Six Sigma Glossary from MiC Quality


Team Tools
Affinity Diagrams

A team-based method of organizing large amounts of data. Typically, brainstormed ideas are written on ‘sticky notes’. These are stuck to a wall and progressively organized into logical groupings by the participants.

Cause and Effect Diagrams

A graphical tool used to list and categorize possible causes of a problem. It looks like a fish skeleton and is sometimes called a ‘fishbone diagram’.

The main categories are often selected as Methods, Equipment, Personnel, Materials, but this is optional:


CE Diagrams

See Cause and Effect Diagram

Failure Mode and Effects Analysis

A method for evaluating risk. Each potential failure mode is evaluated for:

S: the severity of the consequences if it does occur
O: the probability of occurrence
D: the probability of detection before shipping.

Each of these is rated on a scale from 1 to 10, and the three values multiplied to find the Risk Priority Number (RPN). If the RPN is above a specified threshold, action is taken to reduce it. The FMEA is often used as the basis for Control.

Fishbone Diagrams

See Cause and Effect Diagrams


See Failure Modes and Effects Analysis

Force Field Analysis

A team based method of brainstorming the 'drivers' and 'restraints' that affect progress to a desired goal:

Interest Based Bargaining

A type of negotiation based on finding a solution that serves the interests of all parties, also known as win-win negotiation. It has five characteristics:

  • bargaining over positions is avoided
  • people are separated from the problem
  • focus is placed on interests, not positions
  • options for mutual gain are invented
  • objective criteria are used to select the appropriate resolution to an issue
Interrelationship Diagram

Ideas gathered through, eg. affinity diagrams, are grouped in a circular pattern on a flip chart. Arrows are drawn to show the relationships between items, leading from Cause to Effect:

The number of arrows leading 'in' and 'out' of each item are counted and tabulated.

Items that have a high number of 'out' arrows are important drivers. A high number of 'in' arrows suggests important outcomes and candidates for measures of success.

Ishikawa Diagram

See Cause and Effect Diagram


A similar idea to Nominal Group Technique.

    1. brainstorm a list of options
    2. review the list, combining similar ideas etc.
    3. vote for the items worth further discussion - no limit on the number of choices, participants can vote for all items if they like
    4. the items that are voted for by at least half the participants go to the next round
    5. vote again, this time each participant can only vote for half the remaining items
    6. continue until only four of five ideas remain for discussion
    7. proceed with appropriate action
Nominal Group Technique

A method for generating a short list of items to be acted on:

Stage 1:

  • make sure the purpose of the activity is clearly understood, as is the NGT procedure
  • each member of the group writes down ideas in silence
  • discuss and clarify the ideas

Stage 2:

  • cull the list of ideas to a manageable size, say 50
  • members are given index cards, around one card for every 5 ideas listed
  • group members write down their choices of ideas on the cards, one choice per card, and ranks the ideas
  • summarize the scores on the whiteboard and try to agree which will be actioned
Process Decision Program Chart

A similar idea to FMEA. It uses a Decision Tree approach to explore the consequences of decisions:

Risk Priority Number

See Failure Modes and Effects Analysis


Risk Priority Number, see Failure Modes and Effects Analysis