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63-430: The terms "quality assurance" and "quality control" are often used interchangeably to refer to ways of ensuring the quality of a service or product. For instance, the term "assurance" is often used in a context such as: Implementation of inspection and structured testing as a measure of quality assurance in a television set software project at Philips Semiconductors is described. where inspection and structured testing are

126-422: A data-driven improvement cycle used for optimizing and stabilizing business processes and designs. The DMAIC improvement cycle is the core tool used to drive Six Sigma projects. However, DMAIC is not exclusive to Six Sigma and can be used as the framework for other improvement applications. DMAIC is an abbreviation of the five improvement steps it comprises: Define, measure, analyze, improve and control. All of

189-407: A known set of limits. That is, at least, until another assignable source of variation occurs. For example, a breakfast cereal packaging line may be designed to fill each cereal box with 500 grams of cereal. Some boxes will have slightly more than 500 grams, and some will have slightly less. When the package weights are measured, the data will demonstrate a distribution of net weights. If

252-539: A laboratory must do to become accredited. Management system refers to the organization's structure for managing its processes or activities that transform inputs of resources into a product or service which meets the organization's objectives, such as satisfying the customer's quality requirements, complying with regulations, or meeting environmental objectives. WHO has developed several tools and offers training courses for quality assurance in public health laboratories. The Capability Maturity Model Integration ( CMMI ) model

315-434: A lack of statistical expertise at many organizations. The data from measurements of variations at points on the process map is monitored using control charts . Control charts attempt to differentiate "assignable" ("special") sources of variation from "common" sources. "Common" sources, because they are an expected part of the process, are of much less concern to the manufacturer than "assignable" sources. Using control charts

378-407: A low quality culture had increased costs of $ 67 million/year for every 5000 employees compared to those rated as having a high quality culture. QA is not limited to manufacturing, and can be applied to any business or non-business activity, including: design, consulting, banking, insurance, computer software development, retailing, investment, transportation, education, and translation. It comprises

441-416: A means of objectively quantifying the relative importance (strength) of sources of variation. Once the sources of (special cause) variation are identified, they can be minimized or eliminated. Steps to eliminating a source of variation might include: development of standards, staff training, error-proofing, and changes to the process itself or its inputs. When monitoring many processes with control charts, it

504-685: A more comprehensive approach to quality, the US continued to apply the Quality Control (QC) concepts of inspection and sampling to remove defective products from production lines, essentially unaware of or ignoring advances in QA for decades. It is valuable to failure test or stress test a complete consumer product. In mechanical terms this is the operation of a product until it fails, often under stresses such as increasing vibration , temperature, and humidity . This may expose many unanticipated weaknesses in

567-459: A more difficult process, determined in many ways, from the subjective user-based approach that contains "the different weights that individuals normally attach to quality characteristics," to the value-based approach which finds consumers linking quality to price and making overall conclusions of quality based on such a relationship. During the Middle Ages , guilds adopted responsibility for

630-432: A process where SPC is applied is manufacturing lines. SPC must be practiced in two phases: The first phase is the initial establishment of the process, and the second phase is the regular production use of the process. In the second phase, a decision of the period to be examined must be made, depending upon the change in 5M&E conditions (Man, Machine, Material, Method, Movement, Environment) and wear rate of parts used in

693-476: A quality improvement process, which is generic in the sense that it can be applied to any of these activities and it establishes a quality culture, which supports the achievement of quality. This in turn is supported by quality management practices which can include a number of business systems and which are usually specific to the activities of the business unit concerned. In manufacturing and construction activities, these business practices can be equated to

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756-429: A solution to the problem, either in part or as a whole depending on the situation. Identify creative solutions to eliminate the key root causes in order to fix and prevent process problems. One can use brainstorming or techniques like six thinking hats and random word . Some projects can utilize complex analysis tools like design of experiments (DOE), but try to focus on obvious solutions if these are apparent. However,

819-408: A standard product was produced, while quality was the responsibility of machine inspectors, "placed in each department to cover all operations ... at frequent intervals, so that no faulty operation shall proceed for any great length of time." Out of this also came statistical process control (SPC), which was pioneered by Walter A. Shewhart at Bell Laboratories in the early 1920s. Shewhart developed

