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Lean, Six Sigma™ and Kaizen Compared - Raphael L. Vitalo, Ph.D.

  Editors Note: This article represents a major revision of an earlier article titled, Six Sigma™ and Kaizen Compared - Part I. It includes new content and corrects errors that appeared in the earlier versions.  


The Quality Model
  • Key Principles
  • The Origins of the Quality Model
  • Summary
  • Quality's Progeny: Lean and Six Sigma™
  • Lean's Emergence and Its Extension of the Quality Model
  • Six Sigma™ Origins
  • Summary
  • Kaizen’s Origins and Scope
  • A Principle of Conduct—Striving for Perfection
  • A Management Approach That Creates Business Success
  • A Specific Tool for Improving Work Processes
  • Varieties of Kaizen
  • The Beginnings of Kaizen
  • Summary
  •   References
      About the Author
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    A comparison of Six Sigma™ and Kaizen is a complicated task for several reasons. First, each term has more than one meaning. Second, there are two different levels at which to compare Six Sigma™ and Kaizen. You can compare them at the level of making an improvement to a business process (the event or project level) or at the level of a total approach to improving the success of a business. Third, there are many dimensions on which you can compare these approaches—e.g., their respective origins and the various meanings each term has, their scopes of application, the purposes each approach accomplishes, the benefits each produces, etc. Fourth, there is a difference between what people who promote these approaches say and what actually happens in practice. Which do you use to make your comparison?

    In this article, I will share what my research has uncovered about the origins of Six Sigma™ and Kaizen, the various meanings of each term, and the scope each approach claims. I will begin, however, with a review of the Quality Model, since both these methods emerged as implementations of the Quality Model or as instruments for accomplishing one or more of its goals. As to the issue of what the proponents say versus what happens in fact, I will try to share that within each section of the comparison, as best I can.


    The Quality Model

    Key Principles

    The Quality Model is a comprehensive approach for conducting commerce and realizing business success. It defines the ultimate purpose of commerce as maximizing the satisfaction of customer needs and wishes in ways that provide “better living for him in the future” (Deming, 1982a, p. 175). Businesses succeed to the degree that they satisfy their customers’ real requirements and continuously improve in achieving this result. Methods and approaches such as Statistical Process Control [SPC] and Statistical Quality Control [SQC]; Quality Planning, Implementation, and Improvement (Juran Trilogy); Total Quality Management [TQM], Lean, and Six Sigma™ are rooted in the Quality Model. The construct of continuous improvement (CI) as a business strategy has its origins in the Quality model, as has the application of problem solving methods (e.g., Plan, Do, Study Act [PDSA], A3, DMAIC) to making improvements. To the degree these various expressions of the Quality model remain true to their origins, they build on and serve a core set of principles that, when applied, achieve Quality’s goal and lead a company to high performance. Four key principles reveal the foundations of the Quality Model.1 These principles are:

      1. The goal every business must achieve is to enable its customers to succeed in whatever pursuit they apply its offering.
          Corollary. Customers use your business’s offering to accomplish tasks important to them. The greater the success your offering enables your customers to achieve with respect to these tasks, the more satisfied they become and the more likely they are to engage in future commerce with you.
      2. The basic input required for business success is an accurate understanding of the customers’ real requirements.
          Corollary. Real requirements are features of your offering that must be present for the customer to succeed and be delighted with it. The more detailed and complete your understanding of your customer’s uses of your offering, the contexts within which the customer uses it, and the customer’s capabilities in using it—the more likely your offering will delight the customer and enable his or her success.
      3. The engine of a business’s success is the full involvement of its people in problem solving ever better ways to deliver customers what they judge is valuable.
          Corollary. People developing better ways to accomplish the business’s purpose is the driving force behind its success. The more teamed, aligned, and capable a business’s workforce is in thinking through better ways to understand and satisfy customer requirements, the more powerful the business becomes in delivering value. Also, the company is more likely to sustain its success across the challenges the future presents.
      4. The measure of success is the customer’s satisfaction with your business’s product and service offerings and your demonstration of continuous improvement in understanding and productively satisfying each customer’s real needs. As Deming wrote in the fifth of his fourteen points, a business must “improve constantly and forever” (Deming, 1988).

    Exhibit 1 depicts the core elements of the Quality approach to commerce.

    Various quality-model thinkers have added content to the model they feel should be part of its core principles—e.g., that quality must be managed and cannot be allowed to happen on its own. We do not include these as basic principles of the quality model because they are part of every Western model for success. To say that quality must be managed and cannot be allowed to happen on its own is simply to say that you must focus on your goals and work systematically to achieve them. This may be a more Western than Eastern concept, but, at least within a Western cultural view, it applies to all endeavors in life. On the other hand, to assert that your driving purpose as a business must be “satisfying the customers’ real requirements” says something that is not commonly held. The dominant commercial model operates from a basis of self-interest and asserts that the purpose of every business is to maximize the production of profits for its owners. “Making profits” and “satisfying customers” are not equivalent. As Deming and others have clarified, if I drive toward one, I may or may not drive toward the other or realize it to the same degree. For example, one way companies have succeeded in making huge profits and becoming giants in their industry is by restricting their customers’ access to alternative products or services (e.g., IBM in the 1960s and 1970s and Microsoft from its inception to at least the early 2000s). IBM built in proprietary components to its “big iron” computers that forced customers to return to it for hardware upgrades and software. Microsoft required computer vendors to pay it for every machine they built, whether or not they loaded it with Microsoft’s operating system. If they did not, they could not load MS DOS on any of their machines. Consequently, manufactures only loaded MS DOS since adding any other operating system would increase their costs. These market controlling methods, as well as others each company employed, are antithetical to the principles of the Quality model; nonetheless, many companies seek to use them and many more wish they could.


