When a company considers a big investment — say, buying a ₹50 lakh machine — the future is uncertain. Sales might be higher or lower, costs might change, the discount rate might shift. Sensitivity Analysis and Scenario Analysis are two techniques that help you stress-test your NPV before committing real money.
Sensitivity Analysis asks: "What if I change just ONE variable — how much does NPV swing?" You keep everything else constant and tweak one input (sales volume, selling price, cost, discount rate) to find two things: (1) the new NPV, and (2) the switching value (also called the break-even value) — the exact level at which NPV hits zero. The variable with the smallest percentage change needed to make NPV zero is the most sensitive — and therefore the riskiest. This is frequently asked as a 5-mark question in exams — they give you a base-case NPV and ask you to find sensitivity % for two or three variables.
Scenario Analysis is a step up — it changes multiple variables together to paint three pictures: Best Case, Base Case (Most Likely), and Worst Case. Think of it like planning a road trip. Base case: normal traffic, arrive on time. Worst case: heavy rain, highway closed, 3 hours late. Best case: empty roads, arrive early. Each scenario has its own NPV. Management looks at the range of outcomes and decides if the risk is acceptable. If even the worst-case NPV is positive, sleep easy. If it is deeply negative, think twice.
The key difference to remember: Sensitivity = one variable changes, others fixed. Scenario = multiple variables change together, giving holistic outcomes. Examiners love asking students to distinguish these two. Also remember — neither technique assigns probability to outcomes. For that, you need Expected NPV (with probability weights), which is a separate but related concept. Sensitivity and Scenario Analysis are qualitative risk tools; they show what can happen, not how likely it is.