In his theory, kaoru ishikawa emphasizes effective data collection and demonstration. He is famous for advocating the use of quality tools (such as pareto chart and Causality Diagram) to optimize quality improvement. Kaoru ishikawa believes that causality diagram, like other tools, is a tool to help people or quality management teams improve their quality. Because of this, he advocates that open group discussion is as important as drawing charts. As a systematic tool, Ishikawa diagram is very useful, which can be used to find, select and record the causes of quality changes in production, and also to make the relationship between them orderly.

Words of wisdom: standard is not the ultimate source of decision-making, but customer satisfaction.

He believes that the implementation of quality management in Japan is a revolution in business philosophy, and its contents can be summarized as six items: 1, quality first, 2, customer-oriented, 3, customer as the next working procedure, 4, speaking with data and facts, 5, respecting people's management, and 6, functional management.