This research aimed at revealing and characterizing the influence of change events or reasons on cost and schedule performances. The specific objectives were to assess the frequencies of various change reasons with respect to cost and schedule deviations, and to assess the impact intensities of such change events or reasons on performance. Initially, a team of industry experts identified a total of 36 change types and grouped them in 9 major change categories. Then, change log information for

more »

... 5 completed projects was statistically analyzed to quantify the intensity, frequency, and impact of changes on cost and schedule performances. The most recurrent types of change events for both cost and schedule were associated with issues related to construction productivity; planning; supplier and subcontractor; scope errors and omissions; design or engineering errors and omissions; or engineering productivity issues. In addition, this study quantified the specific impact on cost and/or schedule from a change event or reason. Specifically, this study provides evidence that fairly infrequent change events tend to cause large impacts on performance. The results from this study are likely generalizable, since the retrospective project data was representative of multiple project types, sectors, and organizational roles, among other project facets.