Becoming More Efficient and Quantitative in Case Interviews

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Question:

The closest I have gotten to an offer was the final round case interview with Bain. But I got dinged, the feedback was: My pace was too slow, and I am not quantitative enough.

My last shot at the consulting industry is with BCG.  I have about a month to prepare for it, and these are the things I am doing:

1. Cases everyday with my friends

2. Reading publications (books and reports) done by the firm and the specific office I am interviewing with

3. Reading WSJ and business news

4. Your Look Over my Shoulder® Program

Is there anything I can / should be doing?

 

My Reply:

Let me start be interpreting the feedback you've received and make some suggested changes to your preparation plan -- which I would recommend doing very differently.

Here's what "too slow" means.

It does not mean you need to talk faster.

It means you are asking too many questions to figure out a conclusion for one part of the case.

Slow = Inefficient

Stated different, the real problem you have is you're asking the wrong questions -- in particular your questions are not specific enough.

This is a very common problem. In my Look Over My Shoulder® program, the candidate who did Case #2, Example #1 is a perfect example of the problem you're having.

He got the right answer, and I still "dinged" him.  Why?

For the exact same reason you got dinged by Bain.

How you get the answer is as important as if you get the answer. If you really study the recording and transcript of this particular interview, pay very close attention to what questions the candidate asks.

Then, compare those questions to Case #2, Example #2 -- the questions asked by the candidates are different.

The candidate who did it the right way, "zeroed" in on the "exact right issue", often asking a question regarding specific data.

So let me give you an example of the difference in how a "slow" candidate asks questions vs a "fast" one.

Slow Candidate

1) Slow Candidate: I know profits are down 20%, do we know if sales have declined?

2) Interviewer: Yes, we know sales are down 10%.

3) Slow Candidate: I see, next I want to analyze costs. Do we know if costs have changed?

4) Interview: Yes, costs have gone up.

5) Slow Candidate: How much have costs gone up by?

6) Interviewer: Costs have gone up by 10%.

7) Slow candidate: Do we have a breakdown of which costs have gone up?

8) Interviewer: Labor costs have gone up by 30%, all other costs are unchanged.

9) Slow candidate: Do we know what % of total costs is represented by labor?

10) Interviewer: 1/3 of total costs comes from labor.

11) Slow candidate: Do we know how our competitors' costs have changed?

12) Interviewer: Competitors' costs have changed by the identical percentages.

13) Slow Candidate: I see, so this is a industry-wide cost problem. Do we know if profits for our competitors have changed?

14) Interviewer: Yes, profits are also down by 20%.

15) Slow Candidate: Do we know if sales have changed?

16) Interviewer: Yes, sales for competitors are down 10%.

17) Slow Candidate: I see, it looks like industry-wide profitability is being driven by a decline in sales volume and an increase in labor costs. So the question is what should the client do given these two factors. What I want to do next is...

(Okay, notice that it took 17 lines of back and forth to get to this point. See how the "fast" candidate does it.)

Fast Candidate

1) Fast Candidate: I know profits are down 20%, do we know if sales have declined?

2) Interviewer: Yes, we know sales are down 10%.

3) Fast Candidate: I see, that means costs are up 10%, do we have a breakdown as to which costs have increased?

4) Interviewer: Labor costs are up 30%, all other costs remain unchanged.

(In the candidate's head she figures out... if the labor costs are up 30%, and overall costs are up 10%, we know labor is 1/3 of total costs...  got it, remember that, no need to ask the question.)

5) Fast Candidate: Next question, have labor costs for our competitors' changed?

6) Interviewer: They have changed by the same amount.

7) Fast Candidate: My hypothesis is this is an industry-wide problem impacting industry-wide profits. Do we know if competitors' profits are down more, less, or the same as our client?

8) Interviewer: Competitor profits are also down 20%.

(In the candidate's head, she says to herself... competitor profits are down 20%, their costs are up 10%, so it must mean mathematically that sales for competitors are also down 10%. Got it. No need to ask the question.)

7) Candidate: I see, so mathematically we know sales for all players in the industry are down 10%, with labor costs driving up total costs by 10%, reduce profits for the industry overall -- including our client.

So the question we're really try to address is what should our client do, given these two pressures on the industry.  To answer that question, I'd like to...

MY COMMENTS

Notice the line count comparison: The "fast" candidate uses only seven lines of going back and forth vs. the "slow" candidate using 17 lines.

This is what people mean when they say someone is "sharp" or that they "ripped" through a case or problem fast.

It wasn't that they did each step quickly (such as speaking at a faster rate), when someone is fast it really means the things they choose not to do got them to the conclusion faster.

Notice how the slow candidate asks a lot of redundant questions. If profits are down 20%, and sales are down 10%, we already know mathematically via basic algebra (solve for X type stuff) that costs must be up 10%.  Since this is a mathematical certainty, it's a waste of time to ask about it.

