The Delphi method in research and decision-making
The Delphi method helps researchers and organizations gather expert input, refine opinions over multiple rounds, and identify areas of agreement in a structured and transparent way.
What is a Delphi study?
A Delphi study is a structured investigation in which a selected panel provides judgments, reviews summarized feedback, and has an opportunity to reconsider its responses. It can identify agreed priorities or recommendations and clarify differences that remain unresolved.
The Delphi method is the overall approach. A Delphi study is a particular research project using it. A Delphi survey is the questionnaire and feedback workflow through which panelists contribute. Our questionnaire example shows how instructions, ratings, comments, and follow-up feedback fit together.
In research, the method is useful when the question requires informed judgment alongside an incomplete or developing evidence base. It produces evidence about the panel's judgments; agreement alone does not demonstrate that an intervention works or that a forecast will be correct. For definitions of the panel and process, start with our Delphi overview.
The RAND methodological guidance discusses Delphi design, implementation, and reporting. The practical example below applies those broad design concerns to a decision context.
Benefits, uses, and why Delphi works so well for expert consensus
When organizations, researchers, or decision-makers need expert input, a simple survey is often not enough. Some questions are too complex, too uncertain, or too important to answer with a single round of responses. This is where the Delphi method can be especially valuable.
The Delphi method is a structured approach for gathering and refining expert opinion. It is commonly used when evidence is incomplete, when decisions require professional judgment, or when a group needs to identify areas of agreement and disagreement in a thoughtful, transparent way.
Unlike a traditional meeting or one-time survey, a Delphi study usually involves multiple rounds. Experts respond to questions, review summarized group feedback, and then have the opportunity to reconsider or refine their answers in later rounds. Over time, the process helps the group move toward clearer priorities, stronger recommendations, or measurable consensus.
What is the Delphi method?
The Delphi method is a structured process for developing informed group judgments through independent responses, controlled feedback, and reconsideration. A selected panel reviews a common question or set of items, with agreement and disagreement interpreted using rules defined before analysis. It is used in healthcare, policy, education, forecasting, and other fields where expert or stakeholder judgment helps address uncertainty.
Expert panel
A Delphi study begins with a carefully selected group of participants who have relevant knowledge, experience, or stakeholder perspective.
Multiple rounds
Participants usually respond in more than one round, allowing the group to refine opinions as feedback becomes available.
Measured consensus
Agreement can be assessed using predefined criteria such as percentage agreement, median ratings, interquartile range, or stability across rounds.
Why use the Delphi method?
The Delphi method offers several important advantages compared with traditional group discussions, focus groups, or one-time surveys.
It reduces dominant voices
In face-to-face meetings, some participants naturally speak more than others. Seniority, confidence, reputation, or personality can unintentionally influence the group. The Delphi method helps reduce this problem by allowing participants to respond anonymously.
It encourages independent thinking
Because participants usually respond independently, the method helps preserve the value of individual expert judgment before participants review summarized group feedback.
It allows experts to reconsider
Participants can review group feedback and decide whether to keep or revise their responses in later rounds. This creates a thoughtful balance between independent judgment and collective learning.
It makes consensus transparent
A Delphi study can define consensus in advance using measurable criteria, helping make the results easier to interpret, report, and defend.
How consensus can be measured
Many organizations say they want consensus, but they do not always define what that means. A Delphi study can make consensus more transparent by using predefined criteria.
Percentage agreement
For example, the percentage of panelists rating an item as important, appropriate, or acceptable.
Median ratings
Useful when participants rate statements, outcomes, or priorities on a numerical scale.
Interquartile range
A common way to understand how closely clustered expert ratings are around a central value.
Stability across rounds
Helps determine whether opinions are still changing or whether the group has reached a stable position.
Ranking thresholds
Helpful when the goal is to prioritize options, outcomes, risks, or recommendations.
Stakeholder-group comparison
Useful when a study includes different expert or stakeholder groups whose perspectives need to be compared.
Common uses of the Delphi method
The Delphi method is widely used in healthcare and medical research, but its value extends far beyond medicine. It is especially helpful when the question is not simply “What do people think?” but rather “What do informed experts believe after structured reflection and feedback?”
Clinical recommendations
Develop expert guidance, care pathways, standards, definitions, or appropriateness criteria.
Core outcome sets
Identify agreed minimum outcomes for trials, registries, and health research.
Research priorities
Help networks, funders, and societies identify which questions matter most.
Policy and planning
Support structured decision-making when evidence is incomplete or stakeholder perspectives differ.
