What is a Fishbone diagram?

The Ishikawa diagram, or fishbone diagram, is a tool for identifying and organizing cause-and-effect relationships leading to a specific problem or effect. It helps structure causes into categories, making analysis and root cause identification easier.

At the center of the diagram is the 'fish head,' representing the problem. From it extend 'bones' — the main categories of causes (e.g., people, processes, equipment, materials, environment, methods). From each category, smaller 'bones' branch out with specific causes.

Example of use: when reducing product quality, a team can create an Ishikawa diagram to identify what exactly influences defects — insufficient staff training, worn-out equipment, inefficient processes, etc.