Table 1 Common types of Delphi and their key differences
From: Applying real-time Delphi methods: development of a pain management survey in emergency nursing
Delphi technique, description | Anonymity | Iterative process | Feedback | Statistical aggregation |
|---|---|---|---|---|
Classic Delphi: generate ideas, elicit opinions and gain consensus on a given topic [4] | Maintained | • Series of rounds • Round 1 commences with an open-ended questionnaire, with subsequent phases used to evaluate responses | • Controlled feedback by moderator between each round | • At conclusion of the final round |
Modified Delphi: similar process as the classic Delphi, modifications commonly alter round 1, or facilitate contact between panelists [24, 25] | Variable | • Series of rounds • Modifications typically take the form of replacing round 1 (exploratory phase) with pre-generated items from the literature, or replacing round 1 with face-to-face interviews/focus groups | • Controlled feedback by moderator between each round | • At conclusion of the final round |
Decision Delphi: same process as classic Delphi, however purpose is to formulate, assist or make decisions, as opposed to coming to a consensus [24] | Maintained | • Series of rounds • Round 1 commences with an open-ended questionnaire | • Controlled feedback by moderator between each questionnaire | • At conclusion of the final round |
Policy Delphi: follows classic Delphi process, focus is to elicit breadth of views and opinions, both common and divergent, on policy issues, and come to a consensus on future policy [26] | Maintained | • Series of rounds • Round 1 commences with an open-ended questionnaire | • Controlled feedback by moderator between each questionnaire | • At conclusion of the final round |
Internet Delphi: same processes as the classic Delphi, conducted using an online platform [27] | Maintained | • Series of rounds • Round 1 commences with an open-ended questionnaire, with subsequent phases used to evaluate responses | • Controlled feedback by moderator between each questionnaire | • At conclusion of the final round |
Real-time Delphi: similar process as the classic Delphi, uses special software to conduct a ‘round-less’ real-time survey of experts to generate consensus [28] | Maintained | • No rounds, single questionnaire used • Experts can access the system throughout a set time period, review, comment and revise their assessments as needed | • When a panelist assess a statement they are immediately confronted with the aggregated results (quantitative and qualitative) of all other experts’ estimations | • Continuously updated in real-time until end of study timeframe |