Six Sigma Frequently Asked Questions
Glossary of Six Sigma Terms
Six Sigma is a methodology to manage process variations that
cause defects and to systematically work toward managing variation
to eliminate defects. The objective of Six Sigma is to deliver
high performance, reliability, and value to the end customer.
It was originally defined as a metric for measuring defects
and improving quality, and a methodology to reduce defect levels
below 3.4 defects per million opportunities (DPMO). Six Sigma
has grown beyond defect control to a proven methodology for
achieving performance excellence.
Six Sigma, originally developed at Motorola in the 1980s,
is a complete program for addressing how well your organization
meets customer and stakeholder requirements.
That is entirely up to you. Past initiatives contained much
that was useful, but they usually failed for specific reasons.
Lack of executive leadership. Management
fails to demonstrate its commitment through deeds. Successes
are won by innovative mid-level managers, but without active
leadership from the top, matters soon grind to a halt.
Failure to deploy. Good results are obtained
initially through “launch enthusiasm” and mentored
training; but no process is embedded to keep the efforts going
or expand them into other departments.
Seeking shortcuts. Successful pioneer companies
develop programs over the long-term that incorporate many
interlocking elements. Success inspires imitation, but the
next generation of companies often tries to emulate the success
without the hard work. They may adopt only some elements of
the successful pioneer program (or even only the name) hoping
for instant success.
Inadequate measurement. In some initiatives,
there was no way to measure status or progress. Not that there
are no measures (the organization is often over-measured),
but the measures may not relate properly to business results
or to the strategic business plan.
Incompleteness. Some past initiatives addressed
only one facet of a total program: tools without goals (SPC);
goals without tools (ZD); philosophies without infrastructure
(TQM); infrastructure without action (ISO 9001); measures
without tactics (MBO); and so on.
An organization may approach Six Sigma in the same spirit.
Six Sigma incorporates the successful elements of past initiatives
and adds something more. There is a measure—Sigma Performance—that
evaluates processes based on their ability to meet customer
requirements. There are strategies for all three phases of management—process
(re)design, process management, and process improvement. There
are toolkits of tactics and qualitative and quantitative methods
for each strategy.
The goal is to achieve robustness by moving progressively toward
a Sigma Performance Level of 6. At this level the process is
robust against undetected process shifts; that is, variation
is small enough relative to the requirements that a shift will
not result in more than a few defects in a million opportunities.
Sigma Performance measures process performance relative to
customer requirements. It takes into account some degree of
undetected, non-random variation (“shift”). Unlike
the Capability Index, all qualities, both measurable and countable,
can be combined into a single scorecard.
Sigma can be normed to the complexity of the process, using
defects per million opportunities (DPMO) to facilitate comparisons
across different processes.
It does, and for measurable data, Sigma Performance is directly
related to the standard deviation. The two uses of the term
"sigma" should not, however, be confused.
Defects and errors occur because of the collision between what
we must do (customer requirements) and what we can do (process
capabilities). Six Sigma works to minimize the difference between
what your customers need, and the product or service you deliver.
It does so using three fundamental strategies: process management,
process improvement, and process (re)design.
All three strategies must be used to gain the full benefit of
Six Sigma
Identify and control the key input and process variables (X's)
to achieve acceptable outputs (Y's). Detect and correct adverse
changes by fixing what went wrong. The strategy for this phase
is called PDCA (Plan, Do, Check, and Act).
Many organizations do a fair job of process management and
often achieve a 4 Sigma Performance Level; but to achieve higher
Sigma Performance requires process improvement or process (re)design.
Identify and change the input or process variables (X’s)
that account for persistent normal performance to achieve a
sustained higher level of performance (Y’s). Deliberately
create beneficial changes by improving something that can be
done better. The strategy for this phase is called DMAIC
(Define, Measure, Analyze, Improve, and Control).
Identify the key input or process variables (X’s) that
enable new or significantly modified processes to meet customer
requirements (Y’s) the first time “out-of-the-gate.”
The strategy for this phase is called DMADV
(Define, Measure, Analyze, Design, and Verify).
PDCA is used to manage a process.
