Case Interview Prep – Useful Tips and Frameworks

1. Case Interview Preparation: 9 Tips for a Successful Case Prep

1.1 Learn the Theory

By reading this article, you have already taken the first step of getting to know what case interviews are all about. Well done! You can now proceed by learning the theory you need to know to solve them. In general, you should learn how to:

• Identify your case type (e.g. Market sizing, Market entry, Profitability, Growth)
• Structure your thoughts (e.g. Issue tree, MECE, Pyramid principle)
• Use business analysis tools (e.g. ABC analysis, Breakeven, Benchmarking)
• Define common terms of business (e.g. NPV, CAGR, Fixed and variable cost)

In our Case Interview Basics, you can find all the necessary basics.

1.2 Gradually Develop your Business Intuition

As you need to have good business sense to successfully pass your case interview, you should dedicate some time before gradually building up your business intuition. The earlier you start doing this, the easier it will come to you. All you have to do is make it a habit of regularly reading business publications or magazines. You can choose new insights from McKinsey, Bain, and BCG or find other sources that appeal to you. While you do that, try to develop a basic knowledge of business, strategy, and industries, such as retail, airlines, telecom, banking, natural resources, and tech.

1.3 Bring your Mental Math up to Speed

All case interviews involve doing math without a calculator which is why brushing up your math skills should be a constant part of your daily prep plan. Practice until you are a hundred percent comfortable doing basic additions, subtractions, divisions, multiplications, and growth rate calculations in your head. Read our article on Fast Math and make use of our mental math tool in order to practice your efficiency. This will greatly ease the pressure if confronted with a math problem in your interview.

Knowing the shortcuts for a wide range of calculations will help you simplify math problems. For example, break down complex math problems into multiple smaller operations:

97 x 53

= (100 - 3) x (50 + 3)

= 5000 + 300 - 150 - 9

= 5141

1.4 Practice Makes Perfect 

Take a look at our vast Case Library with which you’ll be prepared for all possible case types. Our case collection includes cases that have been used in case interviews in the past. Solving cases on your own can give you a first feeling for them, but the only way to improve the skills you need to pass your interview is to put yourself in a case interview situation. Find a few outstanding candidates you can practice with and practice cases on a regular basis. The more perspectives you can get, the better. Feedback will help you improve. 

On PrepLounge, the world’s largest case interview community awaits you. Simply schedule or accept a mock interview with another candidate on our Meeting Board! Here is how it works:

1. Schedule: After you and your case partner have confirmed the mock interview on the Meeting Board, your meeting is set and should be visible on your dashboard.
2. Communication: We recommend you directly get in touch with your case partner to confirm your method of communication during the interview (e.g. Skype) and case preferences.
3. Interview: During the back-to-back meeting you will take turns with your case partner in order to play both interviewer and interviewee roles. Don’t neglect the part of the session where you play the interviewer role. It will help you notice points of importance and adapt your approach accordingly.
4. Case: There will be two PrepLounge cases randomly selected by default, but you can also change them and pick one of our other 190+ cases or use your own case.
5. Feedback: This is the most important part of your mock interview as it helps you to improve your case performance. Please give valuable feedback to your case partner. You would want them to do the same!

1.5 Get Support from Experts 

To make your case interview preparation as effective as possible, we recommend you also invest in coaching sessions with experienced top consultants. Our experience shows that this will be worth it, as it significantly increases your chance of getting your dream job offer (by four to be exact). Our experts know exactly what interviewers want and can work with you on every aspect of your case performance, whether it is structure, personal fit, confidence, or communication. They can even give you valuable networking tips and help you get a referral.

We offer you a transparent list of all experts, including their professional and educational backgrounds, top skills, individual approaches, reviews, and recommendation rates. This allows you to individually choose the perfect experts for your coaching sessions. You may also benefit from our CoachingPlus Package that comes with an overall discount.

