How to do a case study? Our 2024 Free guide

The case study. This test, dreaded by candidates for strategy consulting firms, is however the one where progress is the most promising, if you train well.

Now a must in 90% of consulting interviews, the case study is extraordinary in its ability to assess analytical, creative, computational and communicative skills, as well as the management of time and pressure of candidates. And that in just 40 minutes.

The aim of this exercise? Test candidates on their problem solving skills, that is to say their ability to find solutions to complex problems Inspired by business cases that took place in real life, the advice interview gives a taste of an authentic mission to anyone who aspires to become a consultant. This exercise is so effective that it is used in the US Army to train officers through complex scenarios and recruit future military leaders.

However, it is an extremely discriminatory exercise, which, once unsuccessful, disqualifies the candidate. You have to know how to master the codes and ways of thinking in order not to fear it.

StratMachina reveals the secrets of successfully preparing for the case study exercise.

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What is a case study?

A case study is an exercise that poses a “business” problem to a candidate who must solve it by finding the best possible solution.

This definition poses two essential elements for the understanding of this exercise. The interviewer poses a problem, and the candidate must manage to find a solution. From this comes an important principle: each case study is unique, has its own problems and its own complexity. Therefore, each solution must be perfectly adapted to the problem posed by the interviewer.

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The different types of cases

In terms of form, oral case studies vary between firms and are of several types.

• Interview-LED at McKinsey: As the name suggests, the interviewer leads the case study and the resolution of the general problem, asking the candidate about all the intermediate steps to arrive at the final solution.
• Candidate at BCG or Bain: the interviewer lets the student unwind their thoughts to solve the problem posed at the beginning, sometimes redirecting them and giving them additional information on request.

On the merits, the cases are also divided into three main categories :

• A third of the cases relate to growth problems (Growth). Example: “The CEO of company X wants to double his turnover within 2 years. What do you advise him?”
• A third of the cases relate to profitability problems (Profitability). Example: “Company X saw its margin drop by 10% last year. How do you explain that?”
• A third of the cases include various subjects:some text
  • Acquisition: “Should the company/fund X buy the company Y?”
  • Pricing: “how to price this solution so that it is profitable?”
  • Market Entry: “Should Company X enter Market Y?”
  • Market Sizing: “What is the size of the Y market?” You will find a corrected example hither.

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The methodology of the case study - on the merits

The case study is composed of several parts

1. Statement of the problem by the interviewer
2. Clarification
3. Problem solving structure
4. Analysis: brainstorming and calculations
5. Conclusion

For educational purposes, we will use the example of a profitability case to illustrate each of the steps.

1. Problem statement

Let's start at the beginning. When the interviewer spells out the problem, they'll talk to you like a customer would talk to a consultant. He will describe a situation to you and then finish with a question. It's up to you to write down the important points of this statement on a piece of paper., and to rephrase the case in your own terms, to make sure to the interviewer that you understood what it was about.

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E.g.:

Interviewer: Your client is a hotel operator. Owning around fifty premium hotels, its margin has recently been negative at -2%. He would like to understand why and put in place levers to increase it.

Candidate: Thank you. As I understand it, our client operates around fifty premium hotels in France and its margin was recently negative at -2%. The question is why and how to increase it.

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The important elements to note here are the activity of the customer (hotel operator), the range (premium), his current margin (-2%), and the problem posed (two problems: why are we there and how to fix it?).

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2. Clarification

Clarifying questions, which come after the problem is reformulated, are there to clarify the case as much as possible. They only aim to understand all the elements of the case in order to draw up an initial resolution structure. Attention: clarifying questions are not intended to solve the case! This is the characteristic of step 4 (analysis). If you go too far in these questions, the interviewer will feel it and will hold you back.

The classic clarification questions are often:

• The client's objective: always ask what the objective is, if there is a numerical or time objective, or if there are other goals not mentioned in the statement that they would like to address.
• The customer's business model: how does my customer make money? Who are its customers? What is his method of remuneration (subscription, one-time, commission...)?
• The customer's geography: where is it located? where does it operate?
• Customer value chain if it is not clear or important for your structure.

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Candidate: Allow me to ask you a few clarifying questions before drawing up a structure.

• Is there an objective order to identify the reason for a negative margin and the levers to bring it back into the green? Answer: yes, we would like to bring the margin down to 2% by next year.
• Where is our customer located? In France.

(Here, the other questions are superfluous given the customer's activity).

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3. Resolution structure

This stage is perhaps the most important part of the case study: it tests the candidate's ability to synthesize and Business Sense immediate. It is on this part that the interviewer gets an idea of the alertness of the candidate, who must succeed. in 1 to 2 minutes to synthesize your problem solving ideas in 2 to 4 parts, each comprising 2 to 4 sub-parts.

This structure should be what is called “MECE”. These are the initials of

• Mutually Exclusive: meaning that the structure is not redundant between the parties, which are mutually exclusive.
• Collectively comprehensive: meaning that the structure addresses all of the issues raised by the problem.

