Root Cause

The cause & effect diagram is the brainchild of Kaoru Ishikawa, who pioneered quality management processes in the Kawasaki shipyards, and in the process became one of the founding fathers of modern management. Other names for the diagram: Ishikawa, fishbone and root cause.

A CAUSE AND EFFECT DIAGRAM IS USED FOR:

  • Need to study a problem/issue to determine the root cause?
  • Want to study all the possible reasons why a process is beginning to have difficulties, problems, or breakdowns?
  • Need to identify areas for data collection?
  • Want to study why a process is not performing properly or producing the desired results?

STEPS IN CONSTRUCTING A CAUSE AND EFFECT DIAGRAM:

  1. Prepare a flip chart or an overhead transparency of the following template:
  2. Write the issue (problem or process condition) on the right side of the Cause and Effect Diagram.
  3. Identify the major cause categories and write them in the four boxes on the Cause and Effect Diagram. You may summarize causes under categories such as:

    -Methods, Machines, Materials, People

    -Places, Procedures, People, Policies,

    -Surroundings, Suppliers, System, Skills

  4. Brainstorm potential causes of the problem. As possible causes are provided, decide as a group where to place them on the Cause and Effect Diagram. It is acceptable to list a possible cause under more than one major cause category.
  5. Review each major cause category. Circle the most likely causes on the diagram.
  6. Review the causes that are circled and ask "Why is this a cause?" Asking "why" will help get to the root cause of the problem.
  7. Reach an agreement on the most probable cause(s).

EXAMPLE OF COMPLETED CAUSE/EFFECT DIAGRAM: