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Difference between TQM and Six Sigma |
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If you have any questions about our Quality Matrix, or wish to make any comments, please feel free to send a message to us at quality@artige.com. |
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| Overview |
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This analysis is just one of many comparisons that are offered as part of the Artige Quality Matrix, which can be seen here in its original form. The definitions that are used in these comparisons are the ones that we at the Artige Company use internally and with our clients, derived from the research that we perform as a matter of due course. These definitions are derived from natural laws of physics and statistics, in order to screen our work from the effects of the business press. The original article where these terms are discussed appears here. In other words, we like to think that this work will withstand the scourges of time and not be categorized as "management du jour". |
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| TQM |
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Definition |
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This is the foundation of the quality methodologies, as conceived by Deming. However, Deming never wanted to codify quality-oriented practices under a theory. He was more interested in the practice end of things. So that left a vacuum that others have rushed in to fill. This means that there is no true body of TQM theory that will increase the quality of products delivered. Instead, Deming left us with his "14 Points of Management", a toolkit that lists all of the concepts that have to do with quality one must be aware of when designing processes. A description of what a quality organization is, not how to accomplish quality. |
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Strange though that at face value those fourteen points left by the quality practitioner seem to be more philosophy than a framework or methodology in which one can design a quality business process. Each one of those points can give rise to a framework and practice in themselves, and there is no fixed manner in which those frameworks can be expressed. So it seems that TQM is readily left open to the reader's interpretation. |
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TQM includes both an empirical component associated with statistics, and an explanatory component that is associated with management, of both people and processes. The terms "hard" and "soft" are commonly used to represent these two components. TQM brought recognition to the fact that tasks can be categorized as value adding or not. The obvious corollary is that non-value adding tasks would be eliminated and the value adding ones improved. Many process design and operation tools have been highlighted in TQM, such as statistical process control, Kanban, and flexible organization, just to name the tip of the iceberg. |
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Note that at the Artige Company, we have mapped TQM back into the natural laws, of physics, general systems theory, thermodynamics and statistics, in order to provide a reference point to work from. This gives us the theoretical backing that Deming declined to document. So while Deming may have provided businesses with a 14-point philosophy in which processes can be designed, we are now able to approach business process design exercises with a firm determination as to what is feasible. |
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| Six Sigma |
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Definition |
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Six Sigma has come to mean two things. First, it is a focal point or slogan used as a means to coach a company into improving its performance. For example, one firm's Six Sigma program is "a highly disciplined process that helps us focus on developing and delivering near-perfect products and services". Second, Six Sigma is a designation for a regulated program that a firm might elect to use to establish a quality management system in an effort to improve the quality of products produced or services delivered, and then desires to maintain that improved level of performance. The latter definition is the one referenced most often in the popular business press. |
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| General Systems Theory |
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For both definitions, Six Sigma draws upon the general system theory and relies heavily upon statistics, especially statistical process control (SPC), and requires quantitative parameters that can be measured on an on-going basis if it is deployed as a quality management system. This methodology utilizes traditional process control at its best, making Lord Kelvin proud. Process control is the practice of operating a system, measuring externally available parameters, and modifying the process based upon the measurements. The calculations are not random, but based upon statistics, especially standard deviations. |
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Actually, Six Sigma gets its name from the table of probabilities for the normal (Gaussian) distribution that is used in many statistical calculations. The standard deviation variable is typically symbolized by the small Greek letter sigma. A standard deviation in this context is the amount of the population of samples that are expected to be perfect. The higher the standard deviation, the fewer rejects are expected. The amount becomes exponentially smaller as the number of standard deviations increases, which indicates that it will be more difficult to maintain a process within higher levels of standard deviation. |
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| Sigma = 2 Std Dev |
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Back in the good old days when SPC was common practice, a process was considered to be in control when it ran with +/- three standard deviations, or three sigma. Note that number sums up to six total standard deviations. Today, one is not satisfied unless the process runs within six-sigma deviation, leaving little room for error or defects. To give some numbers to these sigma values, one could consider the number of defects one could expect in the different scenarios. For three sigma, one could expect 2.6 defects per thousand units. For six sigma, the rate would be one half defect per billion units. However, there is an additional factor that needs to be taken into account, that of the drift in the process being measured. SPC takes that into consideration, so the typical defect rate realized with six sigma processes increases to 3.4 defects per million units. Note that these values are typical, and a properly run SPC regime will measure the true defect rates. |
