The Ishikawa diagram (also called the cause-and-effect diagram) was developed in 1943 by Ishikawa Kaoru.
It is used to systematically determine causes of an occurred or potential problem (effect) in at least five cause categories (5M).
The causalities are depicted in the form of a fishbone diagram.
Development and visualization take place in expert teams under the leadership of a moderator using a whiteboard, flipchart or the like.
The documentation can then take place with Office tools (MS PowerPoint, Visio and the like).
The analysis results in actions to solve or prevent the problem.
Procedure for the development of an Ishikawa diagram:
1. Composition of a team
2. Description of the problem: Content, time, place, extent in the head of the fish
3. Definition of the cause categories: Names of the fish bones.
4. The 5M are usually used: Material, machine, method, man, and milieu (environment).
4. Brainstorming – what causes are there? Assumptions are also allowed!
5. Allocate causes to the 5M
6. Allocate sub-causes (ask why multiple times)
7. Classification/plausibility check for the influence of the individual causes (e.g. by means of experiments, tests, statistical evaluations), and prioritization
8. Development of action to eliminate or prevent the problem. Evaluation of the actions with regard to quality, costs, and time.