The following points compare and contrast the Nominal Group Technique (NGT) and the Delphi Method (DM) (Centers for Disease Control and Prevention, 2006, Sample, 1984 and Wikipedia, 2014):
Similarities
(1.) Both techniques can be used to synthesize or aggregate the opinions of multiple experts.
(2.) Experts get to see and, therefore, know the opinions that other experts have furnished.
(3.) With both techniques, each expert’s opinion carries some weight in the final aggregated, synthesized opinion.
(4.) Both techniques are similar to a brainstorming session.
Differences
(1.) Unlike the DM, the NGT does not employ iterations or repetition of the procedure of expert opinion elicitation and expert opinion aggregation/synthesis – the NGT is a very linear, channeled process.
(2.) Even though experts see/know the opinions, which other experts have furnished, the following are differences in how experts get to see/know the opinions, which other experts have furnished:
a.) With the DM, these experts don’t know which expert(s) gave what opinions(s), because these opinions are provided to the experts with anonymity.
b.) With the NGT, there is no anonymity in the sharing of the opinions that various experts furnish during the session (so experts know which expert[s] gave what opinions[s]).
(3.) The time during which experts get to see/know the opinions of other experts is different with DM from the NGT, namely:
a.) With the DM, experts get to see/know the opinions of other experts during the time that the various iterations are performed.
b.) With the NGT, experts get to see/know the opinions of other experts during the time that experts learn of and rank the opinions of other experts.
(4.) With the NGT, the aggregated/synthesized opinion is both required and reached quickly, comparatively speaking (typically, usually within the duration of a meeting), while the DM is not employed for applications for which the aggregated/synthesized opinion has to be reached quickly (the exception to this is the modified DM for which the aggregated/synthesized opinion is reached and required in real-time, e.g., during a meeting).
(5.) Experts perform some voting with the NGT, but, with the DM, experts simply express their opinions as well as adjust these opinions, based on what they learn from other experts’ opinions (with the DM, experts never actually vote on various opinions by various experts).
Application of the NGT
Even though there are ideal situations when either both the NGT and the DM may be applied, Sample (1984) says that the NGT is probably not used as often as it ought to be used. In general, the situations that should call for the application of the NGT are those situations, which enable one or more advantages of the NGT to be exploited; the following are the situations for which it will be advantageous to apply the NGT (Centers for Disease Control and Prevention, 2006, Sample, 1984 and Wikipedia, 2014):
(1.) There is the need to minimize “noise” – i.e., distractions and unease resulting from inter-expert communications.
(2.) There are participating experts who are either too introverted or unwilling to speak up or others who are too dominating, intimidating and commandeering.
(3.) There is the need to prioritize the sub-opinions generated by the group.
(4.) The topic on which expert opinions will be sought is highly controversial (the NGT procedure assuages/alleviates the heated and highly conflicting intermingling of opinions on topics/issues that are characterized by controversy).
(5.) There is the need to arrive at convergence in a short time, comparatively speaking.
(6.) The application requires only one problem to be addressed at a time.
(7.) The application does not require spontaneous, free-flowing and organic generation and development of ideas/opinions (the NGT procedure is mechanical as well as entails restraining participants to some extent).
An example of a situation for which it will be advantageous to apply the NGT is to inquire of experts whether or not it is appropriate to dismantle the space shuttle program before the USA has developed, tested and gotten the shuttle replacement or successor ready to be flown in space. My conjecture is that the application of a well-applied expert opinion elicitation technique, such as the NGT, will furnish what should be incontrovertible basis for dismantling the space shuttle program before the USA has developed, tested and gotten the shuttle replacement or successor ready to be flown in space. The NGT may be applied for some of the applications of the DM, including forecasting, policy-making and decision-making.
References
Centers for Disease Control and Prevention (2006). Gaining Consensus Among Stakeholders Through the Nominal Group Technique. Retrieved from www.cdc.gov/healthyyouth/evaluation/pdf/brief7
Defense Acquisition University. Nominal Group Technique (NGT). Retrieved from https://learn.test.dau.mil/CourseWare/149_9/M2/ngt.htm
Flylib (2013). Tool 61: Delphi Method. Retrieved from http://flylib.com/books/en/2.890.1.146/1/
Sample, J. A. (1984). Nominal group technique: An alternative to brainstorming. Journal of Extension, 22(2), 1-2
Wikipedia: The Free Encyclopedia (2014). Nominal group technique. Retrieved from http://en.wikipedia.org/wiki/Nominal_group_technique
Similarities
(1.) Both techniques can be used to synthesize or aggregate the opinions of multiple experts.
