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The use of Delphi methods

The Delphi method is a systematic interactive way of gaining opinions/forecasts from a panel of independent experts over 2 or more rounds. It is a type of consensus method which does not require face to face meetings.

The 3 best known consensus techniques are:

  • Delphi process
  • Nominal group technique
  • Consensus development conference

The Delphi process aims to determine the extent to which experts or lay people agree about a given issue and with each other and in areas where they disagree, achieve a consensus opinion. Delphi technique is usually conducted through questionnaires.

Where focus groups purposely use group dynamics to generate debate on a topic, Delphi methods maintain anonymity of the participants, even after the study.

The following steps outline how to undertake a Delphi study:

1.  Design the questionnaire

2.  Invite participants to take part

3.  Send out first round of questionnaire- a typical question may be-


Which of the following CLINICAL areas do you think are HIGH PRIORITY for development of an improved evidence base relating to minority ethnic groups and their health needs?


Clinical Area

PRIORITY for development of an improved evidence base

Comments including any particularly important topics for action.

Mental Health

Low 1 2 3 4 5 High 0 (don’t know)



Low 1 2 3 4 5 High 0 (don’t know)



Low 1 2 3 4 5 High 0 (don’t know)



The questionnaire provides space for respondents to raise any other issues relating to the topic. The first round of the questionnaire aims to categorise opinions under common headings.

4.  Analyse responses from round 1 questionnaire

5.  Prepare the second round questionnaire

6.  Send out second round questionnaire - the follow up to the first round question above might be -


Cancer has been identified as a high priority for developing an evidence base relating to minority ethnic groups. Within this clinical area, what aspects should research focus on?


Research area

PRIORITY for development of an improved evidence base

Comments including any particularly important topics for action.

Identifying risk factors of disease

Low 1 2 3 4 5 High 0 (don’t know)


Identifying barriers to access of services

Low 1 2 3 4 5 High 0 (don’t know)


Improving the patient experience for minority ethnic groups

Low 1 2 3 4 5 High 0 (don’t know)



In this example, the research areas chosen for the second round questionnaire were identified from the free text column in the round 1 questionnaire. Participants have the chance to suggest further areas of focus in the second round questionnaire. The aim of second round is to score agreement or disagreement with statements from first round.

7.  Analyse responses from round 2 questionnaire

8.  Design the third round questionnaire. For the third round, the second questionnaire is repeated but incorporates scores from the second questionnaire results. This
     gives participants a chance to see how the rest of the group prioritised the areas and if the participant then wants to change their opinion on the basis of the group
     consensus, has the opportunity to do so.

9.  Analyse the results of the third round questionnaire for agreement and degree of consensus

10. Report findings


Strengths of the Delphi technique:

  • A rapid consensus can be achieved
  • Participants do not have to be in the same room together to reach agreement
  • Individuals are able to express their own opinions as opposed to “Group think”
  • Can include a wide range of expertise
  • Relatively low cost to administer and analyse
  • There is the potential to gain large quantities of data
  • Offers a method which can be used where data are lacking


Weaknesses of Delphi technique:

  • Does not cope well with widely differing opinions or large changes in opinions (paradigm shifts)
  • The facilitator’s view may dominate in the analysis
  • Differing opinions may not be sufficiently investigated
  • Can be time-consuming
  • Needs high participant motivation
  • Success of the method depends on the quality of the participants
  • The written response format may be less suitable for some potential respondents




                                              © Rosalind Blackwood 2009, Claire Currie 2016