What is Six Sigma

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What is Six Sigma?

It's not a secret society, a slogan or a cliché. Six Sigma is a highly disciplined process that will help your business focus on developing and delivering high quality products and services.

The word "Sigma" is a statistical term that measures how far a given process varies from perfection. For any process you can measure how many "defects" the process produces and then determine how to eliminate them getting as close to "zero defects" as possible. 

Customer Focus

Focusing on the customer is essential to the success of any business. We all recognize this idea. But do we really internalize and practice this idea?

Do we really believe that such a focus has the potential to drive business growth and improve the quality of day-to-day work as well as improve the chance that the business, and thus jobs, will flourish?

Business growth depends on how well you meet your customers expectations in terms of quality, price, and delivery. In turn, your ability to satisfy these needs with certainty is controlled by process capability and the amount of variation in your processes.

Variation has a direct impact on business results in terms of cost, cycle time, and the amount of defects that affect customer satisfaction.

Customers are the life-blood and they must be satisfied at almost any cost. To achieve customer satisfaction - you must be customer focused!

Understanding Six Sigma

Six Sigma revolves around a few key concepts.

Critical to Quality: The product or service attributes that are most important to the customer.

Defect: Failing to deliver what the customer has ordered.

Process Capability: What your process can deliver as compared to requirements.

Variation: What the customer sees and feels.

Stable Process: A consistent, predictable processes that improves what the customer sees and feels.

Design for Six Sigma: Designing to meet customer needs and process capability.

Six Sigma is a business strategy that will provide new knowledge and capability to individuals so they can better organize the process activities of a business, solve business problems, and make better decisions.

Solving business problems, such as eliminating defects and removing waste, results in significant profitability improvement as well as increased customer and employee satisfaction.

Six Sigma is also a process measurement and management system that drives companies to take a process oriented view of the entire business.

Using the various concepts and tools;

  1. key processes are identified, 
  2. the outputs of these processes are prioritized, 
  3. process capability is determined, and 
  4. improvements are made, and a control plan structure is put in place to assure the ongoing success of the business.

The overall message of Six Sigma is that what you value, what you measure, follow up, and emphasize, is a vital determinant of how successful your company will be in improving its performance.

A key activity in Six Sigma is understanding (in quantifiable terms) customer needs and translating these needs into the measurable outcomes of processes. In turn, we need to focus on understanding and measuring the inputs to the process and looking at the root causes of variation in our processes.

Six Sigma HistorySix Sigma Process Road Map

Importance of Variation

What is Six Sigma Variation?

Everyday in business, metrics are reviewed and decisions are made based on average or mean-based performance measures. Customers don't judge us on averages, what they feel is variance in each transaction and each product we ship. Six Sigma focuses on reducing process variation first and then on improving process capability.

Customers value consistent predictable business processes that deliver the quality they expect. 

For any process, variation is the main reason for poor performance. Therefore, variation is a key focus of Six Sigma. Defects arise from variation, arising in turn from either process, material, or design inadequacies.

A defect results when a characteristic doesn't conform to a standard, and can be uniformly or randomly distributed in a process.

Closely related to the concept of defects is the metric Defects Per Unit. Another concept closely related to defects is Process Yield. The larger the number of defects in a production batch, the lower the yield.

There are several types of yield, such as first-time yield, rolled throughput yield and normalized yield. These metrics are closely linked to defects, Defects Per Unit, and ultimately process's Sigma value. The higher the Sigma value the better the process.

Process Distribution ComparisonSupplier Variation Comparison Example

What is Six Sigma Quality?

The Six Sigma methodology focuses on the drastic reduction of process variation and product defects. The result is processes which are very robust, which make very efficient use of resources and assets, and which result in highly efficient organizations.

Six Sigma process capability results in processes that yield less than 3.4 defects per million opportunities (DPMO). This is 99.9997% defect free product. Ultimate results include:

  • Reductions in Cost of Poor Quality,
  • Increases in market share,
  • Reduced cycle times and inventory levels and
  • Increased product reliability.

So What is Six Sigma - It's an Aggressive Goal

Six Sigma Quality Compared To PercentSix Sigma Quality Level Comparison Chart

Consider This...

If all things in life were done right 99.9% of the time, we would have to tolerate the following:

  • 1 hour of unsafe drinking water every month.
  • 2 unsafe plane landings per day at O'Hare Airport in Chicago.
  • 16,000 pieces of mail lost by the U.S. Post Office every hour.
  • 20,000 incorrect prescriptions every year.
  • 500 incorrect operations each week.
  • 50 babies dropped at birth every day.
  • 22,000 checks deducted from the wrong bank account each hour.
  • 32,000 missed heartbeats per person each year.

Looking in this context it’s easy to see the need for Six Sigma levels of quality.

Six Sigma Benefits

If you’re familiar with Six Sigma at all then undoubtedly you've heard the financial stories. It's true, more financial benefit is attributed to the Six Sigma methodology than any business improvement initiative ever.

Research clearly shows that firms that have successfully implemented Six Sigma outperform those that have not in almost every business category. And, the financial benefits are only a part of the story.

The biggest and most important benefit of quality improvement is increased customer satisfaction. Happy customers bring rewards such as increased opportunity! Learn more about Six Sigma from the Global Leader in Quality.


The table below cross references between different quality metrics and the cost of poor quality.

Six Sigma Process Performance ComparisonPerformance Comparison Chart

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