Incorporating risk in capital budgeting

Why risk matters. Capital budgeting decisions rest on estimates of cash flows over many future years, which are hard to predict because of the uncertainty of the economic environment. Even a project's life is uncertain: technological obsolescence, physical deterioration and a fall in demand can cut it short. Risk is the chance that actual cash flows differ from the estimates, and it must be built into the appraisal.

Ways of incorporating risk (overview)

1. Shorter payback (cut-off) period. Inflows further in the future are less certain, so a project with a shorter payback is treated as less risky; payback weeds out risky projects. It is a screen for risk, not a way of discounting: ordinary payback ignores the time value of money.
2. Risk-adjusted discount rate. Cash flows are discounted at a rate that reflects their risk: a riskier project is discounted at a higher rate (risk-free rate plus a risk premium), so it must earn more to show a positive NPV. This is the same logic as wealth maximisation, which values cash flows "discounted at a rate that reflects their risk".
3. Certainty-equivalent approach. Each year's uncertain cash flow is reduced to the certain amount the decision-maker would accept in its place (multiplied by a coefficient between 0 and 1), and the result is discounted at the risk-free rate.
4. Sensitivity and scenario analysis. The NPV is recomputed for changes in key variables (sales, costs, life) or for pessimistic, most likely and optimistic cases, to see how far the decision depends on each estimate.

Conclusion. Risk is brought into the appraisal in several ways: by screening with a shorter payback cut-off, by discounting at a higher rate, by reducing the cash flows to certainty equivalents, or by testing how robust the result is.