MBA Case Interview Preparation Template

Case Interview Preparation Plan: [Your name, target firms, recruiting season]

A preparation workbook for consulting case interviews during MBA recruiting: interview formats, online screening and AI-based assessments, the rules on AI use, structuring with issue trees, the hypothesis-driven approach, case math under time pressure, chart reading, synthesis, and an original practice case with a computed answer. It is for MBA students and applicants aiming at management consulting firms and at strategy roles that use case interviews. Source basis: Minto (1987, 2009) on the pyramid principle and MECE grouping, research on structured interviews and deliberate practice, and firms' public careers pages checked in October 2026, written in our own words. Replace every [bracketed] value and every row marked Example. This is a preparation aid, not recruiting advice, and no firm endorses it. Firm processes change every season: check each firm's careers pages and your recruiter's instructions before you rely on any detail here.

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Contents

1. What a case interview tests
2. Interview formats
3. Online screening and AI-based assessments
4. Rules on AI use during recruiting
5. Structuring: issue trees and MECE
6. The hypothesis-driven approach
7. Case math under time pressure
8. Reading charts and exhibits
9. Synthesis and the final recommendation
10. Running a case from start to finish
11. Original practice case: Northfield Outdoor Co.
12. Preparation plan and timeline
13. Quality checklist
14. Common mistakes
15. Self-test

1. What a case interview tests

A case interview is a work sample. The interviewer presents a business problem of the kind the firm works on, and watches how you solve it in real time: how you frame the question, what information you ask for, how you organise the problem, how you calculate, how you read data, and how you turn analysis into a recommendation a client could act on. Research on selection interviews supports this design: structured interviews, in which every candidate faces comparable questions scored against defined criteria, predict job performance better than unstructured conversations (Schmidt and Hunter 1998; Campion, Palmer and Campion 1997). Consulting firms train interviewers and score cases against criteria for this reason.

The skills most firms describe on their public preparation pages fall into six groups. Use the same six groups as the scoring rubric in mba/mba-case-practice-log, so that your practice and your self-assessment match.

Interviewers also judge presence and judgement: whether a client would trust you in a room. That part is covered in mba/mba-fit-stories.

2. Interview formats

Case interviews differ in who drives the case. The labels below are the ones candidates and career services use. The associations with firms are commonly reported, not official classifications, and practice varies by office, interviewer and round. Check with each firm.

Rounds. Most consulting processes reported by MBA career centres have an online screen for some candidates, then a first round of two interviews and a final round of two or three interviews, each mixing a case with fit or experience questions. The number of rounds and interviews differs by firm and office. Record what each firm tells you in the table below.

3. Online screening and AI-based assessments

Large firms screen many applicants before the first interview, and several use online assessments, some built on game-based tasks or chatbots. These are dated facts with their status as of October 2026. Check before you rely on them.

How to prepare for online assessments without relying on unofficial content:

1. Read the firm's own description and practice material first, and use them only as the firm allows.
2. Train the underlying skills: reading data quickly, ratio and percentage arithmetic, logical deduction, and staying accurate under a timer. Sections 7 and 8 cover these.
3. Simulate the conditions: a quiet room, a stable connection, a timer, scratch paper if allowed, and no help.
4. Treat third-party "simulators" with caution: they are guesses at the format, and some breach firms' terms.

4. Rules on AI use during recruiting

Firms distinguish between preparation and assessment. As of October 2026, BCG's official interview-process page links to guidance on using AI in the application process (https://careers.bcg.com/global/en/interview-process), and McKinsey's Assessment Integrity Expectations page, as recorded in mba/mba-ai-use-policy-check, bars AI tools during its assessments and interviews while describing AI-assisted preparation as acceptable (https://www.mckinsey.com/careers/assessment-integrity-expectations). Candidate reports and career services say that firms generally reject unapproved AI use during live interviews and online assessments. Where a firm gives you an AI tool as part of an exercise, use it only as the instructions allow. Check each firm's current rules, for the office you apply to, before you rely on this.

The practical reason matches the ethical one: an assessment that measures a tool rather than you gives the firm a false signal, and the job will expose the gap. Firms can withdraw offers for breaches of assessment rules.

5. Structuring: issue trees and MECE

The idea. An issue tree breaks the client's question into smaller questions until each one can be answered with analysis. The branches at each level should be mutually exclusive and collectively exhaustive (MECE): no overlaps, so nothing is counted twice, and no gaps, so nothing important is missed. Barbara Minto is generally credited with the MECE principle and developed the pyramid principle while she worked at McKinsey; she set them out in The Pyramid Principle (first published 1987; Minto 2009). Her rule is that ideas at each level summarise the ideas grouped below them, and ideas in a group must be of the same kind.

