Ishikawa diagrams (also called fishbone or cause and effect diagrams) were developed by Kaoru Ishikawa in the 1960s. He developed the diagram as a quality management tool to illustrate the relationship between an outcome and its proposed causes. The diagram assists:
determine the root cause
encourage group discussion
sharing ideas of possible causes in an easy to read format
identifying relationships between possible causes and / or causal sequences
identifying areas where information and knowledge is poor
How to create a fishbone diagram
Step 1. Clearly define the effect to be analyzed. The effect can be stated an problem to be solved or an objective to be achieved.
Step 2. Draw an arrow pointing to the effect.
Step 3. Think of some of the main categories of causes. The following are examples of possible categories:
The original 4 M's
Machine (Equipment)
Method (Process/Inspection)
Material (Raw,Consumables etc.)
Man power
The 8 P's (Used In Service Industry)
People
Process
Policies
Procedures
Price
Promotion
Place/Plant
Product
The 4 S's (Used In Service Industry)
Surroundings
Suppliers
Systems
Skills
Write the main categories to the left of the effect and well above and below the main arrow.
Step 4. For each of the main categories identify causes relating to the category.
Step 5. Explore each of the possible causes and look for what might cause them in their turn.
Step 6. Analyse the diagram:
Which categories are showing many possible causes?
Area there categories that need further investigation?
