Interviewer - Led Case Interview : Hyposthesis and Ideas

New answer on Jul 20, 2020
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asked on Jul 18, 2020
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Hello community

1- Is it expected OR considered a plus posing a hypothesis in a McKinsey Style interview (interviewer led).

Normally the first question is: What key factors should the team investigate in order to xxx (i.e. xxx= the case objective).... or what should the team ivestigate ... which is basically implying constructing a structure. So after presenting the structure or the factors, should I say " I am gonna hypothesize that the issue lies in X..." ? even though the drill down isn't going to be by my choice as in a candidate led interview.

2- How detailed the factors should be (how many levels down) upon listing them in an interviewer led ?

Reason I am asking is because in a candidate led interview that step could be 2 levels down because I get to steer the case later and further drill down a factor, however in this type of interview I might not get the chance to go back to the issue tree / structure that contains the factors to drill it down ...

3- When the interviewer asks for ideas to achieve a certain goal for the client (maybe cut cost, increase profits etc...), how many ideas should I provide : 3 to 4 ? and when presenting the ideas is it OK to say : "... however this comes with that risk or might cause this issue and requires more investigation ..." ?

Thank you in advance for the answers.



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Best answer
replied on Jul 19, 2020
McKinsey Senior EM & BCG Consultant | Interviewer at McK & BCG for 7 years | Coached 350+ candidates secure MBB offers

Hi Kay!

1. Let me first start with a general remark: whether an case is conducted in the interviewer-led or interviewee-led manner is irrelevant to the structuring and for how to deal with hypotheses.

Moreover, stating a hypothesis for the overall problem only makes sense if you really have something to ground your hypothesis on! This is very rarely the case, since case prompts tend to be quite vague at the beginning. Just stating a hypothesis for the sake of it serves no purpose! It would just be a shot from the hip - and this is something you should avoid at all cost during an MBB interview!

If the question is about finding the reasons for an observed phenomenen (e.g., fallen profits), then you can rather say “I would like to first identify the numerical driver of the problem, which can sit either on the revenue or on the cost side (or both). Based on this initial assessment, I would build a hypothesis on the underlying reasons for the detrimental development, then verify the hypothesis, and subsequently derive measures to address these reasons in order to reverse the trend.”

If the question is eseentially a go- or no-go-decision (e.g., "Should we enter the Brazilian market?"), then a MUCH better approach than a blank "Yes/No"-Hypothesis (which feels stupid anyway, right?) is to define the criterion according to which the question can be answered. This implicitly comprises hypothesis-thinking, but in a much cleaner way. All you have to do is to

(1) narrow down the question,

(2) define the criterion according to which the question can be answered with "yes",

(3) outline how you can test whether the criterion is met.

That's it! This is how you address strategic questions without shooting out non-substantiated hypotheses (or rather wild guesses!), while still being super top-down and super efficient.

Hypotheses then are used all along the way of performing the actual analyses! But it is not hypotheses on the overall question, but hypotheses on the various sub-aspects which you need to test in order to eventually answer the overall question.

2. This depends on what you are actually asked. If the interviewer asks for your "approach", then it is all about the logic, and not about brainstorming endless lists of bullet points. If you are asked to list out "which elements to consider?", then this is more a brainstorming then a real case structuring. I would always recommend to verify this with the interviewer - no problem with asking. :)

3. It is not about the number of ideas, but about to show your ability to come up with a sound logic into which a rich set of ideas can be conceptually fitted. Whether you then put 2-3 example ideas into each category or more is not important.

Cheers, Sidi

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Content Creator
replied on Jul 19, 2020
McKinsey offers w/o final round interviews - 100% risk-free - 10+ years MBB coaching experience - Multiple book author

Hi Kay,

1) Hypothesis

Mostly influenced by Victor Cheng practive materials, stating a hypothesis at the very beginning of the case usually turns out to be more counterproductive than helpful.

Unless you are an experienced hire with a strong focus on exactly that one case question to discuss, stating a hypothesis right at the beginning of the case interview is essentially nothing else than poaching with a stick in the dark and guessing around. And here you are: you are perfectly set for a highly unstructured and confusing start into your case! (Please note that even as experienced hire, you might be completely wrong with your hypothesis, especially in the slightly artificial case interview world - so I would not even strongly recommend the early hypothesis there)

However, at the same time it's also a matter of defining 'hypothesis'. If you look at your structure at the beginning of the case interview, it is basically the connection between the current client situation and a specific goal you want to achieve. In other words, this initial structure is also a kind of hypothesis which elements you need to consider and analyze in order to clearly understand the root cause and develop a solution for that. So essentially you can also consider your structure as some kind of hypothesis.

