Special Causes of Variation

Unlike Common Causes, Special Causes of Variation are localised in nature, and are not part of the overall process. They are, therefore, abnormalities and can often be eliminated by the actions of, say, the operator.

Dr. Deming, who died in December 1993 at the age of 93, was the most significant exponent of the use of statistics in process improvement and, indeed, is considered by most to be the father of Total Quality Management.

Other pioneers who worked in Japan, including Dr. Joseph Juran, who had worked with Dr. Shewhart at Western Electric (and had, in fact, been the first person to actually apply one of Dr. Shewhart's Control Charts).

Dr. Juran argued that errors and waste were caused mainly by the failure of management to install the processes and systems necessary to control quality, not the failings of the staff. He introduced the concept of Quality Circles and cross-functional project teams, to ensure that all those involved in a process have an influence on it.