You’ve just been told your next interview involves a case study; are you nervous? Maybe or maybe not; but perhaps the more important question is, are you prepared?
Case studies come in all shapes and sizes depending on the type of company, hiring manager and position you are applying for; but if you remember to prepare, think logically and relax, you’ll come out the other end un-damaged. The point is to see if you can understand material quickly and attack a problem logically, not to see if you know the answer to every question.
First, establish what kind of case interview you are going for. There are normally three types of case studies given by companies; business scenarios, estimation cases and guesstimations/brainteasers. The person you booked the interview with or your headhunter will often be happy to give you as much information as the can. Once you know what you are tackling, it will be easier to focus your preparation.
Business scenarios – remember to research
Business scenarios are used to test your structured thinking and your understanding for business and economics. They will require sector knowledge of the industry you are interviewing for so you should draw from your past experiences to answer the question.
Don’t stress out if you don’t know the business well or haven’t had formal training, do research on the company and the industry and this will give you a foundation; the interviewer will help you out if you need it. You can still draw on your experiences of transferable skills; you may not have specific industry knowledge but you should be able to relate to the scenario.
Estimations – practice makes perfect
Embrace the cliché! Practice is the absolute key to estimation cases. Questions could include “How many blue cars are there in Texas?” or “How many people will live on Earth in 2100?” so preparation can be tricky as the question is unlikely to relate directly to your industry.
Practice really helps, so get on the internet! You’ll be able to find numerous estimation questions which can help get you into the right frame of mind. Work on that mental arithmetic too; if you make an error on a simple sum, they will take note. If you know you’re not strong in that area, take a pad and pen and do your calculations on paper, just be sure to keep talking everything through.
It is more important to demonstrate that you are structured and logical in finding the solution, than it is to arrive at a “correct” answer. If we go back to the example of “How many blue cars are there in Texas?” there is a logical set of steps that will lead you to a reasonable answer.
Step 1 – Estimate the number of people in Texas
Step 2 – Narrow down the number to those who will be able to drive or do drive, factoring in age and affordability.
Step 3 – Then, by determining that there are really only a certain amount of colours which cars can come in (think colours of the rainbow then add silver, black and white), establish the percentage of those who drive who will have blue cars (remembering to consider that blue is going to be a more popular colour then indigo or violet, for example).
Step 4 – Once you have considered the percentage find the number of people who own blue cars.
This is a great way of starting you thought process. Once you’ve come up with a reasonable number, try talking through other factors to consider; such as how many car manufacturers there are in Texas who would have blue cars not yet on sale etc.
Guesstimates or brainteasers – maintain your poise under pressure
Brainteasers can be quite unnerving but with preparation you can learn to deal with these comfortably. They are similar to estimations but are different in that they are often “off the wall” in such a way that it is difficult to know where to start. Don’t feel rattled, take the experience with a pinch of salt and tackle the problem head on. Let’s look at an example:
How many hairs are there on a dog?
To start, there is no answer to this question; there are hundreds of breeds, cross-breeds and mutts in this world and no two will have the same number of hairs. So how do you come up with an answer?
Well I would start with some questions. “Did you have a breed in mind? Size? Shape? Season? Or can I determine that?” Chances are you will need to suggest these details but it will give you an opportunity to think and show that you are considering all the factors involved.
Once you have asked some initial questions, state your plan of action. “First I will propose the size and shape of your average dog. I will then calculate how much surface area is on the dog’s body by dividing the dog into manageable pieces (body, legs, tail, head etc.). Once I have calculated the surface area I will take the average width of a hair and determine how many would fit on that surface area.” Then get to work, pick a kind of dog (perhaps your own or a friends) and guesstimate the surface area.
So, my dog is about 60cm tall (to his shoulder), maybe 120cm from nose to tail and about 30cm wide; yes, he’s pretty rotund but let’s keep the numbers easy, don’t trip yourself up by over complicating things.
Of his total length, about 70cm is his body (the rest being his head and tail) and of his total height, his body is about 30cm tall. So his body shape is 70cm by 30cm by 30cm, which is a surface area of 102m2, if he was a box. Do the same for the 4 legs, head and tail and you should arrive at a workable total surface area (see below for my guesstimates).
- Body – 102m2
- Tail – 3.2m2
- Each Leg – 19.2m2
- Head – 18m2
- Total – 142.4m2
Once you have a workable number, guess how wide a hair might be (around 0.01mm) and figure out how many would be on that surface area.
By following logical steps we were able to get a reasonable answer and by doing so we have not only shown that we can tackle issue which we have little frame of reference, we have also shown off our mathematics and how we are cool under pressure.
Remember, no matter what, ASK QUESTIONS!
Your absolute first response must be to ask questions! It will not only give you precious moments to think about the problem and how you might structure your response, it will probably provide you with further information that may help to steer your answer in the right direction. And try to ask some collaborative questions throughout so the interview feels involved in the process (e.g. would I be right in concluding that … It would appear that … am I on the right tracks?).
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