Case Interview Guide: How to Structure Any Business Problem
Case interviews are used by consulting firms, strategy teams, and PMs at tech companies. They test structured problem-solving under pressure. Here's the complete framework.
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The Two Types of Cases
Business cases (market sizing, profitability, M&A, market entry) and product cases (design a product, diagnose a metric drop, estimate revenue). Tech company PM interviews lean toward product cases; consulting interviews lean toward business cases. Know both.
The Universal Case Framework
1) Clarify the goal (what are we optimizing for?). 2) Structure your approach (name 2-3 buckets you'll explore). 3) Analyze each bucket. 4) Synthesize and recommend. Always say your structure out loud before diving in — it signals organized thinking.
Market Sizing Approach
"How many golf balls fit in a school bus?" The answer matters less than the approach. Start with a reasonable anchor number, break it into components you can estimate, show your math out loud, and sanity-check at the end. "That seems high — let me see if I made an error in my population assumption."
Profitability Cases
Revenue declining or costs increasing? Structure: Revenue = Price × Volume. Costs = Fixed + Variable. Work through each lever, ask targeted questions, and form hypotheses. "Given that the decline is concentrated in the West region and started in Q3, I'm hypothesizing a regional competitive entrant. My next question would be..."
Product Cases for Tech Interviews
"Design Uber for seniors." "What metric would you use to measure Facebook Stories success?" Structure: user + goal → pain points → solution space → prioritization → metrics. Always start with the user. Always end with how you'd measure success.
Practicing Cases
You need 20+ practice cases before a consulting final round. Use case books (Case in Point, Victor Cheng), partner with other candidates, and use AI tools to get structured feedback on your thinking. Record yourself and listen back — verbal tics and unclear thinking are much more obvious on playback.
Key Takeaways
- →Write down the numbers as you calculate — interviewers follow along and can help if you're heading off-track
- →Ask for 30 seconds to organize your thoughts at the start — interviewers expect this
- →Practice math operations quickly: percentages, multiplications, divisions in your head