Wideband Delphi

The Wideband Delphi technique estimates effort based on a consensus. Its origins can be traced to the Delphi Method (see “The Delphi Technique” posted 07.30.09). This technique is not specifically listed in the PMBOK®, but its use belongs in the Estimate Activity Durations process  along with analogous, parametric, and three-point estimating techniques. Both the Wideband Delphi technique and the Delphi Method focus on gathering information from a group of experts individually, sharing these results, and asking the experts for their opinion again based on now knowing the views of others. Wideband Delphi is specifically applied to estimating the required effort for specific tasks and there is more interaction among the experts. The Wideband Delphi technique is led by a coordinator who provides each of the selected experts with a form. There is a group meeting to discuss estimation for the project and then each expert anonymously fills out their form with their effort estimations. These are returned to the coordinator who aggregates the results and disseminates the information to all experts. There is another group meeting in which tasks with widely disparate estimates are discussed in particular. This is a good opportunity to uncover unspoken assumptions about task requirements. After this discussion, the experts again fill out their estimation forms. The coordinator may again distribute these results and ask for revised estimates as many times as needed. As the team progresses through rounds, sharing their knowledge and assumptions, task estimations across the experts should become increasingly similar and this is how consensus is achieved.