Determining significant risks in the variability between design-stage elemental cost plan and final tender sum

AbstractSeveral researches have indicated that pre-tender estimating inaccuracies are significantly influenced by the level of risk information available to estimators. This study first identifies risk factors that influence variability between design-stage elemental cost plan and final tender sum (contract sum) in traditionally procured commercial building projects. It further evaluates the identified risk factors through risk measurement to determine the most significant ones during design development. Project data from New Zealand were obtained through online questionnaire and interview surveys to determine the construction consultants’ perspectives. Responses to the survey were analyzed by using descriptive statistics, risk mean analysis (RMA), degree of risk, coefficient of variation, and Kendall’s coefficient of concordance. A ranking of mean scores of the survey responses enabled the most significant risk factors to be determined. Interviews were analyzed by using thematic and documentary methods t...