The Six-Minute Hypothesis Rule


I am an MBA student at a leading Indian B-school and successfully secured offers following my AT Kearney interview and BCG interview for their [City in India] office last week.

Thanks a ton for all the help in case interview preparation through LOMS and the regular posts sharing others' interview experiences with all the leading firms.

I had three interview rounds each at both A.T. Kearney and BCG, all of which were primarily case interviews with some of them exploring a bit on the personals side.

One thing that really helped me a lot during all these case interviews as well as during my preparation was to state a couple of hypotheses, if I had any, upfront to the interviewer reasonably early in the case.

This helped me get a sense very early in the interview if my planned line of thought would be in the right direction or not.

Also, it ensures that the subsequent questions I asked would hold a lot more meaning to the case in question.

I had heard from a lot of people before coming across your resources that it is of essence to lay out a structure for solving the case right at the start and that asking lots of questions is the most important thing.

But on going through your prep materials, I realized that understanding the problem through some cursory data gathering was the key to laying out a sound structure for the case.

Also, such an approach was received favourably my most interviewers, as it gave a feeling that I was according the respect that the individual case in question deserved, rather than a standard case interview framework or structure being force-fitted to every case.

And the most important of all, as you've stated several times yourself, there is no substitute for practice.

Each person may (and probably should) have his/her own way of going about solving cases. But unless it has been tested during practice extensively, the chances of it coming off in an interview are slim.

I personally practiced about 30-40 cases with different partners in my B-school in the month leading up to the interviews.

Thanks a lot once again for all the help.

I doubt if it would have been possible for me to be as confident as I was for the interviews without your prep resources.

Do let me know in case you happen to come to India any time, and I would be really pleased to meet you.

My Reply:

Congratulations on your offers at ATK and BCG. I'm glad my articles and Look Over My Shoulder® program were helpful.

I have added your contact info to my travel file for India - thanks for the invitation.

It's interesting that you commented about my preference on when to make the hypothesis statement.

I say it is interesting because there is a reasonable amount of debate on this topic.

As you mentioned, some feel you should state the hypothesis immediately (i.e., within 30 seconds of opening the case), and I have personally tended to ask some background questions first before forming a hypothesis.

I thought I'd take this opportunity to expand upon my rationale for that and also explain the risks associated with each approach for others.

I'll start with my trusted rule of thumb to consider what works with clients, and then do that with interviewers.

If you meet a client for the very first time and immediately tell them your hypothesis as to what is wrong with their company before you ever ask them any questions, they tend to look at you with suspicion and distrust.

It is the equivalent of visiting a brain surgeon who takes one look at you and says you need emergency brain surgery -- even though the surgeon hasn't run any tests yet.

So personally, I have tended to ask a few questions before stating a hypothesis and then continually revise that hypothesis as I learn more about the client situation.

Now the big risk in delaying the hypothesis statement is forgetting to state the hypothesis at all.

It is very easy to ask a few questions, be surprised by the answers you're getting, ask a few more questions and before you realize it, 20 minutes of a 30-minute interview have passed by, and you have yet to state your hypothesis.

This is a big problem.

It is definitely better to state your hypothesis immediately upfront than it is to forget to state the hypothesis at all.

When giving mock interviews for Look Over My Shoulder®, I noticed that several candidates ran into this problem of forgetting the hypothesis entirely.

In the debrief sessions, I discovered that these candidates had difficulty determining how to draw the line between asking a few initial clarifying questions vs. asking too many and delving into an unstructured question and answer session with no hypothesis to provide the conversation with some structure.

In my debriefs, I asked these candidates about this -- and they all knew what a hypothesis was and they all knew they were supposed to state one... yet, two out of three candidates did not use one.

If this seems odd to you, here's why this happens.

It's the stress of a real-world interview.

Understanding what you're supposed to do in a case interview is relatively easy.

Actually being able to do it under real-world conditions and stress is much more difficult.

This is why I emphasize not just taking notes on how to do a case, but also devoting as much time as possible to case interview practice.

