Case Interviews and How to Ace Them

What’s an case interview?  Simply put, it’s when the interviewer gives you a scenario, such as a business situation or an interpersonal situation, and asks you questions about how you’d go about addressing it.  This method works well in interviews because the scenario and the related questions (the case) often have nothing to do with the interviewee’s past work experience.  It’s designed to be a complete surprise so that the interviewer can test your true capabilities as a business candidate.

Types of Case Interviews

There are three types of case interviews.  To ace each, you, as the candidate need to understand what the interviewer is really expecting you to demonstrate.

Type 1 – Brain teaser cases – This is usually very short, like 5 to 10 minutes, where the interviewer asks you to estimate the size of a particular market.  My very first brain teaser from McKinsey was, “Estimate the size of the tennis ball market in Hong Kong.” What the interviewer expects in this situation is the following:

• You’re not afraid to ask questions and if the interviewer asks you to make an assumption that it’s reasonable and that you show common sense.
• You communicate a sound framework of how you’ll get to the answer.
• You demonstrate good business sense by including all the obvious players that affect this estimate. E.g. individual tennis players as well as businesses like tennis clubs that would buy tennis balls.
• You can do basic math in your head.  While the interviewer doesn’t expect you to get to the right answer, they do want to see that you can follow your own logic and assumption to an answer.  Saying 10% of 50M is 500K will not impress.  Tip: keep your number simple and general so the math is easier to do in your head.
• You’re poised, clear, and structured in your communication under pressure

The two most common mistakes people make in this type of case are 1) trying too hard to get to the right answer but ignoring the process, and  2) not asking enough questions or making enough assumptions. What the interviewer doesn’t expect from you is that…

• you know all of the world’s trivia such as the population of Hong Kong.
• you get the right answer.  This is NOT the point of the exercise.

Type 2 – Business case interview – This is usually 30 minutes long and can get very involved.   Very often the interviewer will give you a case that he/she just worked on.   This way they have spent several months knowing the industry and the business situation and can give you details easily when you ask questions.  Additionally, they can judge very quickly whether you would have been an asset on the team if you actually worked on this case with them. What the interviewer expects from you is the following:

• Sound listening and questioning skills – In business, we often do not get the complete picture of a situation when we first encounter it.  It’s key for you to listen carefully to the initial case and ask sound questions to get a more complete picture.
• Strong business and analytical skills – Depending on the level that you’re applying for (Analyst vs. Associate), the interviewer has a level of expectation in your business understanding, financial knowledge, strategic frameworks, and how analytical your answer should be.
• Ability to communicate how you plan to solve the problem in a structure framework – Don’t communicate one idea at a time.  It’s better to pause to think and then say something like, “I would look at this issue from 3 angles…” and explain what each angle is.  Also, it’s important to use a known framework (SWOT, Porter’s 5 forces, 3Cs) correctly if it makes sense.
• Ability to think under pressure – I had one McKinsey partner who kept asking me, what else can I think of after I gave him my initial structure of how to think of the problem.  The interviewer will try to say things to rattle you the same way a client may when you become the consultant.  You need to demonstrate that you can be poised even if you don’t know all the answers.

At the end of the day, each interviewer is asking himself or herself as they interview you, “Would I want him or her on my team? Would I be comfortable with him or her speaking with my client?”

Type 3 – Behavioral case interview – This is where the interviewer tells you about a difficult interpersonal situation (e.g. with your client, team member, manager, etc..) and asks you how you’d handle it.   This is a relative new type of case interview.  Companies do not consistently use it but it’s good to be prepared when they do. What the interviewer expects from you:

• Emotional intelligence – Can you fully understand what the underlying interpersonal issues and what is at stake if it’s not resolved?  Do you have your priorities straight? E.g. Getting the job done while maintaining good relationships.  Being right is not.
• Diplomatic communication – Do you know how to diffuse a heated situation effectively to get the work done?  Can you communicate in a way that fosters better relationships?
• Level of self-awareness – Do you know what you can and cannot control in this situation and what to do about each?
• Your ethical boundaries – Understanding where your line is and whether it’s a fit for the company.

Again, as the interviewer uses this type of interview, he or she wants to see that you’re a team player who understands the importance of maintaining good relationships to achieve results and not some ego maniac that the team or the client would not want to work with.

The other key component to acing the case interview is practice, practice, practice.  It’s not enough to practice on your own with a sample case book.  It’s important to practice with other people.  The best people to practice with are consultants or ex-consultants who are senior to you and worked in firms you want to work in.

Don’t be afraid to ask these kind of people for help. When I applied for McKinsey out of college, I was lucky to meet a Stanford MBA student through a family friend who used to work at McKinsey.  He gave me a huge binder filled with the research he did to get into McKinsey.  He was also kind enough to practice cases with me and gave me honest feedback, which was invaluable.