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What are common mistakes you make in case studies?

Anonymous A asked on Feb 27, 2017 - 2 answers

Hi everyone! I just signed up here and starting my case preparation. I haven't done a case practice, yet, as I'm still reading the theory. Before I start, I thought it might be good to know what are common mistakes you make when you solve case studies? Would me cool if you could share some of your mistakes or problems :)

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updated his answer on Mar 01, 2017
McKinsey / Accenture / Got all BIG3 offers / More than 300 real MBB cases / Harvard Business School
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The most common and critical mistakes are:

1) Not claryfying / asking the details of the business model in the begining

2) Not claryfying / quantifying objectives in the beginning

3) Using common frameworks and not adapting them to the case specifics

4) Not diging deep into the root causes of a problem and switching to other parts of your framework

5) Geting some data and not applying it (i.e. you should compare with previous periods / benchmarks / breakdown further into segments)

6) Slow math / math with mistakes / not stating clearly what you are trying to calculate and why

7) Providing a strong conclusion having limited data

8) !!! spending a lot of time on cases, having no fit interview practice


Astrid replied on Mar 01, 2017
PrepLounge Community & Marketing Manager

Welcome Anonymous A,

thanks for joining PrepLounge and asking your question on our Consulting Q&A!

I found some old Q&As that might contain useful information for you, since you just started your case preparation.

A lot of our users have questions about brainstorming at the beginning of the case study. In one of our Q&A, our experts give advice on how to come up with the right ideas.

Ignacio says:

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


1) Ask an interview for a minute to think

2) Think of several buckets of ideas (e.g. organic growth / non-organic growth / differentiation). Remember to think as big as possible

3) Narrow down to each bucket and generate as much ideas as possible

4) Present the structure (buckets) and then your ideas

For the full Q&A, check the following link: Brainstorm more ideas?

Other relevant Q&As are:

This is just a selection, feel free to browse through some more old threads with the tag "Case Interview" and you will find more relevant info :)

Best of luck for your prep!


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