    The Origins of the Quality Model

    One of its earliest contributors to the emergence of the Quality model was Walter Shewhart. He developed the method of statistical quality control while working at Bell Laboratories in the late 1920’s. This method provides a rational basis for understanding variability in outputs and guidance for how one reduces it. Shewhart reported his thinking and methods in his journal articles and his book, “Economic Control of Quality of Manufactured Product” (Shewhart, 1931). W. Edwards Deming, who held a doctoral degree in Physics from Yale University, was introduced to Shewhart while working at the Department of Agriculture. Deming was responsible for courses in math and statistics at the Graduate School of the USDA. He (Deming) had studied statistics with the eminent British statistician Ronald Fisher and sought out other scholars in the field. He was especially impressed by the significance of Shewhart’s formulations. Both men worked together as colleagues and conducted courses over several years on measuring and controlling variation in work processes in the United States.

    In 1938, Deming took a position at the U.S. Census Bureau, to advise them on the application of sampling methods to the completion of the 1940 census. It was in 1940 that the Bureau shifted its procedure from a complete count to a sampling method. Deming had developed a reputation for expertise in sampling theory and practice while at Agriculture Department. Upon completion of the 1940 census, Deming began to introduce Statistical Quality Control (SQC) into industrial operations. In 1941, he and two other experts began teaching SQC to inspectors and engineers. Deming suggested to Stanford University that it offer a series of 10-day courses instructing engineers, inspectors, purchasing managers, and others in these ideas. The initiative ultimately trained 31,000 professionals. While it raised consciousness about quality and contributed to the emergence of American Society of Statistical Quality Control, Deming later judged that his intent of affecting the practices of businesses had failed. Deming writes, “Brilliant applications burned, sputtered, fizzled, and died out” (Deming, 1982, p.101). A major reason he identified for the failure was that “there was no structure to teach management their responsibilities” (ibid, p. 102) and therefore no way to ensure that the focus on quality became pervasive and persistent within each company. This experience resulted in a learning that stimulated Deming’s development of his 14 management points and guided his future efforts to improve business success.

    The development of the Quality movement transferred to Japan in “1946 with the U.S. Occupation Force's mission to revive and restructure Japan's communications equipment industry. General Douglas Mac Arthur was committed to public education through radio. Homer Sarasohn was recruited to spearhead the effort by repairing and installing equipment, making materials and parts available, restarting factories, establishing the equipment test laboratory (ETL), and setting rigid quality standards for products. Sarasohn recommended individuals for company presidencies, like Koji Kobayashi of NEC, and he established education for Japan's top executives in the management of quality. Furthermore, upon Sarasohn's return to the United States, he recommended W. Edwards Deming to provide a seminar in Japan on statistical quality control (SQC)” (Pecht and Boulton, 1995).

    When Deming began his lectures in Japan in 1950, he looked out once more at ‘the wrong audience’ (Walton, 1986). While earnest in their intent to learn, the attendees had no decision-making power in their companies. Thus, when he was asked to extend his teaching on quality and process control in Japan, he requested to meet with the association of Japanese chief executives, the Keidanren. This Ichiro Ishihara arranged for him. These chief executives became Deming’s major audience and an early version of Deming’s 14 management points, one of the major guiding components of the Quality model, was the focus of his teaching. Deming’s strategy for teaching the Quality model was absolutely consistent with his personal learning about the role of management in transforming a business from the traditional approach to the Quality approach to commerce. In essence, without a transformation in leadership there will be no transformation of the business to the Quality model.

    While speaking about Deming's thinking, many people focus singularly on his advancement of statistical methods that monitored variation within processes and outputs and enabled its description and reduction (e.g., process control charts, Pareto charts, histograms, cause-effects diagrams). They mention that he identified four types of variability: common, special or assignable cause; tampering; and structural (Joiner and Gaudard, 1990). They report Deming’s edict that every manager must understand variability and drive it out of all processes. Common variability was random and inherent in the processes as designed and required redesign of the system to eliminate it. Special cause variation was assignable to causes through investigation. Therefore, when detected, it should be investigated immediately and, when its source(s) understood, eliminated. Both SPC and Statistical Quality Control (SQC) embody this emphasis on variation and its diagnosis and elimination. To my knowledge, all the “event-level” tools used in what is now termed “Six Sigma™” were taken from SPC and SQC. While the understanding of variation and the pursuit of its elimination were essential elements in Deming’s model, the reduction of Deming’s contribution to advancing statistical quality control methods and the pursuit of reducing variation is a travesty. Deming did much more than focus on variation and tools for eliminating it. Indeed, the elimination of variation was never the end result that Quality pursued. It was, instead, the minimization of the loss function. The driving intent of continuous improvement is to reduce the loss function in every operation to zero (Deming, 1982a, p. 141).2 This means optimizing every process’s capability by aligning exactly its typical performance with that needed to ensure maximum customer value and eliminating all variability in realizing that target performance. This effort results in offerings that customers “will boast about” (Deming, 1982a, p. 87). The reputation such an outcome creates for a company attracts new customers and expands the business’s market share. With the lower cost a zero loss function delivers, productivity is elevated. Joined with expanding sales, these two outcomes combine to increase profitability, sustain employment, expand jobs, and produce opportunities for advancement for all employees. The Quality model pursues explicitly all of these outcomes. Deming makes clear that realizing the model’s primary end—maximizing the quality delivered to customers—is to be realized in a way that benefits all stakeholders inclusively. “The aim proposed here for any organization is for everybody to gain—stockholders, employees, suppliers, customers, community, the environment” (Deming, 2000, p. 51). Thus, the thinking Deming taught to Japanese chief executives addressed a broad perspective that encompassed a view of the worker, how management should involve workers in the business, the purpose commerce should serve, the inclusiveness of benefits it should deliver to all stakeholders, the role of management including its responsibilities and accountabilities, the breath of people who constitute the stakeholders to a business and the business’s responsibility to them, the necessity of managing from a system’s perspective, the critical importance of developing and using knowledge in management, and the necessity of continuously improving every business product and service and its methods for delivering them.