1.6 Learn and Keep Track of your Progress 

You can do as many cases as you like, but if you do not learn from them, you will not going to improve your case performance. This is why you should do the following: At the end of each case that you solve, whether it is on your own, with a case partner or expert, write down in your own words what mistakes you have made and what you learned. After a few days, redo the case and apply your learnings to ensure that you are making progress. Keeping track of your improvements will keep you motivated and make sure that you don’t repeat the same mistakes.

1.7 Don’t Forget About the Personal Fit

It doesn’t matter how much you ace the case, but if you are not a personal fit for the company, you will not get the job offer. After all, consulting is a people’s business, that includes teamwork and spending a lot of time with your colleagues. In order to ace the personal fit part of the interview, it is important that you understand what an interviewer is looking for in a candidate to decide that he or she is a personal fit. Typically, the interviewer has three primary questions in mind.

Then, you have to learn how to convey to the interviewer that you comply with what he or she is looking for. Practice your answers to personal fit questions with other candidates or experts:

• Why management consulting?
• Why company x?
• Why should we hire you?
• Tell me about yourself!
• Give me an example of a time that you have led a group to achieve a difficult goal!
• Find more Stress Questions

1.8 Practice Confidence

The more you practice, the more confident you will automatically feel. However, feeling confident is not equal to seeming confident. Sometimes you can come across as insecure without even noticing and this can be due to minor communication style habits. Therefore, you should ask your PrepLounge case partner or expert to take your verbal and non-verbal communication into account and to give you feedback on your level of confidence or insecurity. Try to focus on the following aspects during your practice:

1. Sound of your voice. A monotone voice or speaking too fast gives an impression of insecurity and a poor communication style. To avoid that, you can listen to podcasts with great speakers for about 30 minutes to one hour per day. After a couple of days, you will start to speak in a similar manner, as you will absorb their communication style.
2. Smile. Smiling can be a powerful element to show that you enjoy the interview (and interviewer) and are not afraid. You can force smiles (obviously not too much) in case you get feedback that you seem too serious.
3. Eye contact. You should do not need to constantly look the interviewer in the eyes, but you should not look away when he or she asks you something and you should not stare, either.
4. Ability to break the ice. Confident people are not afraid to start small talks with interviewers from the beginning. Keeping silent creates less connection and may be considered a sign of lack of confidence.
5. Posture. You should try to keep straight in the chair most of the time. Leaning too much towards the interviewer can be seen as a lack of confidence.

1.9 Take Breaks

In total you should prepare for well over 50 hours in up to a 6-week time period, practicing on a daily basis. This can be exhausting, and we know that a lot of candidates struggle with a lack of motivation and focus, especially after an intense period of case prep. This is usually because they forgot to implement regular breaks in their prep plan. Professional athletes will always take time to rest to give their muscles time to regenerate, and so should you for your brain muscle. A good strategy is to develop an evening and morning routine that gives you time to relax and maximizes your energy level for the prep during the day. Here are some examples of what you can do:

• 15-20 minutes of exercise in the morning or evening
• A cold shower in the morning
• Meditation or writing a journal
• Define three important things to do for the next day and allocate the time for all activities while doing the most important ones first
• No social media one hour after you wake up and before you go to sleep
• Get enough sleep (at least 7 hours)
• Take breaks between each case or intense case practice session and do something totally different (e.g. workout, play video games)

2. Case Interview Frameworks

There is no magic formula that can be applied to every case but there are frameworks and methods that can be learned; with practice, you can ensure you are able to answer any case that you come up against.​

Anyone that has started delving into case interviews will likely have come across the frameworks designed by Victor Cheng. These are effective frameworks that have been adapted from widely published frameworks such as porters five forces. These can generally be applied to most case studies and learning them should definitely feature in your preparation. ​

Most firms are wise to these frameworks now and will even mark you down for applying one blindly. They want to see you think on your feet rather than apply a learned response. Using these frameworks is a great foundation that you can build upon, sometimes just changing the headings is enough to show you are able to create a bespoke solution.​

2.1 Types of Frameworks​

There are three key framework types that can help tackle the toughest of case interviews. Whilst it is possible to learn particular frameworks prior to interviews, using frameworks from memory can result in being penalized by the interviewer. Deploying one of the following framework types with bespoke parameters is all that is required to develop an exceptional answer.​

