WHICH PROJECT RISK AREA CONTRIBUTES MOST TO COST OPTIMISM BIAS?

Table 6 to Table 9 contain a breakdown of project risk area contributions to optimism bias levels for individual project types. The contributions are expressed as a percentage of the relevant average optimism bias. In most instances, the inadequacy of the business case (i.e. inadequate requirements and inadequate project scope definition) was stated to be the major cause of project time and cost overruns.