Top Five Consulting Case Interview Traps

by Matthew Kuo on December 21, 2012

in Consulting, MBA

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One of the most daunting aspects of the MBA experience is sitting though a case interview.  Anyone in business school recruiting for a consulting or strategy role must go through this rite of passage before getting one of these coveted positions.  The case interviewers have full control in this setting: while some may choose to go easy on you, many others will try their very best to make you look like a fool.  Based on my MBA case interview experience, these are the five most common case interview traps used specifically for that purpose.

  1. Frame of Reference
  2. Utilization and Usage Rates
  3. Tough Math
  4. Missing Data
  5. Anything Else

Frame of Reference

The Trap:

You get to the very end of your case interview with an overall net return for the case question.  The case seemingly does not provide enough context for you to make a decision.  The interviewer asks you whether to go forward with the project and pressures you to come up with a concrete answer.

The Setup:

The case interviewer is testing your ability to synthesize different pieces of information and to some degree your memory.  The typical frame of reference trap is initiated during the introduction to the case prompt.  The interviewer gives you some random contextual information that on the surface seems to just add color to the case.  For example, “Company X earned $10 billion in revenue last year.”

Let’s say that you proceed through the case and come up with an overall net return of $80 million dollars.  $80 million by itself sounds like a lot of money and in most normal situations, you would go forward with a project with this kind of return.  The problem is that $80 million represents less than 1 percent of the company’s overall revenue based on the initial case prompt.

The Solution:

  • Take careful notes during the case introduction and be sure to note any figures that are provided to you
  • When you get to the end of the case ALWAYS reference the information provided in the intro – your recommendation must take the context into account
  • The direction you choose to go with for your recommendation is oftentimes irrelevant as long as you can justify your decision with logic and reasoning

Utilization and Usage Rates

The Trap:

The interviewer asks you to size an opportunity and without giving you much direction or context.  You run through your sizing analysis but forget to address a key multiplier.

The Setup:

The majority of sizing questions will have a utilization or usage component built into the suggested answer.  For example, if you are sizing the revenue potential of a hotel, you need to account for the hotel’s utilization, or occupancy rate.  If you are sizing the revenue potential of a new cell phone, you have to consider consumers’ usage rate, or how many cell phones they buy per year.

The Solution:

  • Always account for utilization and usage in your sizing analysis.  Even if your rate is 100% or 1 per year, addressing it covers you from missing this key component.

Tough Math

The Trap:

The interview progresses to the quantitative portion of the case, and the math required appears to be lengthy and arduous.  The calculation is reasonable but it’s definitely something you’d usually do with either Excel or a calculator, such as long division or net present value.

The Setup:

Being asked to perform complex math in an interview is the ultimate test of your nerves.  The interviewer is trying to gauge how you will react if a client puts you on the spot.  The math required usually isn’t as complex as you think; it’s the pressure of the situation that makes it difficult.

The Solution:

  • Always ask for easier, rounded numbers when you think it is reasonable.  If the interviewer wants your math to be more precise, he or she will let you know.
  • SLOW DOWN – your natural instinct in a case interview is to maintain the flow of a discussion.  However, with complex math you need to proceed carefully.  Be prepared for this change of pace as it generally feels awkward.  Your priority should be not making a mistake.
  • Provide the interviewer with a high level overview of the math you intend to do before crunching any numbers.  An example of a high level formula could be “I plan to calculate units sold, multiply by price to get our revenue, and subtract out cost of goods sold and SG&A to come up with our net profit.”  Again, the instinct is to jump right into the math, but from an interviewer’s perspective, providing this overview makes it much easier to follow.
  • Don’t be silent – provide the interviewer with periodic updates of where you are within your high level formula.  You don’t need to be talking the whole time, but you should try to avoid long periods of silence.
  • Make eye contact – because you are so focused on calculating numbers, the tendency for most people is to keep their eyes on their paper.  Obviously you can’t do complex math without looking, but when you reach your update points, make sure to look up at the interviewer.

Missing Data

The Trap:

The interviewer asks you a very specific question that you clearly do not have enough information to answer.  You ask some clarifying questions and the interviewer stonewalls you.  You then make some broad assumptions and answer the question.  The interviewer tells you that your assumptions and answer are wrong, and that they would’ve given you additional information had you asked for it.

The Setup:

The interviewer is trying to test your ability to work with a client, much of that involves requesting data.  In real life situations, most clients are reluctant to provide consultants with data because it usually precedes additional work on their part.  Therefore, the process of requesting data requires a level of assertiveness on the consultant’s part.

The Solution:

  • Always ask broadly about the availability of additional information.  Case interviewers are not allowed to blatantly lie to you, so even if they’re trying to keep the data away from you, their answer to a broad question should clue you in on whether or not additional information exists
  • If the interviewer is still holding back, be more specific in your questioning.  Some interviewers won’t give you the information until you ask for the category or data point specifically.

Anything Else

The Trap:

The interviewer asks you a broad question expecting multiple examples.  You provide a list of examples which you feel thoroughly cover the range of potential answers.  The interviewer then asks “Anything else?”  Your mind blanks.

The Setup:

There are two possible reasons for the “anything else” question: you either did miss something important, or the interviewer is just testing your intellectual horsepower.  In the latter scenario, you’ve done nothing wrong and have probably covered the question adequately – the interviewer just wants to see how quickly your brain can work under pressure.

The Solution:

  • When the interviewer asks you for a list of examples, assuming you’re able to come up with numerous ideas, hold back on one or two of them in your initial response.  While you won’t always be in a position to do this, it’s the easiest way to provide a quick answer to this trap.
  • Take a second to think about your answer.  Don’t ramble or grasp at straws hoping for a miracle.  Most interviewers will be fine with a few seconds of silent thought if you’ve already provided a reasonable number of examples.
  • Fall back on the basic context frameworks to generate ideas.  Run through the 3 C’s, 4 P’s, Five Forces, and Value Chain in your head.  Usually these frameworks can help lead you towards a relevant example.

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