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How to efficiently complete a case in less than 30 min?

In my previous mock interviews, I've found one problem that I need to work on with: completing the case fast and efficiently. In some cases, I spend around 40 minutes to solve a case. Some feedback that I received was:

(1) Communication: be precise and concise. (I tend to explain too much about why I ask for a data, or why I want to look in to various factors, etc)

(2) Should proceed through the case “faster” in some steps. (My reflection is that I tend to think in a cautious / broad way, and sometimes I'm not confident to jump in a direction shortly and decisively). 

Would appreciate if you could share some improvement tips. Thank you.

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Top answer
Ian
Coach
on Sep 26, 2021
Top US BCG / MBB Coach - 5,000 sessions |Tech, Platinion, Big 4 | 9/9 personal interviews passed | 95% candidate success

Hi there,

The #1 thing you're missing here is structured thinking.

You need to take a moment at all key points of the case to think “What are the options and the only options for what happens next?”.

For example, if we find out that x product we produce is seeing falling profits, there are literally only 3 options for the reason. Either a) The market for that product is down (noone is selling a lot) or b) We are doing something wrong or c) Competition is doing something right.

That's it! If you take 10 seconds to think through structure, you can ask only 3 questions max to drive the case forward.

Pick the right path, don't try to rush down a randomly-chosen path as quickly as possible.

Deleted user
edited on Sep 27, 2021

Hello,

You've got some great advice in this thread, especially for the structured thinking. Here is my additional two cents:

  • Understand what concise case-solving looks like by watching/listening to some example cases. It seems like you have gotten some helpful feedback and have taken the time to self-reflect on what is causing you trouble in cases. Make sure you also understand what “good” looks like here - i.e. what a fast and structured case-solving approach looks like. I would recommend doing this by watching videos/listening to recordings of example cases (you can find a lot of good examples on Youtube), taking note of how the interviewee is moving through the case, and mimicking their approach.
  • Take yourself into ‘case world’. A lot of great candidates try to get into too much detail when starting to solve cases because they are firmly rooted in the real world, and not the interview scenario. While this is a great skill to have in practice, on the job no one is going to ask you to solve a business problem in half an hour, as you have to do in a case interview. So you have to suspend your disbelief a little bit and go with the flow of the interview - the data available to you will be limited, the scope of the answer not as expansive as a real-world business problem, etc.
  • Practice! The best way of working through this issue, once you understand what you need to develop and what “good” looks like, is by practicing over and over again, paying particular attention to your conciseness, level of explanation, and speed as you go through it. You are bound to get the hang of it with practice. Practicing with someone more experienced, like a coach or a current consultant, is most helpful since they can give you more actionable feedback, but practicing with a friend or case buddy will help you improve too.
17
Agrim
Coach
on Sep 26, 2021
BCG Dubai Project Leader | Elite Prep to dominate interviews | 10 years in Consulting + M&A | Free prep plan

You already know where you are going wrong - so focus on those 2 items. If you want to get more targeted feedback and action items - feel free to engage a coach to help you out through a diagnostic process.

Having said that, for the 2 areas you mention - you can do the following steps:

  • Start thinking in a structured manner - not just in your framework but also in everything you say. If you incorporate a structure style of thinking throughout your day - you will develop it as a habit
  • When you practice - keep a stop-watch besides you and note down the time you took in the various sections - structuring, explaining the structure, fit questions, etc. etc. After the case - see where you took longest and start thinking of how you could have done it better. Try to write down your thoughts and try to slim it down. If you keep doing this for a few weeks of practice - then you will start developing it as a habit.

Happy to engage over message if you can give me more specifics of your issues.

Pedro
Coach
on Sep 26, 2021
Bain | EY-Parthenon | Former Principal | 1.5h session | 30% discount 1st session

Hi there,
 

You answered your own question, but let me add some thoughts: 

  1. Going “out of scope” on the structure, because of being overcautious and try to cover every single possibility - including those that were not asked. So if the case is about finding out the reason for a drop in profitability, the structure should not include regulatory or implementation risks, for example…
  2. Over complicate the market sizing. Market sizing should a quick exercise. For that to happen you need a clear structure (laid upfront), and then move on to execution mode in a pragmatical way! 
  • Spending a lot of time discussing and justifying generic number assumptions. You don't need to spend 1 minute explaining 20% of the population is “rich” or that the average automobile life is around 10 years… Just assume something reasonable, check with the interviewer and move on.
  • Choosing numbers that make calculations tougher. You don't really want to assume a segment with 3% or 45% of the population. 10% and 50% are so much better assumptions… If the interviewer prefers something else, you will know.

3. Over-explaining. I.e. saying twice the same thing and taking even longer on the second time. Just like I did right now in this paragraph and actually in the whole answer ;) If I just used the words in bold, this would be a 1 minute read. This way it is a 4 minute read. See the difference?

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