How to prepare for a case interview

About a year ago, I applied for a job as a management consultant at QVARTZ, and happily found myself invited to the office for an interview. Truth be told, even though I was writing my thesis in economics, the world of business was very unfamiliar to me. To my luck, some good friends – and consultants in QVARTZ – shot down my initial naïve idea of just "winging it", and made sure I knew what preparation was needed to show my full potential.

I ended up signing an employment contract with QVARTZ, feeling certain that consulting – and especially QVARTZ – was right for me. I am sure that the friendly advice I was given along the way made all the difference, and I would like everyone to have the tools and insights to go from zero to 100 in case solving and interview techniques. I have therefore made a guide to interview preparation, using my own experience and the data I collected from surveying some of the best experts I know: my colleagues at QVARTZ who have very recently been through the interview process themselves. Enjoy!

The interview process at QVARTZ
As with most jobs, the application process at QVARTZ starts with a written application, including your grade transcripts, your resume and a motivation letter. Once you have submitted these documents, you might receive an invitation to an interview.

The first meeting will consist of a numerical test and a personal interview. The numerical test takes about half an hour and puts your calculation skills to the test. In the numerical test, pen and paper are your only tools. The personal interview aims to determine your fit with the company, taking into consideration QVARTZ' values, the type of work we do, our ambitions, etc. Figuring out if you have a personal fit with QVARTZ is just as important as your computational skills, so do not down-prioritise the preparation for this part! Consulting is a people's business, so make sure to show the person behind the brilliant brain.

If there seems to be a mutual fit between QVARTZ and you, you will be invited to the QVARTZ one-day Recruitment Camp. During the first half of the day, you will get to show your case-solving skills and flair for teamwork during a two-hour group session where you will solve a case together with other camp participants. There will also be two one-hour case interviews with just you alone. After lunch, some participants will be invited to stay on for interviews with partners – and by the end of the day, you will know if you are offered a contract at QVARTZ or not.

One-to-one training
Practising cases face-to-face is a crucial component in the preparation process, and there is probably no better advice than to put yourself out there and expose yourself to many different interviewers, whether it is a relative who follows the interview guide closely, a peer or an experienced consultant. Only then will you train problem solving, structuring, calculating, communication and synthesising under the pressure of someone observing you.

You can use your network to find case interviewers. Reach out on Facebook or LinkedIn for peers preparing for case interviews, ask consultants in your network if they will give you a case or two, or go online. Websites such as Preplounge.com will set you up with cases and people from all over the world to practise cases. I personally reached out to my Facebook friends with a status update and got a great case-solving buddy from a summer course I once took.

Do not underestimate the learnings you get from interviewing someone else, as being on "the other side of the table" will give you good insights on what makes a good presentation.

If you get a chance to practise group cases, jump at it. At QVARTZ, the group case is an important part of the interview process, so accustom yourself with solving a case in a group and showing your team player spirit (and remember: it is not a zero-sum game).

Studying – with a purpose
There are many great case interview books on the market, all with different strengths.

If you start from scratch in business, T. Darling's How to Get Into the Top Consulting Firms provides a soft and clear introduction to the basic structuring of a case, together with some simple cases to get you started.

M. Consentino's Case In Point is a casebook classic, and it covers an extensive set of detailed case frameworks, detailed descriptions of their use and many good and thorough cases to practise on. This book will help you gain a much deeper understanding of business problems, and it will take you to quite advanced levels of case solving. The frameworks presented are detailed and numerous, and it is unlikely that you will be able to apply them in real life, not least because there are simply too many to remember. However, studying the frameworks and their application provides great insights, making the book well worth reading and working with.

V. Cheng's Case Interview Secrets follows the same method as his popular Look Over My Shoulder podcasts, focusing heavily on hypothesis-driven problem solving. The hypothesis-driven method is the most efficient way to solve problems, and Case Interview Secrets focuses on simplifying the case-solving process, boiling it down to applying a logic and simple method to a few basic frameworks, and communicating your findings effectively. The stress of the hypothesis method and the simple frameworks make Case Interview Secrets a great book to end your preparation with, as it focuses on the skills you would want to project in an interview.

Lastly, QVARTZ' own case-solving book will prepare you well for what you will be tested on in the case interviews, covering the basic frameworks used as well as interview examples:

Getting the numbers right
Being quick and correct with the numbers is crucial, and being in an interview situation or a 30-minute GMAT test seldom helps performance. Doing a lot of calculation exercises can help you juggle all the numbers correctly in the interview situation. Prepare for the stress as well, and include some complicated math in one-to-one interview practise sessions – you can do this with anyone, you just need someone to listen while you calculate and explain your answers.

Don’t take the soft too soft
Cracking cases does not cut it alone; a good personal fit between you and your future workplace is crucial. Standard preparation for personal interviews includes shorter and longer pitches (think in terms of a top-down story of who you are, what you come from and where you want to go), stories about how you have dealt with challenging problems, shown leadership, etc., and why you think you would make a good match with the company going forward.

To understand the company better, it is always advisable to do your research on the material provided by the company itself. In QVARTZ, The Big Blue outlines the company values and aspirations.

Preparation time
Great things take time, and case solving is a technique that can be improved forever. Our consultants reported spending from less than a week to more than two months preparing for case interviews, with the majority spending three weeks or more. However, there is no need to compress it into one big chunk – you can start months before your interviews with just a few weekly hours of reading, practising cases with peers, listening to podcasts, etc. I started about five weeks before my interview, the first three weeks with just evening reads and a few cases in the weekend, and the last two weeks going at it full time with one-to-one case solving, preparing personal interviews, pitches, etc.

This may seem like an excessive exercise for just one job. Practicing for a case interview does, however, open the door to a broad scope of employment opportunities, far beyond one single consulting firm. The case interview framework is used across consultancy firms for a reason; the problems it evolves around are similar to the challenges businesses and institutions face, and the logical method it applies simulates the process of solving those problems. Non-consultancy firms, be that public or private, therefore often include problems of case interview nature in their interview processes, as they too need candidates who are strong in problem solving. Strong case-solving skills is thus not only necessary when interviewing for consulting jobs, and practicing case interviews is a good investment regardless of which career path you choose.

I ended up finding one-to-one case solving a lot of fun. I was motivated by the challenge of applying analytical skills and communicating these effectively at the same time, and it felt (and still feels like) a good indicator of my match with the consulting business.

If you are intrigued by the opportunity to work as a management consultant at QVARTZ, do not hesitate to apply! Right now, we are looking for talented new or soon-to-be graduates to join our Copenhagen office. Send your application no later than September 17, 2017. See qvartz.com/career for more.