Six Sigma is a methodology to reduce defects, improve quality of the end products delivered or offered and maximize the business success. Six Sigma has been designed to deliver value to customers by improving quality significantly.
Six Sigma methodology includes
History and Basic Concept
Chip maker Motorola has first used this methodology way back in 1980 to reduce defects in their end-products significantly and made it a great success. Motorola developed a set of practices to systematically improve processes by eliminating defects. Defects may be defined as nonconformity of a product or service to its specifications. The main goal was to achieve a level of performance equal to a defect rate of 3.4 defects per million opportunities – this is a virtually defect free environment i.e. Six Sigma performance.
Six Sigma not only improved Motorola’s products and processes, it also saved the company more than USD 15 billion in the 10 years after it had started using this methodology.
In statistics, sigma means normal deviation from the prescribed limit. Six Sigma aims to reduce the variances of the end products by reducing the number of defects and placing them within the upper and lower tolerance limits. A defect is defined as anything that leads to customer dissatisfaction.
Below table shows different sigma level and corresponding defects per million opportunities.
|Sigma||Defects per Million|
|6 sigma||3.4 defects per million|
|5 sigma||230 defects per million|
|4 sigma||6200 defects per million|
|3 sigma||6700 defects per million|
|2 sigma||310000 defects per million|
|1 sigma||700000 defects per million|
Six Sigma improves the process quality and reduces the cost significantly. Higher the sigma level -> Better the quality of the end product. The ultimate goal of Six Sigma is flawless performance, zero defects.
Benefits of Six Sigma
Differences between Six Sigma and Traditional Approach
Six Sigma: Six Sigma is based on ‘How-to’ approach. The approach focuses on process improvement methods to be used to improve the quality of the deliverable products.
ISO 9000: ISO is based on ‘what-you should be doing’ approach. This approach basically focuses on standardization of a particular process.