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Case study written test

What is a written case interview?

An overview of the new format Bain and BCG are utilizing

Written case interviews are an evolution of the standard case interview format popularized by McKinsey, BCG and Bain.

While the skills tested are similar, the written case format is unique. Instead of assessing a candidate in 45 minutes or less (like a typical case interview), written case interviews run about 2 hours or longer and give the candidate a chance to demonstrate their skills while mimicing the exact work consultants do: absorbing large amounts of data, running analyses and presenting their findings.

In this post, we’ll get you up to speed and cover all the basics:

Overview of the written case interview

At its core, a written case interview is one where the candidate is given a set of materials (e.g., data and slides), a specified amount of time to review the materials and do analysis and time to present their findings to a panel of interviewers.

There are two key differences between a written case interview and a standard case interview. First, the candidate will recieve detailed materials and be given time to review them independently (e.g., no interviewer present). Second, the candidate will be expected to produce written analysis (e.g., a set of slides) that they’ll present to their interviewers.

Currently, the written case is an interview format used primarily by Bain and BCG. Although it is less common than typical case interviews, the format has been gaining popularity recently, especially in the second round interviews of post-MBA consulting roles.

Since the format is newer, it’s important to note that its not universally used (e.g., undergrad applicants don’t typically have a written component) and use can vary from office to office.

For example, Bain’s Sydney office may have slightly different recruiting norms than Bain’s Atlanta office. That said, we highly recommend preparing for both types of interviews, as you don’t want to be caught off guard and the two types of preparation will enhance your overall ability and confidence with cases in general.

So, what can you expect in terms of the format?

Bain vs. BCG’s written case

Overall, the two firms have very similar formats for their written case interviews. This isn’t surprising, as both companies are trying to test similar capabilities, which we’ll get into below. That said, Bain’s written cases tend to be the shorter and more structured of the two.

For both, you’ll be given a problem to answer along with a stack of printed materials to review (e.g. powerpoint slides, industry reports, or market research). You’ll have a set amount of time to prepare your answer to the question in written slide format, using data and supporting evidence from the documents that have been provided. At the end of the allotted time, you’ll be asked to present your slides to your interviewer, who may ask additional questions, push on certain assumptions or debate aspects of your argument.

Here’s how the two firms’ specifics stack up:

As you can see, the presentation format is one of the biggest differences – Bain gives you a bit of a head start by pre-filling some of the slides they want you to create. On the other hand, BCG gives you completely blank slides, so you’ll need to decide how many slides to make and what to put on each one. This is likely why BCG allows more than twice as much time to prepare.

One additional consideration – neither Bain nor BCG will allow you to write or take notes on the materials that are shared, so it’s a good idea to follow this same rule when you’re practicing. You will be able to take notes separately, but can’t mark the documents directly as they are reused by multiple candidates.

Skills tested in written cases

With the written case interview, consulting firms are aiming to test very similar capabilities to the traditional case interview: structured problem solving, quantitative skills, and business judgement.

What’s different about the written case interview is it tests your ability to produce work under time pressure, tell a cohesive story, and persuasively present your argument. It also requires you to sift through lots of data to pull out what’s truly important and drive towards a hypothesis. Unsurprisingly, these are all essential skills for a consultant and the written case interview is designed specifically to see how a candidate will perform in a “on-the-job” scenario.

During the interview, you’ll be evaluated across several areas:

  • Structuring an ambiguous problem: can you approach the problem in an organized manner and take a methodical approach when building your answer?
  • Conducting fundamental analysis: Are you able to solve basic math problems and do you understand the drivers behind your answers such that you can explain the impact of changing assumptions?
  • Identifying key data points: Can you focus in on the primary pieces of evidence you will need to support your argument rather than “boiling the ocean”?
  • Building a cohesive storyline: Do your slides take the audience through your logic and findings in a clear manner?
  • Presenting your work: Are you able to make crisp recommendations and stand behind your work when questioned?
  • Engaging your interviewer in discussion: Are you comfortable conversing about the case more broadly?

Shameless plug: Our consulting interview prep can help build your skills

Common pitfalls and how to avoid them

There are several areas where people often get hung up on the written case interview – don’t fall into these same traps! These are the four pitfalls to avoid:

Answering the wrong question

We can not stress this point enough – make sure you have a crystal clear understanding of what question you’re trying to solve before you begin. Read the question at least twice and keep referring back to it if you need throughout the session. You can’t get time back that you waste on answering the wrong question.

