Cause and Effect Diagrams are for getting to the underlying causes of an effect you are seeing.
They have also been known as:
- Fishbone or herringbone diagrams, due to the shape they make when you create the analysis. The fish head is the issue, and each bone of the fish explores the issues.
- Ishikawa, named after Kaoru Ishikawa, a quality pioneer who came up with the method.
- Fishikawa, a combination of the two names above
They can be used to identify the issues causing a problem, or the components that you need to consider to have the result you want.
Some standard formats to get you started
The different branches should show the main issues / focuses at play in the process. There are standard ones for some areas that can give you a head start when looking for categories for the large branches:
- 5 M’s (Manufacturing) – Manpower, Materials, Machines, Methods, Measurement
- 7 P’s (Marketing) – Product, Price, Place, Promotion, People, Process, Physical Evidence
- 5 S’s (Service) – Suppliers, Surroundings, Systems, Skills, Safety
- 5 W’s – Who, What, When, Where, Why
- 4 P‘s – Policies, Procedures, People, Plant
- Draw a line across your paper through the middle lengthways
- Write your ‘effect’ that you want to analyze in a box to the right of the line
- Draw a branch away from this for each key component
- Draw a sub-branch away from these branches for the sub-cause (cause of the cause)
- Keep adding branches until it stops adding information
An example for me analyzing why I was late for work.
As you can see, each issue is broken down into its sub issues, and those are broken down further, until you can find all the core issues that led to me being late for work. These are now easily identifiable and can be worked upon. The issues can also be used to populate your check sheet for data collection.