Cause and Effect / Fishbone / Ishikawa Diagram in 7 QC Tools

Cause and Effect Diagram

 - It represents the relationship between effect and its causes.

 - It is an important tool in 7 QC tools and very good tool for root cause analysis.

 - Dr. Kaoru Ishikawa who pioneered quality management processes in the Kawasaki shipyards popularized it in the 1960s.

 - This diagram also known as Fishbone diagram, herringbone diagram, ishikawa diagram.

When to use Fishbone diagram

 - When to identifying possible causes for a problem.

 - When team's thinking patterns are different.

Procedure of Fishbone Diagram

1) Identify the problem- Define the issue or process to be examined.

2) Brainstorm- Discuss all possible causes and collect and group them into categories.

3) Draw the backbone- Once the topic is identified, draw a straight, horizontal line (this is called the spine or backbone) on the page, and on the right side, draw a rectangle or oval shape at the end. Write a brief description of the problem in the rectangle or oval shape.

4) Add causes and effects- Causes are added with lines branching off from the main backbone at an angle. Write the description of the cause at the end of the branch. These are usually one of the main categories discussed above. Details related to the cause or effect may be added as sub-categories branching off further from the main branch called primary causes. Continue to add branches and a cause or effect until all factors have been documented. The end result should resemble a fish skeleton.

5) Analyze- Once the diagram has been completed, analyze the information as it has been organized in order to come to a solution and create action items.

Most of the cause and effect diagrams examine a similar set of possible causes for any issue analyzed.

In the manufacturing industry, these are referred to as the 6Ms:

Methods:- Are there well-written and appropriate training guidelines in place? Are certain policies or regulations causing slow-downs or creating unnecessary steps?

Machines:- Are there any maintenance issues with the tools used or the number of tools available?

Materials:- Are there any issues getting raw materials from suppliers? Any problems with transportation (timing) or with the quality of the supplies?

Measurements:- Could there be errors in calculation or contamination that caused false readings? Could the way you measure be inconsistent in some way? Is your equipment regularly calibrated and maintained?

Mother Nature/Environment:- Is there too much moisture in the environment? Are temperatures too hot or too cold? Is there excessive dust or other contamination?

Manpower/People:- Do you have too little of your workforce devoted to a process? Are new people adequately trained? Is the training consistent? Are the right people with the right experience being hired or promoted? Is there a specific position creating a bottleneck or making frequent mistakes?

In the service industry, these are described as the 4S:

Surroundings:- Does your establishment project the right image? Is it run-down? Is it impersonal? Is it comfortable?

Suppliers:- Are there any issues delivering your service? Do you have problems with low quality food deliveries? Are there too many dropped phone calls? Can your server handle traffic spikes? Are you getting enough traffic through advertising channels you're paying for?

Systems:- Do you have policies and procedures in place for all scenarios? Do you have modern cash registers that help your servers place orders and deliver checks efficiently?

Skill:- Are your employees properly trained? Do they have the right experience?

In the marketing industry, cause and effect diagrams will often consist of 7Ps:

Product:- Consider all aspects of what you're selling including its quality, its perceived image, availability, warranties, support and customer service.

People:- When people buy your product or service they may interact with many people: sales people, customer service people, delivery people, and so on. Are there any potential problems with your company culture?

Process/Procedure:- How do you handle problems when they arise? Are they escalated properly? Is your staff trained appropriately and do they follow their training?

Promotion:- Consider advertising, sales, PR, branding, direct marketing, partnerships, and social media.

Price:- How does the price of your product or service compare to competitors? What discounts and payment methods are available?

Physical evidence/Packaging:- How is your product or service consumed? Is how or where you present your product hurting your ability to convert? Are your facilities clean and tidy? Is the packaging cheap or expensive?

Place/Plant:- Is your distribution efficient and cost-effective? Is your product sold in the right stores or neighborhoods? Are your stores convenient for your target customers?

Benefits of Fishbone diagram

 - Helps to determine the root cause.

 - Encourage group participation

 - Good tool for brainstorming

 - Increase process knowledge