Three ways to cut a problem MECE

A tailored structure, not a framework. Classic frameworks (the profit tree, the "3Cs", Porter's five forces, market entry lists) are useful checklists, but interviewers reward structures built for the specific question. Ask yourself: what decision does the client face, and what would I need to believe to recommend yes? Those beliefs become your first-level branches.

Test your structure in 20 seconds

• Does each branch answer a question the client needs answered?
• Could any item sit under two branches? If so, the cut is not mutually exclusive.
• Is there a plausible driver that fits nowhere? If so, the cut is not exhaustive.
• Are the branches at one level of the same kind (all segments, or all process steps, not a mix)?
• Have you said which branch you will explore first and why?

6. The hypothesis-driven approach

A hypothesis is a provisional answer you can test. Consultants start from one because it makes analysis faster: you gather the data that would prove or disprove it, instead of collecting everything. In an interview, a hypothesis shows judgement and gives the conversation direction.

1. Form it early. After clarifying the question, say where you think the answer is: "My initial hypothesis is that the profit decline comes from rising costs per order rather than from lower demand, because revenue has grown."
2. Derive what must be true. If costs per order explain the decline, then cost per order must have risen faster than revenue per order, and one or two cost lines must explain most of it.
3. Ask for the data that tests it. Request cost per order by line for both years.
4. Update openly. "The data confirm cost per order rose, but gross profit per order also fell, so pricing or mix is part of the story. I will look at that next."

Hypothesis-driven work is not guessing. A good hypothesis follows from the facts given so far and from business logic, and you abandon it the moment evidence contradicts it.

7. Case math under time pressure

Case math is arithmetic, not advanced mathematics, but it is done aloud, quickly and without a calculator. Errors come from units, zeros and percentages rather than from hard operations.

Techniques

• Write numbers in scientific shorthand: 1.5m orders times USD 10.40 is $1.5 \times 10^6 \times 10.4 = 15.6 \times 10^6$.
• Round to friendly numbers, say so, and correct at the end if the answer is close to a decision threshold.
• Break percentages: 18% of 450 is 10% (45) plus 8% (36), which is 81.
• Use growth shortcuts: for small rates, $(1+g)^n \approx 1 + ng$; the rule of 72 says money doubles in about $72/r$ years at $r$% a year.
• Label units on every line (orders, USD per order, USD m).
• Sanity check: is the result plausible against something you know?

Drill set (computed, with Excel formulas for checking your practice sheet)

Note on M-06: NPER(rate, pmt, pv, fv) with present value minus 1 and future value 2 returns the exact doubling time, $\ln 2 / \ln 1.09$.

8. Reading charts and exhibits

Use the same routine for every exhibit:

1. Title and source. What is this exhibit about, and over what period?
2. Axes, units and scale. Thousands or millions? Percentages or points? Does the axis start at zero?
3. Legend and categories. What are the series? Are any segments combined?
4. The pattern. What is the largest, the fastest change, the outlier, the break in trend?
5. The so-what. What does this mean for the hypothesis and for the client's decision?
6. The next question. What would you ask for next?

Interviewers often put more data in an exhibit than you need. Say what you are ignoring and why. If an exhibit contradicts your hypothesis, say so and revise it: that is the skill being tested.

9. Synthesis and the final recommendation

Minto's pyramid principle (Minto 2009) gives the shape: lead with the answer, then the reasons that support it, each reason backed by evidence. In a case, the synthesis has four parts.

Before and after (fictional)

• Weak: "So we looked at revenue and costs, and shipping went up, and returns went up, and marketing went up, so there are many issues and it depends."
• Strong: "Northfield should raise its free-shipping threshold and fix returns, because cost per order, not demand, explains the profit decline. Shipping alone added USD 7.2m of cost in two years, more than half the profit gap, and a higher threshold recovers about USD 4.8m. The risk is losing price-sensitive customers; I would test the threshold in two regions first."

10. Running a case from start to finish

Clarifying questions should change your analysis. Good ones ask about the objective (profit, growth, share), the time frame, the geography and business scope, and any constraint (capital, brand, regulation). Avoid questions whose answers you will not use.

