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Difference between ISO 9000 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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| ISO 9000 |
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Definition |
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It is one thing to claim that one's firm produces quality products, but it is another for your trading partners to know that this is true. So a bureaucracy was established where third parties could verify a company's claims of quality products. Question is, how do you measure quality? The answer is to document a firm's practices and audit the firm for compliance to its own procedures. |
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This methodology involves administrating a culture of rules and documentation. A natural fit for enterprises that already operate under a bureaucratic culture. The documentation includes not only current practices, but also the methods for implementing process changes. The audit is meant to verify whether the firm follows the documented rules it wrote up. So in other words, ISO 9000 does not ensure that a product or service is has quality about it. Rather, ISO 9000 certifies that certain process were used, and provides for the manner in which the fact that these processes were used will be confirmed. The assumption is that in always following the same method, the same product (of quality or otherwise) will be delivered. |
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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 ISO 9000 and Six Sigma have a few things in common, in addition to the fact that they both deal with the topic of quality. They are both methodologies that can be used to implement some sort of regime which could potentially instill or improve quality in a firm's offerings. The two methodologies take different approaches, resulting in different outcomes. |
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ISO 9000 takes an indirect approach to improving the quality of an organization. The idea espoused by ISO 9000 advocates is that the process of documenting an organization's processes and verifying that the organization actually follows those processes will ensure quality. Of course, one could document and audit processes that lose money and aggravate customers, but still be certified as an ISO 9000 process. Plus indirect methods by definition will have leeway that allows for circumvention of the intent, while still staying within the boundaries of the regulations. |
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Six Sigma offers a direct approach to improving an existing system, through the disciplined application of continuous improvement, using a statistical approach applied using general systems theory. Six Sigma does provide a framework in which to apply the continuous improvement, the DMAIC approach. While not presenting exact details for every specific situation, it does offer a consistent methodology. This makes this approach well suited for large organizations that need a firm structure and documented tactics in order to institute process improvements. One could consider this method a direct attempt at improving the lot of an organization. |
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So on one hand with Six Sigma we have a methodology that brings us a set of continuous improvement ideas that have an SPC component and a process assessment component, which will integrate the results of the SPC testing. This means that Six Sigma includes a manual component, which will require discipline to maintain. Also, Six Sigma may not be simple or trivial to implement. One must realize that any time process redesign is suggested, effort must be exerted, and probably capital funds will need to be spent. On the other hand, ISO 9000 brings us another process that uses indirect methods to modify quality, but being indirect, has no guarantee of having any effect (good, bad or indifferent) on the quality of an organization. Just that ISO 9000 can be implemented without any change to the underlying processes. |
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In summary, Six Sigma and its continuous improvement methodologies offer a direct method that has a fighting chance to improve quality of business processes. ISO 9000 uses indirect methods in an attempt to instill quality into an organization. Another comparison would be that ISO 9000 is implemented in a top down fashion, while Six Sigma is a combination of direction being offered top down, but improvements being driven from the bottom up by the capabilities of processes. |
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