Delphi Technique- A Review

Balasubramanian et al

International Journal of Public Health Dentistry

REVIEW ARTICLE Delphi Technique- A Review Ramya Balasubramanian, Deepti Agarwal

Abstract Surveys play a major role in health sciences research. Delphi technique is a kind of detailed survey having diversified uses in dental research. It is a method for the systematic solicitation and collation of judgments on a particular topic through a set of carefully designed sequential questionnaires interspersed with summarized information and feedback of opinions derived from earlier responses. Many important clinical issues do not yield to randomized clinical trials or to stepwise quantitative data analysis. In such cases, professionals use their training and personal anecdotal experience to assist decision making in a variety of practice contexts. In these circumstances, consensus opinion of experts provides a formal structured process for decision making. Consensus procedures also use the resources of all participants, commit them to the project, and enhance the future decision-making ability of the group with regard to resolution of the clinical problem addressed. Delphi process consists of a series of rounds; in each round every participant worked through a questionnaire which has to be returned to the researcher who collected, edited, and returned to every participant, a statement of the position of the whole group and the participant‟s own position about the research issue. Every participant reassesses their initial judgments about the information provided in previous iterations. This article aims at describing the methodology of Delphi technique. Keywords: Delphi; Survey; Consensus; Expert Opinion.

Introduction

(RAND), Santa Monica, California, in the early

Field of dentistry has seen lot of revolutions and

1960s. The questions of RAND thinkers, at the

developments. It keeps developing from heaps

time, primarily dealt with the military potential of

of research from various parts of the world.

future technology and potential political issues

Surveys play a major role in health sciences

and their resolution. Olaf Helmer, Nicholas

research. Delphi technique is a kind of detailed

Rescher, Norman Dalkey, and others at RAND

survey

developed the Delphi method, which was

having

diversified

uses

in

dental

research. For a thousand years of recorded

designed

history the Greeks and other peoples, came to a

impediments to a true expert consensus. 'Delphi'

temple in Delphi, a place in Greece to consult

was intentionally coined by Kaplan, an associate

prophetess, who was called Pythia. They

professor of philosophy working for the RAND

predicted the future and the divine purpose in a

corporation in a research effort directed at

normative way in order to shape coming events

improving the use of expert predictions in policy-

to the people. The temple was the locus of

making(1).

knowledge, and the Delphic oracle was probably

Delphi

is

to

a

remove

method

conference

for

the

room

“systematic

the largest database of the ancient world. This

solicitation and collation of judgments on a

gave the world the new technique called Delphi.

particular topic through a set of carefully

The Delphi technique was initially developed by

designed sequential questionnaires interspersed

1

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International Journal of Public Health Dentistry

with summarized information and feedback of

the Nominal Group Technique can be used to

opinions derived from earlier responses” (2, 3).

develop consensus but without the limitations of

The majority of the Delphi efforts during the first

more informal methods of reaching consensus

decade were for pure forecasting, including both

such as committees, which are prone to

short- and long-range forecasts. Follow-up

domination

studies have demonstrated the validity and long-

influenced by personalities (5).

range accuracy of the Delphi technique. While

Delphi methodology

by

powerful

individuals

and

most forecasting studies use Delphi to surface a consensus opinion, others such as the study by Kendall et al. emphasize differences of opinion in order to develop a set of alternative future scenarios. Concept / framework development represents a second type of application of the

The present review aims in providing a broader of

the

methodology

of

Delphi

Formal consensus methodology theorists argue that opinions of experts generated through structured circumstances can generate a closer approximation of the objective truth than would be achieved through conventional, less formal, and pooling of expert opinion. The methods include the nominal group technique, the Delphi the

Glaser

„„state-of-the-art

technique,‟‟ etc. The „„Delphi technique‟‟ and the „„nominal group technique‟‟ are the two methods

Many important clinical issues do not yield to clinical

trials

or

to

stepwise

quantitative data analysis. In such cases, professionals use their training and personal

Methods‟

commonly

used

to

synthesise information from conflicting evidence. Consensus methods are primarily concerned with deriving quantitative estimates through approaches.