(2.) Experts get to see and, therefore, know the opinions that other experts have furnished.
(3.) With both techniques, each expert’s opinion carries some weight in the final aggregated, synthesized opinion.
(4.) Both techniques are similar to a brainstorming session.
Differences
(1.) Unlike the DM, the NGT does not employ iterations or repetition of the procedure of expert opinion elicitation and expert opinion aggregation/synthesis – the NGT is a very linear, channeled process.
(2.) Even though experts see/know the opinions, which other experts have furnished, the following are differences in how experts get to see/know the opinions, which other experts have furnished:
a.) With the DM, these experts don’t know which expert(s) gave what opinions(s), because these opinions are provided to the experts with anonymity.
b.) With the NGT, there is no anonymity in the sharing of the opinions that various experts furnish during the session (so experts know which expert[s] gave what opinions[s]).
(3.) The time during which experts get to see/know the opinions of other experts is different with DM from the NGT, namely:
a.) With the DM, experts get to see/know the opinions of other experts during the time that the various iterations are performed.
b.) With the NGT, experts get to see/know the opinions of other experts during the time that experts learn of and rank the opinions of other experts.
(4.) With the NGT, the aggregated/synthesized opinion is both required and reached quickly, comparatively speaking (typically, usually within the duration of a meeting), while the DM is not employed for applications for which the aggregated/synthesized opinion has to be reached quickly (the exception to this is the modified DM for which the aggregated/synthesized opinion is reached and required in real-time, e.g., during a meeting).
(5.) Experts perform some voting with the NGT, but, with the DM, experts simply express their opinions as well as adjust these opinions, based on what they learn from other experts’ opinions (with the DM, experts never actually vote on various opinions by various experts).
Source: Flylib (2013)
Figure 1: Illustration of the DM Applied in Forecasting the Outcome of Employing an Approach for Product Development
Source: Defense Acquisition University
Figure 2: Illustration of the NGT Applied in Decision-Making Regarding the Relative Importance of Various Issues
Application of the NGT
Even though there are ideal situations when either both the NGT and the DM may be applied, Sample (1984) says that the NGT is probably not used as often as it ought to be used. In general, the situations that should call for the application of the NGT are those situations, which enable one or more advantages of the NGT to be exploited; the following are the situations for which it will be advantageous to apply the NGT (Centers for Disease Control and Prevention, 2006, Sample, 1984 and Wikipedia, 2014):
(1.) There is the need to minimize “noise” – i.e., distractions and unease resulting from inter-expert communications.
(2.) There are participating experts who are either too introverted or unwilling to speak up or others who are too dominating, intimidating and commandeering.
(3.) There is the need to prioritize the sub-opinions generated by the group.
(4.) The topic on which expert opinions will be sought is highly controversial (the NGT procedure assuages/alleviates the heated and highly conflicting intermingling of opinions on topics/issues that are characterized by controversy).
(5.) There is the need to arrive at convergence in a short time, comparatively speaking.
(6.) The application requires only one problem to be addressed at a time.
(7.) The application does not require spontaneous, free-flowing and organic generation and development of ideas/opinions (the NGT procedure is mechanical as well as entails restraining participants to some extent).
An example of a situation for which it will be advantageous to apply the NGT is to inquire of experts whether or not it is appropriate to dismantle the space shuttle program before the USA has developed, tested and gotten the shuttle replacement or successor ready to be flown in space. My conjecture is that the application of a well-applied expert opinion elicitation technique, such as the NGT, will furnish what should be incontrovertible basis for dismantling the space shuttle program before the USA has developed, tested and gotten the shuttle replacement or successor ready to be flown in space. The NGT may be applied for some of the applications of the DM, including forecasting, policy-making and decision-making.
References
Centers for Disease Control and Prevention (2006). Gaining Consensus Among Stakeholders Through the Nominal Group Technique. Retrieved from www.cdc.gov/healthyyouth/evaluation/pdf/brief7
Defense Acquisition University. Nominal Group Technique (NGT). Retrieved from https://learn.test.dau.mil/CourseWare/149_9/M2/ngt.htm
Flylib (2013). Tool 61: Delphi Method. Retrieved from http://flylib.com/books/en/2.890.1.146/1/
Sample, J. A. (1984). Nominal group technique: An alternative to brainstorming. Journal of Extension, 22(2), 1-2
Wikipedia: The Free Encyclopedia (2014). Nominal group technique. Retrieved from http://en.wikipedia.org/wiki/Nominal_group_technique
