Another Look at Continuous Improvement

Dreamstime - Crystal BallEverybody knows that the reality of globalized manufacturing is a continuous spiral of faster, better, cheaper. Regardless of how good your processes, practices and products are, it is essential to keep improving. On Continuous Improvement, a post from November 2015, takes a pragmatic look at continuous improvement, with some thoughts on how that might actually be accomplished. Another look at On Continuous Improvement is always timely. — C.H.


On Continuous Improvement (from November 2015)

Remaining Competitive

Everybody understands the need to be truly competitive in this globalized economy. What’s more, since everybody knows, everybody is trying to improve – so the bar is continually being raised. The 5th of Dr. Edwards Deming’s famous 14 points is characteristically blunt: [1]

“Improve constantly and forever the system of production and service.”

In practice, there are two ongoing modes of improvement. The first mode consists of numerous incremental improvements to existing products, processes and practices. The second mode involves fewer, larger improvements such as new products, new equipment, or R&D advancements. This essay focuses on the first ongoing mode of improvements.

What to Improve Continuously?

Rereading Deming’s 5th point clearly answers the “what to improve” question: “the system of production and service”. The “system of production and service” means the entire assemblage of manufacturing and processes, procedures and practices, along with their interactions and inter-dependencies, through with your organization functions. It is necessary to appreciate that Deming’s use of the term “system” is not an accident.  A “system”, as Deming intends that term, is assembled in order to serve a specific purpose (Deming prefers the term “aim”, rather than “purpose”).

Deming says that the aim (purpose) of a business is to “stay in business, create more and more jobs”. To me, that means a sustainable business that can continue to grow indefinitely.

To be more specific, it is necessary to constantly improve our products, our manufacturing processes, procedures and practices; as well as our business processes, practices and procedures. Further, it is necessary to do so in a manner that advances the overall aim of the system. Improvement in one component of the system at the expense of another component is counterproductive. Usually, most improvement efforts focus on diminishing variation and waste.

How to Improve Continuously?

Deming tells us that wanting to improve is not sufficient. It is necessary to have a method for doing so. Fortunately, there are several methods that are widely used by manufacturers, each with many books, publications, courses and consultants ready to assist. Generally speaking, my personal preferences are Lean Manufacturing (especially for reducing wastes), Shewhart Cycles with control charts (for reducing variation) and Theory of Constraints (for prioritizing improvement efforts).

Lean Manufacturing

Competitiveness starts with the systematic elimination of waste in all of its many forms. “Waste in all of its many forms” includes losses due to hazardous working conditions, unsafe work practices, emissions to the environment, inefficient use of energy, and on and on. Lean Manufacturing provides a proven, readily available means to do that.

Lean Mfg Text Box

Just about everybody in manufacturing has heard about Lean Manufacturing, or about the stunning success of the Toyota manufacturing system, which serves as Lean’s global model. The fact is that Lean Manufacturing is good sense, systematically applied. Lean doesn’t require computers, robots or big capital outlays. It does require access to the know-how, a willingness to apply that know-how, and a person experienced with Lean implementations to lead the effort.

Shewhart Cycles

Dr. Deming was a statistician. Early in his career, Deming met Walter Shewhart, a pioneer in statistical quality management. He learned of Shewhart’s work with control charts and PDCA improvement cycles. Control charts provide a ready method to plot process outputs and, importantly, to distinguish variation due to the process itself (common causes) from variation due to other causes (special causes).

Variation can be reduced by identifying and eliminating special causes. Shewhart Cycles, more commonly called PDCA Cycles, provide a way to do that. Shewhart Cycles consist of four steps:

Deming PDCA CycleStep 1: The first step is to study a process, to decide what change might improve it. Organize an appropriate team. Do not proceed without a plan.

Step 2: Carry out the tests or make the change, preferably on a small scale.

Step 3: Observe the effects.

Step 4: What did we learn? Repeat the test if necessary. Look for side effects.

Theory of Constraints (TOC) [2]

TOC regards a manufacturing facility as a system consisting of interacting and interdependent processes. Those processes are not all equally important to increasing throughput. A few, usually one, process limits — constrains — the system. TOC focuses on identifying the limiting process and addressing that limitation. “Addressing that limitation” means increasing the capacity of that process, such that it no longer bottlenecks the facility. In addition, TOC uses a buffer before the constrained resource and a raw materials release system to prevent overproduction at non-constrained resources.

