Statistical analysis for comparison of overall performance of projects using Weibull analysis on earned value metrics

Most organizations have evaluated project performance primarily through cost and schedule performance measures, such as earned value management, for projects. However, to date, few tools in the project management literature have been proposed for enabling comparisons of the overall performance of projects. This study introduces a simple index, the critical ratio in time (CR(t)), as a measure of the overall performance of a project. The index can be easily calculated on the basis of the earned value (EV) data, which are normally available from a project cost system. Based on the index, a statistical analysis for the comparison of the overall performance of projects using Weibull analysis on EV metrics is proposed. The statistical analysis can be performed on a spreadsheet, such as Microsoft® Excel®. Furthermore, the detailed steps in the analysis are discussed along with an example in which five sample projects are analyzed and compared. Based on the obtained results, the author concludes that the proposed approach on the basis of CR(t) data can provide a robust and effective method for managers to evaluate and compare the overall performance of projects, and can be applicable in evaluating the project whose value has been determined (e.g. contracted projects).