The interview with a consulting company normally lasts about half an hour. Of this time, about 5 to 10 minutes is taken up with preliminary chat and behavioral questions and five minutes of you asking questions about the company. This leaves 5 to 15 minutes for your case interview question or questions. Make them count!
Types of case interviews
What case interviews are not designed to do is to explore educational, professional, or experiential qualifications. If you've reached the case interview stage, take a deep breath - the consulting firm has already weighed your background, GPA, and experience and found you worthy of a deeper skill assessment. This means that the case interview is yours to lose. Triumph over your case interviews and chances are that a slot at the firm will open for you.
Case interviews vary widely, but in general they fall into three groups: business cases, guesstimates, and brainteasers.
Case interviews vary somewhat in their format. The classic and most common type of case interview is the business case, in which you're presented with a business scenario and asked to analyze it and make recommendations. Most cases are presented in oral form, though some involve handouts or slides, and a few (like Monitor Company's) are entirely written. (In a written case, the interviewer will not contribute any other information besides what's on the handout.) Another variation on the case interview is the group case interview, where three to six candidates are grouped together and told to solve a case cooperatively. Consultants from the firm watch as silent observers. Though you should certainly be prepared for these variations on case interviews, you are most likely to come across the traditional, mano-a-mano case interview.
Whether free-standing or as part of a case, learning how to make "back-of-the-envelope" calculations (rough, yet basically accurate) is an essential part of the case interview. As part of a guesstimate, you might be asked to estimate how many watermelons are sold in the United States each year, or what the market size for a new computer program that organizes your wardrobe might be. (For example, you might need to figure out the market size for the wardrobe software as a first step in determining how to enter the European market.) You will not be expected to get the exact number, but you should come close - hence the guesstimate. Non-business school students and others who appear to be weak quantitatively may get stand-alone guesstimates - guesstimates given independently of a case.
Brainteasers are normally logic puzzles or riddles. They may be timed. Often, brainteasers are meant to test both analytic and "out-of-the-box" thinking, as well as grace under pressure.
Simply put, a case interview is the analysis of a business question. Unlike most other interview questions, it is an interactive process. Your interviewer will present you with a business problem and ask you for your opinion. Your job is to ask the interviewer logical questions that will permit you to make a detailed recommendation. The majority of case interviewers don't have a specific answer that you, the candidate, are expected to give. What the interviewer is looking for is a thought process that is both analytical and creative (what consultants love to call "out-of-the-box" thinking). Specific knowledge of the industry covered by the case question is a bonus but not necessary. Business school students and candidates with significant business world experience receive case questions that require a deeper understanding of business models and processes.