Cause & Effect Diagrams for Quality Management

The Cause & Effect Diagram, aka Fishbone diagram, Ishiwaka diagram or Why Why Tool is a tool most commonly used in Quality Management and Risk Management. Its design merges brainstorming (often based on incident reports) and mind mapping techniques to help mangers to identify all possible root causes and potential risks. The most common applications include identiying the following.

• Potential causes of problems in new product design
• Quality defects and their causes that can be prevented
• Symptoms of the cause

How to use the Cause & Effect Diagram

The "head" of the fish's skeleton represents the problem or "effect" as described in a risk register usually appears on the right. The "bones" extend to the left of the head to display various causes. However, to better organize the exercise, each rib denotes a category or classification of these causes. Smaller bones can therefore branch out into causes and even sub-causes. The branching depends on the levels required under each classification.

The "ribs" or classifications can and should vary according to your industry and or functional objectives. For instance, manufacturers often use the '6Ms', which are a group of "ribs" or classifications that have been become a manufacturers' standard after the automobile company Toyota popularized it. 

Brainstorm. Ideally, seek different perspectives from persons in different functional areas. Also inspect the site for hazards. Keep in mind that, while risks relate to the 'effect' end of situations, 'hazards' relate to the 'cause' end. Consequently, you can improve this root cause analysis by appropriately matching hazards (like a lion) with corresponding risks (like injury or death of human beings).

6Ms

1. Man

2. Machine

3. Material

4. Method

5. Measurement

6. Mother Nature/ Milieu (Environment)

7. Management (used by some managers) 

8. Maintenance (used by some managers)

Example using Toyota's 6Ms. (Illustration video also included below)

1. MAN. Includes: skills, job assignment. (HRM; SCM; target/non-target). 

• A risk may involve not using the best practices for interviewing and selecting appropriate candidates; failing to properly onboard candidates, etc.

2. MACHINE. Includes: tools; equipment, condition of ~, etc. 

3. MATERIAL. Includes. production inputs 

4. METHOD: Includes efficiency, complication, existence of procedure. 

5. MOTHER NATURE & MILIEU (ie social environment). Includes weather conditions, culture.

6. MEASUREMENT. Includes variable frequency or levels like temperature, time, quality, adequacy, number of people, etc.  NB. This is sometimes excluded for redundancy if there is a preference to include measurement in the other categories.

Symptom(s): Aids to identifying cause(s).

Other Common Classifications 

1. Marketing professionals commonly use the following 7Ps.

1. Product 

2. Price

3. Place

4. Promotion

5. People

6. Positioning

7. Packaging

 

Service industry professionals commonly use the Service 5Ss:

1. Surroundings

2. Suppliers

3. Systems

4. Skills

5. Safety

 

CONTENT RELATED TO CAUSE & EFFECT DIAGRAMS FOR QUALITY MANAGEMENT & RISK MANAGEMENT

• Hazards 101
• Illustration of the manufacturer's 6Ms fishbone diagram. 

                 

• Simplified illustration of the fishbone diagram method for a resolving a problem (inadequate handwashing) 
• More complex illustration of resolving the problem of patient falls in a Nevada Division of Public and Behavioral Health facility (video starts from relevant section @17:31)
• Incident reports can help to find causes when completing the fishbone diagram.  
• Product Liability Insurance is a planned risk response that proactively transfers risk to a third party. Read about it to find ways to improve production and risk management plan accordingly.
• Risk management is an essential part of a Research & Development (R&D) project.