ideas in a case interview is necessary, but not enough: you must be able to turn it into a compelling recommendation. Otherwise your days and nights of hard work have been totally wasted.

So, how do you make sure that your recommendations come across as relevant, smart and engaging? By mastering CEO-level communication. It sounds easier than it is, since speaking like a CEO often entails doing exactly the opposite of what you would do when telling a story to your mum. Here are 3 key areas to focus on in your communications:

  • Top down: A CEO wants to hear the key message first, and then, if and only if she finds it useful, she’ll ask you to provide details. Always think about what is absolutely critical for the CEO to know, and start with that. You can read more on our section about the Pyramid Principle.

  • Concise: This is not the best time for boiling the ocean or going through an endless number of possible solutions. Consultants want a structured, quick and concise problem recommendation they can implement the next day.

  • Fact-based: Consultants, as CEOs hate opinions based on gut feel rather than facts. They want facts first, to make sure you are in control. Always back up your conclusions with the RELEVANT facts.

How to crack any case interview like a McKinsey, BCG or Bain consultant would

The MyConsultingCoach team, a group of experienced MBB consultants with experience on both sides of the table, has developed a new, proprietary approach to case cracking which replicates how top consultants approach actual engagements.

The key is decoupling problem solving, business concepts and analysis tools to achieve the necessary modularity to apply the same method to solve any case. The synergic action of these three elements will allow you to tackle any problem. Let's look at these in more details.

The problem driven structure

MyConsultingCoach’s Problem Driven Approach is a universal problem solving method that can be applied to any business problem irrespectively of its nature. It is a simplified version of the roadmap McKinsey consultants use when working on engagements. The canonical 7 steps are simplified to 4 as the analysis required for a 6 months engagement is clearly different from that of a 45 minutes case study. However, the underlying flow is the same. Let's look at it.

Identify the problem

Sometimes, prompts are easy to digest. For example - “Our client, a supermarket, has seen a decline in profits. How can we bring them up?”
But more often they’re not and come from varied business areas and industries. For example, “How much would you pay for a banking license in Ghana?” or “What would be your key areas of concern when setting up an NGO?”
In order to successfully solve a case, you will need to identify the problem the client is facing and show the interviewer you can start off on the right foot.
In our video on Identifying the problem, we will learn how to apply a structured hypothesis driven approach to quickly circumscribe the key issues the client is facing. We will cover all aspects of the initial part of the interview, from taking notes, to engaging the interviewer with the right questions to formulating an insightful hypothesis.

Frame a solution

Once you identify the problem you should move on to structure it by developing a custom tailored structure, exactly like real consultants in real life. It will require deeper thought from you, but it will ensure you tackle the right problem, provide a relevant solution and come across as a pro at solving case or any other problems!

Creating a structure involves breaking a problem down in smaller sub-problems which are usually represented using issue trees, allowing the visualization of the dependencies between sub-problems. How do you build a problem driven structure? Let’s look at an example – airline revenues can be broken down as number of customers multiplied by average ticket price. The number of customers can be further segmented into number of flights times number of seats times average occupancy rate. Similarly, the node of average ticket price can be broken down further.

Frame the Airline Case Study

A good structure has several requirements like MECE-ness, level consistency, materiality, simplicity and actionability. You could use several approaches to segment the problem – a mathematical vs. a standard approach; an hypothesis or an issue based approach. Beyond this, there are also several segmentation drivers also to choose.

In our case interview course, we will learn in detail the pre-requisites for devising good structures, as well as how to then deploy and test those structures.

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Lead the analysis

Our lead the analysis process helps you move from the structure to the solution.
First, we navigate our structure to identify the key issues which need to be addressed (while further segmenting the end node, if needed). In our airline example, we could find the average ticket price to be a key issue. We would then look at its drivers and find that the problem is in the Economy Class ticket price. We could then further segment it. Once we’ve done this, we move on to generating solutions tailored to that end node, which in this case would be incentivizing crew for onboard sales, improving assortment in plane or offering discounts for online purchases. Our “lead the analysis video”, which lasts well over an hour, will guide you through the process in detail.

Lead the Airline Case Study

Provide recommendations

Recommendations need to be communicated in a top down way. You need to deliver a one minute, top-down, concise, structured, clear and fact-based summary of your findings.

The Pyramid principle often used in consulting

Our video on ‘Consulting thinking’ will help you go over these concepts in a lot of detail.

Building blocks

When building your structure you’ll come across some familiar themes again and again, recurring concepts which make businesses tick – profit, prices, valuation, market sizing, and more. These are what we call building blocks.
Building blocks, give you the tools to structure cases, applying business concepts to new problems
Building blocks are not frameworks. Frameworks are plug-and-play solutions which tend to be force-fitted to cases.
Building blocks, on the other hand, let you have an analysis of recurring problems in your repertoire without expecting all cases to be identical. These can to be used to build custom structures more quickly and accurately.

Analysis tools

Companies hire consultants for their problem solving and communication skills. These are the same skills which will get you hired by McKinsey, BCG or Bain! This is the reason why consulting thinking is a pillar of our method. Principles such as MECE or the 80/20 are ubiquitous in consulting: mastering them makes the difference between an average and a top. The distinctive characteristic of consultants is that they have a problem solving mentality: they focus on generating solutions to problems by using a fact-based approach. This approach relies on 5 key elements:

  • MECE structures
  • Root cause analysis
  • An Hypothesis driven mentality
  • Fact based "so what's"
  • 80-20 rule

These elements are intrinsically linked; our course elaborates on each in detail.