circumstances, consensus opinion of experts provides a formal structured process for decision making. Consensus procedures also use the resources of all participants, commit them to the project, and enhance the future decision-making ability of the group with regard to resolution of the clinical problem addressed (4). The Delphi method is mainly used when longterm issues have to be assessed. It reduces the tacit and complex knowledge to a single statement and makes it possible to judge upon.

with the longest history (4).

qualitative

experts (1).

in a variety of practice contexts. In these

Consensus methods

„Consensus

information of the participants, who are mainly

anecdotal experience to assist decision making

technique.

technique,

surveys and makes use of the intuitive available

randomized

Delphi method (3).

overview

The Delphi method is based on structural

Delphi

Methods

concentrate on measuring consensus whereas

Content of Delphi studies are always issues about which, unsure and incomplete knowledge exists. Delphi are judgement processes with unsure aspects. For the participation experts are to be involved who on the basis of their knowledge and experience are able to assess in a competent way (1). (Table 1)

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Table 1: Comparison between normal surveys and Delphi surveys (3) Evaluation criteria

Traditional survey

Delphi study

Representativeness sample

Using statistical sampling techniques, the researchers randomly select a sample that is representative of the population of interest.

A Delphi study is a virtual panel of experts gathered to arrive at an answer to a difficult question. Thus, a Delphi study could be considered a type of virtual meeting or as a group decision technique, though it appears to be a complicated survey.

Sample size for statistical power and significant findings

Because the goal is to generalize results to a larger population, the researchers need to select a sample size that is large enough to detect statistically significant effects in the population.

The Delphi group size does not depend on statistical power, but rather on group dynamics for arriving at consensus among experts. Thus, the literature recommends 10–18 experts on a Delphi panel.

Anonymity

Respondents are almost always anonymous to each other, and often anonymous to the researcher.

Respondents are always anonymous to each other, but never anonymous to the researcher. This gives the researchers more opportunity to follow up for clarifications and further qualitative data.

Non-response issues

Researchers need to investigate the possibility of non-response bias to ensure that the sample remains representative of the population.

Non-response is typically very low in Delphi surveys, since most researchers have obtained assurance of participation

Attrition effects

For single surveys, attrition (participant drop-out) is a non-issue. For multi-step repeated survey studies, researcher should investigate attrition to assure that it is random and non-systematic.

Similar to non-response, attrition tends to be low in Delphi studies, and the researchers usually can easily ascertain the cause by talking with the dropouts.

Richness of data

The richness of data depends on the form and depth of the questions, and on the possibility of follow-up, such as interviews.

Delphi studies inherently provide richer data because of their multiple iterations and their response revision due to feedback.

of

Issues for which Delphi is commonly used (6,7) In the literature, Delphi has been applied in various fields such as program planning, needs

3. To seek out information, which may generate a consensus. 4. To correlate informed judgments on a topic spanning a wide range of disciplines.

assessment, policy determination, and resource utilization. Delbecq, Van de Ven, and Gustafson (1975) specifically indicate that the Delphi technique can be used for achieving the following objectives: 1. To determine or develop a range of possible program alternatives. 2. To explore or expose underlying assumptions or information leading to different judgments.

5. To educate the respondent group as to the diverse and interrelated aspects of the topic. Implementing a Delphi technique The Delphi technique is well suited as a means and method for consensus-building by using a series of questionnaires to collect data from a panel of selected subjects Delphi, in contrast to other data gathering and analysis techniques, employs multiple iterations. Iterations refer to the

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feedback process. The process consists of a

collected

series of rounds; in each round every participant

questionnaire. This questionnaire is used as the

worked through a questionnaire which has to be

survey instrument for the second round of data

returned to the researcher who collected, edited,

collection (6). After the first round the data is

and returned to every participant, a statement of

analyzed and responses to questions could be

the position of the whole group and the

grouped or categorized by frequency or other

participant‟s own position about the research

criteria (2). The Delphi questionnaires will be

issue. Every participant reassesses their initial

administered using e-mail, fax, and the web. The

judgments about the information provided in

panellists will be free to use whichever of these

previous rounds. More specifically, the feedback

media was most convenient (3).

