Cause-and-effect diagrams, also known as fishbone or Ishikawa diagrams, are tools used to visually display and categorize the potential causes of problems or effects. They involve drawing a diagram with the problem written in a box on the right side and connected to the main branches of the diagram by an arrow. Potential causes are then categorized and placed on the relevant branches. Common categories include materials, people, environment, methods, equipment, and procedures. The diagram is used to analyze the root causes of problems in order to determine corrective actions.

1. Cause-and-Effect Diagrams
CAUSE-AND-EFFECT DIAGRAMS
What
A Cause-and-Effect (Fishbone or Ishikawa) Diagram is a picture composed of lines and
symbols designed to represent a meaningful relationship between an effect and its causes.
Cause-and-Effect Diagrams are used to investigate either a “bad” effect and thus correct
its causes or a “good” effect and thus learn how to continue doing things in a way that
produces good products or service. Cause-and-Effect Diagrams are designed to portray
complex situations so that they may be better understood and to analyze causes of poor or
bad service so that corrective action can be taken.
Causes contributing to the effects are categorized and assigned to major branches of the
diagram. For every effect there are likely to be several major categories of causes.
Frequently these fall into such categories as those related to:
• Machines or Equipment
• Methods/Procedures/Technique
• People/Crew/Team
• Materials/Component/Ingredient
• Measurements or Metrics
• Environment/Climate/Atmosphere
There can be many other ways to categorize the major causes, depending on the problem
or outcome being studied. Each of the major causes will, in turn, have numerous minor
causes or factors. The Cause-and-Effect tool provides a visual display of the sequence
and relationships of the causes—organized into major categories—which contribute to a
problem.
When
Use this tool in a group when you need to identify the possible causes of a problem and
how the causes interact.
Restructuring Associates Inc. © 2008 1

2. Cause-and-Effect Diagrams
How
• Gather people that have knowledge of, or experience with, the effect you are
studying as well as the processes that produce them. Try to get a diversified
group so that different perspectives are represented.
• Write a summary statement of the problem in a box on the right of the chart with
an arrow across the chart pointing to it.
• Brainstorm the causes of the problem. Everyone should contribute ideas about
possible causes. Remember, list only causes; avoid stating implied solutions such
as “lack of something” where something will fix the problem. The facilitator
writes down the causes as they are suggested.
• Add categories of causes to the diagram by drawing arrows to the main stem of
the diagram and labeling them with the categories. Three to five causes are most
common. Categories will vary depending on the nature of the problem. Some
common categories: materials, people, environment, methods, equipment, and
procedures. Reach agreement on major causes of the problem.
• Break down each of the categories of causes into smaller branches by placing the
brainstormed items on the appropriate branch of the diagram. Draw an arrow to
the larger arrow to show a cause and effect relationship, and write the
brainstormed item next to the line. Some items may be causes for other items on
the brainstormed list and should be drawn to show this relationship. (The arrow
indicates that an item leads to or causes the item it points to.)
• After all brainstormed items are placed on the diagram, analyze the diagram for
underlying root causes. Repeatedly ask "Why?" each item occurs and draw
additional arrows to show causes.
• Rank or prioritize the causes for further study. Pick several that the group thinks
have the greatest impact on the problem or offer the best opportunity for
improvement. Follow up with further study.
• If necessary, assign team members to collect data to clarify what is causing the
problem.
2 Restructuring Associates, Inc. © 2008

3. Cause-and-Effect Diagrams
CAUSE-AND-EFFECT DIAGRAM
Car Won't
Start
Mechanical Operator
Electrical Fuel System
Steering
Wheel
Locked
Motor
Frozen
Bad
Starter
Over
Heated
No Oil
Flooded
Engine
Not in
Park
Or
Neutral
Wrong
Key
Can't
Turn
Key
Battery
Loose
Connection
Corrosion
Starter
Connection
Cracked
Plug
Wi
Loose
Vapor
Lock
Bad
Fuel
Pump
No
Gas
Water
In
Fuel
Ice
Broken
Fuel
Line
Restructuring Associates Inc. © 2008 3