Wideband Delphi

Wideband Delphi is a consensus-based estimation technique used to forecast project parameters such as cost, duration, or resource requirements. It was developed as an extension of the Delphi method, which was originally designed as a forecasting tool for experts in various fields. The Wideband Delphi technique combines expert opinions through a structured, iterative process to converge on an agreed-upon estimate while minimizing the influence of biases and group dynamics.

Purpose and Role: The primary purpose of the Wideband Delphi method is to obtain reliable project estimates by incorporating expert opinions and experiences. This technique is commonly used in project management, software development, and other fields where accurate estimation is crucial for planning, budgeting, and resource allocation.


  • Expert panel: A group of experts with relevant knowledge and experience in the field or domain related to the estimation task.
  • Coordinator: A facilitator responsible for organizing the process, providing instructions, and managing communications among the expert panel.
  • Anonymity: The expert panel members provide their estimates and opinions anonymously to reduce biases and group dynamics.
  • Iterative rounds: The process involves multiple rounds of estimation, feedback, and revision, enabling experts to refine their estimates based on the collective input of the panel.
  • Convergence: The goal is to reach a consensus or convergence on a final estimate through the iterative process.

Importance: The Wideband Delphi method is important for generating accurate and reliable project estimates, which are crucial for successful project planning and execution. This technique reduces the impact of biases and group dynamics while incorporating diverse expert opinions, leading to more reliable and informed estimates.

History: The original Delphi method was developed in the 1950s by researchers at the RAND Corporation as a systematic approach to expert forecasting. The Wideband Delphi technique was later introduced in the 1970s by Barry Boehm as an extension of the Delphi method, specifically tailored for software development estimation. Since then, the technique has been widely adopted in various industries for estimation and forecasting purposes.

Benefits and Pros:

  • Reduced biases: The anonymity of the Wideband Delphi process helps minimize the influence of personal biases, authority, and group dynamics.
  • Expert opinions: The technique incorporates diverse expert opinions, resulting in more informed and reliable estimates.
  • Iterative refinement: The multiple rounds of estimation and feedback allow experts to revise their estimates based on the collective input of the panel, improving the accuracy of the final estimate.
  • Consensus-building: The Wideband Delphi method fosters consensus among experts, leading to more accurate and agreed-upon estimates.


  • Time-consuming: The iterative nature of the Wideband Delphi process can be time-consuming, particularly when involving large panels or complex estimation tasks.
  • Selection of experts: The reliability of the final estimate depends on the selection of knowledgeable and experienced experts, which can be challenging in some cases.
  • Subjectivity: Despite its structured approach, the Wideband Delphi method still relies on subjective expert opinions, which may not always guarantee accurate results.

In summary, the Wideband Delphi technique is a valuable estimation and forecasting tool that combines expert opinions through a structured, iterative process. By minimizing biases and incorporating diverse expert knowledge, the Wideband Delphi method helps generate more reliable and informed estimates, crucial for successful project planning and execution.

See Also