Apart from that technicality, the correct time to explicitly state a hypothesis during your analysis phase is when you have collected some initial data and you start 'connecting the dots'. Once some distinct pieces of your analysis guide you into one specific direction, then it's the correct time to explicitly state your hypothesis and focus in on 'verifying' (in the non-scientific way) your hypothesis!

So: Doesn't matter interviewer oder interviewee-led, opening a case with a hypothesis backfires most of the time.

2) Factors/levels down

I'd practice for 2 levels. Again no difference between interviewer oder interviewee-led. The trick here is to do it top-down and see how it goes and how deep you should go, based on your interviewer's feedback. There is no universally right answer to that - it depends on your interviewer so adapt to that.

3) Number of ideas

I am afraid you are approaching this topic from a wrong perspective. Ideas never means brainstorming. It means structured thinking. Again, start with a top-down structure and see how detailed it makes sense to get at that moment of the case interview. So nobody is looking for a quantitative number, the important point is to approach it in a structured way. Again no right and wrong here - rather try ABS (always be structured).

Is that easy? No. Is it brain surgery or rocket science? Also not. But no short-cuts and a matter of diligent practice.

Hope that helps - if so, please be so kind to give it a thumbs-up with the green upvote button below!


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Content Creator
replied on Jul 19, 2020
MBB | 100% personal interview success rate (8/8) and 95% candidate success rate | Personalized interview prep

Hi Kay,

Great questions.

1) Neither! And interviewer vs interviewee led doesn't make a difference.

If there's a clear, logical hypothesis to be had early on, this may help. However, your framework in of itself is a hypothesis (i.e. I need to look to see if falling Revenues are the cause because of x, y, z). In reality, you should have a few hypothesis/guesses, embedded in a framework, all supported by logical reasoning and contextual understanding! And yes, you should always have a framework, regardless of the case type.

2) This really depends. I recommend you try to stop coming up with rules (I think you're a bit new to this?) and focus instead on "Have I done what matters?". In this case, what matters is whether you've come up with a reasonable approach to answer the question!

3) Again, try not to have quantitative "rules" here. It depends on the case! And it's not about "presenting a bunch of ideas". You can't just list 3 to 4 ideas and expect to do well! Rather, you need a structured, bucketed, logical approach for how you're going to look at, and eventually solve, this problem!

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Anonymous replied on Jul 19, 2020

1 - Great if you are hypothesis-driven, but I wouldn't say you fail the question if you aren't. One example could be: "so profits are falling, I would like to look at revenues and costs. On the revenue side, I would like to look at X, Y, Z; on the cost side at A, B, C. Typically this would be enough, if the structure is fine and you are specific on the revenue- and cost-item buckets. Sometimes the nature of the case would give you details which which would lead you to believe that the issue is either on the revenue- or cost-side and then it is of course great if you bring this up as a first hypothesis after you have presented the structure. if there ISN'T extra info presented to make you form a sound hypothesis, then you could of course just state "I would like to first look deeper at costs, does that sound fair?"

2 - Level of detail: be as top-down as you can, e.g. as in the former example, start with "revenues and costs". then drill down, revenue = price x # of units, say you want to split it into the natural reporting segments perhaps by type of product or geography, and be as specific you can for the case, i.e. in the case of a hospital, mention fixed and varied costs is not sufficient but give examples tailored to the case; i.e. doctor salaries, drugs, hospital lease, etc.

3 - Present as many as you can, and be as creative as possible, start with the most important ones in your mind. Until the interviewer looks bored or wants to move on. The point of the interviewer-led is that he/she will guide you!

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Content Creator
replied on Jul 20, 2020
McKinsey | Awarded professor at Master in Management @ IE | MBA at MIT |+180 students coached | Integrated FIT Guide aut


To add on top what has been already said:

  1. No, and honestly, if it´s not very clear, I see many people making mistakes with this. I don´t think it´s a best practice.
  2. As detailed as possible as general rule, considering you need to gather them all in 3-4 mins.

Hope it helps!



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Sidi gave the best answer


McKinsey Senior EM & BCG Consultant | Interviewer at McK & BCG for 7 years | Coached 350+ candidates secure MBB offers
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