The Nominal Group Technique
Generating possible causes and reaching consensus
by Bjørn Andersen and Tom Fagerhaug
Editor's note: Root Cause Analysis: Simplified Tools and Techniques, written by Bjørn Andersen and Tom Fagerhaug and published by ASQ Quality Press (item H1047), offers approaches to identifying and eliminating root causes. The following excerpt describes a technique used to help determine a problem's possible causes, prioritize ideas and create team consensus.
Often a suspicion exists as to what is causing the problem you are trying to solve. But, before you rush to investigate it, consider the other candidates. This is what possible cause generation is all about. Brainstorming, for example, is a great way to generate ideas about any given subject. While brainstorming has proven the test of time, it's important to have an entire arsenal of tools to help out when a technique doesn't fit the situation, the team can't reach consensus or team members can't use the technique efficiently.
The nominal group technique (NGT) should be one of the tools in everyone's arsenal. This tool facilitates a form of brainstorming in which all participants have an equal voice in contributing ideas for possible causes. It also allows the group to form a more accurate consensus about prioritizing the causes.
This technique is best used when a problem stems from several causes and the team is at a loss as to which cause should be analyzed first. Other opportunities for using NGT include: discussions involving team members who are too intimidated to contribute their ideas, brainstorming sessions that result in an unorganized, overwhelming number of possible causes, and discussions with teams whose members blame one another for the problem at hand.
The steps in nominal group technique
After a problem-solving team is assembled, the facilitator needs to explain the problem, making sure all members understand it. Once this is accomplished, NGT can begin.
1. Each team member generates ideas regarding causes of the problem and writes them on index cards--idea cards. One card is used per idea.
2. The facilitator collects the cards, registers every idea on a flip chart and assigns each idea a letter (from "A" onward). Team members briefly discuss the ideas for clarification and eliminate similar ideas from the chart.
3. Each member then selects up to five ideas he or she
finds important and lists them on a separate card, a ranking card. Everyone
individually ranks the items on his or her list by assigning a point to
each idea (from 5 for the most important or best idea to 1
for the least important or least effective idea).
4. The facilitator collects the ranking cards and totals the points each idea received.
The idea achieving the highest total score is the team's consensus solution or prioritized idea and is the logical starting point for the ensuing activities in the root cause analysis.
An example of using NGT
Let's suppose that a high school faced some severe problems with bullying and generally unacceptable behavior--but not merely among the students. During the last few years, a number of skilled teachers have left the school due to the poor work climate. A team of five teachers, two students, one custodial worker and one administrator was assembled to look into the problems.
The team soon discovered immense differences in opinion as to what caused the low job satisfaction, and the different groups of people tended to blame one another. After a few weeks of fruitless discussions, the task force was no closer to agreeing on causes, let alone to solving the problems. To move the job forward, they agreed to try NGT.
There were plenty of ideas for possible causes that had been recorded in the minutes from previously held meetings. These were defined as the set of ideas to rank, and a list with assigned letters was produced.
The team members individually listed and ranked the five ideas they believed most needed to be addressed, and the facilitator totaled the points each idea received. The highest ranked consensus ideas were identified, and the team was able to move forward.
BJØRN ANDERSEN is an associate professor at the Norwegian University of Science and Technology in Trondheim. He earned his doctorate in production and quality engineering from the Norwegian University of Science and Technology. Andersen is the author of Business Improvement Process Toolbox (ASQ Quality Press, 1998) and an ASQ member.
TOM FAGERHAUG is a research scientist at SINTEF Industrial Management in Trondheim, Norway. He has a master's degree in production and engineering from the Norwegian University of Science and Technology in Trondheim. Fagerhaug is an ASQ student member.