Ishikawa diagram, also called cause and effect diagram, fishbone diagram or Ishikawa is a simple analytical technique for display and subsequent analysis of the causes and consequences, which is the brainchild of Kaoru Ishikawa.
Ishikawa diagram is based on the principle of simple causality - each consequence (problem) has its own cause or a combination of causes. Its objective is therefore to analyze and determine the most likely causes of the solved problem.
Where to use of the Ishikawa diagram in practice?
Due to its versatility, the Ishikawa diagram is used in the field of quality in the search for causes of poor quality, but also in fields of risks or problem solving. It is often used for finding solutions during team techniques such as brainstorming. While problem solving, in the debate or with other analytical technique, the possible causes are systematically searched and represented by the form of the fish bone (hence its name).
The causes are mostly searched at the basic dimensions - following list shows eight typical dimensions used in the production (8M):
- Man power - People - causes caused by people
- Methods - causes caused by rules, regulation, legislation or standards
- Machines - causes caused by equipment such as machinery, computers, tolls
- Materials - causes caused by defect or material properties
- Measurements - causes caused by improper or poorly chosen measurement
- Mother nature - Environment - causes caused by the environment - temperature, humidity or the culture
- Management - causes caused by improper management
- Maintenance - causes caused by improper maintenance
Ishikawa diagram can be used both retrospectively to find the cause of the problem. and forward in product design for preventive identification and elimination of possible causes of the products.
Note: Ishikawa diagram can be illustrated in a form of the mind maps and it can be used a software (e.g. FreeMind).