Once a constraint is addressed and throughput increases, another constraint will be revealed — otherwise, throughput would be unbounded. So, TOC is an ongoing process of identifying and addressing constraints. As production capacity increases, the constraint to increasing revenues eventually moves from the factory to the market or to some business practice or policy.

Concisely, Theory of Constraints provides a convenient way to prioritize opportunities for improvement so as to improve the aim of the system.

Chuck - Red Rocks3Thoughtful comments and experience reports are always appreciated.

…  Chuck Harrington

This blog and associated website (www.JeraSustainableDevelopment.com) are intended as a resource for smaller manufacturers in the pursuit of Sustainability. While editorial focus is on smaller manufacturers, all interested readers are welcome.

Image: PDCA Cycle ID 46845201 © Raducomes | Dreamstime.com


[1] Understanding continuous improvement starts with Dr. Deming. For those not familiar with Deming’s work, I suggest Mary Walton’s The Deming Management Method, Perigee Books (1986)

[2] To learn more about the Theory of Constraints, see Appreciating the Theory of Constraints, this blog, http://jerasustainabledevelopment.com/2015/06/27/appreciating-the-theory-of-constraints/

On Continuous Improvement

Remaining Competitive

Everybody understands the need to be truly competitive in this globalized economy. What’s more, since everybody knows, everybody is trying to improve – so the bar is continually being raised. The 5th of Dr. Edwards Deming’s famous 14 points is characteristically blunt: [1]

“Improve constantly and forever the system of production and service.”

In practice, there are two ongoing modes of improvement. The first mode consists of numerous incremental improvements to existing products, processes and practices. The second mode involves fewer, larger improvements such as new products, new equipment, or R&D advancements. This essay focuses on the first ongoing mode of improvements.

What to Improve Continuously?

Rereading Deming’s 5th point clearly answers the “what to improve” question: “the system of production and service”. The “system of production and service” means the entire assemblage of manufacturing and processes, procedures and practices, along with their interactions and interdependencies, through with your organization functions. It is necessary to appreciate that Deming’s use of the term “system” is not an accident.  A “system”, as Deming intends that term, is assembled in order to serve a specific purpose (Deming prefers the term “aim”, rather than “purpose”).

Deming says that the aim (purpose) of a business is to “stay in business, create more and more jobs”. To me, that means a sustainable business that can continue to grow indefinitely.

To be more specific, it is necessary to constantly improve our products, our manufacturing processes, procedures and practices; as well as our business processes, practices and procedures. Further, it is necessary to do so in a manner that advances the overall aim of the system. Improvement in one component of the system at the expense of another component is counterproductive. Usually, most improvement efforts focus on diminishing variation and waste.

How to Improve Continuously?

Deming tells us that wanting to improve is not sufficient. It is necessary to have a method for doing so. Fortunately, there are several methods that are widely used by manufacturers, each with many books, publications, courses and consultants ready to assist. Generally speaking, my personal preferences are Lean Manufacturing (especially for reducing wastes), Shewhart Cycles with control charts (for reducing variation) and Theory of Constraints (for prioritizing improvement efforts).

Lean Manufacturing

Competitiveness starts with the systematic elimination of waste in all of its many forms. “Waste in all of its many forms” includes losses due to hazardous working conditions, unsafe work practices, emissions to the environment, inefficient use of energy, and on and on. Lean Manufacturing provides a proven, readily available means to do that.

Lean Mfg Text Box

Just about everybody in manufacturing has heard about Lean Manufacturing, or about the stunning success of the Toyota manufacturing system, which serves as Lean’s global model. The fact is that Lean Manufacturing is good sense, systematically applied. Lean doesn’t require computers, robots or big capital outlays. It does require access to the know-how, a willingness to apply that know-how, and a person experienced with Lean implementations to lead the effort.

Shewhart Cycles

Dr. Deming was a statistician. Early in his career, Deming met Walter Shewhart, a pioneer in statistical quality management. He learned of Shewhart’s work with control charts and PDCA improvement cycles. Control charts provide a ready method to plot process outputs and, importantly, to distinguish variation due to the process itself (common causes) from variation due to other causes (special causes).

Variation can be reduced by identifying and eliminating special causes. Shewhart Cycles, more commonly called PDCA Cycles, provide a way to do that. Shewhart Cycles consist of four steps:

Deming PDCA CycleStep 1: The first step is to study a process, to decide what change might improve it. Organize an appropriate team. Do not proceed without a plan.