process allows the selected Delphi participants

Round 2: In the second round, each Delphi

to reassess their initial judgments about the

participant receives a second questionnaire and

information provided in previous iterations. Thus,

is asked to review the items summarized by the

in a Delphi study, the results of previous

investigators based on the information provided

iterations regarding specific statements and/or

in the first round. Accordingly, Delphi panellists

items can change or be modified by individual

may be required to rate or rank-order items to

panel members in later iterations based on their

establish preliminary priorities among items. As

ability to review and assess the comments and

a result of round two, areas of disagreement and

feedback provided by the other Delphi panellists

agreement are identified (2, 6).

(6).

information

into

a

well-structured

Round 3: In the third round, each Delphi

Theoretically,

be

panellists receives a questionnaire that includes

continued until consensus is determined to have

the items and ratings summarized by the

been achieved. However, Cyphert and Gant

investigators in the previous round and are

(1971), Brooks (1979), Ludwig (1994, 1997),

asked to revise his/her judgments or to specify

and Custer, Scarcella, and Stewart (1999) point

the

out that three iterations are often sufficient to

consensus. This round gives Delphi panellists

collect the needed information and to reach a

an opportunity to make further clarifications of

consensus in most cases (6).

both the information and their judgments of the

Steps in Delphi

relative importance of the items. However,

Round 1: In the first round, the Delphi process

compared to the previous round, only a slight

traditionally

open-ended

increase in the degree of consensus can be

open-ended

expected (2, 6).

questionnaire

the

Delphi

begins

with

(2).

process

an

The

can

questionnaire serves as the cornerstone of soliciting specific information about content. The questionnaire could contain ten to fifteen openended

questions.

After

receiving

subject‟s

responses, investigators need to convert the

reasons

for

remaining

outside

the

Round 4: In the fourth and often final round, the list of remaining items, their ratings, minority opinions, and items achieving consensus are distributed to the panellists. This round provides a final opportunity for participants to revise their

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Balasubramanian et al

International Journal of Public Health Dentistry

judgments. It should be remembered that the

Procedure for selecting experts (3)

number of Delphi iterations depends largely on

1. Prepare a Knowledge Resource Nomination

the

degree

of

consensus

sought

by the

Worksheet (KRNW): The purpose of the

investigators and can vary from three to five (6).

Knowledge

before identifying them, in order to prevent

Regarding the selection of subjects for a Delphi

overlooking any important class of experts.

study, choosing the appropriate subjects is the most important step in the entire process

2. Populating the KRNW with names: After the KRNW is completed, the following iterative

because it directly relates to the quality of the

procedure will be used to populate the

results generated. Delphi subjects should be trained

and

competent

within

categories with actual names of potential

the

experts for the Delphi study. Each heading

specialized area of knowledge related to the

(disciplines, organizations, and literature)

target issue. Investigators need to closely examine

and

seriously

consider

represents a different lens for identifying and

the

considering experts. However, this multiple

qualifications of Delphi subjects (2, 6).

lens perspective is necessary to identify as

Linstone, Turoff, and Moore recommend a panel

many experts as possible.

of 15 to 30 participants from the same discipline, or

5

to

10

Nomination

Worksheet is to help categorize the experts

Subject selection

highly

Resource

per

category

from

different

3. Rank experts: Create sub-lists, one for each discipline. Categorize experts according to

professional groupings (8, 9).

appropriate list. Rank experts within each list

Delbecq, Van de Ven, and Gustafson (1975)

based on their qualifications.

recommend that researchers should use the minimally sufficient number of subjects and

4. Inviting experts: Invite experts for each panel, with the panels corresponding to

should seek to verify the results through follow-

each discipline. Invite experts in the order of

up explorations ten to fifteen subjects could be

their ranking within their discipline sublist.

sufficient if the background of the Delphi

Target size is 10-18. Stop soliciting experts

subjects is homogeneous. In contrast, if various

when each panel size is reached.

reference groups are involved in a Delphi study, more subjects are needed. If the sample size of a Delphi study is too small, these subjects may not be considered as a representative pooling of judgments regarding the target issue. If the sample size is too large, the drawbacks inherent within the Delphi technique such as potentially low response rates and the obligation of large blocks of time by the respondents and the researchers can be the result (6).