    Deming’s instruction played a pivotal role in enabling the resurrection of Japanese industry to its place of worldwide importance in the post World War II era. Indeed, Japan as a nation recognized Deming's contributions to the resurrection of their industry by extending to him the Second Order Medal of the Sacred Treasure. Deming’s contributions specifically to the Toyota Motor Corporation were personally acknowledged and appreciated by Dr. Shoichiro Toyoda, the son of the founder of the Toyota Motor Corporation and its chairman from 1992–1999. “Everyday I think about what he [Deming] meant to us,” said Dr. Toyoda, “Deming is the core of our management” (Toyoda, 1988). As you probably know, the Toyota Production System is often cited as a foundation for the lean enterprise model.

    Following Deming’s return to the United States, there was no interest in him or his teachings. Walton writes that “Thirty years after he first taught the Japanese his methods, Dr. Deming was ‘discovered’ in America.” “He was catapulted into national prominence” by an NBC documentary produced by an initially skeptical Clare Crawford-Mason. After a careful fact-checking to verify Deming’s role in the resurrection of Japanese industry, she produced the documentary, “If Japan Can ... Why Can't We?” “It was one of the most successful documentaries in television history” (Walton, 1986, pp. 17–19). Soon after, he published his thinking in a series of books. The growing success of Japanese industry and Deming’s acknowledged role in enabling that success—joined with the decline of US industry—brought him requests for assistance from many American companies. For a full presentation of Deming’s Quality approach to commerce, see Deming Revisited: The Real Quality Model for Commerce.



    Thus far, we can make these points.

    1. The purpose of commerce as defined by the Quality model is to maximize the delivery of value to customers by providing products and services that deliver “better living for him in the future.” This end, the model dictates, must be realized in a way that ensures that all stakeholders benefit. This means “stockholders, employees, suppliers, customers, community, the environment.”
    2. The basic principles of the Quality Model maintain that businesses succeed to the degree that they understand their customers' real requirements and delivers offerings that customers “will boast about” both now and in the future. To achieve this end, businesses must fully involve their people in applying problem-solving methods to continuously improve both their understanding of their customers and their methods and results in delivering value to them.
    3. The thinking Deming taught to Japanese chief executives addressed a broad perspective that encompassed a view of the worker, how management should involve workers in the business, the purpose commerce should serve, the inclusiveness of benefits it should deliver to all stakeholders, the role of management including its responsibilities and accountabilities, the breath of people who constitute the stakeholders to a business and the business’s responsibility to them, the necessity of managing from a system’s perspective, the critical importance of developing and using knowledge in management, and the necessity of continuously improving every business product and service and its methods for delivering them.


    Quality's Progeny: Lean and Six Sigma™

    Both the Lean Enterprise3 model and Six Sigma™ refer to comprehensive business-wide approaches for achieving business success. Based on an historical analysis and an analysis of each of these systems, it is clear that both derive from the Quality Model.


    Lean's Emergence and Its Extension of the Quality Model

    James Womack and his colleagues described the Lean manufacturing model by studying “a new set of ideas pioneered by Japanese companies” (Womack, Jones, & Roos, 1991, p. 3) that underpinned the superior achievement of these companies as compared to other automotive manufacturers around the world. The study was implemented in 1985 by the International Motor Vehicle Program located in the Center for Technology, Policy, and Industrial Development at the Massachusetts Institute of Technology (MIT). Its goal was to enable automobile manufacturers worldwide to advance the prosperity of their host countries and improve the work life of industry employees by transferring knowledge of the more competitive approaches implemented by Japanese automotive manufacturers. The study lasted five years, had 36 sponsoring governmental and industry organizations, produced 116 scholarly publications, and culminated in the publication of The Machine That Changed the World (Womack, Jones, & Roos, 1991). The book introduced the term “Lean production” to characterize their manufacturing strategy and contrasted it with “mass production,” which was the norm in North America and Europe. While the study the book was based on investigated all 11 Japanese automobile manufactures, one—the Toyota Motor Company—emerged as the best representative of the competitively superior approaches employed by Japanese automakers. Over the next decade and half, the “Lean production” model became tightly identified with Toyota’s implementation of what it called the Toyota Production System (TPS). The Lean model was refined and elaborated into “Lean thinking” (Womack & Jones, 2003).

    Prior to the MIT study, Masaaki Imai described a very similar approach to creating business success in his book, Kaizen The Key to Japan’s Competitive Success (Imai, 1986). He too derived his description from his study of Japanese industry and especially the workings of the Toyota Motor Company. He chose the term Kaizen to label this model as it represented to him the essence of the spirit that drove the approach—the commitment to never ending improvement.

    Both authors Imai and Womack have come to recognize that the contents of the model they each describe did not originate in Japan, although there are elements of it that have specific historical roots in Japanese history. Imai recognized and acknowledge the contribution of the Training Within Industry programs developed under the War Manpower Commission to the emergence of the process improvement tool, also labeled kaizen,4 that was employed in Japan and to implementing a shift in management–employee relations (Imai, 1999). He also recognized in a highly limited way the contribution of Deming by referencing the introduction of statistical quality control and the repeated application of Plan, Do, Study, and ACT (PDSA) as a means for developing learning and improving business activities. Womack even more so recognized the early contributions of American engineers and industrialists including Frederick Taylor, Frank Gilbreth, Henry Ford, and others to the foundations of the lean enterprise model. Indeed, the notions of standardized work have their origins in Taylor. The use of time and motion studies to improve processes by identifying and eliminating waste derived from Gilbreth. The concept and demonstration of flow in a product system and even the essence of the lean tool 5S originates in the work of Ford (Roll, 2005). Others made similar contributions. One example is the work of Alfred Warren whose work in Japan began in 1925. His documented guidance to the Tooshiba Horikawacho Factory regarding factory organization and the design of processes incorporated the concepts of one piece flow, balanced lines, cross-functional assignments, and zero work-in-progress inventory (Odaka, 2001). All of these authors were carefully studied by the Japanese and their ideas were integrated into their approach to industry.

