Wideband Delphi: An Overview
Wideband Delphi is a structured, iterative approach to estimation and decision-making that builds on the classic Delphi method. It is commonly used in technology and product development environments to improve the accuracy of forecasts, particularly for complex or uncertain work.
Core Principles
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Expert Consensus
A selected group of subject matter experts individually estimate or evaluate a given problem or task. These estimates are then shared anonymously within the group. -
Iteration with Feedback
Participants review the anonymised results, discuss the rationale behind their own and others’ estimates, and revise their inputs over multiple rounds. This iterative process converges towards a more reliable and defensible estimate. -
Anonymity and Reduced Bias
Individual inputs are kept anonymous during the initial rounds to minimise the influence of authority, seniority or groupthink. This encourages more candid opinions and reduces bias. -
Structured Facilitation
A facilitator manages the process: defining the scope, ensuring clear instructions, and orchestrating the rounds. This keeps discussions focused and productive.
Typical Steps
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Preparation
Define the scope, objectives, and metrics for estimation. Select the right participants. -
Initial Estimates
Each participant independently provides estimates or assessments. -
Review and Discussion
Aggregated results are shared. Differences are examined, assumptions clarified, and outliers explained. -
Revised Estimates
Participants adjust their estimates based on the new information. -
Consolidation
After several rounds, results are consolidated into a final estimate or decision.
Benefits
- Improved Accuracy: Leveraging multiple expert perspectives reduces the risk of overly optimistic or pessimistic forecasts.
- Shared Understanding: Group discussions help uncover hidden assumptions and dependencies.
- Transparency: The process documents rationales and justifications, creating a defensible audit trail.
- Flexibility: Can be applied to effort estimation, risk analysis, prioritisation, or strategic planning.
Key Takeaways
Wideband Delphi works best when:
- The problem is complex or uncertain.
- Diverse expertise is required.
- Stakeholders want a structured, evidence-based estimate rather than a single opinion.
Its iterative, consensus-driven nature leads to estimates and decisions that are typically more robust and better supported than those produced by traditional top-down methods.