The Delphi technique utilizes a consensus-based approach to estimating involving multiple experts. The experts selected for a Delphi approach have subject domain experience and specific application knowledge. Experts conduct discussions in a structured group process designed to produce a consensus. The Delphi method of estimation in software development is the process whereby a group of experts identify the task to estimate, provide an estimation method, discuss the application of the method, and arrive at a consensus regarding the level of effort needed. The experts conduct the approach using multiple voting rounds that provide results that can be evaluated and summarized. The experts may repeat the process of estimate revision until the experts reach a specific number of rounds, reach a consensus, or until the results are stable and the answer is satisfactory. The Delphi approach to estimation makes an estimate available based on experts' collective agreement.
The Delphi approach utilizes expert assessments and involves the coordination of the team and elaboration of requirements for the members of the team to do their estimations anonymously. Estimations with a high level of variation are discussed further and re-evaluated. The results are distributed to the group for further discussion after each round to reach an agreement and review the agreement for relevance. The Delphi method captures factors from several experts and provides a defined practice in the assessment. The Delphi approach is the collective assessment of experts to establish an agreed-upon estimation.