    But singularly unrecognized—given the breath and depth of his contribution—was the contents and thinking embedded in the Deming’s Quality model. As stated earlier, it was to the leaders of Japanese industry—including the heads of its automotive companies—that W. Edwards Deming directed his instruction in the early 1950s before the emergence of practices that were placed under the umbrella concepts of “Kaizen” by Imai or “Lean production” by Womack. At that time, Japanese industry was in ruin. What Japanese companies produced was viewed as inferior to what was produced elsewhere in the world. Across Japanese industry, management’s relationship with its workers was ending its most recent period of extreme turbulence as workers sought redress for long-standing grievances concerning their treatment in the workplace and for the extreme suffering they endured after 1945. Contrary to popular notions, worker strife was not new to Japan. In the 1920s, there were over 250 major strikes. Companies responded by creating enterprise unions. These were structured based on company affiliation and essentially controlled by the employer (Smith, 2003). The management style implemented in Japan was essentially command and control in character. It followed the teachings of Taylor whose work, Scientific Management, was first translated into Japanese in 1912. It had become a core element in the training of Japanese management from that point forward—at least until the emergence of Deming. Beginning in 1938, Japan’s “military dictatorship made all unions dissolve into the Industrial Patriotic Society, abbreviated in Japanese as Sanpo” (Smith, 1998, p. 16). After the War, Sanpo was dissolved and Japanese workers once again began to organize. Initially, the organizing by workers was supported by the U.S. Occupying Authority but, later, the Supreme Commander of Allies in the Pacific (SCAP) acted viciously to thwart worker actions (“the reverse course”) (Smith, 1998).

    Into this decay and turmoil Deming stepped.5 He offered the leaders of Japanese industry a solution to their problems and a promise. The solution was his Quality approach to commerce. The promise was if they implemented the model faithfully, Japanese industry would emerge as world leaders in industry. He told them, “they would capture markets the world over in five years” (Walton, 1986, p. 14). As history records, Japan beat that promise. By 1955, buyers the world over sought out Japanese products.

    The Lean Enterprise model (as well as Imai’s earlier representation of Japanese industry’s approach) incorporates all elements of the Quality Model, as these were central to the Japanese resurrection of its manufacturing industries, including the automotive industry that MIT studied. Thus, in the lean model, the focus of business is on understanding and satisfying the real requirements of customers. It does this by engaging and involving all contributors in continuously discovering and implementing products and services that better satisfy customer values using processes that are progressively waste free. It measures its success and uses this information along with its deepening understanding of the customers it serves to continuously improve its outcomes.

    Also like the Quality Model, Lean recognizes that a business must be understood as a system. It largely incorporates the Quality Model’s broad definition of the members of that system. These members include customers, suppliers, the communities within which the business operates and all other parties who either affect the business’s activities or are affected by its activities. It incorporates the stricture that the maximum satisfaction of customer values must be realized in a way the benefits all stakeholder inclusively. All the members of this “extended value stream”—the graphic depiction of which Deming reports as first appearing in Japan in 1950 (Deming, 2000, p. 58)—must be engaged in applying Lean thinking to their activities in order to fully root out waste and maximize the delivery of value for its customers. Lean's perspective of a business's stakeholders, therefore, aligns with that described by Deming. Indeed, Deming’s recommended relationship between the business and its suppliers is fully represented in the lean model. So too Lean incorporates in its own language the Quality model’s guidance for realizing operational success (Exhibit 2). That guidance begins with understanding customers values, builds into all products and services and their implementing processes features that satisfy customer values, stabilizes (standardizes) all work processes, optimizes them by eliminating waste and better tuning their outputs to match customer values, and then continuously improves all activities of the business and deepens the business’s understanding of its customers (Vitalo, 2012). He even includes mapping each value stream6 as a prior step.

    Exhibit 2. The Origins of 6S
    Deming’s Guidance
    Womack and His Associates’ Guidance
    1. Involve all contributors in understanding customer values.
    2. Design quality into every offering and process.
    3. Make every process stable.
    4. Optimize every process’s capability by reducing its loss function.
    5. Improve constantly and forever every activity the enterprise implements and each of its offerings.
    1. Engage employees in implementing the lean enterprise.
    2. Define value from the customer’s perspective.
    3. Map the value stream.
    4. Establish flow.
    5. Establish pull.
    6. Strive for perfection.

    As regards management responsibilities and conduct, both Imai’s description of the cooperative nature of management–employee relations and Lean’s description (Womack & Jones, 2003; Liker, 2011) rest fully on the guidance embedded in Deming’s 14 management points. This guidance is rationalized by the knowledge Deming documents in his system of profound knowledge.

