Wide band Delphi (WBD)

Wide band Delphi (WBD) is a structured estimation technique involving an expert group. There is a lot of literature around the details of implementing this technique. In brief, this technique involves getting a group of “experts” to make estimates, discuss their assumptions and arrive at a consensus estimate. The estimates made by a group of experts with their varied perspectives are expected to be better than that made by any single individual who may not have the breadth or depth of understanding about the various activities involved.

In this technique, the team of experts begins by analysing the scope / specification of the work being estimated, brainstorms assumptions and creates a work-breakdown structure (WBS). Members of the team then make estimates individually for items in the WBS and note any further changes to the WBS and assumptions. The team then meets together to arrive at a consensus on the estimates. The meeting is facilitated by a moderator who charts the estimates without revealing the estimators and guides the group towards understanding the range of estimates, clarifying any assumptions, revising estimates, in a cyclical process until a consensus is reached.

While implementing the WBD technique it is important to assemble the appropriate team to generate estimates. It is a good idea to involve representatives from different functions who have a stake in the product so they together can agree upon the estimates and feel a sense of ownership of the plan. The technique is useful for new projects or projects where there are multiple factors and uncertainty. WBD helps refine and develop the WBS as well as clarify assumptions around estimates. The technique however, does take time and requires multiple experts to come together and make estimates.