Wideband delphi


The Wideband Delphi estimation method is a consensus-based technique for estimating effort. It derives from the Delphi method which was developed in the 1950-1960s at the RAND Corporation as a forecasting tool. It has since been adapted across many industries to estimate many kinds of tasks, ranging from statistical data collection results to sales and marketing forecasts.

Wideband Delphi Process

and John A. Farquhar originated the Wideband variant of the Delphi method in the 1970s. They called it "wideband" because, compared to the existing delphi method, the new method involved greater interaction and more communication among those participating. The method was popularized by Boehm's book Software Engineering Economics. Boehm's original steps from this book were:
  1. Coordinator presents each expert with a specification and an estimation form.
  2. Coordinator calls a group meeting in which the experts discuss estimation issues with the coordinator and each other.
  3. Experts fill out forms anonymously.
  4. Coordinator prepares and distributes a summary of the estimates
  5. Coordinator calls a group meeting, specifically focusing on having the experts discuss points where their estimates vary widely
  6. Experts fill out forms, again anonymously, and steps 4 to 6 are iterated for as many rounds as appropriate.
A variant of Wideband Delphi was developed by Neil Potter and Mary Sakry of . In this process, a project manager selects a moderator and an estimation team with three to seven members. The Delphi process consists of two meetings run by the moderator. The first meeting is the kickoff meeting, during which the estimation team creates a work breakdown structure and discusses assumptions. After the meeting, each team member creates an effort estimate for each task. The second meeting is the estimation session, in which the team revises the estimates as a group and achieves consensus. After the estimation session, the project manager summarizes the results and reviews them with the team, at which point they are ready to be used as the basis for planning the project.