Walk me through using sensitivity analysis to inform a strategic decision.
A core FP&A interview question — asked in analyst and associate interviews across IB, PE, and the Big 4.
THE SHORT ANSWER
Take a concrete case — entering a new market. Build the base-case model (NPV/IRR or P&L) on explicit assumptions, then isolate the variables that drive the outcome: demand/volume ramp, price, customer-acquisition cost, churn, and the discount rate. Sensitivity analysis flexes one variable at a time across a credible range to see which moves the result most — a tornado chart ranks them, telling you where the decision actually hinges. I'd then find the break-evens (what volume/price makes NPV zero) and judge how plausible those thresholds are. Where several variables move together or interact, I'd add scenario analysis (coherent good/base/bad cases) or Monte Carlo for a probability distribution. The output to leadership isn't a single number — it's 'the decision is most sensitive to X and Y; here are the break-even levels and the probability we clear them' — which focuses diligence and risk mitigation on the few assumptions that matter.
WHAT INTERVIEWERS LISTEN FOR
- ✓Base-case model, then flex one driver at a time across a credible range
- ✓Tornado chart ranks which variables move the outcome most
- ✓Find break-evens and judge plausibility; add scenario/Monte Carlo for interactions
- ✓Conclusion = which assumptions the decision hinges on, not one number
COMMON MISTAKES
- ✗Listing steps generically with no driver/break-even focus
- ✗One-at-a-time only where variables clearly interact
- ✗Presenting a single number, not the sensitivities
Reading isn't the same as answering under pressure.
Interviewers don't hand you the model answer — you deliver yours on a clock. Practice this and 1,000+ questions with AI feedback on every answer.
RELATED QUESTIONS
- How do you build a pricing model?
- How do you present a scenario analysis to the board?
- How would you evaluate entering a new market?
- A company is considering investing in a new project with a projected 5-year payback period. What are the key factors to consider when evaluating the project's viability, and how would you present your findings to stakeholders?
- What are some common challenges that arise when implementing a driver-based planning approach in a company with a complex organizational structure and multiple stakeholders? How would you address these challenges and ensure a successful implementation?
- What is relevant (incremental) costing, and how would you apply it to a make-versus-buy or special-order decision?