Issue Tree

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Question on Using an Issue Tree:

First, I would like to thank you very much for your LOMS program. I found it very helpful.

Your emails are also very useful for me to learn many new things from other people's experiences.

My questions is about how to structure a case after a case question is given.

I am a PhD student and my most comfortable way of setting up a structure is to use the issue tree as you presented in the LOMS program.

However, when I was mock-interviewing with MBA students, I found my structures are very simple compared to what they have.

For example, when I was given a profit case, I only wrote on my paper, revenue, cost, and the components of the two.

Then I started to ask for information around these factors and move along the case.

While the MBA students I interviewed tended to write down many other factors that could cause the drop of the profit and also possible ways to solve the profit decline.

Basically, everything they can think of.

This approach looks to me more or less like brain-storming. But one reason my MBA practice partner told me is that writing down many factors shows the interviewer the breadth of thinking.

I am not sure which way would be better. Since a structure in a case interview is so important, I hope you can help me out here and explain a little bit more what you think of the two approaches.

Also how many layers should I structure initially in a issue tree?

Thank you and look forward to your reply!

 

My Reply:

As you know from LOMS, one of the big differences between candidates who "ace the case" vs. those that don't is that the structure used by a strong candidate can be drawn as an issue tree.

Starting off a case with an issue tree that has multiple layers is a good idea provided 1) you can do it, and 2) you're able to realize if you did it wrong and adapt.
It is not always easy to do, and easy to screw up.

What you do not want to do is have an unstructured brainstorm of every possible reason for why say a company might be unprofitable.

That would be a mistake.

You do not want a laundry list of every possible way a company can be unprofitable and you especially do not want a laundry list of solutions for how to fix a company's profitability problem until after you have isolated the specific cause of the problem.

But, if you have a very structured issue tree that is MECE and you can anticipate which ways you would want to structure the 2nd and even 3rd layer of your issue tree, it's worth doing... especially if you have a very specific hypothesis in mind.

If you feel the need to discover more before going down a few extra layers in the issue tree, on balance I think it will not hold you back from getting an offer if you got the case right using this approach.

There are some downsides to be mindful of.  If you outline three layers of an issue tree before you get any data, you have to keep in mind the possibility that you structured layers 2 and 3 in a sub-optimal way.

So you have to be open to the idea that you might change your structure as you discover data in layer 1.

So maybe you know sales are down, you could segment sales by country, by product, by division, by sales channel.

Which one is the right way?

If you do the structure up front and pick country for the 2nd layer, and then realize the key issue is a difference in sales growth by sales channel, then you have a sub-optimal structure.

This by itself is not a problem. It is only a problem if you set up a sub-optimal structure and don't realize it is sub-optimal once you have enough information to determine it.

When I interviewed, I did not lay out 2nd and 3rd layers of issue trees up front and simply decided on them as I went.

I am hearing that some candidates are doing this today (I guess people are much more prepared these days then when I was interviewing some years ago).

If they can pull it off without confusing themselves, it does comes across well to the interviewer.

If the multi-layer issue tree structure implicitly commits them to a particular problem solving approach and they are not sophisticated enough to realize when there's a mismatch being their initial structure and the data they are discovering early in the case... and if this causes them to not solve the case because of the confusion, then I would say it's not worth doing.

In other words, as you refine your hypothesis, it is to be expected that your issue tree structure may change.

Some people will find it harder to change an issue structure if they've already "committed" to it to the interviewer.

In reality, it is not a problem to change the issue tree structure in the middle of a case -- it is done all the time in real client engagements.

It is more important to solve the case in a structured way, than it is to show a multi-layer issue tree and not solve the case.

As an example, the issue trees diagrams used to solve the hardest cases in Look Over My Shoulder®, all ended up with multiple layers to the issue tree.

Those issue trees were created throughout the interview - built a piece at a time. If you are able to see deeply enough into the issue tree to draw the entire issue tree up front, then do it.

Otherwise, it is okay to start with 1 - 2 layers beneath your hypothesis.

The most important thing is that you finish the case with the right issue tree. When you draw out certain pieces in the issue tree is secondary to getting the right issue tree.

Also I will add it is easier to do a multi-layer issue tree when the case is very numerical such as in a profitability case. It is harder to do this well in a case that is more conceptual like business situation.

In a more conceptual case, there is not a finite number of items in the next level of the issue tree or framework.

So the risk of going too deep in layers up front in the case is you end up with an unstructured brainstorm that is not directly related to testing the hypothesis.

You will notice in my issue tree samples in LOMS that at the top of them I always put my hypothesis at the top.

This is very important.

You will also notice that the branches in the issue tree under the hypothesis will always, always prove or disprove the hypothesis.

I disagree with the characterization that you want to show breadth of thinking by brainstorming every possible reason for a particular client situation.

This is nowhere near as important as being hypothesis driven and highly analytical and structured in terms of how you test the hypothesis.