11. Original practice case: Northfield Outdoor Co.

Prompt (read aloud by the interviewer). Northfield Outdoor Co. is a mid-size outdoor-gear retailer with stores and an e-commerce business. Over the last two years, e-commerce revenue grew, but e-commerce operating profit fell by more than half. The chief executive wants to know why, and what to do about it. (Fictional case written for this template; all figures are invented.)

Clarifying information (give only if asked)

• The objective is to restore e-commerce operating profit within 12 months without shrinking revenue materially.
• The e-commerce business serves one country; stores are out of scope.
• Two years ago Northfield lowered its free-shipping threshold and launched a free-returns policy.

Exhibit 1: E-commerce key figures (fictional)

Questions for the candidate

1. Structure: how would you approach the problem?
2. Calculate e-commerce operating profit in Year 1 and Year 3.
3. Which drivers explain the change? Quantify each.
4. Northfield could raise the free-shipping threshold. The team expects shipping cost per order to fall to USD 8.20, orders to fall by 6% and average order value to rise by USD 5, with all other per-order figures and spending unchanged from Year 3. What is the effect on operating profit?
5. Give your recommendation to the chief executive.

Interviewer guide with computed answers

Question 1. A strong structure splits operating profit into gross profit (orders, average order value, margin) and costs (variable cost per order: fulfilment, shipping, returns; marketing; fixed overhead). A strong hypothesis: since revenue grew, cost per order and margin per order explain the decline, probably linked to the shipping and returns policies.

Question 2. Revenue is orders times average order value. Variable costs are per order; returns cost is orders times return rate times cost per return.

Revenue grew 15.8% over two years (7.6% a year), while operating profit fell by 67%.

Question 3. The operating profit bridge from Year 1 to Year 3:

Per order, the story is sharper. Contribution after variable costs and before marketing fell from USD 25.40 to USD 15.82; after marketing (USD 7.50 per order in Year 1, USD 9.33 in Year 3) it fell from USD 17.90 to USD 6.49. Shipping is the largest single cost driver, consistent with the lower free-shipping threshold; the lower threshold probably also explains the lower average order value.

Question 4. With orders at 1.41m (=1.5*(1-6%)) and average order value USD 93, revenue is USD 131.13m and operating profit rises from USD 5.73m to USD 10.51m, an improvement of USD 4.78m.

A stronger candidate adds a second lever without being asked. Cutting the return rate from 18% to 14% (for example with better size guides) saves USD 0.90m at Year 3 volume (=1.5*(18%-14%)*15). Combined with Option A on 1.41m orders the total improvement is USD 5.63m (operating profit about USD 11.36m), still short of Year 1, so marketing efficiency is the next branch to examine: marketing per order rose from USD 7.50 to USD 9.33.

Question 5. Model synthesis: "Raise the free-shipping threshold now and pilot a returns-reduction programme, then review marketing efficiency. Profit fell because each order became less profitable, not because demand fell: shipping alone added USD 7.2m of cost. The higher threshold recovers about USD 4.8m, revenue stays within 1% of Year 3 (USD 131.13m against USD 132.00m), and returns work adds about USD 0.9m. The main risk is a larger loss of orders than the 6% assumed; test the threshold in part of the market for six weeks before rolling it out."

Scoring guide for the partner

12. Preparation plan and timeline

Deliberate practice, with specific goals, immediate feedback and repetition on weaknesses, builds expert performance faster than repetition alone (Ericsson, Krampe and Tesch-Römer 1993). Retrieval and spaced practice also improve retention of techniques such as case math (Dunlosky et al. 2013). Build your plan around those findings: short daily math drills, live cases with feedback, and a weekly review of your log.

13. Quality checklist

• I restated the objective and the success measure before structuring.
• My structure was tailored, MECE, and I said which branch I would test first.
• I stated a hypothesis and updated it when data disagreed.
• I set up every calculation aloud, with units, before computing.
• I sanity-checked each result and said what it meant.
• I read every exhibit's title, units and axes before the data.
• I summarised at each transition.
• My synthesis led with the answer and used numbers from the case.
• I followed the firm's rules on notes, calculators and AI tools.
• I logged the case and one specific improvement.