The three framework types are; bucket, issue tree, and matrix. All three allow for a methodical approach but are more effective when used to answer different types of questions.​

Issue tree: Great for profitability questions and any market sizing elements. Each ‘root’ of the tree allows for the isolation of the problem and clear analysis. Often this is used in conjunction with a bucket framework.​

Matrix: Usually taking the form of a table but sometimes a pair of the axis (BCG matrix). This framework is great when having to draw comparisons such as in competitor analysis or M&A suitability. The key is to use only the minimum necessary parameters in order to make a clean and simple comparison.​

Bucket: The most commonly used framework, it is very good for finding the root cause and developing a good idea of the bigger picture. Laying this framework out at the start also provides a checklist to work through which should prevent any unexpected mental blocks.​​

2.2 Five Key Frameworks​

2.2.1 Profitability Framework​

This framework takes the form of an issue tree (sometimes referred to as a logic tree), it isolates the clients' profitability problem into its key components. Following its branches, it is easy to identify where the issue lies and visualize where it fits into the bigger picture. The branches of this issue tree satisfy the MECE principle and therefore if followed correctly, it should lead you to the cause.​

Often a case will require you to identify the root cause of an issue and then subsequently recommend solutions. In this scenario, it is likely that a bucket framework will be required for the solution section.​

A profitability question will normally contain a sentence such as “PepsiCo has experienced declining profits” and therefore should be easily recognizable. Any case involving profits or one of its components (revenues and costs) will require a profitability framework.

Three equations to learn:​

1.     Profits = revenue – costs

2.     Revenue = units x price

3.     Costs = Variable costs + Fixed costs​

Profits = revenue – costs​

This is the overarching equation that you are looking at but as always you must dig deeper into each component of the equation to find the crux of the issue.​

Revenue = units x price​

Units can be increased by increasing the number of customers buying the current products (usually sales & marketing) or by increasing the number of products purchased by the current customer base (upselling).​

Increasing the price of a product is usually the quickest way to increase profits but this will affect the number of units that can be sold at that price, the magnitude of the effect will depend on the elasticity of demand and alternatives available to the consumer.​

Costs = variable costs + fixed costs​

To increase profits variable costs can be reduced by reducing the costs of inputs per unit. Increasing buying power or increasing efficiency on a per unit basis, such as automating steps of the manufacturing process, are ways of achieving this.​

Fixed costs can be reduced by removing unnecessary costs or by maximizing the efficiency of current resources. Relocating the office to a cheaper location is an example of reducing fixed costs directly and increasing manufacturing production to 100% from 80% capacity would reduce the fixed cost per unit.​

2.2.2 General Framework​

Developed on a framework made popular by Victor Cheng, this general-purpose framework is capable of being adapted to the majority of case interview questions. This framework can be an alternative to the growth and market entry frameworks below if you are short of preparation time and cannot learn all the suggested frameworks.​

This case interview framework primarily serves as a checklist to ensure you cover all the relevant elements in the case. It is still important to remain disciplined and methodical by exhausting each point before moving on to the next.

a) Consumer:​

Useful mnemonic: Whales Wave With Police Constables​

Who – the demographic of the customer base e.g age, gender, individuals, businesses, etc.

What – the products they are buying and reason for buying this product e.g stapler to help organize paperwork

Where – the location of the customer base e.g UK, Europe, global

Price – the prices that customers have been paying

Consumer risk – how concentrated are these customers, what effect will lose certain customers have on total revenues? (Usually fewer customers = higher risk)​

b) Client:​

Useful mnemonic: Every Dog Is Four​

Expertise – What the client is capable of and where their limitations are e.g great at manufacturing clothes cheaply but bad at luxury design?

Distribution channels – How is the client getting their product in front of customers? e.g wholesale, retail, direct to consumer, e-commerce, etc.

Intangibles – does the client possess anything intangible that may affect the strategic decision? such as strong brand recognition or intellectual property.

