Merge Event Bias in Project Evaluation Techniques – Problems and Directions

Evaluation of project completion time under uncertainty conditions is a known problem in project management (PM). Project evaluation and review technique (classical PERT) is the most known tool for project time analysis for project managers. While its deficiencies have been investigated long ago, it is taught in almost all PM courses, given in books, and is implemented in PM software. In the paper, we consider the effect of merge event bias (MEB) on the accuracy of analytical models of project analysis. MEB has a decisive effect on inaccuracy of the classical PERT and many of its extensions realized in underestimation of project time. We suggest ways how MEB can be included in analytical methods and define directions for future development. The work is directed in situations of high uncertainty in estimation of task durations.