Duration of the study Delbecq, Van de Ven, and Gustafson (1975), Ulschak (1983), and Ludwig, (1994) recommend that a minimum of 45 days for the administration of a Delphi study is necessary. With regard to the

time

management

between

iterations,

Delbecq et al. (1975) note that giving two weeks for Delphi subjects to respond to each round is encouraged (6).

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Statistical analysis

dominant individuals

In the Delphi process, data analysis can involve

concern when using group-based processes

both qualitative and quantitative data. The major

used to collect and synthesize information

statistics used in Delphi studies are measures of

(5,6). Additionally, the issue of confidentiality

central

dispersion

is facilitated by geographic dispersion of the

(standard deviation and inter-quartile range) in

subjects as well as the use of electronic

order to present information concerning the

communication such as e-mail to solicit and

collective judgments of respondents (Hasson,

exchange information (6).

tendency

and

level

of

which often is

a

Keeney, and McKenna, 2000). Generally, the

2. Controlled feedback process consists of a

uses of median and mode are favored. In the

well-organized summary of the prior iteration

literature, the use of median score, based on

intentionally distributed to the subjects which

Likert-type scale, is strongly favored (Hill and

allows each participant an opportunity to

Fowles, 1975; Eckman, 1983; Jacobs, 1996)

generate

(2,6).

thoroughly clarify the information developed

Arriving at conclusion

by previous iterations (6).

One criterion recommends that consensus is

3. The

additional

ability

to

insights

use

and

statistical

more

analysis

achieved by having 80 percent of subjects‟ votes

techniques further reduces the potential of

falling within two categories on a seven-point

group pressure for conformity (6).

scale (Ulschak, 1983). Green (1982) suggests

4. The main advantage of the Delphi method is

that at least 70 percent of Delphi subjects need

that there is no need for participants (e.g.

to rate three or higher on a four point Likert-type

busy professionals or managers) to meet up

scale (5,6) and the median has to be at 3.25 or

and, hence it is a relatively inexpensive

higher (6).

method of gaining a large number of

Time requirements

responses (5).

Delbecq, Van de Ven, and Gustafson (1975),

5. It also allows the involvement of participants

Ulschak (1983), and Ludwig, (1994) recommend

from disparate geographical areas and has

that a minimum of 45 days for the administration

been used in international health research

of a Delphi study is necessary. With regard to

(5).

the

time

management

between

iterations,

Delbecq et al. (1975) note that giving two weeks for Delphi subjects to respond to each round is encouraged (6). Merits and demerits in technique Merits 1. One of the primary characteristics and advantages of the Delphi process is „subject anonymity‟ which can reduce the effects of

Demerits 1. Potential of Low Response Rates: due to the multiple feedback processes inherent and integral to the concept and use of the Delphi process, potential exists for low response rates

and

striving

to

maintain

robust

feedback can be a challenge (6). 2. Consumption of Large Blocks of Time: the Delphi

technique

can

also

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be

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consuming and laborious. Unlike other data

of experts, with a second questionnaire based

collection techniques such as the telephone

on

survey and the face-to-face administration,

questionnaires refine and define the facts or

which can be simultaneously conducted by a

proposals, gauging their accuracy or support

group of people and can be completed in a

from the participants. The real-time or modified

short period of time if the sample size is

Delphi is a shorter variant, where the process

small, the Delphi technique is iterative and

takes place during the course of a meeting,

sequential (6,7).

using mechanisms to summarize responses to

the

results

of

the

first.