Financial Situation – what financial resources does the client have to make the necessary investments or absorb the cost if the project fails?

c) Product:​

Useful mnemonic: Why Eight Children Started Laughing​

What – the details of the product the client sells

The elasticity of demand – how much of a necessity is the product to consumers? For example, petrol has a high elasticity of demand for those with petrol cars it’s a necessity.

Compliments – are there any existing compliments to the product? e.g a phone case compliments a phone

Substitutes – are there any indirect competitors (especially emerging ones) such as tablets were to the laptop market (different products competing for the same consumers).

Lifecycle – how long does the product last? When will consumers be purchasing again? E.g a sandwich may have a lifecycle of 24 hours but a car is more like 5 years.

d) Market:​

Useful mnemonic: My Children Tried Saying Rebellious​

Market share – the breakdown of competitors and their respective market shares of the target market.

Competitor observations – the competitor's response to the same situation or anything notable in how they differ from the client.

The threat of new entrants – what is going to prevent another entrant to the market and what effect would this have?

Supplier risk – how concentrated are the suppliers, what effect would lose the current supplier have? (usually few suppliers = higher risk)

Regulations – are there any regulations that have or will have an effect on the client?​​

2.2.3 Pricing Framework​

Whilst pricing cases are less common it's sensible to know at least the basics of pricing strategies. Without the basics, it would be easy to flunk the case unnecessarily. The three common pricing strategies are cost-based, value-based, and competitor-based.​

Cost-based pricing: The addition of a target profit margin to the full unit cost.

Value-based pricing: The value that the product provides to the consumer. Usually worked out via a cost-saving, additional benefits over and above existing products or similar.

Competitor-based pricing: Taken from what competitors are charging and what this product offers in comparison.

2.2.4 Market Entry Framework​

This market entry case interview framework is a development of the general framework, it places more emphasis on the strategy of understanding the target market and market capture. It is still possible to answer these questions with the general framework but it is likely to convey a lack of originality to the interviewer.​

Market entry questions usually explicitly state the intentions to enter a new market such as “Bosch is looking to enter the South American market”, making them easily recognizable.

a) Market:​

Useful mnemonic: Small Childish People Prefer Marrying Red-heads​

Size – what is the size of the target market?

Customers - who are the customers and what are their needs and preferences?

Product types – what products is the market receptive to? Do changes need to be made to existing products?

Profitability – are the current players in the market profitable and by how much?

Market share – what is the current market structure of its participants?

Regulations – are there any regulations that could affect the client from successfully entering?

b) Financials:​

Useful mnemonic: Fighting Is Overly Exuberant​

Financial situation – what financial resources does the client have to make the necessary investments or absorb the cost if the project fails.

Investment required – to enter the market what initial costs are there? E.g building manufacturing facilities.

Ongoing costs – what costs will be incurred following the initial investment of entering?

Expected revenue & ROI – what is the expected return from entering the market?

c) Client capabilities:​

Useful mnemonic: Children Eat Children Maltesers​

Expertise – what the client is capable of and where are their limitations? e.g great at manufacturing clothes cheaply but bad at luxury design.

Entry experience – has the client entered a market before?

Market entrants – has anyone entered the market before? If so, does the client have the same capabilities?​

d) Entry strategy:​

Useful mnemonic: Tall People Try Oranges​

Timing – when is the best time to enter?

Pilot – will a pilot be used (99% yes) and what size will it be? Who will participate?

Type – how will the expansion be executed? Self-built, M&A, Joint venture?

Operation location – will the new operation be run from head office or the new location?

2.2.5 Growth Strategy Framework​

This growth framework is an alternative to using a combination of profitability and general frameworks. It simplifies the question of growth nicely by segmenting the problem into internal and external factors.​

During a growth strategy case, it is important to remain pragmatic. It is easy to get carried away with elaborate ideas such as ‘build an app’ but hard to offer sensible ideas with real potential for the client and their current operations. This isn’t to say you should not offer all of the ideas in the beginning but then choose which ones you would recommend they explore further based on the situation in front of you. This is a good chance to show good business acumen.

a) Internal​​

Current situation - what is the financial health, growth and profitability of the company today?