Step 2: Carry out the tests or make the change, preferably on a small scale.

Step 3: Observe the effects.

Step 4: What did we learn? Repeat the test if necessary. Look for side effects.

Theory of Constraints (TOC) [2]

TOC regards a manufacturing facility as a system consisting of interacting and interdependent processes. Those processes are not all equally important to increasing throughput. A few, usually one, process limits — constrains — the system. TOC focuses on identifying the limiting process and addressing that limitation. “Addressing that limitation” means increasing the capacity of that process, such that it no longer bottlenecks the facility. In addition, TOC uses a buffer before the constrained resource and a raw materials release system to prevent overproduction at non-constrained resources.

Once a constraint is addressed and throughput increases, another constraint will be revealed — otherwise, throughput would be unbounded. So, TOC is an ongoing process of identifying and addressing constraints. As production capacity increases, the constraint to increasing revenues eventually moves from the factory to the market or to some business practice or policy.

Concisely, Theory of Constraints provides a convenient way to prioritize opportunities for improvement so as to improve the aim of the system.

Chuck - Red Rocks3Thoughtful comments and experience reports are always appreciated.

 

…  Chuck Harrington (Chuck@JeraSustainableDevelopment.com)

 

P.S: Contact me when your organization is serious about pursuing Sustainability … CH

 

This blog and associated website (www.JeraSustainableDevelopment.com) are intended as a resource for smaller manufacturers in the pursuit of Sustainability. While editorial focus is on smaller manufacturers, all interested readers are welcome. New blog posts are published weekly.

Image: PDCA Cycle ID 46845201 © Raducomes | Dreamstime.com


[1] Understanding continuous improvement starts with Dr. Deming. For those not familiar with Deming’s work, I suggest Mary Walton’s The Deming Management Method, Perigee Books (1986)

[2] To learn more about the Theory of Constraints, see Appreciating the Theory of Constraints, this blog, http://jerasustainabledevelopment.com/2015/06/27/appreciating-the-theory-of-constraints/

 

 

The Future and Dr. Deming

Dr. Deming

Deming New Economics Book JacketEdwards Deming is best known for his teachings on statistical methods for quality control. However, his legacy goes well beyond his work on variance. In the final years of his life, Dr. Deming recognized that the Industrial Age was ending and that a new philosophy of manufacturing management was needed. That new philosophy, which he called a “System of Profound Knowledge”, was outlined in Deming’s The New Economics for Industry, Government and Education. [1]

This post builds on Deming and Profound Knowledge, a post to this blog from October 2013. “System” is the key concept in Deming’s new philosophy. This post emphasizes systems thinking by relating Eliyahu Goldratt’s Theory of Constraints, especially as presented in his book The Goal [2] to Edwards Deming’s System of Profound Knowledge. – C.H.


Deming’s System of Profound Knowledge

Edwards Deming is arguably the best known of the later 20th century quality experts. He taught quality methods and practices in Japan in the 1950s and ‘60s; then helped American manufacturers catch up to Japanese in the 1970s, ‘80s and into the ‘90s. Late in his life, Deming formulated a System of Profound Knowledge to serve as a guide to manufacturing managers and leaders to address the future.

Dr. Barbara Berry [3] describes the System of Profound Knowledge as a “management system grounded in systems theory”. She goes on to say:

“Deming believed profound knowledge generally comes from outside the system and is only useful if it is invited and received with an eagerness to learn and improve. A system cannot understand itself without help from outside the system, because prior experiences will bias objectivity, preventing critical analysis of the organization.”

Deming’s System of Profound Knowledge [4] consists of four interdependent components. Manufacturing leaders need to thoroughly understand all of them and how each interacts with the others:

> An understanding of the theory of knowledge

>> A knowledge of variation

>> An understanding of psychology

>> An appreciation for systems

The Goal and System of Profound Knowledge

I’m convinced that Goldratt developed the thinking behind The Goal quite independently from Deming’s work on the System of Profound Knowledge. However, these two eminent management philosophers come to remarkably similar conclusions regarding the bases for a 21st century model of management thinking. Here are some parallels:

Theory of Knowledge

Deming holds that knowledge is more than just information. Knowledge results from systematic evaluation and verification. Systematic analysis, evaluation and verification are achieved through application of a process. Deming suggests the PDSA (Plan – Do – Study – Act) cycle.

