Six Sigma is a highly disciplined process that helps us focus on developing and delivering near-perfect products and services. What is the necessity of Sigma? This word is a statistical term that measures how far a given process deviates from perfection. The central idea behind Six Sigma is that if you can measure how many defects you have in a process, you can systematically find out how to eliminate them and get as close to “zero defects” as possible. To achieve Six Sigma Quality, a process must produce which is no more than 3 to 4 defects per million opportunities. Six Sigma revolves around a few key concepts:

• Critical to Quality which attributes most important to the customer,
• Defect means failing to deliver what the customer desire,
• Process Capability is what your process can deliver,
• Variation is what the customer sees and feels,
• Stable Operations is to ensuring consistent and predictable processes to improve what the customer sees and feels.

Six sigma is designed to meet customer's needs and process capability. Sigma refers to the philosophy and methods, companies such as General Electric and Motorola use to eliminate defects in their products and processes. A defect means simply any component that does not fall within the customer’s requirements. Each step and activity in a company represents an opportunity for defects to occur, and Six-Sigma programs seek to reduce the variation in the processes that lead to these defects.

A process that is in Six-Sigma control is produced no more than two defects out of every billion units. Often, this is stated as four defects per million units, which is true if the process is only running somewhere within one sigma of the target specification. One of the benefits of Six-Sigma design is it allows managers to readily describe the performance of a process in terms of its variability and to compare different processes using a common metric.

While Six Sigma’s methods include many of the statistical tools that were employed in other quality movements, they are employed in a systematic project-oriented fashion through the define, measure, analyze, improve, and control ( DMAIC ) cycle. The DMAIC cycle is a more detailed version of the Deming PDCA cycle, which consists of four steps—plan, do, check, and action—that denotes small and continuous improvement. Small and Continuous improvement is also called kaizen. Kaizen seeks continual improvement of machinery, materials, utilization of proper man power, and production methods through applications of suggestions and ideas come from company teams. The availability of modern statistical software has reduced the drudgery of analyzing and displaying data and is now part of the Six-Sigma tool kit. The overarching focus of the methodology, however, is understanding and achieving what the customer requires, since that is observed as the key to profitability of any production process. In fact, some feels the DMAIC as an acronym for “Dumb Managers Always Ignore Customers.”

Six-Sigma Quality originally developed in the year 1980s as part of total quality management (TQM). Six-sigma quality in the 1990s saw a dramatic expansion as an extensive set of diagnostic tools was developed. These tools have been taught to managers as part of “Green and Black Belt Programs” at many corporations. The tools are now applied to not only the well-known manufacturing applications, but also to nonmanufacturing processes such as accounts receivable, sales, research and development. Six sigma has been applied to environmental, health, and safety services at companies. Six sigma is now being applied to research and development, finance, public affairs, information systems, marketing, legal, and human resources processes.