    Lean does add several elements to the basic tenets of the Quality Model. For example, Lean operationalizes the meaning of what constitutes a customer value as any feature of a product or service offering for which a well-informed and reasonable customer is willing to pay. It also operationalizes the definition of waste as any business activity that does not materially change a product or service output in a way for which a well-informed and reasonable customer is willing to pay. It formalizes the categories of waste (hazard, inspection, interruption, inventory, motion, rework, search, setup, travel/transport, unnecessary processing, and wait) and provides a methodology for waste detection (the gemba walk through, process and machine observation). It introduces the concept of “pull.” Pull means that customer demand triggers the flow of value-adding activities. A pull system, therefore, operates in reverse. A customer order (or shipped product) cascades a signal backwards through the value stream, triggering production and replenishment4 activity as it proceeds. This approach contrasts with the typical “push” approach to production and replenishment in non-service industries.7 With the push approach, activity is driven by targets and schedules that are based on factors such as machine sizing, changeover times, and supply availability. At best, these factors are only partially related to customer demand. Finally, companies implementing lean thinking over time have created tools and methods for enhancing quality and eliminating waste (e.g., Total Productive Maintenance [TPM], Quick Change, Kaizen, Kanban systems, Heijunka box).


    Six Sigma™ Origins

    Six Sigma™, as a business-level strategy, is a “re-labeling” of the approach used by Motorola, Inc. to implement the Quality Model during the 1980’s. As Ramias reports with regard to Six Sigma's origins, "Truth is, the efforts to improve quality through use of statistics went back to the early 1980s, and the creation of Six Sigma as a program was essentially a repackaging of tools and methods going all the way back to Deming." (Ramias, 2005, page 2). More precisely, Motorola's approach was most associated with Joseph M. Juran, a Quality pioneer and contemporary of Deming. Like Deming, his approach to achieving competitive success focused on maximizing quality as defined by the customer and integrated both the measurement-oriented Quality methods of SPC and SQC with team-oriented improvement efforts like Quality Circles, team problem solving, and other involving methods. Also like Deming, he advocated a business-level quality management component as well as event-level improvement methods. For the business level, Juran developed what was labeled the Juran Trilogy—Quality Planning, Quality Control, and Quality Improvement. These were systematic processes to ensure that the outputs and operations of every value stream in the business added value as defined by the customer (Quality Planning), that every system was stable in its delivery of value (Quality Control), and that the business as a whole continuously improved (Quality Improvement). The event-level improvement activities flowed out of implementing Quality Control and Quality Improvement efforts. Improvement activities incorporated measurement and quantitative analysis elements that were pioneered and developed in SPC and SQC. They also included problem solving activities that relied on the knowledge that workers developed through their experience of doing the work and their observations of how current methods succeeded and failed (Pande, Newman, and Cavanagh, 2002). In all regards, Juran’s thinking and methods aligned fully with Deming’s teaching, except perhaps in the area of psychology (Clements, 2011). Juran maintained that people could be motivated through incentives to implement the Quality model. Deming maintained that the drive to learn and excel was intrinsic to people and, while many have had it stultified by life experiences, that intrinsic striving must be present in those implementing the Quality model (Vitalo, 2012).

    Motorola's initial focus was on product quality and the elimination of defects. Beginning in 1986, it began to focus on process capability largely due to the writing and influence of Bill Smith, a Motorola reliability engineer. When Bill Smith gave birth to the term six sigma, the term was a target for performance and not Motorola’s approach to reaching that performance. Smith was attempting to focus attention on creating processes that consistently produced outputs to specification. A six sigma8 process was one that produced less than 3.4 defects per million opportunities (Pande, et al., 2002; page 179). In 1987, Motorola's total approach to quality became rebadged as Six Sigma. In 1991, the term was trademarked. Mikel Harry, who commercialized Six Sigma as a business improvement offering, was initially a consultant with Motorola, then an engineer at Motorola, and finally the head of its Six Sigma Academy.

    While it is popular to credit Six Sigma with billions of dollars in savings and Motorola's winning of the Malcolm Baldrige National Quality Award in 1988, in fact, it appears to have had little contribution to these achievements. According to Ramias (2005), "Motorola won the Baldrige Award not because of its formal Six Sigma program that kicked off in 1987 but because it had made truly awesome improvements in both quality and cycle time over the preceding 8 years. Those achievements were a result of all the TQM and BPI [the business process improvement method developed by Rummler] efforts going on, and they were not’t viewed as a single comprehensive program called 'Six Sigma' or anything else…except in hindsight" (2005, page 2). In fact, “As a formal program, Six Sigma was barely in place when the Baldrige Award was obtained” (2005, page 2). For further clarification of Six Sigma's origins and contributions, see The Mists of Six Sigma™ (Ramias, 2005)9.

    Six Sigma™, as a business process improvement method, is simply a problem solving strategy theoretically rooted in the measurement of process variability and guided by customer requirements. In fact all quality improvement methods—including Kaizen, A3, PDSA—are problem solving methods. They all use the same backbone process: 1. Describe the problem, 2. Analyze it root causes, 3. Develop ways to eliminate causes, 4. Implement solutions, and 5. Measure success. The last step, MEasure success, usually includes extracting learning and applying it to future improvement efforts. In support of Six Sigma™'s commercialization, a new set of terms were developed to express this process—Define, Measure, Analyze, Improve, and Control (DMAIC). In fact, DMAIC is a rather nifty way to capture the basic problem solving process—but, it adds nothing except "niftiest" to solving problems. More importantly, in its commercialized version, Six Sigma™ deviates from the Quality model that produced Motorola's success in several important ways. These include shifting the focus of improvement from quality to productivity and localizing improvement efforts in a small group of employees (Black, Green, and White belts) differentiated by status from all other employees rather than broadcasting the uncovering and making of improvements to include all employees, among others (Quality Digest, 2008; 2008a).

    With regard to the first deviation, Deming held that if you focus on quality then efficiency will follow but that if you focus on efficiency, quality usually does not follow. As to the second, Six Sigma's belt approach returns to the days of Taylorism in the sense that a specialized group is established that segregates learning to a few and wastes the immensely greater opportunities for improvement that the many (all employees) can provide.



