3.3.1 Description of the method


The Delphi method (named so because of the Delphi Oracle) was initiated by the RAND corporation, a nonprofit institution that helps improve policy and decision making through research and analysis[a]. The original definition given in the 50s was that it “entails a group of experts who anonymously reply to questionnaires and subsequently receive feedback in the form of a statistical representation of the "group response," after which the process repeats itself. The goal is to reduce the range of responses and arrive at something closer to expert consensus.”89 Today, the method has evolved and Delphi surveys could aim at different goals or have several designs[b]. It could be define more as “a method for structuring a group communication process” and not as a method to produce consensus90. The method could also be defined as a systematic collection and aggregation tool of informed judgment from a group of experts on specific questions and issues” (Hasson, 201191, p. 1696).

Delphi surveys are used in several domains (politics, psychology, agriculture, etc.) and could vary in different ways. Several types of Delphi often used in health research (non exhaustive) are presented in Table 10.


Table 10 – Types of Delphi designs

Design Type


Target panellists


Number of rounds

Round 1 design


To elicit opinion and gain consensus

Experts selected based on aims of research

Traditionally postal

Employs three or more rounds[3]

Open qualitative first round, to allow panelists to record responses


Aim varies according to project design, from predicting future events to achieving consensus

Experts selected based on aims of research

Varies, postal, online, etc.

May employ fewer than 3 rounds

Panelists provided with pre-selected items, drawn from various sources, within which they are asked to consider their responses


To structure decision-making and create the future in reality rather than predicting it

Decision makers, selected according to hierarchical position and level of expertise



Can adopt similar process to classical Delphi


To generate opposing views on policy and potential resolutions.

Policy makers selected to obtain divergent opinions

Can adopt a number of formats including bringing participants together in a group meeting

Varies : It theoretically needs 5 rounds but could be done in 3 or 4 rounds:

Can adopt similar process to classical Delphi or

1- preformulating the obvious issues by the research team;
2- seeding the list with an initial range of options but allowing for the respondents to add to the lists92, 93

Real time/consensus conference

To elicit opinion and gain consensus on real time

Experts selected based on aims of research

Use of computer technology that panelists use in the same room to achieve consensus in real time rather than post or via Internet94


Can adopt similar process

Adapted from Hasson, 201191, p. 1697 and Keeney, 201195

[a]           http://www.rand.org

[b]           See the special issue 78 of the review ‘Technological Forecasting & Social change” (2011) available at http://www.journals.elsevier.com/technological-forecasting-and-social-ch....

[3]           Note that the number of rounds should ideally be based on the saturation of the responses and is difficult to fix in advance