Mismanaging your time

You will intentionally be given more material than you will have time to read through. If you jump right into the documents without a clear plan, you will waste precious minutes going through irrelevant data. Instead, pretend you’re working through a standard case interview and take a few minutes to think about how you would structure your approach, what pieces of evidence you would need to build an argument, and then start combing through the materials with a clear purpose in mind.

Failing to tell a cohesive story

Interviewers are looking for you to come in with a concrete answer and present supporting evidence to back up your position. The way you organize your thoughts on the slide is just as important as your content. Make sure each slide title has a point and that the presentation as a whole flows logically. Don’t forget to summarize your recommendation at the end.

Missing the “So what?”

Most interviewers have probably given these cases numerous times – so you’ll need to go beyond getting the basics right to stand out. Push yourself to think about the “so what?” implications of your findings and don’t shy away from injecting a little creativity into your answer.

This could be going a level deeper in your summary, touching on potential risks down the line, or calling out areas you might want to look into if you had more time.

How to prepare

Now that you know what to expect from a written case interview and what your interviewer will be looking for, what’s the best way to prepare so you can ace it?

First, review the sample materials that Bain and BCG provide online to familiarize yourself with the format. When going through these, try to simulate a real interview environment as much as possible, including practicing your presentation live with someone else.

Second, dedicate some preparation time to learning what a good slide looks like, including effective titles, formatting and use of charts and data. Here’s an example from a BCG deck on China and another example from McKinsey on digital globalization.

Finally, leverage your standard case interview practice – the structured problem solving approach will serve you well in the written case interview as well!

Case Study Interview Examples: Questions and Answers

You will need to prepare for an interview where case study questions will be asked. While preparation is required for every job interview, extra time is required to adequately prepare for case study interviews.

Providing an answer to a case study question involves much more than simply recounting the issues and problems set forth, it includes identifying the most important issues, employing sound and logical analysis, developing an action plan for addressing the problem(s) and making recommendations. Depending on the firms you’re interviewing with, and the industry you work in, case study questions can be presented in verbal or written format, and address a number of topics.

In case interviews, it’s not uncommon for interviewers to exclude important details when asking candidates to resolve hypothetical business problems presented. It’s okay to ask interviewers for more information, and it’s expected. They want to see if you can identify what information is important, and what is not.

Occasionally, interviewers provide no detail at all to test your analytical skills when adequate resources are unavailable. In these situations, it’s okay to make assumptions, but they must be based on sound logic and analysis of information that is provided.

Interviewers asking case study questions are primarily concerned with how effectively you can analyze a problem, determine key factors, brainstorm ideas, and propose workable, pragmatic solutions that are supported by your analysis.

In the case interview, coming up with the “correct” answer isn’t nearly as important as the process you use for getting there. When answering a case interview question, you want to showcase your ability to analyze a situation or business dilemma, identify the important issues, and develop sound conclusions that flow from your analysis. For this reason, it’s important to use a logical framework for breaking down and analyzing the case. Some of the more common business analysis frameworks that can be employed include Porter’s Five Forces, Value Chain Analysis, Four P’s of Marketing, and SWOT Analysis. The framework you decide to use should be a function of the type of case you’re presented.

Where a specific framework for analysis isn’t readily available or applicable, a general framework or analytical approach can be applied. The most important thing is that your approach to answering the case interiew question is structured and logical.

Regardless of the type of case you’re presented, there will likely be a few main parameters and several factors that influence those parameters. The first thing you want to do is identify the parameters and factors, the then determine which are key to the case output.

For example, assume the case involves a company’s declining profitability. From your initial review of the case information you determine the main parameters to consider are total revenues and total costs.

After defining the two main parameters, you’d then drill down further to the factors influencing each of the parameters you’ve identified. You determine the factors influencing total revenues are average price of goods sold and volume of goods sold. And for total costs, fixed costs and variable costs.

With both the case parameters and factors clearly identified you give yourself the ability to steer the conversation and begin to identify possible solutions. To identify areas of concern, you’ll want to explore the history of the four influencing factors. At the end of your discussion with the interviewer you may determine that it’s rising variable costs that are having the biggest impact on profitability. You’ll then drill down even further to determine what is causing variable costs to rise and come up with more specific recommendations.

Building a graphic representation (tree, decision diagram, etc.) of parameters, factors and other influencing elements will help you structure your thought process, keep from missing key aspects of the case, and make a strong argument for the recommendations you’ll make.

