Fishbone Diagram
The Fishbone Diagram (also called the Ishikawa Diagram or Cause-and-Effect Diagram) is a visual tool for mapping all potential causes of a problem, organised by category. Developed by Kaoru Ishikawa at Kawasaki shipyards in the 1960s, it provides a structured approach to brainstorming multiple causal hypotheses before committing to investigation — preventing the common error of fixating on the first plausible cause found.