June 25

Six Sigma Explained in Layperson’s Language


In the previous section, we delved into the background information surrounding Six Sigma, setting the stage for a deeper exploration of its principles and applications. In this section, we will provide a comprehensive understanding of what Six Sigma truly entails and how it relates to Lean methodologies. By the end of this article, you will have a solid foundation to grasp the essence of Six Sigma and its significance in various contexts.

Exploring Six Sigma:

To begin, let's establish a high-level understanding of Six Sigma. At its core, Six Sigma is closely linked to the concept of variation or standard deviation. In any process or activity, there is inherent variation, making it nearly impossible to achieve identical results consistently. For instance, consider the daily commute to your office. The time it takes to reach your destination will likely vary each day. This variation is an integral part of the Six Sigma framework.

In Six Sigma, the term "Sigma" refers to the standard deviation or variation. However, before delving into the technicalities and formulas of standard deviation calculations, we will focus on a simple example to elucidate the concept. Imagine a plane landing on a strip. To ensure safety, the plane must land precisely at the center of the strip. However, due to variation, it is challenging to achieve pinpoint accuracy consistently.

To accommodate this variation, the landing strip is wider than the plane's wheels, allowing for a margin of error. Here, the width of the landing strip represents the tolerance for variation. In the context of Six Sigma, a pilot's performance is considered Six Sigma when they can land the plane within half the allowable tolerance range. By utilizing only half the tolerance, the pilot demonstrates exceptional precision and adherence to standards.

Applying Six Sigma in Different Contexts:

You might wonder how Six Sigma applies to other fields beyond aviation. Let's explore an industrial example to illustrate its versatility. Suppose we are manufacturing rods, and the desired size is 100 millimeters. The design specifications permit a tolerance range of ±6 millimeters, meaning a rod ranging from 94 to 106 millimeters would be considered acceptable.

To assess the manufacturing process's adherence to these specifications, we inspect a sample of 200 rods and record their measurements. Creating a histogram based on these measurements reveals the frequency distribution of dimensions. Observing the histogram, we can infer that most rods fall within the range of 97 to 103 millimeters, rather than the wider tolerance range of 94 to 106 millimeters.

This indicates that the manufacturing process has performed exceptionally well, as it has effectively limited the variation within a narrower range of ±3 millimeters instead of the allowable ±6 millimeters. Such a feat demonstrates a Six Sigma capability within the production process, as it consistently produces items well within the defined tolerance.


In conclusion, Six Sigma is a powerful methodology that focuses on minimizing variation and ensuring consistent, high-quality results. By understanding the principles and techniques of Six Sigma, individuals and organizations can enhance their processes, reduce defects, and achieve greater efficiency and customer satisfaction.

By delving into the concept of Six Sigma through practical examples, such as landing planes and manufacturing rods, we have uncovered its universal applicability across diverse domains. Whether in aviation, manufacturing, or any other sector, the pursuit of Six Sigma's rigorous standards empowers individuals and organizations to drive continuous improvement and deliver exceptional outcomes.

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