Handling and presenting uncertainty in cost-benefit analysis

The problem of uncertainty in cost-benefit analysis (CBA) is that the decisions cannot be 100% certain, since the information is not 100% complete. This uncertainty should be analysed, presented and handled in a way that improves the choice between project alternatives, enhances risk mitigation in chosen projects. We review 19 country (or state/province) guidelines for transport appraisal, and contrast and compare the recommendations of methods for analysing uncertainty, which uncertain variables are to be analysed and finally how uncertainty is presented in the CBA. Together with the findings from this literature review and recommendations from a workshop of experts, we also provide recommendations for how to present uncertainty in cost-benefit analyses.