Scriptapedia/Nominal Group Technique

Nominal Group Technique

This script may be used to get an initial idea of central concepts at the beginning of a project or as a subscript (e.g., within "Graphs Over Time") to generate an initial set of ideas (e.g., variables or dynamics).


Best practices

Primary nature of group task:



Preparation time: 10 minutes

Time required during session: 20 minutes

Follow-up time: 0 minutes




Individuals or teams with sets of ideas


List of ideas


  • Facilitator with experience in system dynamics modeling and either nominal group technique (NGT) or brainstorming with groups


  1. Ask the participants to write down ideas about things that involve the problem variable. These might be causes or consequences of the problem, or any elements a participant feels are important to the issue at hand. Ask the participants to do this as much as possible in terms of variables.
    • Explain that a variable is something that may increase or decrease over time. It does not already have a value on a particular scale, such as "young employees." In this case, the average age of employees would be included so that the value may increase or decrease over time.
    • Also avoid categorical or nominal variables, such as the type of a chosen holiday. Duration of holidays or costs of holidays are aspects which may be used in a model.
    • If it is not possible to formulate an idea as a variable, the facilitator and the rest of the group can work together to find a variable.
  2. Give the participants a few minutes to write down their own ideas.
  3. Explain that the facilitator is going to gather ideas and show them on the board or computer screen for everyone to see. Ask each participant for one idea and write this on the white board or blackboard.
    • Pay attention to the conversion into variables and check to see if the other group members know what the person contributing the idea means. Allow a clarification of meaning, but not a discussion on the relevance or importance of the idea.
      • Explain that in this phase, the person contributing the idea has the last word. If he or she prefers a particular formulation, even if others object, the proposed formulation will be put on the central board or screen. In the next phase, when starting to build the model, a relation will only be included when all participants agree. So while in NGT, consensus is the goal during the phase of drawing relations, in this stage an individual participant ‘has the power.’
  4. Stop collecting ideas after two or three rounds.
    • Emphasize that the aim of this phase is only to create an initial list of variables so that model building can begin, and that variables that were not written on the board for the group are not automatically discarded. During the model building process, variables from the individual lists or even entirely new variables can be added.

Evaluation Criteria:

  • Number of ideas generated
  • Extent to which the meaning of ideas is clear to participants




Initially described for GMB by Jac Vennix (1996).




Delbecq A, A. Van de Ven, G. H. Gustafson. 1975. Group techniques for program planning: a guide to nominal group and delphi processes. Glenview: Scott, Foresman and Co.

Vennix JAM. 1996. Group model building: facilitating team learning using system dynamics. Chichester: Wiley.

Stroebe W, BA Nijstad, EF Rietzschel. (2010). Beyond productivity loss in brainstorming groups: the evolution of a question. Advances in Experimental Social Psychology 43: 157-203.


There are two main reasons for using NGT instead of brainstorming in this phase. During brainstorming, all participants may contribute ideas simultaneously, which will enliven the atmosphere in the group. In NGT, the facilitator controls how many ideas are brought to the board or screen by gathering ideas in a round robin fashion. The goal is not to have dozens of ideas, but an initial list to get started with modelling. Second, research has shown that NGT results in more ideas and ideas of better quality than does brainstorming (see Stroebe, Nijstad and Rietzschel, 2010 for an overview). In particular, the latter is important here.

This script is most effective when the central issue, as indicated by the problem variable, has already been discussed with the contact client and preferably also by the participants present in the session. In this way, the group needs only a few minutes to discuss the problem variable and can then proceed to eliciting variables.