- Plan the process management system: Link
your daily work to your business strategy and customers' requirements;
determine and document the best steps for completing the work,
what will be checked, how, how often, etc.
- Do the actions specified in the plan.
- Check actual performance against the Process
Management Plan (PMP): Measure and review process outcomes
(Y's) and key input and process variables (X's) on a regular,
timely basis.
- Act when there is a gap between the "as-is"
of do and the "should-be" of plan. This may require normal
control activities to identify and fix what went wrong; but
it may lead to a decision to initiate a DMAIC
improvement project.
This systematic process management methodology assures that processes
are maintained at the best performance level achievable, given
the present design of the process.
DMAIC is used to improve a process.
- DEFINE the problem and the process involved,
and align with customer needs, wants, and expectations.
- MEASURE the current process performance
from many points of view to focus the problem.
- ANALYZE to determine and verify the root
cause of the focused problem.
- IMPROVE by implementing countermeasures
that address the
root causes. If this requires significant redesign, we link
to the appropriate step of DMADV.
- CONTROL to maintain the gains. This links
to the Plan step of process management.
This systematic process improvement methodology assures that
the root causes of chronically poor process performance are
identified and addressed so as to achieve a sustained improved
level of performance. Improvement actions may lead to significant
redesign of the process.
DMADV is used to (re)design a process.
- DEFINE the opportunity, project plans,
risk assessments, etc.
- MEASURE and determine customer needs, wants,
and expectations.
- ANALYZE the design options to select the
approach that best addresses customer needs.
- DESIGN the process by selecting design
elements and specifying the details. Cascade the customer
requirements to system, subsystem and element levels and compare
to available capabilities.
- VERIFY the design performance.
This systematic design methodology can build processes that
will reliably meet customer expectations. It can be used when
DMAIC leads to significant redesign or
when a new product, service, or process is contemplated.
The Act step of PDCA may lead to a decision
to initiate a DMAIC improvement project when the problem is
not a departure from normal performance, but the normal performance
itself.
The Control step of DMAIC links to the Plan
step of process management to incorporate the changes into the
process management plan.
The Verify step of DMADV links to the Plan
step of process management to incorporate the new product or
process into the process management plan.
The Analyze or Design steps
of DMADV may lead to a decision to initiate a DMAIC improvement
project if the available process capabilities cannot meet the
requirements at that design stage.
Design for Six Sigma (DFSS) is the goal of the process (re)design
strategy (DMADV). It means that we set out to create a design
that is Six Sigma capable. This involves a tradeoff between
the top-down cascade of design requirements (from customer to
system to subsystem to design element) and the bottom-up stacking
of process capabilities (from element to subsystem to system
to customer). The DFSS goal is to balance these two constraints
using transfer equations that relate the X’s at the lower
level, to the Y’s at the higher level, and either adjust
the allocation of requirements or improve the process capabilities.
It is not an either/or proposition—these programs are
complementary, and your organization should be pursuing all
three.
- ISO 9001 is a model for quality management
systems. It provides a foundation for process management by
helping to define the processes needed to obtain the planned
results.
- Six Sigma is a model for designing, managing,
and improving process results. It focuses on the effectiveness
or accuracy of the process.
- Lean Enterprise is a model for designing,
managing, and improving process flow. It focuses on the efficiency
or speed of the process.
Improving process accuracy through Six Sigma improves the flow,
because there will be less rework and correction. As well, Lean
strategies, like elimination of non-value adding work or simplification,
will improve the results by eliminating opportunities for error
and the complexities that leads to error.
The book Fusion Management, by STAT-A-MATRIX CEO Stan Marash
examines the history and confusion of improvement initiatives
and shows how they can be fused into a single unified approach
to your business.
There are seven essential steps to implementing Six Sigma.
- Understanding and commitment of top leadership
- Access to current information on customer
needs—your critical data pool
- A process-management system to measure
current performance and identify where you need to make improvements
- Resources—Black Belts and Green Belts—trained
to design and improve processes and to assist process owners
- Ongoing management involvement and review
to reinforce process management, improvement, and design.
- Communication to ensure that customer focus,
and Six Sigma methods are embraced throughout the organization.
- Assigned responsibilities for Six Sigma within the organization
Anywhere from two to five years. There are no short-cuts. Progress
depends very much on how well top management leads the initiative.