Similarly, Goldratt suggests that managers use a scientific approach to thinking. The introduction to the 1st edition of The Goal says: “The secret to being a good scientist, I believe, lies not in our brainpower. We have enough. We simply need to look at reality and think logically and precisely about what we see. The key ingredient is to face inconsistencies between what we see and deduce the way things are done. This challenging of assumptions is essential to breakthroughs.”

Some years after the publication of The Goal, Goldratt presented a set of Thinking Processes.[5] The Thinking Processes are tools for use in analyzing relationships within systems. Like the scientific method and PDSA cycles, the Thinking Tools provide a means for systematic analysis, evaluation and verification.

Knowledge of Variation

Variation and its causes lie at the heart of Deming’s work with quality. Deming teaches that two modes of variation exist: common cause and special cause. The former are an intrinsic characteristic of the production process. The later are due to sporadic events outside the production process. Deming uses simple experiments including his famous red bead experiment to demonstrate the futility of trying to control common cause variation from within the process.

The Goal tells the story of a Boy Scout hike. The scout hike provides an analogy for a manufacturing process consisting of serially related operations. The effect of variation in walking speeds over time in a line of hikers provides insight as to the nature of a constraint and the effects of that constraint on throughput and on work in process inventories. The scout hike also demonstrates that the process itself can be modified in order to reduce the common cause variation.

Psychology

Deming recognized that people are not simply extensions of the machinery. He decried command and control management and advocated “leadership, for a change”. Deming appreciated that people are motivated intrinsically, and that extrinsic efforts to motivate are futile, if not counter-productive.

The Goal is extensively psychological. First, it is a business novel — an exposition of principles through a story that readers can readily relate to. Secondly, Jonah — one of the primary characters — is a Socratic teacher. The story demonstrates human reactions to change and human behaviors under stress.

An Appreciation for Systems [6]

“Perhaps Dr. Deming’s greatest contribution and biggest departure from the past was to view an organization as a system. He defined a system as a network of interdependent components that work together to try to accomplish the aim of the system. The aim for any system should be that everybody gains, not one part of the system at the expense of any other.” [7]

Similarly, The Goal presents a manufacturing organization as a system. As the title of the book suggests, the system exists to pursue an aim — a goal — that may not be obvious to everybody involved with the system. The story examines components of that system, their dependencies and their interactions. They learn that actions to optimize individual components of a system do not result in optimizing the system as a whole with respect to the goal of that system. They also learn that Pareto’s Principle doesn’t necessarily apply when analyzing systems. Said briefly: The Goal could be a text for Systems Thinking 101.


What does all of this have to do with Sustainability? Both The Goal and The System of Profound Knowledge provide insight as to how manufacturing organizations can survive and prosper in the 21st century. Both advocate significant changes in management thinking. Interestingly, the first editions of The Goal (1980s) define the goal of a manufacturing organization as “make money now and in the future”. Later editions (1990s) modify that to “become an ever-flourishing company” [8] — recognizing, as Deming did, that the aim of an organization goes beyond making money.

Chuck - SedonaThoughtful comments and experience reports are always appreciated.

…  Chuck Harrington (Chuck@JeraSustainableDevelopment.com)

P.S: Contact me when your organization is serious about prospering in the globalized 21st century … CH

This blog and associated website (www.JeraSustainableDevelopment.com) are intended as a resource for smaller manufacturers in the pursuit of Sustainability. While editorial focus is on smaller manufacturers, all interested readers are welcome.


[1]  The System of Profound Knowledge is discussed in detail in Edwards Deming, The New Economics for Industry, Government and Education – 2nd Edition, MIT Center for Advanced Educational Services (1994)

[2] Goldratt, E. and J. Cox, The Goal: A Process of Ongoing Improvement, 3rd Revised Edition, North River Press (2008)

[3] Dr. Barbara Berry, There is a Relationship Between Systems Thinking and W. Edwards Deming’s Theory of Profound Knowledge, available for download at: http://www.berrywood.com/wp-content/uploads/2011/08/DemingPaper.pdf

[4] The System of Profound Knowledge is discussed in detail in Edwards Deming, The New Economics for Industry, Government and Education – 2nd Edition, MIT Center for Advanced Educational Services (1994). Additional information is available on-line at: https://www.deming.org/theman/theories/profoundknowledge

