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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