Delphi Method or NGT Method?

WHICH IS BETTER, DELPHI METHOD OR NGT METHOD?

Nominal Group Technique or method is best used when the panel may not know the full scale of this issue or problem.  These issues can be resolved by a combination of individual and group creativity using input from all panel members based on merit not status or position in the organization.

Delphi Method has been around since the 1950's and was developed by a team of researchers from the Rand Corporation.
It utilizes multiple rounds from panellists who are experts in their fields and have contributed significantly to the body of human knowledge.  They are surveyed on a specific issue or problem and they respond to the issue in each round till a quorum is reached to render a viable solution.

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 References

Delbecq, A. ;Van de Ven,A; and  Gustafson,D.; "Guidelines for conducting NGT meetings," in Group Techniques for Program Planning (Glenview, 111.: Scott Foresman, 1975).

DeStephen, R.; Hirokawa, R.; "Small group consensus: Stability of group support of the decision, task process, and group relationships," Small Croup Behavior, 19, 1988, 227-39.