The Delphi technique is a systematic and interactive forecasting method that was originally conceived as a way to obtain the opinion of a panel of experts without necessarily bringing them together face to face. The experts answer a questionnaire in two or more rounds.
After each round, a facilitator provides an anonymous summary of the experts’ forecast from the previous round as well as the reasons they provided for their judgments.
Thus, experts are encouraged to revise their earlier answers in the light of the replies of other members of their panel.
It is believed that during this process, the range of the answers vis-i-vis the variations, will decrease and the group will converge towards the “correct” answers.
Finally, the process is stopped after a pre-defined stop criterion (e.g., number of rounds, the achievement of consensus, stability, and consistency of the results), and the mean or median scores of the final rounds determine the results.
Delphi is based on the principle that forecasts from a structured group of experts that are more accurate and valid than those from an unstructured group of individuals.
The technique can be adapted for use in face-to-face meetings, and then is called mini-Delphi or Estimate-Talk-Estimate (ETE).
The person coordinating the Delphi technique is known as a facilitator and facilitates the responses of their panel of experts, who are selected for a reason, usually that they hold knowledge on an opinion or view.
The facilitator sends out questionnaires, forms, check-list, etc. and if the panel of experts accepts, they follow instructions and present their views.
Responses are collected and analyzed, and then common and conflicting viewpoints are identified.
If consensus is not reached, the process continues through thesis and antithesis, to gradually work towards synthesis, and building consensus.
History of Delphi technique
The name “Delphi” is derived from the Oracle of Delphi. The authors of the method were not happy with this name because it implies “something oracular, something smacking a little of the occult.”
The Delphi method is based on the assumption that group judgments are more valid than individual judgments. It was developed at the beginning of the Cold War to forecast the impact of technology on warfare.
In 1944, General Henry H. Arnold ordered the creation of the report for the U.S. Army Air Corps on the future technological capabilities that might be used by the military.
Different approaches were tried, but the shortcomings of traditional forecasting methods, such as theoretical approach, quantitative models, or trend extrapolation, in areas where precise scientific laws have not been established yet, quickly became apparent.
To combat these shortcomings, the Delphi method was developed by Project RAND during the 1950-1960s (1959) by Olaf Helmer, Norman Dalkey, and Nicholas Rescher.
It has been used ever since, together with various modifications and reformulations, such as the Imen-Delphi procedure.
Experts were asked to give their opinion on the probability, frequency, and intensity of possible enemy attacks. Other experts could anonymously give feedback. This process was repeated several times until a consensus emerged.
Characteristics of the Delphi technique
We enumerate below a few key characteristics of the Delphi technique:
Structuring of information flow
The initial contributions from the experts are collected in the form of answers to questionnaires and their comments to the answers.
The panel director, also called facilitator, controls the interactions among the participants by processing the information and filtering out irrelevant content.
This avoids the negative effects of face-to-face panel discussions and solves the usual problems of group dynamics.
Participants comment on their forecasts, the responses of others, and on the progress of the panel as a whole. At any point in time, they can revise their earlier statements.
While in regular group meetings, the participants tend to stick to their previously stated opinions and often conform too much to the group leader, the Delphi method prevents it.
The anonymity of the participants
Usually, all participants maintain anonymity. Their identity is not revealed even after the completion of the final report.
This stops them from dominating others in the process using their authority or personality, frees them to some extent from their personal bias, minimizes the ‘bandwagon effect,’ allows them to freely express their opinions, encourages open critique, and admits errors by revising earlier judgments.
Uses of Delphi technique
Delphi has been widely used for business forecasting and has certain advantages over other structured forecasting approaches. Initially, applications of the Delphi technique were in the field of science and technology forecasting.
The objective of the method was to combine expert opinions on the likelihood and expected development time of the particular technology in a single indicator.
One of the first such reports, prepared in 1964 by Gordon and Helmer, assessed the direction of longterm trends in science and technology development, covering such topics as scientific breakthroughs, population control, automation, space progress, war prevention, and weapon systems.
Other forecasts were dealing with vehicle-highway systems, industrial robots, intelligent internet, broadband connections, and technology in education.
Later the Delphi method was applied in other areas, especially those related to public policy issues, such as economic trends, health, and education.
It was also used successfully and with high accuracy in business forecasting. The Delphi method has also been used as a tool to implement multi-stakeholder approaches for participative policy-making in developing countries.
The government of Latin America and the Caribbean (LAC) have successfully used the Delphi method as an open-ended public-private sector approach to identify the most urgent challenges for their regional ICT- for- development of LAC Action Plan.
The major weakness of the Delphi method is that future developments are not always predicted correctly by a consensus of experts. Firstly, the issue of ignorance is important.
If panelists are misinformed about a topic, the use of Delphi may only add confidence to their ignorance. Secondly, sometimes unconventional thinking of amateur outsiders may be superior to expert thinking.
One of the initial problems of the method was its inability to make a complex forecast with multiple factors. Potential future outcomes were considered as if they did not affect each other.
Later on, several extensions to the Delphi method were developed to address this problem, such as cross-impact analysis that takes into consideration the possibility that the occurrence of one event may change probabilities of other events covered in the survey.
Still, the Delphi method can be used most successfully in forecasting single scalar indicators.
Despite these shortcomings, today, the Delphi method is a widely accepted forecasting tool. It has been used successfully for thousands of studies in areas varying from technology forecasting to drug abuse.