Ishikawa Fish Bone

Dr Kaoru Ishikawa made many contributions to quality, the most noteworthy being his total quality viewpoint, company wide quality control, his emphasis on the human side of quality, the Ishikawa diagram and the assembly and use of the “seven basic tools of quality”:

1.      Pareto analysis                                    which are the big problems?

2.      Cause and effect diagrams                 what causes the problems?

3.      Stratification                                       how is the data made up?

4.      Check sheets                                       how often it occurs or is done?

5.      Histograms                                          what do overall variations look like?

6.      Scatter charts                                      what are the relationships between factors?

7.      Process control charts                         which variations to control and how?

 

He believed these seven tools should be known widely, if not by everyone, in an organisation and used to analyse problems and develop improvements. Used together they form a powerful kit. One of the most widely known of these is the Ishikawa (or fishbone or cause and effect) diagram.

Like other tools, it assists groups in quality improvements. The diagram systematically represents and analyses the real causes behind a problem or effect. It organises the major and minor contributing causes leading to one effect (or problem), defines the problem, identifies possible and probable causes by narrowing down the possible ones. It also helps groups to be systematic in the generation of ideas and to check that it has stated the direction of causation correctly. The diagrammatic format helps when presenting results to others.