Ishikawa or 6M Diagram Kaoru Ishikawa (1915-1989), Japanese chemical engineer who invented the diagram of cause and effect which is one of the essential instruments of problem solving. This diagram, in the shape of a fishbone, shows the relation between an observed effect and its causes.Development:The effect observed must be perfectly defined thanks to QQOQCCP (see definition). Define the potential causes listed through brainstorming and distribute them by family according to the 6M (Manpower, Machinery, Materials, Method, Mother Nature, Measurement).Go out on the field and confirm the potential causes through observation (Gemba, Gembutsu, Gemjitsu).Eliminate the potential non-confirmed causes.Choose the causes to be analyzed.Go back as far back as possible to the root causes (5 Whys?).Visualize the real causes quantified on the diagram. This method is used in the training course: Structural Method of Problem Solving.