Using Robust Statistical Methodology to Evaluate the Cost Performance of Project Delivery Systems: A Case Study of Horizontal Construction
The objective of this study is to demonstrate the application of the bootstrapping M-estimator (a robust analysis of variance [ANOVA]) to test the null hypothesis of means equality among the cost performance of the three project delivery systems (PDS). A statistical planned contrast methodology is utilized after the robust ANOVA analysis to further determine where the differences of the means lie. The results of this research concluded that traditional PDS (Design-Bid-Build [DBB]) outperformed the two innovative PDS (Design-Build [DB] and Construction Manager/General Contractor [CMGC]), DBB and CMGC outperformed DB, and DBB outperformed CMGC, for the Cost Growth and the Change Order Cost Factor performance. These findings can help decision makers/owners make an informed decision regarding cost related aspects when choosing PDS for their projects. Though the case study of this research is based on the sample data obtained from the construction industry, the same methodology and statistical process can be applied to other industries and factors/variables of interest when the study sample data are unbalanced and the normality and homogeneity of variance assumptions are violated.