+1-631-475-0231 barrister@yannalaw.com

Rational Science

Home » Opinion » Public policy and Politics » Delphi Methods

Delphi Methods

Adapted from Exhibit 9, “Delphi” Methods and the “Agent Orange” Settlement, of the Viet Nam Combat Veterans’ Settlement Presentation to Hon. Jack B. Weinstein, Chief Judge, USDC/EDNY on 8 November 1984

I have taken the liberty of consolidating a variety of sources dealing with the theoretical foundations of Delphi in order to briefly summarize the basic philosophical foundation underlying the method and techniques. * * * the paraphrases and oversimplifications are my fault not those of the distinguished sources from whom I appropriated the material.


Delphi may be characterized as a method for structuring a group communication process to allow a group of disparate individuals, as a whole, to deal with a complex problem. To accomplish this “structured communication” Delphi provides feedback among individual contributors of information and knowledge; assessment of the group judgment or view; opportunity for individuals to revise views; and some degree of anonymity for the individual responses.

  • It is not, however, the explicit nature of the application which determines the appropriateness of utilizing Delphi; rather, it is the particular circumstances surrounding the group communication process necessarily associated with those circumstances. * * * One or more of the following properties of the application indicates a need for employing Delphi methods and techniques:
    The problem does not lend itself to precise analytical techniques but can benefit from subjective judgments reached through collective effort.
  • The individuals needed to contribute to the examination of a broad or complex problem have no established history of adequate communication among themselves and may represent diverse backgrounds, experience, and expertise.
  • More individuals are needed to consider the problem than can effectively interact in a fact-to-face exchange.
  • Time and cost make frequent group meetings economically inefficient and the associated transactional-costs of such meetings prohibitive.
  • The efficiency of face-to-face meetings can be increased by a supplemental group communication process.
  • Disagreements among individuals are so intense or so politically sensitive or emotionally charged that the communication process must be refereed and some measure of anonymity assured.
  • The heterogeneity of the participants must be preserved to assure validity of the results.

The early success of environmental litigation as an effective driving force in American society and the evolution of the environment movement out of the DDT litigation of 1966, as well as the successful management of the Agent Orange litigation from 1978 when it was begun, through October of 1983 when a Plaintiffs’ Management Committee took over, are both examples of the practical applications of Delphi methods and techniques to the resolution of complex legal issues in the context of social, political, economic, and legal uncertainty. The historical association between Delphi and military/industrial/social/political policy making, particularly during the war in Viet Nam cannot be overlooked.

Delphi methods are among the most cost-effective and economically efficient procedures for reaching consensus on complex and controversial matters. Certainly a method of which can involve many more people than can be effectively brought together as a conventional committee meeting should make a Delphi effort attractive.

The Delphi Process

The Delphi process originated as a “paper-and-pencil” exercise which was a combination of a polling procedure and a conference procedure. The modern form, sometimes called a Delphi Conference, or realtime Delphi uses interactive computer communications over secure virtual private networks.However, the inherent limitations of even state-of-the-art electronic data processing requires that the characteristics of the communications be well defined before the Delphi Conference is placed on-line.

Delphi efforts pass through four distinct phases:

  • Exploration of the subject under discussion. Each individual contributes additional information they believe is pertinent to the issue.
  • Reaching an understanding of how the group views the issue; determination of what matters the members agree or disagree about and what they mean by relative terms such as importance, desirability, or feasibility.
  • If there is significant disagreement, then that disagreement is explored to bring out the underlying reasons for the differences and to evaluate them.
  • A final evaluation occurs when all previously gathered information has been initially analyzed and the evaluations have been fed-back to the respondents for further consideration.

* * * Although Delphi seems like a very simple concept that can easily be employed, there have been notable failures particularly in the area of military and government policy. Some of the reasons for the failure of a Delphi are:

  • Imposing preconceptions of a problem upon the respondent group.
  • Not allowing consideration of diverse and controversial perspectives on the problem.
  • Poor techniques of summarizing and presenting the group response.
  • Failing to assure common interpretations of the evaluation scales utilized by the participants.
  • Ignoring or failing to explore disagreements so that an artificial consensus is generated.
  • Underestimating the demanding nature of a Delphi and failing to allocate enough human and economic resources to the effort.

* * * The realtime Delphi is conceptually analogous to a randomly occurring conference call where a written record might be automatically produced.

The Evolution of Delphi

Project Delphi was the name given to an Air Force-sponsored Rand Corporation study, starting in the early 1950s, concerning the application of expert opinion to the selection, from the point of view of a Soviet strategic planner, of an optimal U.S. industrial target system and to the estimation of the number of A-bombs required to reduce the munitions output by a prescribed amount.

The objective of the original study was to obtain the most reliable consensus of opinion of a group of experts by a series of intensive questionnaires interspersed with controlled opinion feedback.

The alternative method of handling this problem at that time would have involved a very extensive and costly data-collection process and the programming and execution of computer models of almost prohibitive size.

The original justifications for this first Delphi study are still valid for many Delphi applications today when models require so many subjective inputs that unverifiable opinions and personal judgments become the dominating parameters.


One of the most perceptive insights of modern systems analysis has been the demonstration that systems are most stable and collective judgments most informed and least precipitous the greater the opportunity for dynamic, interactive, positive and negative feedback opportunities operate among the disparate elements of any complex system. There is, of course, no more complex system known to natural science or philosophy than a group of individual human organisms attempting to reach a consensus.