What is an Ishikawa (fishbone) diagram used for?

• A. To create a timeline of process changes.
• B. To compare means across groups.
• C. To identify the best process settings.
• D. To identify potential root causes across categories such as People, Method, Machine, Material, Measurement, and Environment.

Answer: (D)

An Ishikawa diagram helps you map out potential causes of a problem in a structured, visual way. By placing the problem at the head of the fish and drawing major branches for typical categories—often People, Methods, Machines, Materials, Measurements, and Environment—you and your team can brainstorm specific factors within each area. This layout makes it easier to see how different elements might contribute to the issue, identify gaps in data, and focus your investigation on true root causes rather than just symptoms. It’s a versatile tool for exploring multiple factors across categories to guide corrective actions. It isn’t used for creating timelines, comparing means across groups, or directly selecting optimal process settings, which rely on other techniques.