Also, in looking at how you describe what your MBA friends are doing in their cases -- proposing solutions to the profit problem in a case -- that is a very common mistake that with sufficient practice with LOMS you will be quick to realize.

You fundamentally can not solve a problem until you have defined it.

This is a classic mistake that you will see repeated over and over again the LOMS examples. I call it the "pet theory" mistake where the candidate has a pet theory as to the right solution to solve the client's problem.

Never ever propose a solution to case until you have determined the problem!

Never ever propose a hypothesis that is a Solution.

A hypothesis should almost always be a hypothesis about either a) The Problem, or b) The Problem + The Solution.

A hypothesis should almost never be a solution without an explicit statement of the problem.

For example, a bad hypothesis is:

1) My hypothesis is the client should lay off 20% of its employees to improve profitability.

A good hypothesis (which might still be disproved mind you) is this:

2) My hypothesis is the client's labor costs have increased much more than its competitors as a % of sales and that the right course of action is to layoff 20% of employees.

What is the big difference between these two hypotheses?

The first does not explicitly state the problem.

The second one does.

Notice also how much it easier to prove or disprove the second hypothesis.

All you need to do is compare labor costs as a % of sales for the client vs. competitors. You immediately know if that's the problem or not.

If you look at the first hypothesis, how do you prove that a 20% layoff is analytically the right decision or not?

It's just an opinion that is difficult, or at least much more confusing, to prove one way or another.

I refer you back to the Look Over My Shoulder® cases for many examples of candidates using both "good" and "bad" hypotheses.

I would recommend going through the LOMS cases one more time, this time specifically focusing on the hypothesis and issue tree structuring.

By the way, one of the reasons I recommend going through LOMS five times, is because each time you go through it you can focus on a different aspect of the case.

For example, in your situation you are now very aware and focused on issue tree setup. In all likelihood, when you went through the LOMS cases the first time you were probably focused on just getting a sense of how a case is supposed to be done.

Now that your skills have improved, when you go through LOMS again you have sufficient skills to notice new things -- bad habits to avoid & good habits to emulate.

Okay, a final point on this.

Be careful to avoid assuming that your friends with MBA's know what they are talking about just because they have an MBA and you don't.

The problem with MBAs and one of the reasons McKinsey started the PhD recruiting program many years ago is that some MBAs are good at talking, but not that good at problem structuring.

McKinsey thought that it was easier to teach business terms and concepts to someone who was very strong analytically and in problem structuring, than it was to teach problem structuring to someone who was already familiar with business concepts.

From McKinsey's perspective, its best to find someone who is both excellent at business concepts and problem structuring, but the firm found they ran out of enough candidates that were good at both to meet their recruiting goals.

Good ideas without good structure is not useful in consulting for the simple reasons that clients already often have good ideas without structure.

The reason they get stuck and need consultants is they don't know how to structure their decision making process -- but consultants do.

That's why top firms look for candidates with strong case structuring skills. And it is also why I emphasize its importance so much in my emails, in the free Case Interview Secrets videos, and in Look Over My Shoulder®.

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3 comments… add one
  • Gregory Aug 1, 2015, 3:34 pm

    Super helpful, eloquently written, and a follower of your own advice. You’re a tremendous help. Thank you.

  • Roy Aug 1, 2015, 3:35 pm

    Is an issue tree a requirement? In LOMS, even the cases where you think the candidate did pretty well (for example Case 1, Example 1), there is no issue true to accompany the solution. This candidate does use your business situation framework soundly however. So with this distinction between using a framework and writing an issue tree, would you say the former is always necessary and the latter is preferable, but not always done?

    • Victor Cheng Aug 4, 2015, 12:07 am

      Roy,

      I’d say if you are given a full case like in LOMS (as opposed a pre-defined part of a previously structured case), you always need to have the problem structured into some kind of organizing structure. Whether it’s a framework of some sort or an issue tree depends on the specifics of the case. The best structure to use is one that breaks the problem into smaller pieces that can be more easily analyzed in a way that’s seems aligned with the specific case at hand.

      For a market entry, that tends to be a business situation framework. For a pricing or profitability issue, that tends to be a profitability framework. For others, it may be an issue tree.

      One mistakes some CIBs, especially the ones with MBAs make is they try to force a framework on to a case that clearly doesn’t apply. For example, at one time a lot of MBA ps were trying to apply Michael Porters 5 Forces Frameowkr onto every case they have. The 5 forces framework is useful in analyzing industries (an element of the 5 forces are already included in the business situation Framework, in particular the branch about competitors). Some CIBs would insist on using the 5 forces framework on a market entry problem where consumer demand was unclear (and in need of greater demand side understanding to solve the case) and there was no competition.

      The bigger issue was understanding customer demand (the customer portion of the business situation framework) that analyzing non existent competition. So it wasn’t so much that the 5 forces framework was wrong lee say, just that it wasn’t particularly relevant in this particular case.

      A framework does not get you out of having to be thoughtful about your approach and to see if it makes sense.

      Victor

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