    Thus far, we can make these points.

    1. Both the Lean Enterprise model and Six Sigma™ are derivatives of the Quality Model for achieving success in business.
    2. The Lean Enterprise model is a comprehensive, company-wide approach to conducting commerce. It was formulated based on systematic research of the practices employed by superior performing automotive manufacturers during the 1980s. While the study pool included all 11 Japanese automakers, the Toyota Motor Company specifically seemed to best represent the practices that were uncovered as accounting for the superior performance of these companies. The thinking incorporated by these companies—especially as regards the singular importance of maximizing the delivery of value to customers as judged by the customers (Deming’s meaning of “quality”), the involvement of all employees in continuously improving every business activity, the role of management in leading the initiative, the concept of the value stream and the importance of systems thinking and managing the business as a system, the breath of stakeholders to a business and its responsibility to each, the concept of the extended value stream and the necessity of its commitment to implementing lean for lean enterprise to success, the necessity of management operating from a base of knowledge in guiding the enterprise, and essentially every other foundational element of the lean model—all derive from Deming's instruction of the heads of Japanese companies during the early 1950s. It became incorporated in the approach Toyota advanced and termed the Toyota Production System (TPS).
    3. Within the lean enterprise model there are tools and methods for implementing local improvements in outputs, processes, and workplaces (e.g., TPM, kaizen, quick change, 5 or 6S). But, these tools are to be applied in the context of implementing the business-wide strategy and not just as cost reduction or productivity enhancing activities.
    4. Six Sigma™ refers both to a business-wide strategy for implementing a flawed version of the Quality Model (as judged from Deming’s perspective) and to the limited activity of improving the reliability of work processes in satisfying business defined requirements.
    5. Six Sigma™ is a re-labeling of the approach used by Motorola Inc. during the 1980’s for implementing the Quality Model business-wide. That approach was an amalgam of the thinking of Deming, Juran, and Crosby but perhaps most identified with the work of Juran. As a comprehensive approach to creating success, it used Juran's Trilogy at the planning level. For its measurement-focused improvement activities, it used SPC and SQC. For its team problems solving, it borrowed methods from Quality Circles and Crosby’s team problem solving. Six Sigma's modifications to this approach shifted the focus to productivity or efficiency and segregated the leading of improvements efforts to a separate group of employees who are provided with status symbols (belts) that mark them as apart from all other employees.
    6. At the business process improvement level, Six Sigma™ emphasizes the measurement and quantitative analysis elements that were previously pioneered and developed in SPC and SQC. Its backbone methodology—DMAIC—is the same as every other quality improvement tool—i.e., the basic process of problem solving. Just as Six Sigma rebadges total quality management at the business-level, DMAIC rebadges problem solving at the project level.


    Kaizen’s Origins and Scope

    Kaizen (pronounced ki-zen) is a Japanese word constructed from two ideographs, the first of which represents change and the second goodness or virtue. Kaizen is commonly used to indicate the progressive long-term betterment of something or someone (continuous improvement) as in the phrase Seikatsu o Kaizen suru which means to “better one’s life.” The term Kaizen is used in three ways. The first use is consistent with its literal meaning. The second use is as a company-wide management program that establishes a culture focused on continuous improvement of all processes and workplaces through the elimination of waste. The third use is as the label for a specific method for improving work processes and workplaces by the identification and elimination of waste.

    A Principle of Conduct—Striving for Perfection

    In its first use, Kaizen means the pursuit of perfection in all one does. In this use, the term is applicable across the areas of one’s life and represents a guiding ethic for conducting a life.

    A Management Approach That Creates Business Success

    In this second use, Kaizen represents the element of continuous improvement that is a fundamental part of the Quality Model for leading a company to commercial success. In a business context, it is expressed in all activities, personal and teamed, that develop and use learning to make processes better at satisfying customer requirements. In this use, Kaizen has its origins in the fifth of W. Edwards Deming’s 14 management points: “Improve constantly and forever the system of production and service” (Deming, 1982, p. 49). It is commonly expressed as “continuous improvement.” Deming represented continuous improvement as the repeated application of the cycle of Plan, Do, Study, Act (PDSA) to all business activities in the pursuit of making them ever better in delivering value to customers. Its use as a business strategy inside the United States is usually incorporated under the adoption of Deming’s Quality model (e.g., as part of Total Quality Management) or as an element within the Lean Enterprise model described by Womack and his associates (Womack, Jones, and Roos, 1991; Womack and Jones, 2003). Outside the United States, the term Kaizen, on its own, more frequently refers to a comprehensive company-wide management program best represented by the work of Masaaki Imai (1986). This program establishes a culture focused on the continuous improvement of all processes and workplaces through the elimination of waste. As stated by Imai, this use of Kaizen means “everyday improvement by every person, everywhere” (Imai, 2010). The creation of a culture of continuous improvement begins at the top with management. Every manager models and teaches the commitment to continuous improvement by applying it to his or her role and to the systems and processes he or she controls. It spreads across the various functions that constitute a business—executive, administrative, and operational. It is owned by every individual who, as with each manager, seeks ways every day to improve the performance of his or her role and who participates actively in the improvement of the work processes the worker implements and the workplaces he or she operates within. When used in this manner, the term Kaizen umbrellas many other concepts and tools such as customer orientation, total quality control, QC circles, suggestion systems, standardization of work, cooperative employee management relationships, total productive maintenance (Imai, 1986, p. 4). While Imai identifies Japanese management culture as the origin of this approach, in fact it mirrors precisely, but incompletely, the teaching of W. Edwards Deming who brought to the leaders of Japanese industry in the early 1950s these very concepts. He also elaborated the rationale for this approach to business success in what he termed his “system of profound knowledge.” For a detailed explanation of Deming’s thinking see Deming Revisited: The Real Quality Model.