882-438: A sub-standard article. Any source of variation at any point of time in a process will fall into one of two classes. Most processes have many sources of variation; most of them are minor and may be ignored. If the dominant assignable sources of variation are detected, potentially they can be identified and removed. When they are removed, the process is said to be 'stable'. When a process is stable, its variation should remain within

945-460: A team at AT&T that included Harold Dodge and Harry Romig he worked to put sampling inspection on a rational statistical basis as well. Shewhart consulted with Colonel Leslie E. Simon in the application of control charts to munitions manufacture at the Army's Picatinny Arsenal in 1934. That successful application helped convince Army Ordnance to engage AT&T's George D. Edwards to consult on

1008-432: A tool in any quality improvement effort to track quality data. Product quality data is statistically charted to distinguish between common cause variation or special cause variation. Walter Shewart of Bell Telephone Laboratories recognized that when a product is made, data can be taken from scrutinized areas of a sample lot of the part and statistical variances are then analyzed and charted. Control can then be implemented on

1071-426: Is a continuous activity, ongoing over time. When the process does not trigger any of the control chart "detection rules" for the control chart, it is said to be "stable". A process capability analysis may be performed on a stable process to predict the ability of the process to produce "conforming product" in the future. A stable process can be demonstrated by a process signature that is free of variances outside of

1134-489: Is created and data are collected to establish the relative contribution of each root causes to the project metric (Y). This process is repeated until "valid" root causes can be identified. Within Six Sigma, often complex analysis tools are used. However, it is acceptable to use basic tools if these are appropriate. Of the "validated" root causes, all or some can be. The purpose of this step is to identify, test and implement

1197-745: Is natural to the process (" common " sources of variation); these processes he described as being in (statistical) control . Other processes additionally display variation that is not present in the causal system of the process at all times (" special " sources of variation), which Shewhart described as not in control . Statistical process control is appropriate to support any repetitive process, and has been implemented in many settings where for example ISO 9000 quality management systems are used, including financial auditing and accounting, IT operations, health care processes, and clerical processes such as loan arrangement and administration, customer billing etc. Despite criticism of its use in design and development, it

1260-472: Is sometimes useful to calculate quantitative measures of the stability of the processes. These metrics can then be used to identify/prioritize the processes that are most in need of corrective actions. These metrics can also be viewed as supplementing the traditional process capability metrics. Several metrics have been proposed, as described in Ramirez and Runger. They are (1) a Stability Ratio which compares

1323-435: Is the systematic measurement, comparison with a standard, and monitoring of processes in an associated feedback loop that confers error prevention. This can be contrasted with quality control , which is focused on process output. Quality assurance includes two principles: "fit for purpose" (the product should be suitable for the intended purpose); and "right first time" (mistakes should be eliminated). QA includes management of

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1386-611: Is usual for teams to invest a lot of effort into assessing the suitability of the proposed measurement systems. Good data is at the heart of the DMAIC process. The purpose of this step is to identify, validate and select a root cause for elimination. A large number of potential root causes (process inputs, X) of the project problem are identified via root cause analysis (for example, a fishbone diagram ). The top three to four potential root causes are selected using multi-voting or other consensus tool for further validation. A data collection plan

1449-453: Is very important to always provide positive morale support to team members in an effort to maximize the effectiveness of DMAIC. Replicating the improvements, sharing successes and thanking team members helps build buy-in for future DMAIC or improvement initiatives. Statistical process control Statistical process control ( SPC ) or statistical quality control ( SQC ) is the application of statistical methods to monitor and control

1512-878: Is well-placed to manage semi-automated data governance of high-volume data processing operations, for example in an enterprise data warehouse, or an enterprise data quality management system. In the 1988 Capability Maturity Model (CMM) the Software Engineering Institute suggested that SPC could be applied to software engineering processes. The Level 4 and Level 5 practices of the Capability Maturity Model Integration ( CMMI ) use this concept. The application of SPC to non-repetitive, knowledge-intensive processes, such as research and development or systems engineering, has encountered skepticism and remains controversial. In No Silver Bullet , Fred Brooks points out that

1575-450: Is widely used to implement Process and Product Quality Assurance (PPQA) in an organization. The CMMI maturity levels can be divided into 5 steps, which a company can achieve by performing specific activities within the organization. During the 1980s, the concept of "company quality" with the focus on management and people came to the fore in the U.S. It was considered that, if all departments approached quality with an open mind, success