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| DMAIC |
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As you can see from the previous paragraph, it is possible to deploy a Six Sigma program with steadiness and purpose. However, SPC is only one portion of a Six Sigma program. Essentially, Six-Sigma extends the process control concepts to process design and improvement. It requires that one take a system view of the business or manufacturing processes and treat them in a systemic manner. An acronym associated with Six Sigma is DMAIC, which stands for the continuous improvement process of Define, Measure, Analyze, Improve and Control. This is a circular process, where the results of the first pass are used to run the second iteration. |
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The hardest part of Six Sigma is defining the system that describes the business process. It is completely up to the business or process owner to select the best places for splitting an enterprise into monitorable systems. The first two parameters of Define and Measure are the numerically manageable parameters. Metrics and goals need to be defined, seeking out those that can be measured and consistently reported upon, that reflect upon some sort of process output. As the process is operated, process measurements are collected and recorded on a periodic basis. |
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The final three parameters of Analyze, Improve and Control act upon the metrics that were recorded, and are of a more qualitative nature. Here one compares the results against the self-determined boundary conditions and goals. The process is investigated when the boundary conditions are exceeded, and problem solving is engaged in an attempt to determine what went wrong and what could be done to improve the process. The metrics also allow for one to be proactive, and start problem solving based on trends that are observed before the boundary conditions are crossed. Main point is that the DMAIC process is never halted, otherwise complacency will set in. |
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The Six-Sigma methodology requires human intervention, as this process occurs around and about the business processes. The data collection aspect can be automated, but does not have to be. The analysis and improvement aspects cannot be automated at this time. The requirement for human intervention, along with its inefficiencies, brings along indirect issues, such as group dynamics and process ownership. To address these inescapable issues, many Six-Sigma methodologies incorporate personnel practices, summarized through the use of mentoring and granting of titles to the practitioners, based upon colored belts. |
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Note that there is difference of opinion on the effectiveness of hierarchical organizations, and quality organizations typically run flat. On top of that the notion that the practitioners of Six-Sigma are limited by the level of expertise that they possess and are only able to draw upon is curious for a quality organization to pursue. Nonetheless, discipline is strongly promoted, as the tighter the control limits (higher the number in front of sigma), the more tedious the effort to maintain control will be. For the most part, Six-Sigma is an incremental methodology. |
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| The Difference |
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The Differences and / or Similarities |
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At first glance, one would think that TQM and Six Sigma do not have much in common, other than the fact that they both deal with the topic of quality. One is a philosophy of what makes up a quality organization, and the other is a program that claims an organization can achieve a certain level of quality if it were to apply general systems theory and statistics in a consistent manner. As is typical for comparisons to TQM, this instance ends up being a parent-child situation, where TQM provides the ideals while Six Sigma provides a specific approach. |
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The difference is that TQM, through its 14 Points, provides guidance that an organization can reference when designing their processes and operations, while Six Sigma, through its DMAIC approach, provides additional direction over that offered by TQM to design processes with higher quality in mind. Both of these process design methodologies share a background based upon general systems theory and statistics, just that Six Sigma offers a more certain path to accomplishing a quality organization than TQM does. |
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Specifically, Deming's fifth point "Improve constantly and forever ..." would infer the need for some sort of continuous improvement methodology such as Six Sigma. In addition, the thirteenth point "Institute a vigorous program ..." would cover the DMAIC approach that Six Sigma would like an organization to implement. So this would make Six Sigma a subset of TQM, and not a peer concept for comparative purposes. |
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Note that Six Sigma does contravene a few of Deming's 14 points. They would be the seventh "Institute leadership", the ninth "Break down barriers...", and the last one where everyone is supposed to participate. The unashamed belting of individuals, setting up a hierarchy of quality workers, flies in the face of Deming's tenets concerning a quality organization. One major argument that can be distilled from Deming's 14 points is that all workers are capable and should be given the resources to accomplish their tasks, and have input into the design and operation of the tasks. An organization setup under TQM principles would be flat, and the workers would teach each other as need be. Six Sigma's color belt pecking order now gives a respectable face to an organization while allowing it to maintain its previous hierarchical structures. |
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As we always like to add, Six Sigma is not the only method of deploying disciplined and never-ending process improvement methodology. Other methods exist, some which require manual intervention, others that can be implemented with more automation. On top of that, a disciplined approach is not always the correct answer. In some instances a radical approach may be called for. It all depends on the circumstances at hand. |
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