    A Specific Tool for Improving Work Processes

    In its third use, Kaizen identifies a group of problem solving methods for making work process improvements. The methods that have been placed under the label Kaizen are varied and range from suggestion systems (referred to as Teian Kaizen) to planned events conducted in the workplace that systematically uncover waste in a work process and workplace and eliminate it (sometimes referred to as Gemba Kaizen). In this latter use, Kaizen's origins are in World War II (Huntzinger, 2002; Kato, 2006). Kaizen, then known as Job Methods training, a component of the War Department's Training Within Industry program, was a simple and effective process that enabled supervisors in concert with workers to devise ways to greatly improve the yield from work processes. Its development was spurred by the World War II necessity to produce very much more of everything that was needed for the war effort, faster than anyone ever had done in the past. Before going further into Kaizen's origins as a method for making improvements, let's clarify the varieties of methods that now fall under the label Kaizen.


    Varieties of Kaizen Methods

    The collection of Kaizen methods can be organized into the following categories:

    Individual versus teamed,  
    Day-to-day versus special event, and  
    Process or value stream level versus subprocess level.  

    Individual Versus Teamed
    While almost all Kaizen approaches use a teamed approach, there is the method described as Teian Kaizen or personal Kaizen (Japan Human Relations Association, 1990). Teian Kaizen refers to individual employees uncovering improvement opportunities in the course of their day-to-day activities and making suggestions. It does not include making the change itself, but simply the suggestion for the change. However, when used at Toyota within its suggestion system, the employee suggesting the change is the one who almost always makes the change (see The suggestion system is not suggestion). Vital Enterprise’s also uses the term Teian Kaizen to mean a personal Kaizen wherein a worker applies our Kaizen method (documented in the Kaizen Desk Reference Standard) to improve his or her own job. This effort also unfolds on a day-to-day basis. To my knowledge, all other uses of Kaizen are teamed efforts.

    Day-to-Day Versus Special Event
    A teamed example of a day-to-day Kaizen approach is Quality Circles. Here, a natural work team (people working together in the same area, operating the same work process) uses its observations about the work process to identify opportunities for improvement. During any day or perhaps at the end of the week, the team meets and selects a problem from an earlier shift to correct. They analyze its sources, generate ideas for how to eliminate it, and make the improvement. This continuous improvement of the work process is made in the context of regular worker meetings.

    Special event Kaizens are currently most common. These methods plan ahead and then execute a process or workplace improvement over a period of days. When they focus at the subprocess level, they take place at the work site with the purpose of eliminating waste in a component of a value stream. These special events are performed in the gemba—meaning, "where the real work is being done"—e.g., on the shop floor or at the point where are service is being delivered.

      Process or Value Stream Level Versus Subprocess Level
      Most times, Kaizen refers to improvements made at the subprocess level—meaning, at the level of a component work process. For example, imagine the end-to-end production process associated with manufacturing shoes. This is also termed the value stream. It includes all the activities of that transform raw inputs into shoes (output) and delivering them to customers. One subprocess would be the set of operations that apply the sole to the shoe body. Gemba Kaizen, also referred to as Point Kaizen, is an example of this level of Kaizen application. On the other hand, the term Kaizen has been used by some, but not many, to refer to improvements at the value stream or business level (e.g., Flow kaizen or Kaikaku).10 This improvement activity yields structural change to the overall workflow.

      The Common Elements
      All Kaizen methods that include making change (as opposed to just suggesting a change) have these features in common.

      They focus on making improvements by detecting and eliminating waste.
      They involve the worker or workers who execute a work process.
      They also involve checking with all others who are affected by the work process being improved so that their ideas are obtained and concerns addressed
      They use a problem solving approach that observes how the work process operates, uncovers instances waste, measures its presence, generates ideas for how to eliminate waste, selects and makes improvements, measures its effectiveness in eliminating waste, and extracts learning for sharing across the business.


    The Beginnings of Kaizen

    As stated earlier, Kaizen as a specific tool for improving work processes originated in the World War II TWI Job Methods training program. Kaizen methods that suggest improvements also originated in the work TWI. As a suggestion rather than action improvement programs, Imai points out that, "Less well known is the fact that the suggestion system was brought to TWI (Training Within Industry) and the U.S. Air Force" (1986, page 112). Huntzinger (2002) also traces Kaizen back to the Training Within Industry (TWI) program. TWI was established to maximize industrial productivity from 1940 through 1945. One of the improvement tools it developed, tested, and disseminated was labeled "How to Improve War Production Methods." It taught supervisors the skill of improving work processes. This program's name was changed to "How to Improve Job Methods" (War Production Board, 1945, page 191) and is now most often referred to as Job Methods training. It taught supervisors how to uncover opportunities for improving work processes and implement improvements. It incorporated a job aid that reminded the person of the improvement process. This process began with recording the present method of operation including details about machine work, human work, and materials handling—much like a process observations would. It used challenging questions, to provoke the discovery of improvement opportunities. It provided tips for eliminating waste—e.g., discard unnecessary steps, combine steps where possible, simplify the operations, and improve sequencing. It incorporated operator involvement in identifying waste and developing better ways to do the process. It instructed people to check out their ideas with others, conclude the best way to make the improvement, document it, get authorization, and make the improvement. Its improvements included classic poka yoke solutions like the use of jigs and guides to reduce or eliminate errors. TWI emphasized incremental improvements focusing on the processes closest to the person and making improvements that did not require wholesale redesign of machines or tools.

