Fishbone (Ishikawa) Diagram

Skill level: Basic to advanced

Description

A fishbone diagram graphically outlines potential root causes of a service problem or opportunity. The chart uses lines and arrows to depict cause and effect and looks similar to a fish skeleton.

Another name for the fishbone Diagram is “Ishikawa diagram” because it was first developed by Kaoru Ishikawa.

Benefits

  • Simple way to show inputs to a process
  • Graphic nature is easy to understand

How to Use

  • Step 1.  Define the problem, representing it as the main arrow in the middle of the diagram.
  • Step 2.  Brainstorm all major factors that contribute to the problem.
  • Step 3.  Draw an arrow from each major factor to the problem.
  • Step 4.  Draw a line for each possible cause to the major factor.
  • Step 5.  Draw a line for each input to the process flow inputs.
  • Step 6.  The resulting fishbone diagram should look like the figure below and show possible weak areas in the process that could cause the problem. It is very important to brainstorm and then classify what you uncover in this type of diagram.

Relevant Definitions

Brainstorm:  A technique in which a group of people freely and spontaneously present their ideas.

Example

A dental office is concerned about the quality of service to its patients. In order to better understand bad service overall, the dental team brainstorms the makeup of bad service and then creates a fishbone diagram.  From the diagram below, they can see all of the inputs and begin work on a root cause analysis.

fishbone_diagram_Figure1

 

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