What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools

What is a Cause and Effect Diagram, Fishbone diagram or Ishikawa Diagram?

→ “Cause & Effect Diagram (Fishbone Diagram or Ishikawa Diagram) is a diagram which represents the meaningful relationship between an effect and its causes is called Cause & Effect Diagram (Fishbone Diagram or Ishikawa Diagram).”
→ Dr. Kaoru Ishikawa developed the first cause and effect diagram in 1943 while consulting for Kawasaki steelworks in Kawasaki Shipyards.
→ Dr. Joseph M. Juran named it as Ishikawa diagram


1) Cause & Effect Diagram:

➝ "A diagram which represents a meaningful relationship between an effect and its causes is called Cause & Effect Diagram."


What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools

2) Fishbone Diagram or Ishikawa Diagram:

→ "A  cause and effect diagram is called a fishbone diagram because it looks like the bone of fish."
→ Dr. Kaoru Ishikawa developed the first cause and effect diagram in 1943 while consulting for Kawasaki steelworks in Kawasaki Shipyards so Dr. Joseph M. Juran named it as "Ishikawa diagram"

What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools

3) Steps in Constructing Cause & Effect Diagram:

  1. State the undesirable effect or Problem
  2. Identify the main cause groups.
  3. Identify causes and sub-clauses.
  4. Also, add detailed level causes and Identify potential root cause(s).


➤ Step 1. State the undesirable effect and draw the backbone and draw a line - Cause and Effect Diagram:

→ Define a problem statement (effect). 
→ Write it at the center-right of the chart or whiteboard. 
→ Draw a box around it and draw a horizontal arrow running to it.
What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools

➤ Step 2. Identify the main cause groups - Cause and Effect Diagram:

→ Brainstorm the major categories of causes of the problem. 
→ For manufacturing Industry, it is "6M" 
→ "6M" stands for :
  1. Man/People
  2. Machine
  3. Material
  4. Method
  5. Measurement
  6. Mother nature / Environment


→ For marketing Industry "6M"  is replaced by "8P"
→ "8P" stands for :
  1. Product (or service)
  2. Price
  3. Promotion
  4. Place
  5. Process
  6. People (personnel)
  7. Physical evidence
  8. Performance
→ For Service Industry "6M"  is replaced by "4S"
→ "4S" stands for :
  1. Surroundings
  2. Suppliers
  3. System
  4. Skill
What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools

➤ Step 3. Arrange causes and sub-causes suitably - Cause and Effect Diagram:

→ Write the categories of causes as branches from the main arrow
→ Brainstorm all the possible causes of the problem.
  Ask: “Why does this happen?” As each idea is given, the facilitator writes it as a branch from the appropriate category. 
 Causes can be written in several places if they relate to several categories


What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools



➤ Step 4. Identify potential root cause(s) - Cause and Effect Diagram:

→ Again ask “why does this happen?” about each cause. 
→ Write sub–causes branching off the causes
→ Continue to ask “Why?” and generate deeper levels of causes.
→ At last, you will get the Potential root cause.

What is Cause and Effect Diagram (Fish bone diagram or Ishikawa Diagram) examples - 7 QC Tools

4) When we can use the Cause & Effect Diagram (Fishbone Diagram or Ishikawa Diagram):

→ When identifying possible causes for a problem
→ To identify all of the contributing root causes likely to be causing a problem
→ Especially when a team’s thinking patterns are different


5) Benefits of Cause & Effect Diagram (Fishbone Diagram or Ishikawa Diagram):

 Helps to determine the root cause
 Increase Process Knowledge
 Encourage group participation
 Good tool for brainstorming
 Identifies areas for collecting data



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