Cost-benefit analysis (CBA) is a structured decision-support technique that monetizes (or otherwise quantifies) the expected positive and negative consequences of a policy, regulation, or project and compares them on a common scale, usually net present value. It is widely used by finance ministries, regulatory agencies, multilateral lenders, and think tanks to rank competing options and justify public spending.
A standard CBA workflow involves:
- Scoping the policy alternatives and the counterfactual baseline ("do nothing").
- Identifying impacts across affected populations and time horizons.
- Valuing impacts in monetary terms, including market prices, shadow prices for non-market goods (e.g., the value of a statistical life, travel-time savings, carbon prices), and willingness-to-pay estimates.
- Discounting future flows to present value using a social discount rate.
- Comparing net present value, benefit-cost ratio, or internal rate of return across options.
- Sensitivity analysis to test how results change under different assumptions.
In the United States, CBA has been embedded in federal rulemaking since Executive Order 12291 (Reagan, 1981) and reinforced by Executive Order 12866 (Clinton, 1993), with methodological guidance in OMB Circular A-4. The UK uses the HM Treasury Green Book; the European Commission publishes a Better Regulation Toolbox and a Guide to Cost-Benefit Analysis of Investment Projects for Cohesion Policy. The World Bank and Asian Development Bank require economic analysis for project appraisal.
CBA has well-known limitations. Distributional effects can be obscured when aggregate net benefits are positive but losses concentrate on vulnerable groups. Valuing non-market goods — biodiversity, cultural heritage, dignity — is contested. The choice of discount rate strongly influences long-horizon issues such as climate policy, as debated between Nicholas Stern and William Nordhaus. Critics also point to optimism bias in infrastructure forecasting, documented by Bent Flyvbjerg.
For MUN delegates and junior researchers, CBA is most useful as a framework for structuring trade-offs, not as a mechanical answer machine.
Example
In 2023, the UK Department for Transport published a cost-benefit analysis of HS2 Phase 2b that contributed to the government's decision to cancel the Manchester leg.
Frequently asked questions
CBA monetizes both costs and benefits to produce a net value, while cost-effectiveness analysis compares costs per unit of a non-monetized outcome (e.g., cost per life-year saved) and is common in health policy.
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