Six Sigma is becoming a proven approach for businesses and organizations to improve their
performance. The spectrum of companies actively engaging in Six Sigma today is wide from
industrials like Celanese, Caterpillar, GE, Honeywell, and 3M to service/retail organizations
like Starwood Hotels, Sears, and Home Depot. Six Sigma has even started in the financial
industry with Bank of America and JPMorgan Chase initiating major deployments in the past
two years. Probably the most exciting area is in the public and healthcare sectors with
success stories emerging from city government and John Hopkins Medical.
So what is all this excitement about? Haven’t these quality tools been around for years? Is it
just the fact that people have strange names like Champion, Green Belt, Black Belt and for
the chosen few, Master Black Belt? Okay, if it is not the names then what? Six Sigma’s
success revolves around the fundamental elements needed for any successful organization.
Six Sigma starts with a vision of delivering products and services to customers with no
defects from the eyes of the customers. For companies it is vital to deliver these products
and services at a profit. Once the organization has created their own vision of Six Sigma, the
business leaders need to define their organization’s objectives in numerical terms. These
“high-level metrics,” often called big Y’s in Six Sigma, are the foundation for identifying
project y’s that Six Sigma Belts will execute projects on. With big Y’s in hand, business
leaders called Six Sigma “Champions” breakdown these organizational level Y’s into smaller
y’s a project leader called a Green Belt or Black Belt can work from.
So what’s next, do business leaders take a hands-off management by objectives (MBO)
approach of, “I don’t care how you do it as long as you get results!”? For Six Sigma
organizations the answer is a loud “NO.” Champions do care how projects are executed and
have appointed highly trained Master Black Belts to assist and mentor project leaders in
applying the Six Sigma method to manage their projects. I believe this is the key to Six
Sigma’s success. In a past life I participated in a high-level meeting with executives from the
world leader in the production of a product we all know. The purpose of the meeting and
visit was to evaluate a critical new product design. All of the high-tech executives were
dressed in dark Italian business suits complemented with gold and diamonds. I listened
closely to each question these executives asked. I never once heard “how much?”, “when?”
or even “why?” – every question was “by what method?.” Methodology is what Six Sigma is
about.
Six Sigma Methods
There have evolved two key methods for carrying out Six Sigma projects. The first method
is the most well-defined and works best if you have a problem with an unknown solution in
existing products, processes or services. This method is called DMAIC or Define, Measure,
Analyze, Improve and Control. The newest method, which is in the developing stages, is
called Design for Six Sigma or DFSS. The goal of DFSS is to develop a new product,
process or service that is defect-free in the eyes of the customer. A number of consulting
companies have invented roadmaps for DFSS like IDOV (Identify, Design, Optimize and
Validate) and DMADV (Design, Measure, Analyze, Design and Verify).
Six Sigma and Design of Experiments
Once an organization has decided on the method and the project y’s, Belts are marched off
to training “waves” bringing management-approved projects to class. DMAIC Green Belt
training is normally two one-week sessions separated by one month. Black Belt training
waves are extended by two additional months with two more weeks of training. The
emphasis during the extended two weeks of Black Belt training is often on learning more
details about advanced tools such as Design of Experiments (DOE).
So where does Design of Experiments fit into Six Sigma? Six Sigma is about understanding
and controlling the variation of key process variables known as inputs or x’s in order to
obtain improved results on project outputs or y’s. In Design of Experiment terms these
inputs or x’s are often referred to as factors and the outputs are referred to as responses. In
nearly all Six Sigma projects the relationship of the project y’s takes on the form of
yf(x1,x2,...xn). Wait a minute, isn’t this what Design of Experiments is all about? Of course,
for almost 100 years Design of Experiments has been proven to be one of the best known
methods for validating and discovering relationships between responses and factors. In Six
Sigma terms it is discovering the relationship between outputs called y’s and inputs called x’s.
Today’s Six Sigma Belts are primarily taught to focus their use of Design of Experiments in
the Improve phase of DMAIC and the Optimize phase of IDOV. For DMAIC Six Sigma
training the most common experimental designs taught are factorial and fractional factorial
designs. Some curriculums introduce response surface designs and optimization designs at a
high level. DFSS includes the experimental designs taught in all levels of DMAIC training
and often expands to include the concept of robust designs. As an alternative to the classical
approach, there are also a number of consulting companies teaching Taguchi designs as the
preferred method for robust design.
Final Remarks
Six Sigma looks as though it is here to stay and even in today’s slow economy one of the few
areas where there still are a number of new positions. The Six Sigma process is a great step
toward creating learning organizations with its well-defined roadmaps and management
structure. As with most new methodologies Six Sigma will mature and grow as it expands
into new areas such as DFSS. As Six Sigma professionals learn more about the power of
properly planned experiments, Design of Experiments will be integrated into most phases of
the Six Sigma roadmap and not just considered an advanced tool for the improvement and
optimization phases. Experienced practitioners of statistical methods like Design of
Experiments should learn the language of Six Sigma and help integrate new methods into
the Six Sigma process to improve its effectiveness.
About the Author
Peter Peterka is the leading consultant for www.6sigma.us. Peter has eleven years of experience performing as a Master Black Belt, working with numerous companies, including 3M, Dell, Dow, GE, HP, Intel, Motorola, Seagate, and Xerox. You can signup for Peter's Six Sigma Certification at www.6sigma.us.