The Top 5 Mistakes In a Case Interview (and How to Avoid Them)

the image is the cover that discusses case interview mistakes and ways to avoid them. the image displays a chewing gum stock to a shoe as an analogy for a mistake

Last Updated on February 13, 2024

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, 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 information is based on more than 1,600 case interviews I have conducted over the last few years (updated in February 2024).

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 a candidate 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 of working on a solution before understanding what their solution would solve. For instance, let’s assume we are working with a client who 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, and 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, so in that sense, they are skipping an important step and potentially implementing a solution that would not impact the desired outcome.

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). To do that, you first need to understand the issue and you can do that by following the approach I bolded above in your case interview framework.

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. Even if, your interviewer would perceive your unstructured approach as deficient and decrease your score related to problem-solving abilities.

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 to fully understand the case, the client, and the problem in the same way 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. You might also base your analysis on assumptions that you did not test with the interviewer first, another big issue I often observe,

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 to Recover From Mistakes In Case Interviews

On a more general note, no candidate is perfect. McKinsey, BCG, and Bain know this. Hence, making a mistake during a case interview should not be a definite deal-breaker to landing a top-tier strategy consulting offer unless

  1. It happens more frequently within one case
  2. You mess up throughout several cases on the interview day
  3. One mistake triggers a chain reaction of you losing your cool and falling apart in front of the interviewer

To make sure you handle all kinds of mistakes during case interviews correctly and don’t let them ruin your day, we have compiled the key strategies for you to deal with and recover from your mistakes or errors in a case interview.

Avoid Mistakes In the First Place

The most efficient strategy is to avoid making the mistake in the first place. Of course, this is obvious but it’s not a platitude. In 80% of the cases, where we have seen candidates mess up. it is the result of them speaking before they think.

Many candidates, at some point during the interview, have an epiphany and blurt out a random fact, a wrong conclusion, a statement not based on facts or using untested assumptions, or numerical results after having hastily calculated it mentally.

Think before you speak at all times and you will make sure that you are already better than 80% of all candidates in this regard.

Sanity Check Your Results and Outcomes

A general case interview habit you should adopt is to sanity-check results and outcomes. Whenever you get to a new insight, ask yourself ‘Does this make sense?’, ‘Is it in the right ballpark or completely off (watch your 0s)?’

Candidates who use this case habit generally perform better than others both in the process (structure, creativity, and business sense) and the product (the recommendation).

Also, chances are that you will spot any mistake yourself and correct it calmly and naturally, leading the interviewer through the process.

Keep Your Composure

If you happen to make a mistake, keep calm and focused. Carry on confidently. Interviewers also want to see how you deal with setbacks. Therefore, see it as an opportunity. If you don’t make it a big deal out of it, the interviewers normally wouldn’t make it a big deal either. One thing we see over and over again:

Candidates let one mistake ruin their whole interview. Even if they performed well for 30 minutes and then made a mistake, they completely lost it and their performance crashed. Make sure that the mistake does not lead to a chain reaction of you breaking apart in front of the interviewer, Remind yourself that a one-off thing is not a big deal.

Carry on and focus all your mental resources on the next steps.

Be Coachable

Interviewers generally want you to succeed. So, if they point out your mistake or probe something you said, you should start going into problem-solving mode about what could be wrong right away. If they start to guide you it is usually because they want you to get back on track.

In that case, listen and demonstrate that you are coachable. Show that you are interested in what they have to say and take their feedback into account.

Expect to Be Pressure-Tested

Once you made a mistake in a specific area (e.g., problem structure, pen-and-paper math, etc.) interviewers might probe this area going forward to see if it was an exception or the rule. Hence, expect the area where you made a mistake to become the focus of more attention either in the same interview or in the next round after interviewers have discussed your performance.

The more confidence you show, the better you will fare in this pressure test.

How We Help You Avoid Pitfalls and 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 help you by

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.

To improve your skills in all areas of the interview, check out our targeted offers below.

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