In a normally distributed process, 99.73% of measurement will fall within ☓σ, and 99.99932% will fall within ±4.5σ.įor a process, the sigma capability is a metric that shows how well that process is performing. Moreover, sigma is a statistical term that refers to the standard deviation of a process around its mean. Six Sigma derives from the normal or bell curve in statistics, where each interval indicates one sigma or one standard deviation. (Also see: History of Continuous Improvement). Now, it has become a project-driven approach for process improvements that follows the five-step process, also called the DMAIC cycle. General Electric recognized benefits of $2.5 billion per year due to Six Sigma policies and made it a company-wide strategy. Later, it became a popular management approach at GE with Jack Welch in the early 1990s.

While working at Motorola in the year 1986, Smith created Six Sigma as a general approach to measuring quality in business performance terms. The term Six Sigma was first coined by American engineer Bill Smith, who is known as the father of Six Sigma. wrong size, shape, or weight). To correct this, the factory uses Six Sigma to determine what’s causing the variation/defects and works to reduce them to a six-sigma level. Now, randomly sampled output discovers that out of every 1,000 widgets, fifty are flawed (e.g. The widgets are all supposed to be a certain size, shape, and weight. Six Sigma methodologies are used to identify and remove the root cause of defects or reduce the process variation (using statistical or process analysis methods) and also the costs that are associated with it.įor example, let’s say XYZ factory produces widgets. In other words, any process performance outside of the defined specification is considered waste or a defect. Waste or defects are measurable product characteristics that do not meet the requirements of the customer (i.e. In other words, the extent to which process performance varies around the mean. Variation is the range of difference between the statistical mean and all data points that are used to calculate the mean. Hence, it focuses on variation reduction and waste elimination. The purpose of Six Sigma is to satisfy customers by producing quality products. However, it is not a standard, certification, or metric like a percentage. It is a Quality Philosophy and a management technique. Six Sigma refers to the practice of delivering products and services that perform at high standards. Specifically, Six Sigma is a continuous improvement process with a focus on the following:

It is a systematic problem-solving approach centered around defect elimination and variation reduction, leading to process improvement. Six Sigma is a framework designed to make an organization more competitive by focusing on being effective and efficient.

6 sigma methodology