A Case Interview is a job interview technique used primarily by the management consulting industry that candidates must successfully work through if they want their dream management consulting job at a top tier firm.
Depending on the role, case interviews are also given by blue chip corporate companies as they help to assess a candidate for a job, by evaluating their mental capabilities and logic skills under time pressure. Case interview questions are generally a business problem, an abstract logic problem or a market sizing exercise involving a good amount of arithmetic, and they are intended to make a candidate think fast on his or her feet, while utilizing good reasoning and common sense.
Management consulting companies recruiting for new hires need to see that their future team members are able to swiftly analyze data, logically work through a problem and work out basic math with large numbers, whilst under pressure. In short, they want the best brains available because in turn, their corporate clients demand it.
A case interview question is generally not designed with a specific right or wrong answer. Rather there may be several solutions to a business problem, a broad tolerance range for a market sizing question, or simply multiple answers to a logic problem, and often a case interview may end up being an exploration of several key issues whereby the interviewer will be assessing your verbal reasoning skills along the way.
To show yourself in the best possible light when given a case interview question, it is recommended to thoroughly prepare beforehand by reading through the worked solutions of case interview questions that others have been asked and doing mock interviews with close friends or family.
Case interviews are typically conducted one-on-one and the candidate would generally be offered a pen and paper, or perhaps even a marker and whiteboard, where he or she can then brainstorm, document calculations, and then structure out an answer. A case interview is intended to be interactive as you inquire deeper into the question, seek clarifications, and then pose ideas back to the interviewer and or seek guidance as you move your logic forward.