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Introduction
Recently, both service and production organizations are committed to use Six-Sigma to improve all aspects of the company's products and services. The Six-Sigma program is credited to Dr Mike Harry, a statistician who is the main founder of Six-Sigma Academy in Scottsdale, Arizona. Motorola, a huge US Company, is an early corporate adopter of the Six-Sigma program in the world. Other US firms such as General Electric, Texas Instruments and Allied Signal are also the big beneficiaries of this technology.
The Greek alphabet letter σ is used for sigma to identify the variability. A sigma quality level indicates how often defects are likely to occur. Higher sigma quality level is a sign that process would produce lesser defects. One way of reading and speaking the language of Six-Sigma is through determining the number of defects per millions opportunities. We say the Six-Sigma quality level is equal to 3.4 defects per million opportunities (DPMO) and can be shown as 3.4 DPMO (the normality assumption of the process must hold and a shift of up to ±1.5σ for the mean of the process is allowed). An "opportunity" is defined as any chance for nonconformance or not meeting the required specifications. With Six-Sigma program implemented in an organization, management can expect impressive savings in cost reduction and waste elimination. It is believed that most organizations operate at Three-Sigma, which translates to 66,000 errors per million. In statistical terms, Six-Sigma quality means that for any given product or process quality measurement, there will be not more than 3.4 defects produced per 1,000,000 opportunities. By comparison, typical quality levels for manufactured products today achieve about Four-Sigma, which translates to about 6,000 defects per 1,000,000 opportunities. [10] Crompton Corporation (n.d.), relates sigma levels to the defects per millions. An airline safety rate at Six-Sigma level is equivalent to 3.4 unsafe trips per million.
Originally, it was understood that Six-Sigma can benefit large manufacturing companies because of dealing with repetitive processes and easy to track the flow of goods along the line. General Electric, Motorola and Honeywell, all manufacturing goods, were the first organizations implemented Six-Sigma. The big news of the savings generated by Six-Sigma for these companies other organization in both fields of service and manufacturing raced to get...