The top 5 mistakes in a case interview (and how to avoid them)

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A case interview is a type of interview that is commonly used by management consulting to assess a candidate’s problem-solving and analytical skills. It involves presenting a candidate with a business problem or scenario and asking them to solve it in real time. The interview is designed to simulate the types of problems that consultants encounter on the job.

Offer rates for different consulting firms

Chances to receive an offer as a qualified candidate from the top firms are at around 1% and increase for the different tiers up to 10%. Compared to other industries, the success rate of applicants is extremely low in this competitive industry.

  • McKinsey, BCG, Bain (MBB): 1-3%
  • Tier-2 firms (e.g., Kearney, Strategy&): 3-5%
  • Big 4 consulting divisions (e.g., EY Parthenon): 3-10%
  • Boutique firms (e.g., OC&C Strategy Consultants): 1-10%
  • Inhouse consulting firm (e.g., Lufthansa Consulting): 5-10%

There is a greater variety in offer rates in firms other than the MBBs and tier-2 segment.

Given the importance of case interviews in securing a job in management consulting and their role in eliminating candidates, it’s essential to know what not to do during a case interview.

On this page, we talk a lot about what to do to ace a case interview. In this article, we’ll turn this around and go over some of the common mistakes candidates make and provide tips on how to avoid them.

The five most common mistakes in a case interview

Failing to understand the client’s problem

It’s essential to understand the client’s problem thoroughly before working on any solutions. This refers both to understanding what the interviewer wants them to do and then understanding what the client is struggling with as the case progresses.

Initially, listen actively and ask clarifying questions. Candidates should listen actively to the interviewer and ask clarifying questions to ensure they understand the problem thoroughly.

Many candidates I coach in an initial session make the mistake to work on a solution before understanding what their solution would solve. For instance, let’s assume we are working with a client that struggles with customer satisfaction that has gone down.

The obvious approach would be to understand what has exactly gone down (how is it measured, in what area of the business/customer journey), by how much, and why (root causes), then work on measures to remedy the issue.

However, in their initial structure, many candidates would look at capabilities and measures to improve customer satisfaction, then prioritize these questions as they try to move forward in the case. This approach would not allow them to understand what’s going on with the business.

You cannot work on a solution or consider the capabilities needed to implement solutions without understanding if these solutions would actually solve the problem (= if they are effective). In order to do that, you first need to understand the issue and you can do that by following the approach I bolded above.

Ace the case interview with our dedicated preparation packages.

Not having a structured approach

A structured approach to problem-solving is critical in a case interview. Candidates should have a clear and organized way of breaking down a problem and approaching it systematically.

What I see often is that candidates state a couple of buckets they want to look at without considering the bigger picture of how these buckets would constitute and allow a consistent and holistic analysis of the situation and how these buckets are related to each other.

If you are doing this, you are fishing in the dark and unlikely to hit the issue of the client.

Using our question from above about customer satisfaction, you need to come up with a structure that allows you to understand why customer satisfaction is dropping.

For instance, you could look at the steps of the customer journey and drill deeper into those. This would allow you to systematically isolate where the issue is coming from.

For more on case structuring and frameworks, check out this article here.

Not asking enough questions

Case interviews are a two-way dialogue. Asking questions is a crucial part of the process, and candidates should be comfortable doing so.

I often see that candidates refrain from asking anything. In the feedback, they then tell me that they fear that asking questions makes them appear weak and not knowledgeable in front of the interviewer.

Nothing is further from the truth. You need to elicit information from the interviewer in order to understand the case, the client, and the problem same as you would elicit information from actual clients later on the job. You need to ask clarifying questions whenever you are unclear, the same as you would ask the CEO clarifying questions later on to make sure you understand them or the issue correctly.

If you don’t ask you will not get sufficient information to understand what is going on and work on a faulty or incomplete solution for the case.

Lacking data analysis skills

Case interviews often involve data analysis in the form of exhibit interpretation and math, and candidates should have strong data analysis skills to excel in this type of interview.

When you get a chart, you need to have a clear objective in mind about how the information displayed on the chart can help your understanding of the situation. There are many ways to screw up a chart analysis.

For instance, candidates often fail to spot what is interesting on a chart, discussing every data point in detail instead of focusing on the key insights. Others might spot the insights, yet fail to contextualize them and move on from there.

You need to have a clear action plan ready when analyzing a chart that builds on the insights, the implications, and the next steps. Learn more about chart interpretation in my book The 1%: Conquer Your Consulting Case Interview or in this link.

When dealing with math, many candidates stall and do not know how to proceed. Either they fail at setting up the logic, during the calculations, or both. You need to become bulletproof by learning the basics of case math and then practicing to increase accuracy and speed.

For more details on how to work your way through case math, check out this article here.

Not being prepared for the recommendation

The ultimate goal of a case interview is to make recommendations to the client. Candidates should be able to make well-supported recommendations that address the client’s problem.

What I often see is that candidates stumble here even though they have just worked on the problem for 30 minutes. A recommendation is simple.

Discuss what you would recommend (1-3 actions based on the problem and solution you have worked on), support each action with 1-3 supporting arguments (findings from the case), and propose 2-3 next steps, demonstrating that you would be able to move the situation forward on your own.

Avoid repeating the case problem (both the interviewer and you know what the prompt was) and discussing your different analyses in a bottom-up approach. Turn it around and focus on a strong top-down recommendation as described above.

Bonus tips

  1. Clearly articulate your thought process: Candidates should clearly articulate their thought process as they work through the problem. This will help the interviewer understand how the candidate is approaching the problem.
  2. Show confidence and maintain eye contact: Confidence and eye contact are critical during a case interview. Candidates should show confidence in their abilities and maintain eye contact with the interviewer.
  3. Avoid assumptions and conjecture: Candidates should avoid making assumptions and conjecture during a case interview. They should rely on data and evidence to support their recommendations or probe assumptions with interviewers before making definitive statements.

To succeed in a case interview, candidates should understand the client’s problem thoroughly, have a structured approach to problem-solving, ask clarifying questions, have strong data analysis skills, and make well-supported recommendations. If you are using this advice, you are already steering clear of a majority of case-ending mistakes.

How we can help you avoid these mistakes

We have specialized in placing people from all walks of life with different backgrounds into top consulting firms both as generalist hires as well as specialized hires and experts. As former McKinsey consultants and interview experts, we focus on teaching the best habits and strategies to ace every case interview.

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Reach out to us if you have any questions! We are happy to help and offer a tailored program to help you break into consulting.

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