Case Interview: Complete Prep Guide

Case Interview Complete Prep Guide. Ask any consultant, and they’ll have their own take and probably a few tips. “Be More Structured” – that’s the most famous tip. “Just do lots of case interview practice.” There’s another zinger. “Be good at mental math.” Thank you, Captain Obvious! But when you’re looking for specific, actionable case interview preparation guidance – wouldn’t you like to hear from experts that work with thousands of candidates a year?

When we’re asked for case interview tips, We. Do. Not. Mince. Words. And trust us – our recommendations go beyond “Learn case interview frameworks.” Our Case Interview prep guide gives you a head start on all things case interview.

Here’s the reality: you can do everything else perfectly during consulting recruiting, but ultimately, it is your case interview performance that will be the difference between you remaining a candidate or becoming a consultant. Most of the time, a case interview will be based on a project that the consulting firm has actually worked on. So the consulting cases are a reasonably good way to test and see who will be the best potential consultants.

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We know that the consulting case interview can be nerve wracking whether you are a senior experienced hire or just an undergraduate. However, with enough practice and preparation, you should go into each case interview with confidence – knowing that you have the right approach to crack any case that comes your way. This goes beyond just knowing case interview frameworks. To get to that point, see below for our complete case interview prep guide.

Heed these, or perish.

Case Interview Complete Prep Guide

In order to succeed in the case interview, you must first learn how to prepare for them – here are 15 case interview tips for preparation.

1. Start Preparing for Case Interviews Early

Recruiting season will come quicker than you think, as it will for most other candidates. If you’re in school, look into your program’s historical consulting recruiting timeline. Work backwards to start your case interview prep early enough so you can stay a step ahead of your peers.

In an ideal scenario, start watching case interview prep videos at least six months before your first case interview. See the following timeline below for prep.

  • ADCs (Advanced Degree Candidates): Start case interview prep in February. Your peak recruiting season is August.
  • U.S. undergrads: Start case interview study in March. Junior and Senior recruiting peak is in September.
  • International undergrads: Start case interview prep in April. Internship and full-time recruiting peak is in October.
  • MBAs: Start case interview practice in June. Enroll and immediately start prep, before you even set foot on campus.
  • Everyone else: The optimal time to apply is in March or July – so you’re looking at starting case interview preparation September or January.

That’s right – get moving! The case interview won’t wait – and a normal turnaround between application and interview is 2 weeks. That’s not enough time for any normal human to prepare unless you go completely AWOL.

2. Use Audio Case Interview Resources

Some of the most underutilized tools for case preparations are podcasts and YouTube. These resources feature firms like McKinsey, Bain, and BCG providing a wealth of valuable information. Not to mention our own Management Consulted YouTube Channel that has over 100 free videos on everything from consulting recruiting to case interview prep to negotiating a consulting offer.

Why is it important to listen to or watch case interviews? Because you cannot get all of the information you need for case interviews by reading books. The case interview is out loud. Firms are judging not just your thinking ability, but more importantly, your ability to communicate through ideas.

To get started, watch our Case Structure Walkthrough video. Even better, get personalized coaching. Having an expert listen to you and give feedback while you practice a case will improve your results more than anything else.

On our YouTube channel, consultants and ex-consultants interview “candidates” as well as one another. They provide comments on the things the candidate does well or poorly.

Once you have listened to multiple case interviews, read (or skim) case interview books (see our recommended list). However, reading case interview books should only ever be 10% of your prep. 40% of your case interview prep should be watching or listening to others and giving cases, and then the remaining 50% should be you in the hot seat.

3. Practice Case Interviews Out Loud… A Lot

You’ll need to go through a lot of practice cases. Expose yourself to the wide variety of potential business problems that are introduced during case interviews. There is no magic number of cases you need to practice before you’ll be ready. But at the very least, you should aim for no less than 20. Most candidates who land offers practice in the range of 30-50.

In addition, case interview variety is important. Though you don’t need to have practiced a specific type of case (i.e. Profitability vs. Market entry vs. M&A) to crack a case interview, it’s what we recommend. Additionally, practicing a large number of cases will help you see the patterns that exist amongst similar case interview types. That can then allow you to more efficiently reach sound conclusions.

4. Quality Case Interview Practice Matters

As often as possible, you should aim to practice with experienced consultants or peers who have practiced a lot of cases and gotten offers. Unsurprisingly, there can be times when even just one practice case interview with a really great consultant can teach you more than your ten previous cases combined.

This is especially true if you have been practicing with the same partner. You may have established bad habits, or your partner may not have the experience to give you some advice that others might spot instantly. Your goal isn’t to feel good about case interviews – it’s to be good at case interviews.

