Also called cause-and-effect diagram or root cause analysis. A graphic illustration that identifies cause-and-effect relationships among factors in a given situation. It consists of a "head" which states a problem and bones along the spine which represent factors and categories of factors.

The Ishikawa Diagram, originally developed by Kaoru Ishikawa for industrial quality control, was the first graphic to focus on identifying the causes of an undesired effect.

NASA also developed a similar technique called a Fault tree diagram which uses a box and arrow to display the various possible scenarios for a given event.