[5] The Thinking Processes are discussed in detail in Goldratt’s It’s Not Luck, North River Press (1994)

[6] For more on systems, see Systems and Constraints, this blog: http://blog.jerasustainabledevelopment.com/2013/09/25/systems-and-constraints/ and More on Processes and Systems, this blog: http://blog.jerasustainabledevelopment.com/2013/05/15/more-on-processes-and-systems/

[7] Deming Institute website, www.deming.org

[8] Cox and Schleirer, editors, Theory of Constraints Handbook, Introduction by Eliyahu Goldratt, McGraw Hill (2010)

 

On the Shoulders of Giants

Of Giants and Manufacturing

The cathedral in Chartres, France is a truly remarkable example of what committed people can accomplish. Magnificent 12th and 13th century stained glass windows are the http://www.dreamstime.com/royalty-free-stock-photos-vitrages-chartres-cathedral-image21220268cathedral’s crowning glory. My personal favorite set of those windows shows the four Evangelists, each perched on the shoulders of a major Old Testament prophet. The windows embody an idea perhaps best expressed by Sir Isaac Newton: “(I)f I have seen further than others, it is because I was perched on the shoulders of giants”.[1]

Thriving in manufacturing in the 21st century will require a new generation of thought leaders, riding on the shoulders of 20th century giants. My vote for the four giants of 20th century manufacturing management thinking is Edwards Deming, Eliyahu Goldratt, Taiichi Ohno and Peter Drucker. It is useful to consider what these four (and a fair number of other) 20th century giants said, in order to find and build on common themes. The following post from last year looks at two of those giants and the common ground beneath their teachings.

====================

Deming and Profound Knowledge

From: 3 October 2013

A recent post to this blog discussed systems thinking and Eliyahu Goldratt’s Theory of Constraints, especially as presented in his book The Goal.[2] This post continues that line of thinking by relating The Goal to Edwards Deming’s System of Profound Knowledge.

Deming’s System of Profound Knowledge

Edwards Deming is arguably the best known of the later 20th century quality experts. He taught quality methods and practices in Japan in the 1950s and ‘60s; then helped American manufacturers catch up to Japanese in the 1970s, ‘80s and into the ‘90s. Late in his life, Deming formulated a System of Profound Knowledge to serve as a guide to manufacturing managers and leaders.

Dr. Barbara Berry [3] describes the System of Profound Knowledge as a “management system grounded in systems theory”. She goes on to say:

“Deming believed profound knowledge generally comes from outside the system and is only useful if it is invited and received with an eagerness to learn and improve. A system cannot understand itself without help from outside the system, because prior experiences will bias objectivity, preventing critical analysis of the organization.”

Deming’s System of Profound Knowledge [4] consists of four interdependent components. Manufacturing leaders need to thoroughly understand all of them and how each interacts with the others:

>> An understanding of the theory of knowledge

>> A knowledge of variation

>> An understanding of psychology

>> An appreciation for systems

The Goal and System of Profound Knowledge

I’m convinced that Goldratt developed the thinking behind The Goal quite independently from Deming’s work on the System of Profound Knowledge. However, these two eminent management philosophers come to remarkably similar conclusions regarding the bases for a 21st century mode of management thinking. Here are some parallels:

Theory of Knowledge

Deming holds that knowledge is more than just information. Knowledge results from systematic evaluation and verification. Systematic analysis, evaluation and verification are achieved through application of a process. Deming suggests the PDSA (Plan – Do – Study – Act) cycle.

Similarly, Goldratt suggests that managers use a scientific approach to thinking. The introduction to the 1st edition of The Goal says: “The secret to being a good scientist, I believe, lies not in our brainpower. We have enough. We simply need to look at reality and think logically and precisely about what we see. The key ingredient is to face inconsistencies between what we see and deduce the way things are done. This challenging of assumptions is essential to breakthroughs.”

Some years after the publication of The Goal, Goldratt presented a set of Thinking Processes.[5] The Thinking Processes are tools for use in analyzing relationships within systems. Like the scientific method and PDSA cycles, the Thinking Tools provide a means for systematic analysis, evaluation and verification.

Knowledge of Variation

Variation and its causes lie at the heart of Deming’s work with quality. Deming teaches that two modes of variation exist: common cause and special cause. The former are an intrinsic characteristic of the production process. The later are due to sporadic events outside the production process. Deming uses simple experiments including his famous red bead experiment to demonstrate the futility of trying to control common cause variation from within the process.

