The Nominal Group Technique and the Delphi Method

Today I am introducing going to discuss two group methods for gathering and evaluating subject matter expertise are the Nominal Group Technique (NGT) and the Delphi method.  The NGT offers a more immediate result which can then be refined through additional meetings as necessary.  The Delphi, adaptive to networked data calls, is conducive to gathering a wider and more reflective response however the technique is more time and labor intensive.  Though the intent and goals are similar, each approach has its supporters and critics.  Before recommending one process over another, Table 1 details the significant parallels and differences between NGT and Delphi. 

Table 1 - Compare and Contrast NGT with Delphi
Nominal Group Technique	Delphi Method
Compare
group brainstorming
forecast oriented
structured group of individuals
encourage contribution
facilitator moderated
solution ranking
seek group consensus
Contrast
Session time limit	Process stopped based upon predefined criteria
Each member writes their ideas in free form	Each member completes a questionnaire and comments
No discussion, questions, or clarification allowed	Participants are physically separated
Participants do not initially consult or discuss their ideas with others	Participants remain anonymous
Each member reads aloud their idea	Facilitator provides an anonymous summary of the each members’ contribution
Each member in turn states one idea	Participants remain anonymous
Wording may be changed only when the idea’s originator agrees	Participants may change their earlier answers
One round in one session	Two or more rounds over longer duration
Similar to up or down vote, therefore may be better for more narrow problems	May be better for more significant issues because of more time to research and respond

Delphi should be used if polling is appropriate and sufficient time is available.  The Delphi input may also be more candid than with the NGT.  However with Delphi there is more procedural work involved in gathering, evaluating, and repeating the session.

Despite the possibility of group influence upon individual participants, the NGT has the advantage of immediacy.  Prior knowledge of the subject can also be injected by means of the weighted rankings – this is helpful to get to the relevant results more quickly.  While not well adapted to larger groups, a smaller group is actually a strength if the participants are well versed in their respective areas.  However, the NGT requires an authoritative facilitator to instill discipline into the process, ensure a balanced representation of ideas, and arrive at a valid conclusion.  For an example of how NGT may be used Vella, Goldfrad, Rowan, Bion and Black (2000) formed a group of 10 doctors and 2 nurses to establish clinical and health services research priorities in critical care in the United Kingdom and Republic of Ireland.  Of the 1000 suggestions submitted for research, the expert group, considers 106 of the most frequently suggested topics of which 37 attracted strong support, 48 moderate support and 21 weak support.  The group’s views represented the views of the wider community of critical care staff (r = 0.73, P < 0.01).  The statistically valid results indicate that NGT was a feasible method to establish priorities for clinical and health services research in critical care based on the views of a small selected group of the principal clinicians involved – doctors and nurses.

With either NGT or Delphi there is administrative overhead associated with collecting the input and managing the participants; these are not simply brainstorming sessions and should be used appropriately to ensure the best results.  Yet if the investment in time and resources to create an NGT program yields supportable results, then the effort may actually prove to be an economical collection model over time if reused.

References

Vella, K., Goldfrad, C., Rowan, K., Bion, J., & Black, N. (2000). Use of consensus development to establish national research priorities in critical care. BMJ: British Medical Journal, 320(7240), 976.