Drivers of financial performance - for this particular company what impacts profitability the most?

b) External​

Industry - what is going on in the industry? (market share, growth rates, new entrants)

Customers - who are the customers and what have their historical buying trends been?

Competitors - who are they and what have they been doing? How have they grown themselves

2.3 The Best Frameworks When Solving Cases

A framework may help you to solve the business problem in your case interview in a more structured and concise way. You should know the most common types of cases in order to determine which might be a suitable framework you can apply. Our coaches Guennael and Vlad explain their approaches:

2.4 How You Should (Not) Use a Framework

With frameworks, you are structured in every case. They give you a helping hand and guide you like a red thread through your case.  However, you should not be too fixated on specific frameworks. A framework should always be adapted to the respective situation. Our coach Sidi explains why:

2.5 How to Develop Your Own Framework in 4 Steps

In order to address unique issues in case interviews, it is important to develop your own frameworks. Our expert Benjamin gives you tips on how to do it:

3. How to Solve a Case Study in 10 Steps [Infographic]

Step 1: Listen actively and take notes. Write down every piece of information, especially numerical data.

Step 2: Restate the question. Pause, paraphrase and make sure you understand the problem statement by confirming with the interviewer.

Step 3: Clarify the objectives and identify the problem. Ask specific questions and double-check on objectives. Make sure you completely understand the problem.

Step 4: Write out your structure. Ask your interviewer for a minute to prepare your structure and organize your notes. Identify your case type and use an issue tree to customize your structure. The branches of your issue tree should be MECE.

Step 5: State your hypothesis. Now that you have set up the issue tree, your task is to test each branch to see if it is the root cause of the problem. Where to begin? A hypothesis based on an educated guess helps here.  (e.g. "Since you have mentioned that revenues are more or less flat, my hypothesis is that the problem is mostly driven by the cost side of the business. If it is okay with you, I will start by […]")

Step 6: Think out loud. Sharing your thoughts allows the interviewer to interact. Refine or rebuild your hypothesis as you find out more.

Step 7: Gather more data in order to test your hypothesis. Proactively ask for relevant data and always segment it (e.g. using the ABC analysis). Try to evaluate whether trends have been company-specific or industry-wide.

Step 8: Dig deeper while staying structured (MECE!) throughout the case. Always refer to the structure you have set up at the beginning of the case but be flexible as the case evolves. If you conclude that your hypothesis is false, eliminate that branch and go to the next one. Summarize findings when switching major branches. If your test confirms your hypothesis, go deeper into that branch, and drill down to the lower levels until you identify all proven root causes.

Step 9: Choose a recommendation and use the Pyramid Principle to structure your conclusion. Ask for a minute to gather your thoughts and then state your recommendation. You need to deliver a one-minute, top-down, concise, structured, clear, and fact-based summary of your findings.

Step 10: Stand by your conclusion. Your interviewer will likely challenge your recommendation (either to see if you can handle pressure or to assess if you really believe in what you are saying).

4. PrepLounge: The Key to Your Success

To become the best, you must learn from the best. That is exactly what PrepLounge can offer you. The vast PrepLounge community makes it easy to find case partners with the same ambitions and goals as you. Whether you are looking for a professional case coach or other aspiring consultants, you will have no problem finding case partners in the build-up to your interview. Our PrepLounge coaches – from Bain to McKinsey – are uniquely qualified to provide you with insights into the mastery of a case interview.

Apart from case partners from every imaginable background, PrepLounge provides a colossal collection of online resources to give you the best preparation leading up to your case interview. We will provide you with questions and answers to the most important consulting case types and share in-depth knowledge for the best possible case interview preparation. You will be able to find case partners to practice online and always be on top of the latest insights and news regarding consulting jobs and top consulting firms.

As a PrepLounge member, you will receive access to all these perks. PrepLounge will accompany you all the way from your application through to your contract negotiation. You strongly diminish your chance of success without sufficient preparation. Invest in your future and give yourself the best chance at acing your case interview! Exchange your experience with peers from all around the world in our Consulting Q&A. Join our case interview community today and embark on your journey into consulting!