Failure to consider and actively manage the causes of optimism bias will result in cost and time overruns, and benefits shortfalls over and above those that could be achieved if the causes are identified and actively managed. However, by taking account of risks when defining the nature and scope of a project and then developing strategies for the effective management of risks, it is possible to reduce the optimism bias and raise confidence levels in project estimates. Therefore the degree to which there is evidence that project risks have been identified and will be managed should be assessed during project appraisals to reduce the likelihood of cost and time overruns, and benefits shortfalls when the project is delivered.