Using a framework or structured approach to developing a recommendation for a case study interview question provides the added benefit of giving the interviewer something to take back and present to his or her superiors to make the case that you’re the right person for the job.

Whatever you do, don’t force-fit frameworks. If a particular framework doesn’t apply to the case, don’t use it. Most frameworks incorporate universal concepts that can be applied to various business issues. Use the concepts you’ve learned in school or through prior work experience to support your analysis of the case. Show your interviewer that you understand these business concepts well enough that you can apply them to the specifics fo the business issue being presented in the case.

Below we’re going to present several case interview questions organized by question type. To perfect your ability to perform well in case interviews, we recommend reviewing each question and then developing a logical framework or approach for answering each one.

As is the case in real life, there is usually no single correct answer to standard case interview questions. As long as you’re able to prove your case, using sound analysis and by demonstrating an understanding of the main case issues, you’re likely to do well. Below are some common standard case interview questions that provide great practice for case interviews.

  • What would be your approach for introducing a product into a foreign market? What are the risks and benefits to consider i.e. producing in your own country vs producing in the new country, etc?
  • Company ABC is struggling, should it be restructured? Identify the three main problems it’s facing. What is the most important problem the company is facing? How would you recommend the company address this problem? How would you turn this company around? Provide your reasoning for your recommendation(s).
  • A toy company has been experiencing decline sales for the last two seasons. Research suggests that introducing several new product lines is the solution. Develop a marketing strategy for the company’s largest product line, including pricing, product packing, etc.
  • A large chain of retail clothing stores is struggling with profitability. Bases on your review fo the company’s financial statements, what problems can you identify? Can this company be turned arounds? How would you go about deciding?
  • A new Eddie Bauer Store is being opened up in London. Discuss all the marketing issues regarding the opening of this new location.

To perform well on standard case inteview questions you should be able to:

  • Take in information quickly and remember what you hear.
  • Identify key issues, prioritize and logically solve problems.
  • Make quick, yet accurate, decisions.
  • Manage time efficiently.
  • Perform under pressure.
  • Be aware of resource constraints.
  • Identify customer needs.
  • Be original and creative.

A market sizing case interview question is one where you’re asked to determine the size of market for a particular product. These types of case interview questions are popular, and actually not difficult to answer if you practice. The following a few examples of market sizing case interview questions.

  • Please provide the total weight of a fully loaded Jumbo Jet at the time of take off.
  • How many light bulbs are there in the United States?
  • How many photocopies are taken in the United Kingdom each year?
  • How much beer is consumed in the city of New York on Fridays?
  • How many people sell AMWAY products in the United States?
  • If there are 7,492 people participating in a tournament, how many games must be played to find a winner?
  • How many golf balls will fit in the Empire State Building?
  • How many car tire are sold in Canada each year?
  • Given thhe numbers 5 and 2000, what is the minimum number of guesses required to find a specific number if the only hint you’re given is “higher” and “lower” for each guess made?
  • How do you determine the weight of a blue whale without using a scale?

The following are tips for answering market sizing case interview questions:

  • Take time to think before you answer the question.
  • If given a pen and paper, take notes and write down key information. Use the paper to make calculations, write down ideas and structure your answer.
  • Ask additional questions if you feel you are missing information. The interviewer is often expecting you to ask to find missing information.
  • Use lateral thinking and be creative. There isn’t always just one right answer. Just make sure your answer is backed up by sound logic and numbers that make sense.
  • Make sure you know your math. At minimum you’ll need to perform some basic arithmetic or mathematical calculations.
  • These quesitons are often used to test your ability to structure, as well as your ability to think laterallly, make logical links and communicate clearly.
  • Make mental calculations quickly by making sensible estimates and rounding numbers up or down.
  • Does your answer make sense? If you’re answer doesn’t make sense, chances are you’ve made a bad assumpation, estimate or calculation. Go back and carefully check your work and provide a new answer.
  • You can use business frameworks (SWOT, Porter’s Five forces, etc.) or mind mapping to support your analysis and answers, as long as it makes sense.
  • Many market sizing questions revolve around issues being faced by an organization or industry. Commercial awareness can be very important to answering market sizing questions.

Questions involving logic problems are designed to test your ability to think quickly and logically. These questions also require you to be able to perform numeracy quickly, while under pressure. The following are a few logic problems followed by their answers. Review the questions, develop your own answers, and then check your answers to see how well you did.

