The Delphi Technique

The Delphi technique is a commonly used and a flexible method for gathering data and harnessing the views of respondents within their field of expertise. This technique is useful where clear-cut information is unavailable and reviews of experts and practitioners on complex matters are vital.


  • Duration
    Long (more than 1 hour)
  • Complexity:
  • Group size:
    15 to 25 persons

Description Long

The Delphi technique is a widely used and accepted method for achieving convergence of opinions regarding real-world knowledge sought from experts within certain topic areas. This method was mainly developed by Olaf Helmer, Nicholas Rescher, Norman Dalkey, and others at the RAND corporation in the 1950s, based on the rationale that, "two heads are better than one, or...n heads are better than one" (Dalkey, 1972, p. 15). In a Delphi process, which is usually 3 to 4 rounds of iteration, a series of questionnaries are developed based on the outcome of the previous ones. The results in the iterative rounds are collected and returned to the participants. During sucessful iteration process, participants are able to reassess their responses according to the complied responses of all participants. The responses to the questionnaires are made anonymously, which consequently enhances the probability that opinions are considered without being persuaded by the owner of the idea.



  1. Prepare questionnaire and pre-test it.
  2. Provide clear written instructions to panel members.


  1. Round 1: Create, develop and send out a questionnaire with open-ended questions to the experts. The questionnaire serves as the foundation in order to acquire specific information regarding the area of investigation from the Delphi panel.
  2. Round 2: Distribute a second questionnaire and ask Delphi participants to review the items summarized by the investigators based on the information provided in the first round.
  3. Send a copy of the collective list to experts and ask them to rate or evaluate each item by some criterion of importance.
  4. Document the areas of disagreement and agreement as a result of round two.
  5. Round 3: Send the summarized items and their rating to each Delphi and ask experts to revise their judgments or to justify the reasons for disagreement.
  6. Round 4: Distribute the list of remaining items, their ratings, minority opinions, and items achieving consensus to the panelists. This round provides a final opportunity for participants to revise their judgments.

Hints from experience

You can use either quantitative or qualitative scales in the Delphi method. Questionnaires may or may not include open-ended questions. Iteration with feedback continues until consensus is reached, as determined by the moderator (usually from 3 to 5) Participants could be geographically dispersed.


Hsu, C. C., & Sandford, B. A. (2007). The Delphi technique: making sense of consensus. Practical Assessment, Research & Evaluation, 12(10), 1-8. Retrieved 5 August 2015 from,

Linstone, H. A., & Turoff, M. (Eds.). (1975). The Delphi method: Techniques and applications (Vol. 29). Reading, MA: Addison-Wesley. Retrieved from,

Rowan Free Press,. (2012). The Delphi Technique: City Employs Manipulative Method at Statesville Blvd Meeting. Retrieved from

Somerville, J. A. (2007). Critical factors affecting the meaningful assessment of student learning outcomes: A Delphi study of the opinions of community college personnel. Unpublished doctoral dissertation, Oregon State University, Corvallis, OR. Retrieved from,

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