Case Interview 101

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.

IS CASE INTERVIEW THE SAME AS CONSULTING INTERVIEW?

No, it’s not. You will generally have 4-6 interviews in two rounds, with each interview lasting approximately 50-60 minutes. Here’s the typical breakdown of each interview:

  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 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.

A FEW EXAMPLES OF CASES?

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 unknownfacts. 

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.

WHAT SKILLS ARE BEING TESTED IN A CASE 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. 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 Priority 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 Priority-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.

WHAT IS THE 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

IS THERE A DIFFERENCE IN CASE INTERVIEWS 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 aother 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.

HOW TO GET READY

Case interviews is an art that can be mastered. We developed a wide array of resources to put you in the best position to succeed. Here, a few tips that might be of use:

  1. Familiarize yourself with the basics of the case interview: In the different pages of the case interview section of our websiteyou can find advanced deep dives for all the main skills tested in case interviews. Our aim is helping you to build a solid skillset that enables you to crack all cases.
  2. Become quicker at math: Getting simple calculations wrong is not a good enough reason to fail a case. We developed a section of our website  to teach you tips and tricks that will speed up your calculation power.
  3. Find a case partner: Practice makes perfect. Join My Consulting Coach to find partners from all over the world to practice with and boost your skills. For free. 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. Get a coachOn the internet you'll find lots of material (recordings, guides, videos...) teaching the art of case interviews. However learning a theory is different from practising it.  Our Mentors are ex-MBB (McKinsey, Bain, BCG) consultants who each have at least 2 years of experience and all secured a promotion to the next level in the organisation. Not only do we ensure that you acquire a sound technique to solve all cases, we also train you to handle pressure and uncertainty, so that no interviewer will take you by surprise. 
  5. 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.