14. Common mistakes

1. Reciting a memorised framework instead of building a structure for the question asked.
2. Overlapping branches (for example "costs" and "operations" at the same level), which leads to double counting.
3. Starting calculations before saying what you are calculating and why.
4. Losing a zero or mixing units (thousands and millions, per order and total).
5. Reading an exhibit's data before its title, units and axes.
6. Holding on to a hypothesis after the data have disproved it.
7. Asking for data without saying what you will do with it.
8. Ending with a summary of the analysis rather than a recommendation.
9. Ignoring the interviewer's hints, which usually point to the branch that matters.
10. Practising only with friends who give no critical feedback, or only reading cases instead of doing them aloud.
11. Using unofficial copies of firm assessments or AI tools during an assessment, which breaches the firm's rules.
12. Neglecting fit and experience questions, which often weigh as much as the case.

15. Self-test

1. What does MECE stand for, and who developed the principle?
2. Name the difference between interviewer-led and candidate-led cases, and why the association with particular firms should be checked rather than assumed.
3. Revenue rises from USD 80m to USD 100m in two years. What is the annual growth rate?
4. Why is a tailored structure scored higher than a standard framework?
5. In the Northfield case, why is applying only the shipping saving to Year 3 orders not a valid answer to question 4?
6. What are the four parts of a synthesis?
7. Give two reasons not to use AI tools during an online assessment.
8. Price falls 5% and volume rises 8%. What is the revenue change?
9. What does deliberate practice add to simple repetition?
10. An exhibit's vertical axis starts at 80, not 0. What should you say?

Sources and further reading

• Minto, B. (2009). The Pyramid Principle: Logic in Writing and Thinking (3rd ed.). FT Prentice Hall. First published 1987.
• Schmidt, F. L., and Hunter, J. E. (1998). The validity and utility of selection methods in personnel psychology: Practical and theoretical implications of 85 years of research findings. Psychological Bulletin, 124(2), 262-274.
• Campion, M. A., Palmer, D. K., and Campion, J. E. (1997). A review of structure in the selection interview. Personnel Psychology, 50(3), 655-702.
• Ericsson, K. A., Krampe, R. T., and Tesch-Römer, C. (1993). The role of deliberate practice in the acquisition of expert performance. Psychological Review, 100(3), 363-406.
• Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., and Willingham, D. T. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4-58.
• BCG, interview process and case interview preparation (checked 2026-10-28): https://careers.bcg.com/global/en/interview-process and https://careers.bcg.com/global/en/case-interview-preparation
• McKinsey and Company, interviewing and Assessment Integrity Expectations (pages did not load for this review on 2026-10-28; check them directly): https://www.mckinsey.com/careers/interviewing and https://www.mckinsey.com/careers/assessment-integrity-expectations
• Further reading (books by name only): Victor Cheng, Case Interview Secrets; Marc Cosentino, Case in Point.

Answer key

1. Mutually exclusive, collectively exhaustive. Barbara Minto developed it while at McKinsey and set it out in The Pyramid Principle.
2. In interviewer-led cases the interviewer sets the sequence of questions; in candidate-led cases you drive the analysis. The associations (interviewer-led with McKinsey, candidate-led with BCG and Bain) are commonly reported, and practice varies by office, interviewer and round, so ask the recruiter.
3. 11.8% a year: =(100/80)^(1/2)-1 returns 0.1180.
4. It shows you understood the specific decision and makes the analysis efficient; a recited framework often includes irrelevant branches and misses case-specific drivers.
5. Because orders fall 6% and order value rises, revenue, gross profit and every per-order cost change too. The shortcut (=1.5*(10.4-8.2), USD 3.30m) ignores those effects. The full recalculation gives USD 4.78m: higher order value adds gross profit per order and fewer orders save fulfilment and returns cost, which outweighs the gross profit lost on the 0.09m orders that disappear.
6. Answer, reasons with numbers, risks, next steps.
7. It breaches the firm's assessment rules and can lead to withdrawal of an application or offer; and it gives the firm a false signal about skills the job will require.
8. Plus 2.6%: =(1-5%)*(1+8%)-1 returns 0.026.
9. Specific goals at the edge of current ability, immediate feedback and focused repetition on weaknesses (Ericsson, Krampe and Tesch-Römer 1993).
10. Point out that the truncated axis exaggerates differences, and read the actual values before drawing conclusions.

Revision history

Standard and licence note

Structure aligned with widely used consulting preparation practice, Minto's pyramid principle and research on structured interviews and deliberate practice. The text, practice case, exhibits and numbers are original and fictional; no firm-published case or assessment content is reproduced, and this template is not affiliated with or endorsed by any firm or school. Firm processes and AI rules change: check each firm's current careers pages before you rely on them. Template licence: MIT.