Cut Your Practice Cases In Half

case interview preparation, case interview, case frameworks

Good news: if you work with a coach, especially early on, your number of needed practice cases is cut in half! Spend time reviewing each case you do out loud. Keep a bank of learnings and actually re-do areas of the case to get better. If you do that, your number is cut in half again! In fact, we’ve found interesting evidence that this approach works: at firms like McKinsey, Bain, and BCG, the number of average practice cases for candidates that get offers is lower (15-20) vs. the norm (30-50). Why? They focused on quality case interview practice vs. quantity case interview practice.

As a result, it’s important to reach far and wide across your consulting network and practice case interviews with as many experienced consultants as you can. Also, don’t be afraid to ask consultants who you network with to help you practice once for case interviews. If you maintain a good relationship with them and they think you have a shot, they should be willing to help.

Expert Coaching

Again if you want expert coaching, we’re here to help. We recommend Black Belt Interviewer, which gives you 8 hours of 1:1 coaching. Our success rate speaks for itself. 60% of our “Black Belts” land offers at Top 10 firms
vs. a 3% acceptance rate industry-wide!

5. Get Comfortable with Mental Math

Quite often, mistakes in calculations can be the difference between a successful or disastrous interview. If you’ve made mental math mistakes in practice cases or during case interviews, you know from experience that being corrected by your interviewers can cause you to become flustered and disrupt the flow of the case interview.

Keep your case interview mental math skills fresh by practicing using online tools (see our Mental Math Drills) or in your head on walks to work or to class. Even spending five or ten minutes a day will vastly improve your skills and help prevent easily avoidable errors in your cases. If you want structured help in this, we built a whole course on Mental Math for Consulting.

Most importantly, for the 6 months prior to the case interview, go off your calculator. This really helps in your case interview preparation. Dinner tips, bonuses, whatever – calculate them in your head first. (You can always check, but push yourself here – the case interview payoff will be worth it.)

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Case Interview Preparation Tips: Execution

Let’s now actually get to our best pieces of advice to implement during an actual consulting case interview.

6. Start Every Case Strong

A strong start will be a huge advantage in your journey to crack the case interview. When the interviewer provides with you with the prompt, pay extremely close attention and write down everything you possibly can.

Specifically, there are 4 things the interviewer shares at the start of each case:

  • Industry Information
  • Company Information
  • Key Case Data
  • Case Business Problem

Out of those 4 things, you need to make sure you get the Client Industry, Company, and Case Business Problem down – the storyline will end up being much more important than the data. Over the course of a 30-60 minute case, it will likely be helpful to refer back to your notes and remind yourself about the context and objective(s) of the case.

Clarifying Questions

Next, ask up to 3 clarifying questions to make sure you and your case interviewer are on the same page. This is especially important if the client in the case interview is in an industry you don’t understand very well. It is totally fair game for you to ask about how a product works. Or ask about anything else that you feel is important to help you come up with a relevant and specific framework for the case. After these questions, you should have a really good understanding of what the client’s business entails.

Lastly, if you have an extra clarifying question to burn, try to probe and understand why the client has set its objective. In some case interviews, this may be obvious. For example, if the company is trying to increase its profitability. In other case interviews, it may be more vague. The prompt may end with the interviewer saying that the client is trying to do something such as introduce a new product.

In such a scenario, try to gather more information by asking questions about why this new product is being created. Is it to steal market share? Is it to compete with other existing products? Or is it to just increase profitability? Though this may cross the line into something you should include in your framework (which your interviewer may instruct), it doesn’t hurt to clarify the client’s objectives and gather some more information before creating your framework.

7. Stay Hypothesis-Driven Throughout the Case

After hearing the case interview prompt, you should create a framework that is built to test a theory based on what you think could potentially be the root cause of the client’s problem. There are two kinds of hypotheses: an open case interview hypothesis and a defined case interview hypothesis.

Open Case Interview Hypothesis Example

An example of an open case interview hypothesis could be along the lines of: “I understand that our client is experiencing a decrease in profitability even with an increase in volume. Based on my intuition, I believe that the reason could be that the price of our client’s products is falling and I would like to take a look at that first.” These are common when the prompt does not specifically ask a “yes” or “no” question.

Defined Case Interview Hypotheses

On top of that, there are defined case interview hypotheses. Defined case interview hypotheses are perfect in situations like market entry cases or mergers and acquisitions cases, when the question is “should the client do X or not?” In those cases, it makes more sense to the listener if you come out strong with a “Yes” or “No” case hypothesis, backed up with the reason why it matters.

Testing Your Hypothesis

As you go through your case, you should be continually testing your hypothesis and revising it as you are provided with more data. Continuing on the previous example, let’s imagine that you received information from your interviewer that prices have actually increased. A follow-up hypothesis could be: “If your volume has increased and our prices have increased, then that must mean the costs of our products have increased if our overall profitability has decreased. I would like to test that out next – do we have any information about our client’s costs?”

