What is Sigma in Six Sigma

What is Sigma in Six Sigma, and What Does It Mean for You?


In Six Sigma, 'Sigma' (represented by the Greek letter 'σ') is a statistical term that measures process deviation from perfection or the standard. The 'Six' in Six Sigma refers to the statistical concept of having less than 3.4 defects per million opportunities (DPMO), which equates to a process being 99.9997% defect-free. This level of performance is considered a "six sigma" level, hence the name. The goal of Six Sigma methodology is to improve the quality of process outputs by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes. It uses a set of quality management methods, including statistical methods, and creates a special infrastructure of people within the organization who are experts in these methods. So, in essence, 'Sigma' represents the measure of quality that strives for near perfection in Six Sigma.

What is Sigma in Six Sigma? 6σ

Sigma is a statistical term that measures the standard deviation of a process. (σ)

In Lean Six Sigma, sigma is used as a measure of process quality. Six Sigma means no more than 3.4 defects per million opportunities. This level of quality is achieved by designing processes capable of meeting customer requirements and continually monitoring and improving those processes.

While achieving Six Sigma may seem daunting, it is attainable through proven statistical methods and the commitment of everyone involved in the process. By striving for Six Sigma, businesses can improve their bottom line by reducing waste, increasing customer satisfaction, and improving efficiency.

Sigma is also used as a measurement tool to determine how much variation exists within a group or population.


Sigma is a statistical measure that quantifies the dispersion of a data set around its mean. It also determines how much variation exists within a group or population.

Sigma can be calculated using the following formula: sigma = square root of [(the sum of (xi – mean) squared] / (n-1)]. where xi is each data point, mean is the arithmetic average, and n is the number of data points.

Sigma can also be interpreted as the standard deviation of a population. A high sigma value indicates that there is more significant variation within the population, while a low sigma value indicates that there is less variation.

The lower the standard deviation, the more consistent the results.

A six sigma event occurs when there is only one instance of a problem occurring within a group of 1 million people. This means that 99.999% of the time, the same thing won’t happen. A process can be considered Six Sigma if it produces less than 3.4 defects per million opportunities.

An example of a Six Sigma process would have a yield of 99.9997%. To achieve a Six Sigma quality level, a process must have a sigma value of at least 6.0.

Sigma is also used as a measurement tool to determine how much variation exists within a group or population.

The term “six sigma” was coined by Motorola in 1986. It refers to the ability to achieve quality with a standard deviation of 0.3 (or 3%). This means that 99.7% of the time, the process is working correctly Achieving Six Sigma requires a commitment from everyone involved in the process, from management to front-line workers. It also requires the use of statistical methods to identify and solve problems.

To monitor this, we can use Control Charts to identify our variation overtime.


The more the standard deviation, the wider the range of values.


If we take a random sample of 100 people, the average result would be 50. However, if we took another random sample of 100 people and got the same result, then we would say that the distribution was symmetrical.

How Six Sigma uses statistics to improve quality and productivity


Six Sigma is a data-driven approach to quality improvement that was developed by Motorola in the 1980s. Six Sigma aims to reduce defects in manufacturing and other business processes to less than 3.4 defects per million opportunities. To achieve this, Six Sigma uses statistical methods to identify and eliminate sources of variation in process outputs.

By reducing variation, Six Sigma can improve the quality of products and services while also increasing productivity and reducing costs. Although it was initially developed for manufacturing, Six Sigma has since been adopted by many other industries. Today, Six Sigma is an essential tool for businesses looking to improve their quality and competitiveness.

Benefits of using Six Sigma in business


Six Sigma is a data-driven approach to improving business processes by reducing defects and increasing efficiency. The Six Sigma methodology can be applied to any business process, from manufacturing and product development to customer service and marketing. By identifying and addressing sources of variation in a process, Six Sigma can help businesses to reduce defects, save money, and improve customer satisfaction.

In addition, the Six Sigma approach can solve complex problems by breaking them down into manageable steps. As a result, Six Sigma has become an essential tool for businesses looking to improve their bottom line.



Case studies of successful Six Sigma implementations


Six Sigma is a data-driven approach to improving quality and reducing defects. The Six Sigma method can be applied to any process in any organization, from manufacturing to customer service. Many businesses have successfully implemented Six Sigma and achieved impressive results. For example, Motorola was one of the first companies to adopt Six Sigma, and within a few years, they had reduced their defects per million opportunities by over 99%.

General Electric is another company that has benefited fromSix Sigma; after implementing the approach, they saw a dramatic drop in their customer complaints. And Honeywell International saw a 40% reduction in scrap and rework costs after implementing Six Sigma. These are just a few examples of businesses that have seen success with Six Sigma. Six Sigma can be a powerful tool for businesses looking to improve their quality and bottom line when properly implemented.

How to get started with Six Sigma if your business is interested


If your business is interested in Six Sigma, there are a few things you need to do to get started. First, you need to identify a Six Sigma Champion. This is someone responsible for leading and overseeing the Six Sigma initiative within your company. Once you have a champion, you need to select a Six Sigma Green Belts team.

These employees will receive training in Six Sigma methods and tools and help implement Six Sigma projects within your company. Finally, you need to decide what type of Six Sigma approach you want to use. There are two main approaches: DMAIC (Define, Measure, Analyze, Improve, Control) and DMADV (Define, Measure, Analyze, Design, Verify). Once these things are in place, you can begin implementing Six Sigma within your company.


Sigma is a business strategy used for decades to improve quality and productivity. It can be applied in any industry, and the benefits are clear. If you’re interested in learning more about Six Sigma and how it could benefit your business, get in touch with us. We would be happy to help you get started on your transformation journey. Thanks for reading!

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Reagan Pannell

Reagan Pannell

Reagan Pannell is a highly accomplished professional with 15 years of experience in building lean management programs for corporate companies. With his expertise in strategy execution, he has established himself as a trusted advisor for numerous organisations seeking to improve their operational efficiency.

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