Project planning under uncertainty using scenario analysis

For nearly fifty years, project professionals have used models such as Program Evaluation and Review Technique (PERT) to estimate the uncertainty of project duration. Simulation packages such as the Graphical Evaluation and Review Technique (GERT)--like many other similar packages, a micro-simulation approach--subsequently emerged to model probabilistic project networks and project schedule uncertainty at the activity level. But these models estimate repeated activities within loops of identical duration; these estimate that the duration of one activity does not influence the duration of another activity. To provide a simpler approach for modeling and analyzing projects with uncertain network structures, where repeated activities do not share identical durations, the authors present a macro-level scenario approach, one that provides exact results, identifies several project network scenarios.