1638-563: The project team . The following are to be defined: The purpose of this step is to measure the specification of problem/goal. This is a data collection step, the purpose of which is to establish process performance baselines. The performance metric baseline(s) from the Measure phase will be compared to the performance metric at the conclusion of the project to determine objectively whether significant improvement has been made. The team decides on what should be measured and how to measure it. It

1701-466: The quality of raw materials, assemblies, products and components, services related to production, and management , production and inspection processes. The two principles also manifest before the background of developing (engineering) a novel technical product: The task of engineering is to make it work once, while the task of quality assurance is to make it work all the time. Historically, defining what suitable product or service quality means has been

1764-607: The software engineering processes and methods used to ensure quality. Various methods or frameworks are employed for this, such as ensuring conformance to one or more standards, e.g. ISO 25010 (which supersede ISO/IEC 9126 ) or process models such as CMMI , or SPICE . In addition, enterprise quality management software is used to correct issues such as supply chain disaggregation and to ensure regulatory compliance ; these are vital for medical device manufacturers. Consultants and contractors are sometimes employed when introducing new quality practices and methods, particularly where

1827-584: The American Society for Quality. 75% of senior or C-suite titles believed that their organization exhibits "a comprehensive, group-wide culture of quality." But agreement with that response dropped to less than half among those with quality job titles. In other words, the further from the C-suite, the less favorable the view of the culture of quality. A survey of more than 60 multinational companies found that those companies whose employees rated as having

1890-422: The DMAIC process steps are required and always proceed in the given order. The purpose of this step is to clearly pronounce the business problem , goal, potential resources , project scope , and high-level project timeline . This information is typically captured within the project charter document. At this stage, it is written down what is currently known, one seeks to clarify facts, set objectives and form

1953-494: The Minto Pyramid Principle's SCQA and MECE tools. The result is a framed solution supported by easy-to-follow logic. Some organizations add a R ecognize step at the beginning, thus yielding an RDMAIC methodology. This is additional to the standard DMAIC steps but it should be considered. Think about replicating the changes in other processes. Share new knowledge within and outside of the organization. It

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2016-413: The application of control charts to munitions manufacture at the Army's Picatinny Arsenal in 1934. That successful application helped convince Army Ordnance to engage AT&T's George Edwards to consult on the use of statistical quality control among its divisions and contractors at the outbreak of World War II. After World War II, many countries' manufacturing capabilities that had been destroyed during

2079-447: The capability index. A process signature is the plotted points compared with the capability index. When the process triggers any of the control chart "detection rules", (or alternatively, the process capability is low), other activities may be performed to identify the source of the excessive variation. The tools used in these extra activities include: Ishikawa diagram , designed experiments , and Pareto charts . Designed experiments are

2142-492: The complexity, conformance requirements, changeability, and invisibility of software results in inherent and essential variation that cannot be removed. This implies that SPC is less effective in the software development than in, e.g., manufacturing. In manufacturing, quality is defined as conformance to specification. However, no two products or characteristics are ever exactly the same, because any process contains many sources of variability. In mass-manufacturing, traditionally,

2205-480: The control chart in 1924 and the concept of a state of statistical control. Statistical control is equivalent to the concept of exchangeability developed by logician William Ernest Johnson , also in 1924, in his book Logic, Part III: The Logical Foundations of Science . Along with a team at AT&T that included Harold Dodge and Harry Romig, he worked to put sampling inspection on a rational statistical basis as well. Shewhart consulted with Colonel Leslie E. Simon in

2268-408: The cost of production. If the manufacturer finds the change and its source in a timely manner, the change can be corrected (for example, the cams and pulleys replaced). From an SPC perspective, if the weight of each cereal box varies randomly, some higher and some lower, always within an acceptable range, then the process is considered stable. If the cams and pulleys of the machinery start to wear out,

2331-459: The environment, a device, or a mission, product assurance plays a particularly important role here. It has organizational, budgetary and product developmental independence meaning that it reports to highest management only, has its own budget, and does not expend labor to help build a product. Product assurance stands on an equal footing with project management but embraces the customer's point of view. Software quality assurance refers to monitoring

2394-484: The extensive division of labor and mechanization resulting from the Industrial Revolution , it was possible for workers to control the quality of their own products. The Industrial Revolution led to a system in which large groups of people performing a specialized type of work were grouped together under the supervision of a foreman who was appointed to control the quality of work manufactured. During

