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How can you brainstorm in a structured way during a case study interview?

Pedro Rueda
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replied on 02/15/2017

Brainstorming creatively in a structured/MECE way when under pressure is one of the hardest things to do.

Let's have a look at a basic example: "how can client X gain market share?". A great start to answering the question would be; "Let's look at ways that X can do this in the long-term vs the short-term", OR "Let's see, in general, to grow a business you can change WHAT you sell (e.g., new product vs. old product) or change WHO you sell to (existing customer segment vs. new customer segment).". This way the interviewer can see that you have a structured mind and that you can also prioritise what really is important. Next, you would create yourself a table with Existing Product & New Product ( on the horizontal axis) VS Existing segment & New segment (on the vertical axis). Then, you start brainstorming ideas into each of the 4 boxes. This way, you will be able to come up with loads of things and the interviewer will be very happy with your structured mindset.

Other examples of dimensions that can be used to encourage structured brainstorming are:

  • Existing VS New (applies to customer segments, products, distribution channels)
  • Organic VS Inorganic (e.g. when thinking about growth)
  • Short-term VS Long-term (e.g. when making a decision that required direct implementation)
  • Internal VS External (e.g. when talking about operations)
  • Customer-focused vs Non-customer focused
  • Revenue-based vs Cost-based

Once you have gone through a few ideas and have structured them into sections/buckets it is good practice to select the best ones according to some parameter. For instance, select ideas which have high impact and high implementability. It is important to note that every case is different and so you must always put a lot effort into customising the answer and prioritising what is most relevant.

Francesco replied on 02/15/2017
Ex BCG | MBB Specialist | #1 Expert for meetings done (900+) and recommendation rate (100%)

Great question Pedro; here are the things I would recommend you to do:

  1. Recap all the information till that moment. This will give you time without sounding you don’t know where to go.
  2. Always try to identify 2-3 key elements that would constitute the fundamental pillars.
  3. After having defined the key pillars, then start to brainstorm for each of them.

Bonus: you may ask for time after step 1 if needed, to think more on the appropriate structure to apply before brainstorming.

Let’s see a concrete example.

Interviewer: So, generally speaking, how would you decrease the cost of raw materials?

Step 1: Recap the situation

Interviewee: So, if I got it right, you would like now to move to the elements that could decrease this cost. If it is fine for you, I would like to do a small recap and then move through the key elements that can help to do so. At the beginning you asked me what brought a decline in profits. We have identified the problem lays in Product A, and in particular in the cost area. We then found out that the main increase in cost was related to raw material.

Interviewer: That’s right.

(Notice that you may have likely gained 30 seconds of additional time just summing up information)

Interviewee: Do you mind if I take 1 minute to think about it?

Interviewer: Please take your time.

Step 2: present the key pillars of the structure

Interviewee: Thanks; I believe there are two key areas to decrease the cost of raw material; we may decrease the cost of each unit, or we may decrease the number of units we buy. I would like now to go a bit deeper in these two components.

(Notice that even if you are brainstorming, you are first putting down a list of the MECE pillars of a structure. This is fundamental to brainstorm correctly)

Step 3: brainstorm elements inside each pillar

Interviewee: Well, in order to decrease the cost per unit we may do a couple of things, keeping in mind we want to maintain revenues at the same level: number one, decrease the quality of the units that we use; number two, negotiate with the supplier; number three, find another supplier.

In order to decrease the number of units, we may do two things; we may implement a more efficient method to use them, so that we would have to buy fewer of them. We may also substitute some of the units with something else that may be cheaper and with the same effect on the final product.

Of course, the best way to do correctly step 2 and 3 would be to have good structures already in place and/or have read a lot of cases, to backup your references.



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