Consultants at top firms like McKinsey, Bain, and BCG don’t just blindly search for data and information – they actively theorize on potential solutions and see if they are wrong or right. And if they’re wrong, they move on quickly to other hypotheses. By doing the same in your case interviews, you can exemplify that you can both think and act like a consultant.

8. Be Case-Specific

Forget about Porter’s Five Forces, SWOT analysis, or any other cookie-cutter case interview frameworks and structures that you learned or memorized when it comes to structuring your framework. In fact, using such a structure may immediately cause you to be eliminated as a potential candidate during a case interview.

Though there are recognizable patterns amongst certain business problems, consultants love to see that you’re thinking critically about the problem at hand. To the extent possible, create a framework that’s specific to the case by listening carefully to the prompt and creating buckets that clearly relate to the prompt.

Another easy way to be case specific is to use the client’s name or its products whenever you can. This is just a small adjustment that will demonstrate to your interviewer that you’re thinking about the client.

9. Ask About Trends

When provided with data, don’t just leave it at what you’re provided. Most of the time, you’ll only be given the information you ask for. For example, if you are given information about a company’s revenue for the past 12 months, ask if there is any information for the company’s revenue for the past few years as well. If you are provided your client’s market share, also ask if there is information of what the market share used to be for the past few years. Knowing the trends behind data will provide you with crucial information that may be essential for you to crack the case.

10. Analyzing Case Charts and Graphs

Consulting charts and graphs can be confusing, and a lot of times, they’re made to be this way. The most important thing to do is to take your time – you have 5 minutes to solve every case interview quantitative problem. Start off by over-communicating to your interviewer and stating all the obvious details, such as what’s on the X and Y axis or the title of the chart or graph.

This accomplishes two things. First, it buys you some more time as you analyze the case interview data. Second, it helps your brain process the information since you’re talking about it aloud. After stating all the obvious things about the data, you can then dive into analyzing what it all really means.

11. Round Your Case Math Numbers Whenever Possible

It’s more important to do the right calculations rather than getting an extremely specific number. Whenever possible, round your numbers to the nearest five, hundred, million, and etc. Your interviewer will expect most candidates to do this and will let you know if you are rounding too much.

Note: McKinsey requires almost perfect numerical accuracy. McKinsey interviewers work from a pre-determined answer key, so you can only round to the 1s place in a McKinsey interview. In addition, you should only round on the final step in a McKinsey case interview. Your mental math must be on point!

12. Think Out Loud as Much as You Can

Your goal is to over-communicate to your interviewer. Case interviews should be thought of as simulations in which you are communicating your thoughts to a client. During the actual job in consulting, though the data you are conveying may be obvious to you since you have been working with the information for months, that may not be true for the client. As a result, when you’re doing your calculations or explaining your framework, explicitly state every step to be as clear and easy to follow as possible.

13. Follow the Data, not the Case Framework

The framework you initially create is not going to always get you to the right answer. There are going to be times when only a small part of your framework is relevant, but it is enough to get you some data that opens up other aspects that you hadn’t previously considered.

As a general rule, the data is more important than your initial framework. As in the real world, the best consultants let the data lead them rather than their hypotheses, and you should show that you can do the same.

14. Finish with a Strong Recommendation

When you’re working with top-level management as a consultant, they will want answers that are concise and to the point. As a result, your recommendation should start off with the key information first. We recommend the following structure:

  1. A few sentences on your recommendation that directly answers the case’s objective(s).
  2. Two or three reasons that support your recommendation based on the data and information uncovered in the case.
  3. Next steps or potential risks you see with the recommendation or the client’s current situation.

15. Maintain a Positive Attitude and Confident Persona

Consultants love positive and confident people. As you go through your case, even if you stumble here and there, make sure that you don’t lose your enthusiasm and energy – no matter what. Mistakes will be much more easily forgiven if you own them and carry on like nothing happened rather than getting flustered and sounding nervous.

It’s important for consultants to feel like they can put you in front of clients and that you’ll be able to remain confident in difficult situations. This highlights the needs for really focused case interview prep. In the end, remember that consultants are testing your ability to solve business problems but also your mental math and qualitative skills as well.

Case Structure Walkthrough

Case Interview Conclusion

The case interview is a beast – no question about it. You must prepare, and intelligent case interview preparation will save you countless hours and headaches. Follow our key steps on how to prepare, and what to do if you are having trouble with specific parts of the case, and you’ll win the case interview game.

A final word of encouragement – while the case interview preparation process may seem daunting, it is also a tremendously fun learning experience. Enjoy developing insights using business frameworks. Tie learnings from cases to things you see in the news. Develop your mental math skills. And finally, share your enthusiasm for cases in your interview.

At the end of the day, consulting firms will train you – but they are looking for your raw ability through the case interview. Take an intentional and systematic approach to your case interview preparation.

Good luck, and have fun!

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