2457-476: The finished product will need to be reworked or scrapped. Statistical process control was pioneered by Walter A. Shewhart at Bell Laboratories in the early 1920s. Shewhart developed the control chart in 1924 and the concept of a state of statistical control. Statistical control is equivalent to the concept of exchangeability developed by logician William Ernest Johnson also in 1924 in his book Logic, Part III: The Logical Foundations of Science . Along with

2520-406: The limitations of the methods being used in mass production at the time and the subsequent varying quality of output. Taylor, utilizing the concept of scientific management, helped separate production tasks into many simple steps (the assembly line) and limited quality control to a few specific individuals, limiting complexity. Ford emphasized standardization of design and component standards to ensure

2583-479: The long-term variability to the short-term variability, (2) an ANOVA Test which compares the within-subgroup variation to the between-subgroup variation, and (3) an Instability Ratio which compares the number of subgroups that have one or more violations of the Western Electric rules to the total number of subgroups. Digital control charts use logic-based rules that determine "derived values" which signal

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2646-409: The manufacturing process (machine parts, jigs, and fixtures). An advantage of SPC over other methods of quality control, such as " inspection ," is that it emphasizes early detection and prevention of problems, rather than the correction of problems after they have occurred. In addition to reducing waste, SPC can lead to a reduction in the time required to produce the product. SPC makes it less likely

2709-453: The measurement phase of a quality assurance strategy referred to as the DMAIC model ( define, measure, analyze, improve, control ). DMAIC is a data-driven quality strategy used to improve processes. The term "control" is the fifth phase of this strategy. Quality assurance comprises administrative and procedural activities implemented in a quality system so that requirements and goals for a product, service or activity will be accomplished. It

2772-423: The medical field because it helps to identify the standards of medical equipment and services. Hospitals and laboratories make use of external agencies in order to ensure standards for equipment such as X-ray machines, Diagnostic Radiology and AERB. QA is particularly applicable throughout the development and introduction of new medicines and medical devices. The Research Quality Association (RQA) supports and promotes

2835-542: The models for quality assurance defined by the International Standards contained in the ISO 9000 series and the specified specifications for quality systems. In the system of Company Quality, the work being carried out was shop floor inspection which did not reveal the major quality problems. This led to quality assurance or total quality control, which has come into being recently. QA is very important in

2898-597: The new statistical theories coming out of Britain, especially the work of William Sealy Gosset , Karl Pearson , and Ronald Fisher . However, he understood that data from physical processes seldom produced a normal distribution curve (that is, a Gaussian distribution or ' bell curve '). He discovered that data from measurements of variation in manufacturing did not always behave the same way as data from measurements of natural phenomena (for example, Brownian motion of particles). Shewhart concluded that while every process displays variation, some processes display variation that

2961-424: The part in the form of rework or scrap, or control can be implemented on the process that made the part, ideally eliminating the defect before more parts can be made like it. The quality of products is dependent upon that of the participating constituents, some of which are sustainable and effectively controlled while others are not. The process(es) which are managed with QA pertain to Total quality management . If

3024-417: The product, and the data is used to drive engineering and manufacturing process improvements. Often quite simple changes can dramatically improve product service, such as changing to mold -resistant paint or adding lock-washer placement to the training for new assembly personnel. Statistical control is based on analyses of objective and subjective data. Many organizations use statistical process control as

3087-404: The production process, its inputs, or its environment (for example, the machine on the line) change, the distribution of the data will change. For example, as the cams and pulleys of the machinery wear, the cereal filling machine may put more than the specified amount of cereal into each box. Although this might benefit the customer, from the manufacturer's point of view it is wasteful, and increases

3150-412: The project, and gain approval to release resources. One common criticism of DMAIC is that it is ineffective as a communication framework. Many improvement practitioners attempt to use the same DMAIC process, effective in solving the problem, as a framework for communication only to leave the audience confused and frustrated. One proposed solution to this problem is reorganizing the DMAIC information using

3213-428: The purpose of this step can also be to find solutions without implementing them. The purpose of this step is to embed the changes and ensure sustainability, this is sometimes referred to as making the change 'stick'. Control is the final stage within the DMAIC improvement method. In this step, the following processes are undertaken: amend ways of working, quantify and sign-off benefits, track improvement, officially close

