Why do employers use them?

To assess the way you think. Commercial thinking is not something you are trained in at university, and it’s hard to know whether you have the capacity to do so. Case studies are designed to test whether you’ve got what it takes to be a consultant, e.g. whether you’ve developed the judgement and expertise to advise clients of whether it is a good idea to enter a new market, how to respond to changes in competitive strategies or simply where you can most efficiently cut costs.

Which employers will ask a case study?

Although traditionally the domain of consultancies, case studies are being used more and more in corporate settings. As candidates become increasingly familiar with the concept of case studies, employers respond by making them more complex and elaborate.

Types of case studies:

1. Brain Teasers

2. Guesstimates (Market Sizing Questions)

3. Business Case studies

Brain Teasers or “Why are manhole covers round?” – Why Questions

The most famous examples were dreamt up by Microsoft. As a general rule, brainteasers will ask you questions you’ve never thought about before. The idea behind is to test how quickly you can think on your feet when you’re presented with a question or problem you’ve never encountered before. However, they’re quite rare now so you don’t need to worry too much about them. If you want to know why manhole covers are round, please see our section on practice tests.

Guesstimates – “How” Questions

Guesstimates or market sizing questions come in all shapes and sizes – you might be asked how many apple trees there are in the UK, how many bottles of champagne are consumed in the UK each year or how many solar panels have been put on British roofs during the last year. What all of them have in common is that they are “How” questions. Generally, they are related to the industry you are applying to – a retailer may ask you how many blouses are bought each year while De Beers might ask you how many diamonds are sold in Britain. Always think of your response in terms of “How is this important to a business operating in the area?” as employers may go on to ask you questions like “Is is worth expanding into this area or should we exit the market?” or “Given the current market, how can we use our market share most effectively?”

Guesstimates come in four forms:

1. Population-Based: How many post offices are there in the UK?

Best way of answering: I live in a town of 12,000 people, we’ve got 3 post offices. Taking this as the average, I’ll assume that one post office serves about 4,000 people. The UK population is 60,000,000, so there are 15,000 post offices in the UK.

2. Household-Based: How many toasters were sold in the UK last year?

Best way of answering: One household has about one toaster. The average British household consists of 3 people. Given that the UK population is 60,000,000, there are 20,000,000 households. Assuming a toaster needs to be replaced every 4 years, one quarter of all households are going to buy a toaster every year, i.e. 5,000,000 toasters are sold in the UK each year.

As an aside, you might consider any other places using toasters, such as hospitals, food courts and work places. Considering that these places buy approximately 500,000 toasters each year, there are 5,500,000 toasters sold in Britain each year.

3. Individual-Based: How many novels are sold in the UK each year?

Looking at the UK’s population of 60 Million, and estimating average life expectancy in this country at 80 years, we can now calculate how many people there are in each age band. Realistically, there are fewer old people than young people, but to keep things simple we’ll just assume that there are 750,000 people in each age band. Assuming that people between the ages of 15 and 80 are going to read novels (children are going to read children’s books while elderly people might have difficulty reading as their eyesight deteriorates), there are 75 age bands with 750,000 people each there are a total of 56,250,000 people who will read books. To simplify, I’ll assume that 56,000,000 people read books every year. I’ll suppose that on average each adult buys 3 novels a year. Multiplied by 56 Million, 168,000,000 novels are sold each year.

4. “What do you think” questions: These questions can range from: “How heavy is a car?” to “how long would it take to evacuate London?”

As a general rule, it’s best to break down the case into its smaller components. To use the car example: Think of all the components of a car, e.g. steel exterior, windows, wheels, engine, interior as well as variable weights (number of passengers, fuel, luggage). Assign weights to each of them, making sure that you base your assumptions on some kind of logic (e.g. fuel will weigh less than water as it has lower density). Add up your values to reach an approximate total.

Other Examples:

• How many books are sold in the UK each year?
• How many households use digital TV?
• How many petrol stations are there in the UK?
• How many light bulbs are sold in Australia each year?
• How many Scandinavians are born each year?