So, I have decided to come up with a more concrete rule of thumb for when to state your hypothesis which I will call:

"The Six-Minute Hypothesis Rule"

In a 30-40 minute interview, if you have not stated a hypothesis by the sixth minute of the interview, you're probably making a mistake and at serious risk of forgetting to state the hypothesis entirely.

My suggestion is regardless of what you have discovered by the sixth minute of the interview, state your best guess hypothesis at that point and just work with it.

Otherwise, the risk is just too high that you'll get distracted by some surprising aspect of the case and forget the hypothesis entirely.

Keep in mind, you can and should revise the hypothesis as you progress in the case. So, it is not that critical that the initial hypothesis be perfect.

One more tip, if you plan to use a delayed hypothesis statement, it would be a good idea to tell the interviewer you are doing that deliberately.

So, you say something like, "Before I state a hypothesis, I'd like to ask a few clarifying questions." This way the interviewer knows you were intending to state a hypothesis and doesn't think you forgot.

And if you did forget, the interviewer now can remind you of your original intention, which is less of a penalty than forgetting entirely.

Also, I should add that it is not wrong to state the hypothesis at the start of the case.

To the interviewer, it does seem a little mechanical and formulaic, but as long as you structure your issue tree well, solve each branch, and revise the hypothesis when the data suggests to do so, you can deliver a strong performance even stating the hypothesis upfront.

One caveat to this.

In the McKinsey interview format that most offices are using or are migrating toward, the interview process is artificially broken up into semi-independent sections.

The whole case study interview consists of about five sections (about six minutes each), each focusing on a different aspect of the same case - sort of jumping around from one part of the case to another.

Usually, there is a section on "What's your gut intuition as to what is going on here?"

Another section would be the interviewer giving you his/her hypothesis, and then you structure it with an issue tree.

In this kind of format, each section itself is usually about six minutes.

If you happen to get the section of the interview where the interviewer asks you for your hypothesis, then you do have a few minutes to ask some clarifying questions -- but you don't have more than five minutes typically.

Just keep that in mind from a time-management standpoint.

So that's my thought of the day -- The Six-Minute Hypothesis Rule.

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2 comments… add one
  • C Oct 5, 2014, 11:07 am

    Hi Victor,

    This article was really helpful – thanks. However, it did raise two more questions for me:

    1) Presenting an initial hypothesis upfront makes a lot of sense when the question is about evaluating a course of action (i.e. acquisition). However, in some cases (for example, a profitability case), I find it hard to come up with a useful hypothesis at the beginning. Instead, I work through the profitability framework to uncover the driver of the problem, and then put forward a hypothesis about whether it can be fixed.

    Given it often takes longer than six minutes (or maybe I’m too slow!), do you think this is the right approach?

    2) Can you think of any cases where a hypothesis might not be helpful at all?


    • Victor Cheng Oct 5, 2014, 12:08 pm


      It’s always useful to have a hypothesis from the outset. However, sometimes it’s useful to not state the hypothesis out loud if the hypothesis is overly arbitrary and based on absolutely no data. A profitability case is a perfect example.

      When I do a profitability case I start with an arbitrary hypothesis that it’s a rise in costs that has led to the decline in profitability. I usually do not say this out loud initially.

      If costs haven’t increase, I usually say “well clearly it’s not a cost issue, it must be revenue related. Let’s analyze revenues next.” In this case, I implicitly stated a revised hypothesis without being overly explicit and conversationally awkward about it.

      It is more important to by hypothesis DRIVEN in your thinking and how you are verbally describing your thinking that to actually say the word hypothesis. When I interviewed originally, I never actually stated a hypothesis in my case interviews. But if was very obvious to the interviewer very quickly that I had one in mind.

      The reason I came up with the 6 minute rule was because I noticed that one of the most common mistakes CIBs were making based on how I originally taught my case approach was to completely forget to have a hypothesis and to simply ask the interviewer an endless series of unrelated questions with no purpose in mind. The 6 minute rule was created as a reminder guidepost to prompt CIBs to check with themselves that by that point in time they should have some hunch of what is likely going on in the case and to given them a point of focus,

      It’s actually better if the stating of the hypothesis verbally is done in a conversational style – much like how you might talk to a client over lunch about a problem they are facing.


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