Find answers to commonly asked questions about quality concepts.

  1. What is SPC (Statistical Process Control)?
  2. What is statistical control and why is it important?
  3. What is total quality?
  4. Why is quality important?
  5. What are ISO 9000 standards?
  6. What is six sigma?

What is SPC (Statistical Process Control)?

Statistical process control is the practice of using statistical methods such as control charts and capability analysis to monitor and control a process. SPC allows users to take appropriate actions so that the process remains in a state of statistical control. It also allows users to improve the process's ability to produce output that meets or exceeds customer expectations.

Statistical process control methods are applied to virtually any type of organization, including service, manufacturing, and educational organizations.

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What is statistical control and why is it important?

A process is said to be in statistical control when all special causes of variation have been eliminated and only natural (or common) cause variation remains. On a control chart, this is illustrated by data that falls within control limits and by the absence of non-random patterns or trends.

Statistical control is important because it shows you what the process is capable of producing over time. Statistical control allows you to make predictions about how the process will run in the future, based on how it ran in the past. It helps you see if the process is currently capable of producing output that meets specifications 100% of the time.

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What is total quality?

Total quality is the involvement of everyone in continuous improvement of systems to produce products and services which result in customer loyalty now and in the future.

To produce quality, a system must be in place that allows everyone in the organization to do his or her best. Long-term success requires a never-ending journey of improvement through the application of theory and a systematic process.

Continuous improvement is vital to all systems in the organization: design, production, delivery, service, and learning. All products and services that help achieve the organization's purpose should be addressed through improvement activities.

The result of total quality is fulfillment of customer needs and expectations so well that customers keep coming back for products and services and boast about them to their friends and neighbors.

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Why is quality important?

Quality is important because improving quality improves business. Dr. W. Edwards Deming developed the Quality Chain Reaction.

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What are ISO 9000 standards?

The ISO 9000 standards are a generic core of quality system standards that apply to a broad range of industry and economic sectors. They offer guidance for quality management and general requirements for quality assurance.

These standards describe elements that quality systems should include, but not how a specific organization should implement them. How an organization designs and implements a quality system is affected by its objectives, products, processes, and specific practices.

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What is six sigma?

The words six sigma are associated with variety of meanings. For example the words can have a technical meaning, a philosophical meaning, or be understood simply as a measurement. Six sigma can be a result, an action, or a goal. The uses for the words “Six Sigma” as they apply to a methodology for achieving business improvement are as follows:

  1. Six Sigma is a philosophy and methodology for achieving business improvement.
  2. The “sigma score” is a universally applicable measurement of performance for business processes. Use of this score allows a valid comparison of the performance of different processes.
  3. A score of six on the sigma scale is the goal to which “Six Sigma” companies strive. At this six sigma level, a process (whether it produces data or widgets) outputs less than 4 defects for every million opportunities.
  4. Six Sigma is a structured and disciplined method for reaching an improvement goal.

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