When you apply at a strategy consultant such as McKinsey, Bain, or BCG you will not only have your resume tested or be asked to participate in written cases: you will also get case interview rounds. Though previous rounds are already pretty selective (for example: some 66% of applicants fail the McKinsey PST), the case interview rounds are even worse. Only one out of 10 candidates is selected in each round (and many firms have two rounds, some include a final round with a partner) and that makes the case study interview one of the most selective types of interviews.
How does the Case Study Interview work?
Once you’ve made it to the case interview rounds, you can already count yourself as one of the happy few. But what’s next? The case study interview will typically feature a “business case” in which you and the interviewer sit down to “crack” a difficult business situation. For example: a firm might want to expand into new territory or launch a new product, or an imaginary CEO asks you to cut costs at his company.
Many of these cases are drawn from the real life experience of the (senior) consultant or partner sitting across the table and they mirror typical questions you might face as a consultant as well. Because you’re suddenly confronted with an unfamiliar question in a line of business you know nothing about, with significant pressure to perform: only when you ask the right questions will you be able to solve the case on time and demonstrate you are a born consultant.
The fact that this situation (unfamiliar business, high pressure to perform) is quite similar to consulting work, makes your performance during a case study interview quite predictive for your day-to-day consulting work. If you perform well during the case interview, then you’ll perform well while working as consultant for the firm. That is the hypothesis at least…
How can I ace the case study interview?
When you want to make it to the next round and make sure you get an offer at the end of the process, you’ll have to make sure you practice the skills relevant for consulting. You’ll have to show that your case interview success is repeatable, and that you did not guess the right answer or worked purely from a gut feeling. It’s these repeatable skills that are both relevant “in the field” as a real consultan, as during the case study interview that the interviewer is looking for and we’ll walk trough these skills below.
Be hypothesis driven
Even though the world of business is a mess and far away from the scientific work being done in labs and on universities, it does help to approach problems with the scientific method. Always start your analysis with an hypothesis, that you set out to prove or disprove by gathering data. For example: you receive a case study during your interview about a company with falling profits and you think the problem of a companies’ profit lies with it’s high costs (opposed to low revenues). You start by asking questions and gathering data that (dis)prove your hypothesis:
“I know that profits are calculated by taking revenue and subtracting costs. This company has falling profits and my hypothesis is that this is caused by rising costs. Do you have any information on how their costs developed over the years?”
There are three things that you should take away from this example.
- Make the thought process explicit: state the framework or structure that you are using and the approach you take. This helps the interviewer in following your thoughts and shows you are using repeatable skills, not random guessing.
- State your hypothesis: you can do it as bluntly as in the example above (“my hypothesis is…”) but other ways are fine as well. Just make sure you work hypothesis-driven and make it explicit that you do.
- Ask for the data: try to gather the data that you need to disprove your hypothesis and ask for the data you need from the interviewer.
Break it down
One of the hardest things to do during a case study interview is to remain calm enough to take a step backwards and look at the problem from a distance. This will allow you to break down these problems in their component parts: what are the drivers for each problem you see? Breaking down (or segmenting) markets/industries/company departments might also reveal information that would otherwise have remained hidden. For example:
- Company Profits: might look normal (“Company X makes $5 mln profit a year”), but when you segment the profits per business unit, you might see that Business Unit A is making a profit of $ 10 mln and B & C a loss of $ 2.5 mln each.
- Markets: might seem to be shrinking overall, but maybe one market segment is declining rapidly and others are growing
- Customers: it might seem that every customer wants the same, but you might want to segment them down to determine individual wishes and find a niche for your company
Ace the math
One of the things you’ll be doing a lot as consultant is analysis and quick judgement calls based on numbers. Not being able to handle big numbers well or not being able to calculate from the top of your head quickly and correctly might disqualify you during the case interview. Why focus on math when calculators and spreadsheets are abundant? First of all: they are slow and now always available. Secondly: being able to calculate quickly will prevent mistakes during board meetings or presentations (when you get a question from the audience) and allow you to spot the mistakes of yourself and others (“is the result I’m seeing the number I expect?”). Read up on our tips and practice material on case interview math in our dedicated article.
Practice the case study interview
One of the best ways to make sure you ace the case study interview is by practicing them, a lot. The best way to do this is by finding a partner and going through cases together: you can find plenty of cases on the internet for free. Another way to practice is to read up on case interview skills and check the book we published:
- Cracking The Case: the best way to prepare for your case study interview, with sample techniques and frameworks you can use during the case interview itself. Includes 2 fully explained cases made by candidates, annotated with expert tips on what went well and what went wrong.