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What is Six Sigma?
Six Sigma is a quality management program that is designed to achieve a
“six sigma" level of quality for products. In the mid 1980s, Motorola
pioneered Six Sigma and it has since been adopted by many other
companies and manufacturers. Service companies also implement Six Sigma
strategies to improve customer service and relations. The idea behind
Six Sigma is that failures in quality and customer satisfaction occur
after the sixth sigma of likelihood in a normal distribution curve.
Hence, the idea is that there are less defects per product or customer
service. Motorola defines the success of six-sigma quality in terms of
the number of Defects Per Million Opportunities.
Why Use Six Sigma?
Many companies and critics of Six Sigma believed that achieving six
levels of quality was impossible, but many companies have proved the
critics wrong. Some companies even go beyond six-sigma. An example of
this is GE Aircraft Engines, which operate at Nine Sigma levels of
quality. Six sigma is practical because it reduces the amount of errors
in customer service and products. This leads to increased customer
satisfaction, increased revenue, more returning customers, and the
acquisition of new customers. Companies that can implement six-sigma
successfully have higher standards of quality and usually produce
better products and services.
Why is it only Six Sigma?
Many people do not know how six-sigma relates to 3.4 defects per
million. Essentially, people do not know how having six levels of sigma
improves quality significantly. Many companies used to have less sigma,
usually about three or four. However, Motorola was the first to use six
levels. Six is the perfect number because whereas four sigma makes sure
that there are only about 2.6 problems in a thousand. However, the
problem arises with deviation. Imagine a manufacturing process in which
a drill makes a hole that is supposed to be 100 micrometers. With
four levels of Sigma, only about 1 in 400 will be defective. This
unfortunately does not take into account the average value of
measurement, which will shift over time. So, if the measurement
gradually drifts as each new hole is drilled, about 6.6% of the output
will be off by 1.5 sigma in each direction at anytime. If the process
has drifted by 150 micrometers, then the hole will be off by 300
micrometers, which is an extremely large defective rate. Using 6 sigma,
with a 1.5 sigma shift to make up for average deviation, the ratios are
much lower and therefore the defective rates are much more sensible.
The same drift in a six-sigma process will still only produce a defect
for products or services that are more than 4.5 sigma away from the
average in the same direction. Using the mathematics of a normal curve,
this works out to 3.4 defects per million which is much more
acceptable.
Conclusion
Customers value quality above all other things in a business. If a
business produces a high quality product or service, more customers
will return, and that business will gain new customers. Six-sigma helps
to ensure the quality of goods and services is only the best.
Six-sigma, when implemented correctly, is very effective and that is
why many companies today use Six-sigma. This process was pioneered more
than 20 years ago by Motorola, and has proven its lasting qualities
through its continued use in the business world. Any company that wants
to gain and retain customers while producing a high-quality product
should consider the use of Six-sigma.
Dana Schorden enjoys writing about Six Sigma. Learn more at Six Sigma
Weblog ( http://www.sixsigmablog.org/training/ ), a weblog with daily
six sigma training tips and news.
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