January 1, 2020
By Darren Dolcemascolo
One can spend an inordinate amount of
time debating on online forums about the
merits of Lean versus Six Sigma.
However, much of the time spent on this
debate is wasted. I do not believe Six
Sigma versus Lean is actually a
contest. Both methodologies (or
management systems) have merit and have
been used successfully. The question
is: do we need to use both of them to
have a successful improvement system in
organizations? If so, when and how?
I firmly believe in the saying "there
is more than one way to skin a cat."
I do not believe it is necessary to use
both Lean and Six Sigma. I think
the Lean Management system can be used
very successfully on its own; however, I
also think both Lean and Six Sigma can
be used together with much success.
Let's define our terms. When I
use the term "Lean", I am
referring to the Toyota Production
System / Toyota Way. (I realize
there has been much debate recently as
to what Lean is versus the Toyota
Production System, but please let us
ignore that for now. Originally,
"Lean Production" was used to describe
Toyota's system.) Lean is a
continuous improvement philosophy of
providing the customer with a defect
free product or service when it is
needed and in the right quantity through
the elimination of waste. Lean
includes the concepts of Continuous
Flow, Pull, Built in Quality, and Basic
Stability. Perhaps, most importantly,
Lean includes the idea of building a
culture of "Respect for People."
While there are many Lean "tools", the
problem solving process now known as A3
Problem Solving (or Toyota Business
Practices) is absolutely central to
becoming Lean. This is how kaizen
(continuous improvement) is accomplished
in a systematic manner over time.
What about Six Sigma? Six Sigma
is aimed at achieiving better quality /
less variation in processes. It
also has a "problem solving" process
called DMAIC (Define Measure Analyze
Improve Control), which is central to
Six Sigma. Six Sigma has a focus
on understanding what the customer needs
(Voice of the Customer), measuring how
well the current process meets those
needs, determining which factors or
causes need to be addressed or improved
to improve the process, and implementing
and monitoring/sustaining the improved
process. There are many tools of Six
Sigma, almost all of which pre-date it.
Some of the tools of Six Sigma are
statistical methods while others are
more qualitative tools. There are
also some tools that are taught as part
of Lean as well as Six Sigma (such as a
Fishbone/Cause and Effect Matrix).
The question should not be: Should I
use Lean or Six Sigma? Rather, the
question should be: "What kind of system
do we need to develop in order to
improve our business? I believe
there are four basic requirements for a
successful improvement system:
1. A problem solving process that
permeates the organization.
Everyone must understand and practice
it. I believe this can be Toyota
Business Practices/A3 or DMAIC. A
problem is defined as the gap
between the current condition and the
target condition or standard; a problem
solving process aims to identify the
root cause or critical causes and
then identify, test, and implement
countermeasures to address the causes.
2. There must be one or more ways in
which the organization utilizes the
problem solving process to make
improvements. In the Six Sigma
world, there are DMAIC projects.
With Lean, we have Daily Kaizen, Kaizen
Events, and other A3 "projects."
Some combination of these should be
taught and practiced.
3. A set of tools from which problem
solvers can utilize as needed.
Depending on the nature of the business,
statistical methods such as those taught
in six sigma may be useful.
General problem solving tools will
almost always be useful, and several
Lean/TPS tools will be useful.
4. A methodology for Developing and
Aligning Goals and Measuring to those
Goals must be in place. I don't
believe that improvement efforts should
be purely cost-cutting efforts. An
organization should use Strategy
Deployment to develop goals and identify
the right initiatives/projects to work
on. Value Stream Mapping is also a
methodology that can be used at a high
level to identify the right improvement
activities on which to focus.
Success should be measured based on the
key metrics identified- not purely on
I believe Lean, Six Sigma, and Lean Six
Sigma practitioners should recognize that
there are several ways to make
improvements to a business. We need
to be open to the idea that there are
often multiple ways to achieve our goals.
Utilizing the basic 4 requirements above,
a system that can achieve success can be
built in any organization.
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