Delphi Survey

Objective: A Delphi Survey is a systematic multistage process in which experts are enquired about their opinions as well as about potential developments on specific topics.

"Delphi Surveys are used to gather collective forecasts through questionnaires about likely or possible developments in particular areas. Delphi Surveys can be carried out face to face, online or by post. In online versions, participants are given their own login and password to access the site. This is useful when the expert participants are very busy people.

The technique aims to derive the benefit of the opinions of a group of experts while avoiding the disadvantages of group-think and group dynamics where certain individuals dominate the discussion. It is believed that during this process the range of the answers will decrease and the group will converge towards the "correct" answer.

The process takes place in a number of stages:

  • The first questionnaire either asks the participants to individually identify issues and generate as many ideas as possible or to answer more close-ended questions such as the likely dates for specific developments.
  • The second questionnaire anonymously feeds back all the ideas and forecasts sent in the first round to all participants. This questionnaire also provides space for participants to refine each idea, comment on their strengths or weaknesses and suggest new ideas.
  • An additional questionnaire then summarizes the input from the second questionnaire and asks for further clarification, strengths, weaknesses, and new ideas. This stage can be repeated as many times as necessary until consensus on key points is reached.
  • The end product is either a consensus amongst the participants on likely and possible future developments or a wide range of possible developments and their relative strengths and weaknesses" (

Regarding the participants, "people are chosen to participate in a Delphi Survey because of their expertise or specific knowledge of the topic area. This expertise does not have to be academic and could instead be the knowledge of an experienced service user. It is important that the participants reflect a wide range of views and perspectives so that there will be a meaningful exchange of ideas" (

According to Iqbal and Pipon-Young (2009), "researchers must also decide how to conceptualise and define ‘expertise’. The method may be undermined if panellists are recruited who lack specialist knowledge, qualifications and proven track records in the field (Keeney et al., 2001), although of course expertise comes in many guises and may include those who are ‘experts by experience’ (Hardy et al., 2004). In general, a varied panel is considered best in producing a credible questionnaire, and individuals who might provide a minority or differing perspective should be actively recruited to the panel (Linstone & Turoff, 2002). With regard to the recruitment process itself, panellists are often recruited via letter or e-mail. Recruitment can be broadened through ‘snowballing’ (asking panellists to pass on invitations  to other relevant individuals)."

Participation level Target groups Number of participants Duration/Timeline Implementation Frequency Budget
Consultation Experts / Research Groups Up to 100 Longer than a week Adaptable Any Low
Needed skills:
Organizational requirements:
  • People with subject expertise
  • Questionnaires