Six Sigma

Six Sigma is a process improvement methodology that aims to eliminate defects in any process. With its data-driven approach, Six Sigma has been widely adopted in industries ranging from manufacturing to healthcare, and has helped organizations achieve success.

The name “Six Sigma” originates from the statistical term used to measure process quality. In statistical terms, “sigma” represents the standard deviation, which is a measure of variability in a process. The term “Six Sigma” refers to a process that has a deviation of six standard deviations from the mean. In other words, it produces results with a defect rate of only 3.4 defects per million opportunities. The name was first coined by Motorola in the 1980s as a way to describe its quality control program and has since been adopted by many other organizations worldwide. The goal of Six Sigma is to achieve a process that is so consistent and predictable that it produces results with a defect rate of only 3.4 defects per million opportunities.

Six Sigma Certification

Six Sigma offers a range of certifications, including white belts, yellow belts, green belts, black belts, and master black belts. These certifications are designed to give individuals a comprehensive understanding of the Six Sigma methodology and how it can be applied to real-world problems. However, certification has become so widespread that quality is difficult to assess. Certification does not necessarily indicate capability.

Eliminating Defects

One of the key objectives of Six Sigma is to eliminate defects in a process. Defects are defined as any process output that does not meet customer requirements. The Six Sigma methodology uses data to identify the root causes of defects and implements solutions that eliminate them. The goal is to reduce defects to a level of 3.4 defects per million opportunities (DPMO).

Lean and Six Sigma

Organizations commonly choose between lean and Six Sigma for an improvement methodology. However, the approaches are complementary rather than substitutive. Six Sigma is a useful methodology, especially when solving difficult quality control problems that require rigorous statistical analysis. However, its reliance on statistical analysis limits the number of people capable of effective practice. Consequently, it can be difficult to scale training. Moreover, it can confine expertise to skilled engineers who are not engaged in frontline operations. Because frontline operators are most familiar with the work and its problems, management should provide skills and authority to solve them. This enables daily continuous improvement. Finally, practitioners may fall into the trap of seeing statistical analysis as the way to solve every problem. However, most problems require far simpler forms of analysis.

Six Sigma Project

A Six Sigma project is a structured approach to problem-solving that uses the DMAIC (Define, Measure, Analyze, Improve, and Control) methodology to eliminate defects in a process. This structured approach ensures that the right data is collected, analyzed, and used to make informed decisions that lead to meaningful, lasting improvements.

Six Sigma DMAIC - define, measure, analyse, improve, control

Example Six Sigma Project

Problem Statement: A manufacturing company has received numerous customer complaints about long wait times when calling their customer service center. The wait time is negatively impacting customer satisfaction and causing a loss of business.

Project Goal: The goal of the project is to reduce the average wait time for customers calling the customer service center to no more than 2 minutes.

Define Phase:

  • Define the problem: Long wait times for customers calling the customer service center
  • Identify the customers: Customers who call the customer service center
  • Define the project goals: Reduce the average wait time to no more than 2 minutes

Measure Phase:

  • Collect data: Conduct a survey of customer wait times and record the time they spend on hold.
  • Analyze the data: Analyze the wait time data and determine the average wait time
  • Identify the root cause of the problem: Analyze the data to determine the reasons for the long wait times

Analyze Phase:

  • Identify potential solutions: Develop a list of potential solutions to reduce wait times
  • Evaluate the potential solutions: Evaluate the potential solutions to determine which will be the most effective
  • Select the best solution: Select the solution that will most effectively reduce the wait time

Improve Phase:

  • Implement the solution: Implement the selected solution
  • Monitor and control the solution: Monitor the solution to ensure it is working effectively
  • Document the solution: Document the solution and its results

Control Phase:

  • Monitor the process: Continuously monitor the process to ensure it remains effective
  • Implement corrective action: If necessary, implement corrective action to maintain the solution
  • Standardize the process: Standardize the process to ensure it remains effective

Beyond Six Sigma: How Lean Delivers Deeper and More Enduring Benefits

By sharing several specific examples, Art Byrne shares why lean continuous improvement practices are superior to Six Sigma for solving problems and describes the situations where using Six Sigma is necessary. He also discusses why he’s not a fan of belt certification — and the approach he thinks is a better way to teach and learn lean thinking, practices, and tools. In addition, he addresses some of the questions and comments about a Lean Post, “Ask Art: How Useful is Six Sigma and the Black Belts and Green Belts that Come with It?” These include:   

  • Why leaders will miss huge opportunities for improvement when they view and use lean practices only as cost-costing efforts.  
  • Why “learn by doing” beats belt certification for developing lean leaders.
  • Why do leaders need to focus on developing a lean culture, not simply applying lean tools?
View the presentation

Additional Resources

See: Lean Thinking and Practice; Theory of Constraints