In short, the structure should get to the point, without repeating itself and mentioning all the topics that are potentially going to be addressed during the resolution of the case.

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Candidate: I am proposing a three-part structure. First I would like to do a market analysis to verify that the problem does not come from there. Then I would analyze the internal capacities of our company to make a profit. I will end by outlining potential levers to restore the margin to 2% in the short term.

1. Market analysisSome text
   1. Demand problem: declining growth? fewer customers for the premium segment?
   2. Competitors: new players like Airbnb? drop in PDM?
   3. Customer trends: abandon premium and hotels - teleworking, inflation, other solutions that are easier to access?
2. Internal analysis of the companySome text
   1. Revenues: Price (evolution)? volume (evolution)? others: hotel restaurants, etc.?
   2. Costs: fixed (marketing, administrative), variable (commission fees, platforms, water, electricity, food)?
3. Levers to increase the marginSome text
   1. Revenues: organic (increase volumes or prices); external (M&A or diversification for example in segments other than premium).
   2. Costs: dependent on what has been developed previously.

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4. Analysis: brainstorming and calculations

Once the structure is stated, it must be validated with the interviewer, then bounce back on it (if we are interviewing with an interviewer, the interviewer will ask you the first question).

In this longer stage of the case study, you have to be smart and be a real Sherlock Holmes to pinpoint the source of the problem and then propose solutions.

The behavior to have:

• Think methodically, in “baby steps”. Go from the most obvious to the least obvious.
• Think out loud so that the editor can follow you or redirect you if necessary.
• Constantly saying “So What?” Each idea you state should be turned into a case resolution element.

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example

Candidate: Have we noticed a drop in demand in the hotel sector?

Interviewer: Yes, a 30% drop.

Candidate: I understand. This can be due to several things: a competitive factor such as the arrival of substitutes such as Airbnb or a macro factor such as a decrease in tourism or purchasing power.

Interviewer: It's due to Airbnb that has shaken up part of the sector.

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Here, the observation “there was a drop in demand” was transformed into the conclusion “the arrival of Airbnb is one of the causes of the decline in our client's profitability”. It is the “So what” logic that must be used for each observation to reach a conclusive element.

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5. Conclusion

The conclusion summarizes the elements found during the brainstorming, but aims above all to give a final recommendation to our customer.

This is why it is important to write down on a corner of your draft, as the case goes by, the important interim conclusions that form the thread of your conclusion.

The perfect conclusion contains the following steps:

1. The main recommendation
2. The justification: with the elements found during the case.
3. The risks of the recommendation
4. The next steps.

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Example:

I recommend that you increase your turnover by pivoting to the model of a sustainable and even more premium hotel.

Indeed, you are subject to competition from Airbnb and are not exploiting your occupancy rate to its full potential. Switching to such a trend could help boost your numbers and therefore increase your margins.

The risks being to lose some of your customers who will not want to follow you in this new strategy.

The next steps are to start a marketing campaign in this direction and to start this strategy on a selection of hotels.

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The right attitude

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The attitude to have in a case study is that of a good doctor: make a good diagnosis, be a good communicator, and be empathetic. Without any of these three elements, the case study will not be considered successful.

Make a good diagnosis - understand the problem, and only the problem. The candidate must focus on how to solve the case study and not get lost in the off-topic.

Be a good communicator - convey your ideas correctly. The case study is a conversation and not an interview: it is a question of sharing your thoughts with the interviewer and, in turn, taking into account the remarks of the interviewer in order to better advance in the resolution. Bain calls it being “Coachable”: knowing how to question yourself, reorient yourself quickly and listen to your interlocutor is an essential quality for a consultant.

Empathize: a cold and incomprehensible doctor is a very bad doctor. The same is true for a consultant, who must put himself in his client's shoes to solve his case. The client must therefore be, like a patient, reassured by his consultant. This requires a benevolent, jovial and relaxed attitude on the part of the consultant. There is nothing better for an interviewer than to interview a candidate who conveys a good mood and a joyful desire to solve the case that is given to him.

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How do you prepare for it?

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How long does it take to train?

In general, candidates take around 2 to 4 months to practice the case study before beginning their hiring processes. However, it is not always possible to free up free time over such a period, especially for a candidate who has a series of academic and professional constraints. Stratmachina offers a Masterclass accelerated, which allows you, in just 32 hours of intensive distance and ultra-flexible training, to master the case study.

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With whom to train?

The common practice is to train with another candidate who interviews at the same time as you. The advantage is that you can make progress together by correcting each other and sharing case studies.

There is also the option of training with professional coaches, consultants or ex-consultants at BCG, McKinsey or Bain, who are fully aware of the expectations of these strategy consulting firms and can guide you on your methodology as well as your “fit” part.

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What to train with?

Casebooks are good resources: you will find them on the internet or among your school's academic resources. You can also have access to a large database of corrected cases via our webinars or by subscribing to our training.

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