1. At 3:15, how many degrees there between the two hands of a clock? (J.P. Morgan interview question).

2. A fire fighter has to get to a burning building as quickly as he can. There are three paths that he can take. He can take his fire engine over a large hill (5 miles) at 10 miles per hour. He can take his fire engine through a windy road (7 miles) at 9 miles per hour. Or he can drive his fire engine along a dirt road which is 8 miles at 12 miles per hour. Which way should he choose?

3. You spend 21 dollars on vegetables at the store. You buy carrots, onions and celery. The celery cost half the cost of the onions. The onions cost have the cost of the carrots. How much did the onions cost?

4. You spend a third of all the money you have on a piano. Half of your remaining money you use to buy a piano chair. A quarter of the rest of your money you use to buy piano books. What porportion of you original money is remaining?

5. Why are manhole cover always round, instead of square?

6. In the Chicago subway system there are two escalators for going up but only one for going down to the subway. Why is that?

7. You find three boxes at the store. One contains onions. Another contains potatoes. The third contains both onions and potatoes. However, all three of the boxes are labeled incorrectly so it’s impossible to tell which box contains what. By opening just one box (but without looking in) and removing either a potatoe or onion, how can you immediate label the contents of all the boxes?

8. There are 8 bags of wheat, 7 of which weigh the same amount. However, there is one that weighs less than the others. You are given a balance scale used for weighing. In less than three steps, figure out which bag weighs less than the rest.

9. There are 23 rugby teams playing in a tournament. What is the least number of games that must be played to find a tournament winner?

The following are the answers to the 9 logic problems above:

If you thought the answer was zero degrees, you’d be incorrect. At 3:15, the clock’s minute hand will be pointing at 15 minutes, exactly 90 degrees clockwise from vertical. At 3:15, the clock’s hour hand will exactly one quarter of the distance between 3 O’clock and 4 O’clock. Each of the 12 hours on the clock represents 30 degrees (360 degrees divided by the 12 hours on the clock). Consequently, one quarter of an hour is exactly 7.5 degrees, so at 3:15 the minute hand will be at 97.5 degrees. So there is a difference of 7.5 degrees between the hour hand and minute hand at 3:15.

Fire Fighter

Driving his fire engine 5 miles at 8 miles per hour takes 37.5 minutes. Driving his fire engine 7 miles at 9 miles per hour takes about 47 minutes. Driving his fire engine 8 milles at 12 miles per hour takes 40 minutes. So he should choose to drive his fire engine over the hill.

Answering this problem just requires some simple algebra. If we assume the cost of celery = x, then the cost of onions = 2x, and cost of the carrots is 4x, such that the total cost of all vegetables = x + 2x + 4x = 7x = 21 dollars. Consequently, x = 3 dollars. Hence, the onions cost 6 dollars.

You spend a third of all the money you have on a piano, so you’re left with two thirds (2/3). You spend half (1/2) of the remaining two thirds on a piano chair, which leaves you with just one third of what you started with (1/2×2/3=1/3). You spend a quarter (1/4) of what you have remaining (1/3) on piano books, which leaves you with one twelth of the original (1/4×1/3=1/12).

Manhole Cover

A square manhole cover can be dropped down the hole if turned diagonally to the hole, where round covers can’t be dropped down manholes.

Chicago Subway

People coming into the subway tend to arrive at different times, so the flow of people down the escalators is a more even stream. Conversely, when people get off the subway they typically all arrive at the escalators at about the same time. Consequently, two escalators are need to handle people leaving the subway, where only one is required for people arriving.

Three Boxes

Just open the box that is labeled “Onions and Potatoes”. Since none of the boxes are labeled correctly, this box must contain only onions, or only poatatoes. If you remove a potatoe from this box, the box must be the “Potatoes Only” box.

One of the remaining two box has to be the “Onions Only” box. However, the only you currently have it labeled “Potatoes Only”, and the other is label “Onions Only”. So the box labled “Potatoes Only” must be the box that contains only onions, and the box labeld “Onlions Only” must be the box that has both potatoes and onions.

Bags of Wheat

Immediately, take any 2 of the bags and place them to the side. Weigh 3 of the remaining six bags against the other 3 bags. If these bags weigh the same, that means the bag that weighs less must be one of the two that you immediately placed to one side. If this is the case, weigh the 2 bags you placed to one side against each other to find out which one weighs less. You’ve now found in your bag.

