Kaoru Ishikawa

The Ishikawa diagram organizes possible causes of a problem into branches leading toward a single observed effect. It is also called a fishbone or cause-and-effect diagram and is widely used in manufacturing, healthcare, and service-process analysis.

Ishikawa was one of the leading figures who developed and popularized quality-circle practice in Japan during the 1960s. These small employee groups used basic quality tools to identify and solve problems in their own workplaces.

The set commonly associated with Ishikawa includes cause-and-effect diagrams, check sheets, control charts, histograms, Pareto charts, scatter diagrams, and stratification or flow-based analysis. He argued that ordinary workers could solve many quality problems by mastering these accessible tools.

Ishikawa treated quality as a company-wide responsibility rather than a final inspection performed by specialists. His approach involved employees across design, production, management, and customer service in preventing defects before products reached buyers.