Forecasting
Gather expert judgment about future trends, risks, opportunities, or scenarios.
Competency frameworks
Build consensus around skills, standards, training requirements, or professional expectations.
Delphi vs. traditional surveys
A traditional survey is usually a single snapshot of opinions, preferences, or experiences. It can be very useful, but it does not normally include structured feedback or multiple rounds of reflection.
| Traditional survey | Delphi study |
|---|---|
| Typically one round of responses. | Often includes multiple rounds or real-time feedback. |
| Collects opinions, experiences, or preferences. | Refines expert judgment toward clearer agreement, priorities, or recommendations. |
| Participants usually do not see group feedback before responding. | Participants may review summarized feedback and reconsider their views. |
| Useful for many general research and feedback needs. | Especially useful for complex issues where expert consensus is needed. |
What is Real-Time Delphi?
Real-Time Delphi is a modern variation of the traditional Delphi method. Instead of waiting for one round to close before feedback is prepared and the next round begins, participants can often see updated group feedback while the study is still active.
This can make the process faster and more flexible. Participants may revise their answers in response to emerging group trends without requiring multiple fully separate survey rounds.
Faster feedback
Participants can often see how their responses compare with the group while the study is open.
Flexible revision
Participants may adjust their ratings or comments as group patterns become clearer.
Why software matters in Delphi studies
A Delphi study can become difficult to manage manually, especially when there are many experts, multiple rounds, complex rating scales, open-ended comments, controlled feedback, or consensus calculations.
Specialized Delphi software can help researchers and organizations manage the process more efficiently. It can support participant invitations, structured questionnaires, multi-round surveys, feedback summaries, response tracking, and reporting.
Round management
Support for multi-round workflows, participant reminders, and response tracking.
Structured feedback
Help participants review group results, comments, and summary statistics between rounds.
Analysis-ready exports
Export data for consensus analysis, reporting, steering-committee review, or publication support.
How Surveylet supports Delphi studies
Surveylet was designed to support Delphi and Real-Time Delphi studies, including studies that require multiple rounds, expert panels, structured feedback, and consensus-oriented analysis.
Rather than treating Delphi as a basic survey, Surveylet supports the unique workflow of consensus research. This can be valuable for researchers, organizations, and study teams that need more than a simple questionnaire tool.
Expert panels
Support structured participation by invited experts, clinicians, stakeholders, or decision-makers.
Multi-round studies
Manage Delphi workflows where participants review feedback and refine responses over time.
Real-Time Delphi
Support more dynamic consensus-building when teams need a faster and more flexible process.
Using the Delphi technique in decision-making
Suppose a professional association needs to select priorities for a training program. An initial survey can reveal preferences, but the Delphi process allows members to reconsider those preferences after reviewing the group's reasons and the spread of ratings.
- Define the decision. Specify the target learners, available resources, and what the panel can recommend.
- Prepare the options. Describe each proposed priority clearly and explain where it came from.
- Collect separate judgments. Rate importance independently from feasibility.
- Review feedback. Show the distribution and the reasons supporting different positions.
- Reconsider. Let participants retain or revise their ratings.
- Document the result. Identify supported priorities, unresolved concerns, and decisions that remain with the association.
Delphi supports the decision process; it does not remove the need for accountable decision-makers. A highly rated option might still require funding or further evidence. A low-ranked but essential requirement may need separate consideration.
For specific applications, explore our risk-identification guide and Delphi questionnaire example.
Plan a Delphi research study before launch
A useful Delphi protocol explains who will contribute, what they will judge, how feedback will work, and how the study will end. Make these decisions before reviewing results.
Panel and independent input
Define eligibility and the stakeholder perspectives you need. Plan how identities will be handled in feedback and how participation will be tracked. Use the panel-size guide and stakeholder-balance guide to document your rationale.
Rounds and decision rules
Specify the rating dimensions, feedback, item-revision process, planned rounds or active period, and stopping rules. Define consensus and disagreement criteria in advance; agreement and stability answer different questions.
Reporting and common pitfalls
Record recruitment, participation, attrition, wording changes, feedback, unresolved items, and protocol departures. The reporting guide and common mistakes guide help you prepare a transparent account of the study.
Planning a Delphi or Real-Time Delphi study?
Surveylet helps researchers and organizations manage expert panels, multiple rounds, structured feedback, and consensus-building workflows online. If your team is planning a Delphi, Real-Time Delphi, modified Delphi, consensus process, or core outcome set project, Calibrum can help you determine the right structure and level of support.