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3276-657: The quality control short courses that trained American industry in the new techniques during WWII. The graduates of these wartime courses formed a new professional society in 1945, the American Society for Quality Control , which elected Edwards as its first president. Deming travelled to Japan during the Allied Occupation and met with the Union of Japanese Scientists and Engineers (JUSE) in an effort to introduce SPC methods to Japanese industry. Shewhart read

3339-406: The quality of a finished article is ensured by post-manufacturing inspection of the product. Each article (or a sample of articles from a production lot) may be accepted or rejected according to how well it meets its design specifications , SPC uses statistical tools to observe the performance of the production process in order to detect significant variations before they result in the production of

3402-485: The quality of a production process. This helps to ensure that the process operates efficiently, producing more specification-conforming products with less waste scrap. SPC can be applied to any process where the "conforming product" (product meeting specifications) output can be measured. Key tools used in SPC include run charts , control charts , a focus on continuous improvement , and the design of experiments . An example of

3465-566: The quality of goods and services offered by their members, setting and maintaining certain standards for guild membership. Royal governments purchasing material were interested in quality control as customers. For this reason, King John of England appointed William de Wrotham to report about the construction and repair of ships. Centuries later, Samuel Pepys , Secretary to the British Admiralty, appointed multiple such overseers to standardize sea rations and naval training. Prior to

3528-409: The quality of research in life sciences, through its members and regulatory bodies. The term product assurance (PA) is often used instead of quality assurance and is, alongside project management and engineering, one of the three primary project functions. Quality assurance is seen as one part of product assurance. Due to the sometimes catastrophic consequences a single failure can have for human lives,

3591-515: The relevant skills and expertise and resources are not available within the organization. Consultants and contractors will often employ Quality Management Systems (QMS), auditing and procedural documentation writing CMMI , Six Sigma , Measurement Systems Analysis (MSA), Quality Function Deployment (QFD), Failure Mode and Effects Analysis (FMEA), and Advance Product Quality Planning (APQP). DMAIC DMAIC or define, measure, analyze, improve and control (pronounced də-MAY-ick) refers to

3654-548: The specification does not reflect the true quality requirements, the product's quality cannot be guaranteed. For instance, the parameters for a pressure vessel should cover not only the material and dimensions but operating, environmental, safety , reliability and maintainability requirements. ISO 17025 is an international standard that specifies the general requirements for the competence to carry out tests and or calibrations . There are 15 management requirements and 10 technical requirements. These requirements outline what

3717-556: The time of the First World War , manufacturing processes typically became more complex, with larger numbers of workers being supervised. This period saw the widespread introduction of mass production and piece work , which created problems as workmen could now earn more money by the production of extra products , which in turn occasionally led to poor quality workmanship being passed on to the assembly lines . Pioneers such as Frederick Winslow Taylor and Henry Ford recognized

3780-524: The use of statistical quality control among its divisions and contractors at the outbreak of World War II. W. Edwards Deming invited Shewhart to speak at the Graduate School of the U.S. Department of Agriculture and served as the editor of Shewhart's book Statistical Method from the Viewpoint of Quality Control (1939), which was the result of that lecture. Deming was an important architect of

3843-522: The war were rebuilt. General Douglas MacArthur oversaw the rebuilding of Japan. He involved two key people in the development of modern quality concepts: W. Edwards Deming and Joseph Juran . They and others promoted the collaborative concepts of quality to Japanese business and technical groups, and these groups used these concepts in the redevelopment of the Japanese economy. Although there were many people trying to lead United States industries toward

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3906-533: The weights of the cereal box might not be random. The degraded functionality of the cams and pulleys may lead to a non-random linear pattern of increasing cereal box weights. We call this common cause variation. If, however, all the cereal boxes suddenly weighed much more than average because of an unexpected malfunction of the cams and pulleys, this would be considered a special cause variation. The application of SPC involves three main phases of activity: The proper implementation of SPC has been limited, in part due to

3969-422: Was possible if management led the quality improvement process. The company-wide quality approach places an emphasis on four aspects (enshrined in standards such as ISO 9001): The quality of the outputs is at risk if any of these aspects is deficient. The importance of actually measuring Quality Culture throughout the organization is illustrated by a survey that was done by Forbes Insights in partnership with

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