Using Six Sigma statistical thinking to improve business processes
A Cummins case study

Page 5: Improvement methodology

Quality is therefore customer driven, with a link between customer expectations and the processes that provide the results that customers require. Cummins has therefore moved from a results orientation to a balanced results and process-driven method of working, focused upon the customer.

The starting point for Six Sigma is to understand the critical inputs that determine the quality of output. Once processes have been developed to understand these inputs and their levels of predictability, managers are then in control of process variation. Six Sigma involves setting up projects that focus upon identifying and controlling these critical inputs, so that processes and outputs can be improved and sustained.

Six Sigma is therefore not about improving the technology. It is more about developing a cultural change within the organisation, influencing how Cummins and its staff think and work. It is about increasing the emphasis on process and process capability. This requires training, understanding, motivation, recognition and leadership.

The methodology involves statistical analysis to quantify repeated Common Cause Variation which can then be reduced by the Six Sigma improvement team. This also identifies Special Cause Variations characterised as unique, assignable problems, handled by problem solving techniques.

Cummins | Using Six Sigma statistical thinking to improve business processes


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