    The linkage to Lean and Kaizen flows from the introduction of TWI into Japan in the early 1950s by the SCAP and it utility as a means for acting on Deming’s teaching. The method was translated into Japanese, used extensively, and remained unmodified until 1955 (Kato, 2006). At that time Toyota commissioned Shigeo Shingo to upgrade the course with additional content. Shingo introduced more extensive time and motion measurement and analysis and renamed the course the “P-Course” (Kato, 2006). The “P-Course” replaced TWI's Job Methods training as Toyota’s Kaizen training program and continued to be used until 1978 when Toyota again revised the program. Kato points out that Shingo also taught the upgraded Kaizen P-course “ Matsushita Electric Corporation and many other Japanese companies.” By the time of the International Motor Vehicle Program's study of Japanese methods in 1985, Kaizen had been incorporated as a process improvement method in many Japanese companies for almost four decades.



    So, we can make these points.

    1. Kaizen and Six Sigma™ are associated with the Quality Model for achieving success in business.
    2. The term Kaizen has many different uses ranging from referring to a principle of personal conduct to a company wide strategy for achieving business success (Imai, 1986). In the United states, one of its most common uses is as the name of a lean enterprise tool for improving work processes. In this use, it refers to a systematic and specialized application of problem solving to uncover and extract waste from a work process.
    3. Kaizen as a company wide strategy for achieving business success is derived from the writings of W. Edwards Deming although the completeness of that connection seems to be unrecognized. It abstracts from Deming’s work the ideas that improvements must benefit customers; that they must occur everyday, everywhere, and be implemented by everyone; that management must lead the implementation and that managers must be models and agents of its adoption; and that management and non-management employees must operate cooperatively.
    4. The term “Kaizen” has two uses. One use refers to the principle of continuous improvement and describes a fundamental element in the Quality Model and in Lean thinking. The second use refers to methods that either suggest (e.g., Teian Kaizen) or generate and implement improvement ideas.
    5. Of the methods that both generate and make improvements, some methods are done by an individual, but most are done by teams; some are done day-to-day (e.g., Quality Circles) and some as special events; and some focus on business-level processes (value streams) to make large change (Kaikaku or Flow Kaizen) and some focus at the subprocess level, where the real work is done (Gemba or Point Kaizen).
    6. All versions of Kaizen that both generate and make improvements use the same generic problem solving process approach as does SixSigma™ although Kaizen pre-dates SixSigma™. They describe the current work process, detect and measure the presence of waste, generate ways to eliminate that waste, implement the improvement ideas, and measure the effects of the improvement made.
    7. Kaizen predates Six Sigma™ by almost five decades and the introduction of Lean thinking by almost four decades. Its origins trace to the United States where its concepts and methods were pioneered, tested, and later exported to Japan. Japanese companies adopted this method, integrated it into their Quality efforts, refined and elaborated its process, and sustained its use.



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    1A reviewer of this article cautioned me to distinguish the Quality Model from the Quality departments that populate businesses, since most readers will be familiar with the later and not the former. Establishing a bureaucracy with sole responsibility for “Quality” is inherently antithetical to the Quality Model, as it tends to concentrate concern into one administrative unit. The Quality Model is about involving everyone in owning and acting to continuously improve. As well, most of these departments became repositories for “standards” and data that is not shared and leveraged into better performance. Finally, some of these departments remain essentially rooted on post hoc discovery of defects, a practice denounced from the very earliest times by Deming. Your Quality Department may be very different from this picture, but if it is not, do not confuse it with what we refer to here as the “Quality Model.”
    2 The Taguchi loss function mathematically represents the loss due to the gap between what is produced and what a customer ideally seeks. Deming praised Taguchi’s work because it made clear that value lost progressively increases as variation increases from the intended condition. Even a stable system, therefore, can exhibit loss unless its nominal output precisely satisfies its customer’s value.
    3The original name of the model was Lean Production (Womack et al., 1991). The model is also referred to as: Lean Manufacturing, Lean Thinking, and Lean Enterprise.
    4As you will see below, the term Kaizen has multiple meanings. These different uses of the term will be explored fully below.
    5For a stark description of the circumstances on the ground in Japan when Deming arrived, read Walton’s description of the experiences Deming recorded in his diary. See Walton (1986), especially pages 10–21.
    6Deming does not use this precise language (i.e., “value stream”). Deming depicts the value stream as a “flow diagram” (Deming, 1982, p. 4). The production system begins on its left side with suppliers and ends on its right side with customers. His guidance states that “every activity, every job is part of a process” and that mapping these processes represents the enterprise’s “theory” about how it generates the product or service delivered to the ultimate customer. He explains a process as a sequence of stages through which work passes. In each stage, inputs change state and are passed to the next stage. All stages must operate together as a whole. “Each stage works with the next stage and with the preceding stage toward optimum accommodation, all stages working together toward quality that the ultimate customer will boast about” (Deming, 1982a, p. 87).
    7In service industries, pull is inherently the trigger for service delivery. No one can initiate a service operation until a customer requests it. An automotive repair shop cannot initiate an oil change for your car until you deliver your car to it and request the service. Neither can a health care provider respond to a person’s illness until the person presents him- or herself and requests care. The challenge in the service sector is to be available to serve when service is needed. This is the challenge of making the service flow. On the other hand, the supply processes associated with service delivery will generally not be pulled and these areas would be targeted for implementing pull.
    8The "sigma" in "Six Sigma" is not the equivalent of the term "sigma" as used in statistics. Six sigma is not six standard deviations from the mean. For clarification of this issue, see Burns, 2007.
    9Thus, the claims made about Six Sigma contribution to Motorla's success are incorrect (iSixSigma, 2005) as well as its relationship to the statistical concept of sigma (see Footnote 6, above).
    10Most people identify Kaikaku as radical change and in this way distinguish it from kaizen, which refers to incremental change.


    Published January 11, 2013, Revised January 12, 2013

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