Relationship among different elements of consulting thinking

Problem driven structure vs frameworks

The framework approach is too fixed and does not allow much room at all for customization. With this method, you would typically start by identifying the case type along a number of dimensions such as topic (profitability, M&A, market entry), interviewer stance, company and so on. Then, you would move on to selecting the appropriate framework, apply it, perform the calculations and give an answer. This is not what a consultant does when she gets to the client's site at 9am (more often than not at 7am). Instead, she will break problems down and find solutions quickly, efficiently and, more importantly, creatively. Make sure you do the same in your case interview.

Comparison between Problem Driven Structure and Framework approach

Learn more about our method and why case interview frameworks don't work in this video:

Let's take a break from all this theory and look at what to do to prepare efficiently and effectively for your case interview.

4 steps for an effective case interview preparation

Too many candidates try to steam ahead into their prep without having made any kind of plan to guide their efforts. As a result, they will spend their time inefficiently and end up with a patchy preparation.

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To plan effectively, you first need to know what you are preparing for; consulting interviews have two sections: Fit and Case. Both are equally important, and to get hired you must be successful in both.

1. Learn the theory

The MCC Academy is a comprehensive, all-in-one package, teaching you everything you need to know about the case interview. We designed the course around a sensible suggested structure for a candidate with little business background. While following that structure is the simplest course of action, a more experienced candidate can easily adapt it to their specific needs. Your case interview preparation approach depends on:

  • Background: whether you are new or not to case interview will affect the amount of background reading you need to do. Anyways, you will need to learn about our problem driven structure approach.

  • Timeframe: clearly time will affect you preparation. We usually advise our clients to prepare for around 60 hours, obviously the more practice you get the better it is. It is similar to an S-curve.

2. Self practice

For solitary preparation, perhaps one of the best uses of your time is to work on your mental mathematics. This skill is neglected by many applicants much to their immediate regret in case interview. Find our mental math tool here or in our course and practice at least 10 minutes a day from day one to the day before the interview. Once you covered our Building Blocks (week 2), then you should start working through the cases in My Consulting Coach's case bank alongside your work on the course. To build your confidence, start out on easier cases, work through with the solutions and don't worry about time. As you get better, though, you can move on to more difficult cases and try to get through them more quickly. You should practice around 8 cases on your own to build your confidence.

3. Practice with a case partner

Regardless of your background, you will need to put in significant time practicing cases. As such, finding good case partners is perhaps the single most important aspect of your preparation. My Consulting Coach offers an intuitive, user-friendly and - importantly - FREE meeting board where you can get in touch with fellow consulting applicants from across the globe with whom to practice case studies. Candidates are listed along with their background and case experience and the board has easy-to-use tools for both direct invitations and scheduling open meetings. We recommend you to practice 1-3 cases per day with peers depending on your time. You can start doing so once you covered our Building Blocks (week 2), to then double down on your effort when you are done with the course and have more time (week 4 onwards according to our schedule). My Consulting Coach provides 45+ interactive cases for you to crack with your partners, so you will have plenty to keep you busy! Two tips:

  • Practice with as many different candidates as possible: the more different perspectives you’ll get, the more you’ll be able to get feedback and fine tune your performance

  • Don’t neglect the part of the part of the session where you’ll play the interviewer role: getting in the feet of the interviewer will help you get her perspective and adapt your approach accordingly

4. Expert help

This step is optional, but very useful. The most effective way to prep for a consulting interview will always be to get help from someone who has worked as a consultant for a top firm. Nobody else will be able to spot your weaknesses as quickly or offer better advice to deal with them. Of course, you will never be able to secure the time of these individuals for free. However, it is worth considering the difference in your salary over even a just few years between getting into a top tier firm versus a second tier one. In the light of thousands in increased earnings, getting expert help is one of the best investments you can make for your own future. Should you decide to make this step, My Consulting Coach can help, offering a premium service to match you with coaches - each of whom is selected to have years of experience as a working consultant with a top firm. If you are a busy student or professional who wants to walk out of the interview room without regrets, check out our Mentoring Programs.

A final note: keep track of your progress

At My Consulting Coach we strongly believe that your mistakes can be your best source of learning. After every case practice with us you'll receive the Performance Radar, a written report with feedback and scores for all key areas (Problem Solving, Structure, Communication, Numerical Agility). The scores will enable you to track your progress and the written feedback will help you pinpoint the areas where you should focus your efforts as well as those where you have improved. You'll always be in control.

Fit Interview

Most candidates spend their time preparing only for case interviews and neglecting fit interviews. This is a major problem, as both these components of the selection process are accorded equal importance by recruiters and good performance in one will not make up for a poor showing in the other. The bottom line is that consultancy firms simply will not employ someone who they doubt will be a good fit with the company, regardless of how many cases they can crack.

The fit interview will be especially important if you are coming into consulting via a less standard route. You will need to be able to provide a compelling narrative to explain why, even though you are coming from elsewhere, consulting is the right move for you at this point in your career, as well as how your previous experiences have furnished you with the relevant skills for consulting.

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