The "slow" candidate tends to not realize the mathematical relationship or is not fast enough at math to do the calculation in the middle of an interview under some pressure, and to then quickly interpret what that means for the case.

You can combat this habit by being very conscious about really thinking very critically after each back and forth with the interviewer, asking yourself, "What do I now know that I didn't a second ago?"

I remember I had one case interview where I solved the entire case that others took 45 minutes to solve, and I took six minutes asking only four questions -- importantly it was the right four questions.

So for your specific situation, you want to get "fast" and "pick up the pace" mainly by 1) doing the mathematical relationship stuff in your head, not waste questions on it, and 2) cut out unnecessary questions.

On a separate note, a non-quantitative candidate will do the following:

1) Candidate: Have sales for the client decreased?

2) Interviewer: Yes.

3) Candidate: I see, have costs changed?

4) Interviewer: Yes, they have gone up.

A quantitatively-oriented candidate would ask the questions slightly differently:

1) Candidate: Have sales for the client decreased?

2) Interviewer: Yes.

3) Candidate: By how much?

4) Interviewer: Sales have declined by 10%.

5) Candidate: I see, have costs changed?

6) Interviewer: Yes, they have gone up.

7) Candidate: By how much?

8) Interviewer: They are down by 10%.

As a consultant, when precision is important, you need to quantify everything to determine order of magnitude.

I don't have the time to cover this idea in detail, but sometimes I will do math in terms of figuring if a number is "big" vs. "small."

So there's a judgment as to whether a specific number is necessary to draw a conclusion, or just having a general idea of the numbers is sufficient.

So a "fast" candidate will be able to recognize the difference and avoid asking for overly specific numbers when it's not necessary to draw a conclusion.

For example, if you know that your competitors' costs have changed in identical ways as the client's costs. And if you know the competitors' revenues have changed by an identical % as your clients, depending on the question being asked, you may not need to know the exact % change in costs or profits for either.

Why?

Because you can conclude it's an industry problem without knowing the exact % changes. So if that's all you need to determine at that point in the case, why bother asking for more specific data?

It's not necessary to answer the question.

This is what interviewers mean when they say a candidate has difficulty with ambiguity. Someone who's training is in math will want to know the exact numbers.

But in consulting (on the job), we don't have the luxury of infinite time and people to analyze everything. We have to take shortcuts by only getting data that's just sufficient enough to answer the question at hand.

The example at the start of my reply was an example of a candidate being "slow" quantitatively. But it is also quite common for candidates to be "slow" in analyzing qualitative data.  In my Look Over my Shoulder®, there were lots of examples of this common mistake too.

Typically the person has a PhD in physics, math or some other quantitative field, and they completely miss or are slow to grasp qualitative insights which are equally important as getting quantitative insights.  This is the weak spot of people with this background.

There's the equivalent of a one-hour discussion on this specific topic in Look Over My Shoulder® so I won't cover that point here, so I have time to cover how I think you might want to prepare differently.

Originally, your plan was the following:

1. Cases everyday with my friends.

2. Reading publications (books and reports) done by the firm and the specific office I am interviewing with.

3. Reading WSJ and business news.

4. Your Look Over my Shoulder® Program

I think given the specific feedback around what's holding you back from getting an offer, I would forget about #2 and #3.

Reading general business news and books will not help you. The most useful preparation items will be practice cases with friends with a specific emphasis on the items I mentioned above, and using and truly studying the Look Over my Shoulder® program.

While I'm on this topic, let me point out something about Look Over my Shoulder® program. The biggest complaint I've gotten about the program is, "I didn't learn anything new" in the program. As in, "There wasn't some kind of new mistakethat I had never heard of before."

The "new" part of the program is not the fact there is some new mistake you've never heard of. The "new" information that's in the program that's not available anywhere else in the world is a step-by-step examination of why and how someone made the mistake you may already be familiar with.

It's the step-by-step breakdown of the process leading to the mistake or good outcome that is the "new" information. And the difference between success and failure is very subtle.

In hindsight, I think it was a mistake on my part to suggest the program has new mistakes in it. To be more precise, I should have said the program reveals how and why certain mistakes were made, rather than the mistake itself being the new information.

The purpose of the program is take people who know what to do and actually get them good at doing it... especially under pressure.

And the key to making that happen is to make you hyper aware of when you're making a process mistake that is about to lead you into an incorrect conclusion or "No" conclusion problem.

The goal is when you are in a live interview and you are about to make a very common mistake (which is thoroughly documented, defined, dissected, and analyzed in Look Over My Shoulder®), an alarm bell will go off in your head:

** WARNING **  **WARNING ** (You forgot to ask X question!!!! Stop! Don't skip this step!)

Now why would this alarm bell go off?

If you study failures and the steps leading up to them, you get good at spotting the warning signs leading up to when you're about to make a mistake.