Subsequent

3. Potential of Molding Opinions: the iteration

the respondents immediately. The policy Delphi

characteristics of the Delphi technique can

is a forum for ideas where the decision maker is

potentially enable investigators to mold

interested in having informed group present

opinions. An assumption concerning Delphi

options and supporting evidence rather than

participants is that they are equivalent in

having a group reach a decision (9).

knowledge and experience. However, this The Delphi technique in Public Health

assumption might not be justified (6). 4. Centralise

opinion:

the

consensus

method,

it

Delphi tries

to

is

a

obtain

consensus and to „centralise opinion‟ and important minority issues may be missed due to nonconformity of general opinion. Loss of objectivity and researcher bias in analysing findings and generating questions are also possible (5).

The Delphi technique is becoming increasingly popular in health and social research and has been used for various purposes in obtaining a wide variety of outcomes. In the Indian scenario to arrive at the consensus regarding the various health sector reforms a Delphi study was conducted in 2000 and 2001 among experts. The questions were: (i) within the context of health sector reforms, what are

Classification of the Delphi technique

the priority issues for India? (ii) is there a

There are several types of Delphi (8)

consensus in the country on the health sector



The Classic Delphi



The Policy Delphi



The Decision Delphi



The Group Delphi

reforms? If yes, in which areas? (iii) what are the areas where differences exist? And (iv) how should

The Policy, Decision and Group Delphi are variations of the Classic Delphi.

the

identified

priority

issues

be

addressed? (10). Examples of Delphi in public health include „Policy Delphi‟ applied to achieve national level policy making on child health indicators in Hong Kong (11). In a recent study, a modified Delphi technique was used to

Another author classifies Delphi as conventional,

develop international policy options for severe

real-time and policy. The conventional Delphi is

acute respiratory syndrome (SARS) and SARS-

the classical forum for the prioritization of facts.

like

It consists of a questionnaire sent out to a group

evaluation reported it to be an effective tool in

emerging

infectious

diseases

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and

its

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certain Public Health debates. This method was

Conclusion

also used in evaluation of Public health functions (12-14). A Delphi study was conducted regarding

The Delphi method is a versatile research tool

reproductive and maternal health in United

that researchers can employ at various points in

Kingdom (5).

their research. Use of the Delphi method for forecasting and issue identification/prioritization

Delphi researches in dentistry

can be valuable in the early stages, particularly

The Delphi technique has also been used to

in selecting the topic and defining the research

achieve consensus of opinion on an array of oral

questions (3).

health issues. Delphi studies were used in various branches of Dentistry for policy making, consensus decisions and even in developing dental curriculum (4). Delphi was conducted to find out factors influencing dental decision making (15), to identify core competencies in geriatric dentistry (16). Delphi technique was applied

for

deriving

consensus

regarding

curriculum for periodontics (17). Modified Delphi survey was used for decision analysis regarding prophylaxis of post-radiation osteonecrosis (18). A Delphi panel was used to survey criteria for successful periodontal therapy in anterior teeth

Based on literature review, it appears that Delphi is the most popular consensus method because of the need and value of obtaining consensus opinions and may be applied to evaluate clinical, educational, and policy issues in oral health care (7). It can be considered as a wonderful research tool to derive consensus and solutions in many of the unresolved oral health issues at national and international levels.

Affiliations of the authors:

1. Dr. Ramya Balasubramanian, Senior Lecturer, Department of Public Health Dentistry, R.V.S Dental College and Hospital, Coimbatore, Tamil Nadu, India, 2. Dr. Deepti Agarwal, Senior Lecturer, Department of Public Health Dentistry, Dr.D.Y.Patil Dental College, Pune, Maharashtra, India.

(19) and also to study the current trends in restorative dentistry in the United Kingdom (20).

Conflict of Interest:

In the Indian scenario there are lot of dental

Source of Funding: Nil.

public health issues remaining unresolved and the literature review shows very few Delphi studies has been carried out in this context.

The author(s) declared no conflict of interests.

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Dr. Ramya Balasubramanian , MDS, Senior lecturer, Department of Public Health Dentistry, R.V.S Dental College and Hospital, Coimbatore, Tamil Nadu, India. email id – [email protected]

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