McKinsey Guidelines for Case PreparationKellogg students who participate in McKinsey & Company’s Case Interview Workshops are usually asked to bring a prepared case to be used in breakout sessions during the workshop.  These guidelines are distributed in advance to aid participants in their case preparation.
What is a case Interview?   A case is a description of a real business problem.  Case interviews are designed to test problem-solving skills.  A case interview typically lasts 20 to 30 minutes and is a verbal exchange between the interviewee and the interviewer.  During a case interview, the interviewee asks the interviewer questions to get enough data to recommend a solution; the interviewer provides the information that is asked for and helps the interviewee stay on track to develop an approach.  At the end of the interview, the interviewee should be able to recommend a solution to the original problem presented by the interviewer.  Understand that the interviewee is not often expected to find a solution to the problem; a logically structured, fact-based recommendation is usually enough.  
Remember, the case interview is designed to mimic a typical McKinsey client engagement: clients hire McKinsey to make a recommendation about a problem that they are having.  The objective of the interviewee is to identify the key issues of the problem, develop potential approaches to making a recommendation, and if possible, hypothesize a solution.
Helpful Guidelines for preparing your Case The following sections provide guidelines developed by McKinsey & Company to assist you during your case preparation.
Selecting Your CaseMcKinsey interviewers choose their cases based on past business experiences.  When developing your own case, we suggest, if possible, that you do the same.   Try to draw on real-world experiences or business problems that you have been exposed to as part of your Kellogg courses.  These experiences and problems provide a great foundation for a case.   You can also pick an interesting situation being covered in the media (e.g. BusinessWeek, The Wall Street Journal, etc.).

Kicking-off Your Case Interview

Most cases start out with a phrase such as “A CEO of a hockey equipment manufacturer has asked McKinsey to... You are the Associate on the team and we need to get back to the CEO with our preliminary answer to his or her question within the next half an hour.”
The following questions pose typical problems that you could expect in case interviews.  The case you develop for the workshop might involve the solution to a similar question.  Keep these types of questions in mind when developing your case content.
* “How should Company X respond to significant environmental changes?”
* “What products and to what customer segments should a company sell?”
* “Should Company X add capacity?”  
* “How should Company X react to a new competitor?”
* “Should Company X enter/exit a new/old market?”  

Case Content & Delivery
As mentioned earlier, the “meat” of a case is a dialogue between the interviewee and interviewer.  The interviewee asks a series of questions to gather data necessary to solve the case.  The interviewer will ask probing questions, or redirects the conversation if the interviewee becomes stuck or heads in a wrong direction while approaching the problem.
To effectively deliver a case, it is critical that the interviewer has a deep understanding of the facts and background of the case.  Thus, most of our interviewers have a background sheet(s) to refer to during the course of the interview.  Some interviewers take this one step further and prepare summary charts of the key data the interviewee may need to solve the case.
Background sheets should contain all the information that the interviewee will need to logically solve the case.  We suggest that you prepare a background sheet for your practice case, but please do not feel obligated to go into great detail.  A solid understanding of the problem, the relevant business issues, and possible solutions will be sufficient.  Below, we have summarized some major categories of information you might want to compile for your practice cases.

Element		Description
Problem definition		Be very clear in the problem that the client has asked you to solve.
Industry		Understand what industry the client competes in and what industry we are helping to evaluate (if different).
Competitive environment		Understand the environment, including how concentrated the industry is and why it has been growing, shrinking, or staying the same. Understand the relevant changes to the competitive environment including changes in regulation, pressure from new competitors, impact of technology, impact of demographic trends, etc.
Customers segments		Understand the size, profitability and growth of the key customer segments.
Competitors		Understand the market share, growth, profitability and strategic starting points of our leading competitors. Understand what the best players in the industry do and why this is successful for them (you should also understand why these strategies would work or fail for your client).
Client’s strategic starting point		Understand the client’s distinctive competencies and capabilities.
Economics of business decision		Have detailed support of the revenues, costs for the company, major business units and customer segments as necessary. Have detailed support of the revenues, costs, capital expenditures and potential NPV of any business strategy alternatives. Understand the breakdown of revenue and costs (e.g. fixed versus variable).

This list is by no means exhaustive, but we hope it gives you a good start.  If you have difficulty preparing your case, please call Chuck Baren at (312) 551-3909 for guidance.