However, upon weighing the sets of 3 bags against one another you find that one set weighs more than the other set, place one of the bags from the set of heavier bags aside and weigh the remaining two bags to find out which one is heavier. If they are of equal weight, the you know that the bag you place to one side is the bag you’re looking for.

Rugby Tournament

In a tournament, every rugby team except the winner is eliminated from the tournament after being defeated just once. Hence, the number of games required to find a tournament winner is going to be one less than the number of teams, or 22 in this case.

The following are examples of common business case interview questions:

  • How would you work with a subordinate who is underperforming?
  • You’re consulting with a large pharmacy with stores in multiple states. This company has improved sales but experienced a decrease in revenue. As a result, it is contemplating store closings. Explain how you’d advise this client?
  • You are working directly with a company’s management team. It is organizing a project designed to significantly increase revenue. If you were provided with data and asked to supervise the project, what steps would you take to ensure it’s successful?
  • You have been assigned to work with a small company that manufactures a popular product. However, a competitor begins selling a very similar product which incorporates state of the art technology. What would you advise your client to do?
  • You have been assigned to advise a company with a large Western European market. Company management wants to open the Chinese market. What advice do you have for this company?
  • The firm has assigned you to consult a company intending to drop a product or expand into new markets in order to increase revenue. What steps would you take to help this company achieve its objective?
  • You have been assigned to consult a shoe retailer with stores throughout the nation. Since its revenue is dropping, the company has proposed to sell food at its stores. How would you advise this client?

In addition to the guides and articles presented on our website, there are several other good resources, including workshops, mock interviews, books and interactive online resources, that will prepare you for case interviews. Some of the resources we recommend are listed below.

How to Crack Written Case Interviews

Although most case interviews are live, where you’re sitting across from the interviewer as you work through the case, some firms use written case studies in their recruiting process. Their goal in doing so is to simulate actual consulting work even more closely than in a traditional case interview.

The format

Similar to a classic case interview, the candidate is asked to make a recommendation about a specific business problem.

The candidate is given a series of paper documents, sometimes up to 50 pages, which include the client context, interview insights, press articles, market or company data, and so on. Some of the documents are usually not useful for the resolution of the case — so expect some red herrings!

You will have to structure the problem, run some numbers and generate some ideas – just like in a live case interview. Ultimately, your responses will be delivered in the form of a short presentation.

The exact format of the written case varies with firms and offices, but you may have a couple of hours to prepare a written presentation and then time to present and discuss it with the interviewer, who will play the role of the manager or the client. You might be provided with pencils, pens and sometimes a basic calculator. We recommend you bring any additional items you might want, such as highlighters and a ruler.

The evaluation criteria

You will be evaluated on both the content of the presentation and on its form. On the content, the evaluation criteria remain similar as for classical case studies. On the form, the quality of your slides and of your oral presentations will be assessed.

Although you may have longer in a written case than a live case, the test is generally more difficult to pass. Candidates often fail due to seemingly basic reasons, such as not answering the questions directly, having inadequate slide presentations, or errors in the quantitative analysis.

Tips for doing well

To do well in a written case, we recommend focusing on getting the following right

1. Organize your time

Start writing the first slides during the first half of the allocated time.

Begin by reading the questions you need to answer, then quickly browse the documents provided and read the ones that contain the information you need to answer the questions.

Mark the pages that will be useful for each question, then put the other documents aside. This will save you time because, as we mentioned, there will certainly be more information than necessary.

We recommend starting with the quantitative question because it often structures the final answer. The more creative questions should be faster to solve and can be answered last.

2. Start with the answer

A common mistake in a written case is focusing too much on the analyses where one ends up omitting the overarching client questions. To avoid this, start your presentation with an executive summary by repeating the client questions, giving a direct answer, and listing the key supporting points. From there, add a slide for each key analysis and wrap up with a conclusion slide with next steps.

3. Design professional slides

Slides must have straight lines, aligned objects, neat handwriting, etc. They should contain only essential information. Remember this is a presentation, not prose.

Each slide must have a short title, carrying a message summarizing the slide. The titles of each slide put end-to-end must tell the story you want to communicate.

4. Substantiate qualitative conclusions

Use numerical data as much as possible and do not make any statements without being supported by well-defined facts or assumptions — which you can footnote.

Overall, a written case will involve the same problem-solving dimensions as a case interview. You’ll be asked to structure the problem, run some numbers, analyse data, generate ideas, and synthesize your findings. Therefore, to succeed in this kind of assessment you still need to know how to be successful in a standard case interview.

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