The Goal tells the story of a Boy Scout hike. The scout hike provides an analogy for a manufacturing process consisting of serially related operations. The effect of variation in walking speeds over time in a line of hikers provides insight as to the nature of a constraint and the effects of that constraint on throughput and on work in process inventories. The scout hike also demonstrates that the process itself can be modified in order to reduce the common cause variation.

Psychology

Deming recognized that people are not simply extensions of the machinery. He decried command and control management and advocated “leadership, for a change”. Deming appreciated that people are motivated intrinsically, and that extrinsic efforts to motivate are futile, if not counter-productive.

The Goal is extensively psychological. First, it is a business novel — an exposition of principles through a story that readers can readily relate to. Secondly, Jonah — one of the primary characters — is a Socratic teacher. The story demonstrates human reactions to change and human behaviors under stress.

An Appreciation for Systems [6]

“Perhaps Dr. Deming’s greatest contribution and biggest departure from the past was to view an organization as a system. He defined a system as a network of interdependent components that work together to try to accomplish the aim of the system. The aim for any system should be that everybody gains, not one part of the system at the expense of any other.”[7]

Similarly, The Goal presents a manufacturing organization as a system. As the title of the book suggests, the system exists to pursue an aim — a goal — that may not be obvious to everybody involved with the system. The story examines components of that system, their dependencies and their interactions. They learn that actions to optimize individual components of a system do not result in optimizing the system as a whole with respect to the goal of that system. They also learn that Pareto’s Principle doesn’t necessarily apply when analyzing systems. Said briefly: The Goal could be a text for Systems Thinking 101.

===================

What does all of this have to do with Sustainability? Both The Goal and The System of Profound Knowledge provide insight as to how manufacturing organizations can survive and prosper in the 21st century. Both advocate significant changes in management thinking. Interestingly, the first editions of The Goal (1980s) define the goal of a manufacturing organization as “make money now and in the future”. Later editions (1990s) modify that to “become an ever-flourishing company”[8] — recognizing, as Deming did, that the aim of an organization goes beyond making money.

Chuck at Rene 2 - August 2014Thoughtful comments and experience reports are always appreciated.

…  Chuck Harrington

(Chuck@JeraSustainableDevelopment.com)

P.S: Contact me when your organization is serious about pursuing Sustainability … CH

This blog and associated website (www.JeraSustainableDevelopment.com) are intended as a resource for smaller manufacturers in the pursuit of Sustainability. While editorial focus is on smaller manufacturers, all interested readers are welcome. New blog posts are published on weekly.

Photo: © Tashka | Dreamstime.comVitrages Of Chartres Cathedral Photo


[1] The “On Shoulders of Giants” idea is attributed to Bernard of Chartres, who was Chancellor of the cathedral school at Chartres around 1124. The “Giants” window dates from, perhaps, 50 – 100 years later. Isaac Newton’s quote was about 500 years later. Professor William Cook’s “The Cathedral”, a DVD course from The Great Courses, Chantilly VA, Lecture 12, does a nice job of describing and explaining these wonderful windows.

[2] Goldratt, E. and J. Cox, The Goal: A Process of Ongoing Improvement, 3rd Revised Edition, North River Press (2008)

[3] Dr. Barbara Berry, There is a Relationship Between Systems Thinking and W. Edwards Deming’s Theory of Profound Knowledge, available for download at: http://www.berrywood.com/wp-content/uploads/2011/08/DemingPaper.pdf

[4] The System of Profound Knowledge is discussed in detail in Edwards Deming, The New Economics for Industry, Government and Education – 2nd Edition, MIT Center for Advanced Educational Services (1994). Additional information is available on-line at:  https://www.deming.org/theman/theories/profoundknowledge

[5] The Thinking Processes are discussed in detail in Goldratt’s It’s Not Luck, North River Press (1994)

[6] For more on systems, see Systems and Constraints, this blog: http://blog.jerasustainabledevelopment.com/2013/09/25/systems-and-constraints/  and More on Processes and Systems, this blog: http://blog.jerasustainabledevelopment.com/2013/05/15/more-on-processes-and-systems/

[7] Deming Institute website, www.deming.org

[8] Cox and Schleirer, editors, Theory of Constraints Handbook, Introduction by Eliyahu Goldratt, McGraw Hill (2010)