If top management is out front leading the effort, then Six
Sigma will permeate the organization quickly and more permanently.
STAT-A-MATRIX provides training and implementation support
for Six Sigma. Skilled consultants diagnose where process change
would benefit your organization the most. Then, attuned to your
needs and culture, they apply the strategies calculated to produce
rapid and profitable results. STAT-A-MATRIX consultants work
with senior managers and organizational leaders to develop a
plan involving personnel who manage and work in a targeted process.
This provides your organization’s leadership the expertise
necessary to create and sustain improved sigma levels and achieve
success.
Black Belts are individuals who have sufficient expertise in
DMAIC and DMADV to lead a major improvement or (re)design project.
Candidates are assessed in three stages:
- The organization ensures that the candidate possesses the
personal and leadership skills, and experience to
lead project teams.
- The candidate attends an intensive four-week training
program with weekly sessions spaced about a month
apart. At the end of each week and after the entire four weeks,
the candidate must pass a written examination.
- The candidate leads to conclusion a successful Six
Sigma project authorized and validated by the organization,
and submits a report to the examiner. This report must demonstrate
the candidate’s mastery of the tools and methods of
Six Sigma. Any tools not required by the project itself can
be demonstrated by means of separate case studies.
No—our Black Belt course teaches you the necessary statistical
tools. We also teach you how to use the statistical software,
MINITAB, to help you apply statistical analyses to the data.
Our Black Belt training teaches you when to use the statistical
tools and how to interpret the results throughout the DMAIC
problem-solving process.
Yes—in the competition for people’s time, the “regular
job” always wins, so the Six Sigma projects must become
the Black Belt’s regular job, at least for the duration
of the project. Organizations have learned that Black Belts
are more successful when they are removed from all or part of
their regular duties and assigned to their improvement or (re)design
projects. A Black Belt may work on more than one project.
Green Belts are individuals who have sufficient expertise in
DMAIC or DMADV to contribute to a major improvement or (re)design
project through data collection, analysis, and other activities.
They may sometimes lead smaller scale improvement projects.
This will vary from company to company. Candidates take a one-
or two-week training class and pass a written examination. Project
work is normally assigned and evaluated by the organization
itself.
The Six Sigma approach is about reducing variation in processes
so that you can consistently meet customer needs. The benefits
to improving sigma include:
- Lower costs
- Enhanced resource use
- New ideas
- Increased job satisfaction
- Increased profitability
Not every process needs immediate improvement. Start by considering
which processes concern your customers the most and place your
priorities there. For example, a hospital might learn from surveys
that their customers care less about the time it takes to be
admitted than they do about safe medical procedures and proper
medications.
There is a systematic process for selection that begins with
top management. They list what processes are “hurting”
the organization. Their direct reports then translate the broad
topics into doable projects. Once the projects are prioritized,
then process improvement teams are assigned to work on the problems.
A training project must first be a Six Sigma project; that
is, there must be an evident opportunity for improvement of
a chronic problem. In addition, the project should provide scope
for the candidate to practice as many of the important skills
as possible.
Usually six to twelve people depending on the complexity of
the problem and the need for cross functional representation.
The team should consist of a team leader, usually a Black Belt,
one or more Green Belts to help with data analysis, and subject
matter experts to provide the technical skills and knowledge.
In addition, each team should have a sponsor and a coach.
The project sponsor is a member of senior management who champions
the project among the executive team, coordinates and resolves
conflicts for resources, and assists with managerial obstacles.
The coach, or Master Black Belt, advises the team on Six Sigma
methods, provides advanced methods when needed, facilitates
on team dynamics, and provides supplementary training when required.
Three to six months, but usually no longer than nine months.
If the project is too short it is either not a true sigma project
or nothing is done to satisfaction. If the project takes too
long, frustration and impatience sets in and everyone grows
anxious to move on. Such projects need to be divided into “bite-sized”
sub-projects.
It depends on the resources available and how much time management
is willing to assign to the project. Typically, team members
spend about 25% of their time working on the project. This time
should be carefully tracked by the accounting department. Also,
this time is allocated during working hours not after the workday
is over.
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