I have a friend who is a pilot. He subscribes to a magazine whose sole purpose is to publish the findings from the crash investigators that provide a detailed analysis of every plane crash that happened in the last 30 days, and why the crash happened.

He reads this magazine every month, because when he flies his family around, he does not want to kill them by making the same mistake that killed someone else last month.

And you know what causes plane crashes? It is rarely a single mistake. It is usually a series of three to four mistakes in a row -- any one of which would not have been fatal, but all of them in a row was fatal.

I see parallels to those voice recorder "black box" transcripts and the pattern I notice in the Look Over my Shoulder® interviews for those candidates who got "dinged".

Rarely did the candidate make one big mistake, much more often they made an entire series of little mistakes whose cumulative effect caused them to miss an important insight in the case and they got stuck.

(It's the series of process mistakes that leads an interviewer to conclude a candidate is "slow".)

If you go through the Look Over My Shoulder® program skimming it, looking for the new mistake you never heard of, you probably will not find it.  (And in my video describing the program, I will revise my description of the program to clarify that expectation.)

What you want to do is study both the failures and successes... multiple times. Until both become routine... where you can spot the entry points to common case interview mistakes from a mile away, and can also use the good habits, automatically.

So here's what my pilot friend does. When he's in a situation that's unexpected, like suddenly fog has rolled in, and visibility is close to zero...

Do you know what goes through his head?

He remembers all the crash scenarios he studied in detail that began with zero visibility.

He immediately recognizes the mistake people tend to want to do (in this case, the tendency is to look out the window, rather than at your instruments, and when that simple mistake happens in general, it means you will crash and die in about 30 seconds).

What he does next is he forces himself to stick to the good habit (in this case, ignore what you see outside, or what you think you see outside, or what direction you think your plane is going, and just go by what the instruments say is going on even if your body senses are telling you the instruments are wrong -- the second lethal mistake that kills people in zero visibility situations).

For my friend, he realizes when he is entering in a situation where his colleagues tends to make mistakes, he knows what mistakes they tend to make, he knows why they tend to make them, and he knows how they make them... and by recognizing the death spiral pattern is able to avoid it entirely.

Though getting dinged in an interview is nowhere near as bad is getting killed in a plane crash, I think the training process pilots use to avoid death is probably a pretty decent process to avoid get rejected in a case interview.

And that was my motivation behind why I created the Look Over my Shoulder® program the way that I did.

Moving on, here's the deal with cases.

They are exhausting.

When you do a case live, you have to really think.  It takes a lot of energy to do that.  The problem I see in those who are less prepared is that they put their thinking energy into what's the next step I'm supposed to do in the case from a process standpoint (as opposed to an insight standpoint).

Those who are prepared automatically know what's next from a process standpoint in the case, and they can devote their thinking energy to truly analyzing the implications and insights in the case.

They don't waste their "think" time on the mechanics of asking for a particular kind of data in a particular way and sequence.

This is the other way you "speed" up processing time, you don't waste time thinking about process steps that should just be habitual and routine. This takes awareness of what those habits are and practice.

So my recommendation is to not just read the Look Over My Shoulder® transcripts or listen to them, but rather to actively engage in the material in some way.

If you're reading the transcripts and are not using a pen to make notes, observations, and rewriting the transcripts into a more efficient way to ask questions, you're not using the program in its most useful way.

If you're passively listening to the recordings and not hitting the pause button every few minutes to ask yourself, "What did the candidate forget to do? Would I have done it differently? Was there a more efficient way to get to that answer?"

Afterwards (or even in parallel) you want to practice cases with your friends to get used to using the new habits under the pressure in a more interactive environment. In particular, you will want your friend to constantly interrupt your train of thought by asking you questions about your responses.

Many candidates get a little caught off guard by this, so this is good to practice live when you have the opportunity.

It's also another reason you want as much of the procedural aspects of the case to be habitual and automatic, so when the interviewer asks you a legitimately interesting question, you can think about an appropriate answer without losing where you are in the case.

There is an update on this post at: http://www.caseinterview.com/obligation-to-dissent

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2 comments… add one
  • Dan Nov 1, 2011, 12:04 pm

    Hello:
    I am very interested in your website and think it is a fantastic learning tool to prepare for case interviews. However, I am struggling with your above example about profits being down by 20%, sales down by 10%, and, therefore, cost being up by 10%. Let’s assume P=10=R-C=30-20. If profits are down by 20%, then P=8, Revenue down by 10%, then R=27. But that doesn’t mean that C is 22. P=8=27-C, C=19. What am I missing?

    Thanks.

  • victor Nov 1, 2011, 12:19 pm

    Dan

    You’re correct. There’s an error in my example. If you replace the % symbol with the $ symbol, the example should work out. This is what I intended, but I wrote the example incorrectly.

    Victor

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