Purpose

Cause and effect diagrams organise ideas. They enable a problem solving team to explore, identify and visually display all of the possible causes of a problem, or variation, there by determining what data needs to collected to determine the root cause.

How does it work ?

• Gives the 'big picture', displaying the collective knowledge and consensus of a team's approach to a problem. This is beneficial in building support for the solutions generated.
• Enables the content of a problem to be the main focus, rather than the problem's history.
• Generates a focus on causes, not symptoms.

Method

1) Define the problem clearly.

• Make sure everyone agrees with the problem statement.
• Include as much information as possible on the 'what', 'where', 'when' and 'how much' of the problem.)

2) Construct the Fishbone Diagram.

• Place the problem statement in a box on the right-hand side of the board/paper.
• Draw the major cause categories in the process and connect them to the backbone of the fishbone chart.
• Method, Equipment, People, Materials [ MEPM ] are favoured as traditional causes. Some flexibility is necessary depending on the problem being investigated. Other causes which may be required are; Procedures, Policies, Environment or Measurement. There are no fixed rules for the number of causes - make the diagram fit the problem.