What Is Lean Six Sigma?

Lean Six Sigma combines lean manufacturing and Six Sigma to help organizations improve their processes and reduce waste. Here’s why it’s effective.

Written by Erdem İŞBİLEN
Published on Apr. 04, 2023
What Is Lean Six Sigma?
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Lean Six Sigma brings together principles from lean manufacturing and Six Sigma. Lean manufacturing is a philosophy that emphasizes the elimination of waste and the improvement of production flow through collaborative team effort. Six Sigma is a data-driven methodology that uses statistical analysis and problem-solving tools to identify and eliminate defects as well as process variations. Lean Six Sigma combines these methodologies to increase organizational efficiency.

Why Is Lean Six Sigma Important?

The combination of lean and Six Sigma methodologies provides a comprehensive approach to process improvement that can help organizations streamline their operations, reduce costs and improve quality, thereby leading to significant improvements in efficiency and customer satisfaction.

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Lean Six Sigma Techniques

Lean Six Sigma uses a variety of techniques to improve processes and reduce waste.


Value Stream Mapping 

VSM is a tool we use to identify and eliminate waste in a process by mapping out the entire value stream, from the start of the process to the end.



DMAIC (Define, Measure, Analyze, Improve, Control) is a problem-solving methodology used to improve existing processes by identifying and eliminating the root cause of problems.

What Are the 5 Phases of Lean Six Sigma?

The Lean Six Sigma methodology typically consists of five phases known as DMAIC, which stands for define, measure, analyze, improve and control.

  1. Define
  2. Measure
  3. Analyze
  4. Improve
  5. Control



Kanban is a visual management tool that helps manage and control the flow of work by using cards or other visual indicators to signal where tasks are within a given project workflow.



5S is a workplace organization methodology that aims to improve efficiency and productivity by creating a clean, safe and organized work environment.The term 5S stands for the five Japanese words that describe the steps involved in the method: seiri (sort), seiton (set in order), seiso (shine), seiketsu (standardize) and shitsuke (sustain).



Poka-yoke is a mistake-proofing technique used to prevent errors from occurring in a process by designing products or processes that make it impossible for errors to occur. We can accomplish this by implementing physical or visual cues that alert the worker to a potential mistake or prevent the mistake from happening in the first place.

For instance, most modern microwave ovens have a safety mechanism that prevents the oven from operating if the door is not properly closed. This ensures that the user will not accidentally turn on the microwave with the door open, which could result in injury. This is a perfect example of Poka-Yoke implementation that protects users from injuries.


Statistical Process Control (SPC) 

SPC is a technique used to monitor and control a process by using statistical methods to measure and analyze data. Control charts, process capability analysis and sampling plans are among these statistical methods used in SPC. 

Sampling plans help us determine how many samples of a product or process output we should take for analysis. The goal is to obtain enough data to make accurate inferences about the overall process performance while minimizing the cost and time required for data collection and analysis. 

Control charts help identify when a process is producing results that are outside of the expected range, which can signal the need for corrective action.

Process capability analysis involves calculating statistical metrics such as Cp and Cpk, which measure how well the process is centered and how much variation it produces. 


Root Cause Analysis (RCA) 

RCA is a problem-solving technique used to identify the underlying causes of problems by asking “why” until we reach the root cause.


Advantages of Lean Six Sigma

  • Improved Quality
  • Increased Efficiency
  • Cost Reduction
  • Improved Customer Satisfaction
  • Cultural Change
  • Competitive Advantage

Improved Quality

Lean Six Sigma methodologies are designed to improve process efficiency and reduce defects. By using data-driven analysis and process improvement techniques, Lean Six Sigma can help organizations improve product or service quality, which can lead to greater customer satisfaction and loyalty.


Increased Efficiency 

Lean Six Sigma helps organizations identify and eliminate waste, non-value-added activities and other process inefficiencies. These improvements help reduce process cycle times, increase throughput and reduce costs, all of which lead to greater efficiency and productivity.


Cost Reduction

By reducing defects and inefficiencies, Lean Six Sigma can help organizations reduce costs associated with rework, scrap and other forms of waste. This can result in significant cost savings and improved profitability.


Improved Customer Satisfaction

Lean Six Sigma helps organizations focus on customer needs and expectations, which can lead to improved customer satisfaction and loyalty. By reducing defects and improving quality, organizations can increase customer trust and confidence.


Cultural Change

Lean Six Sigma methodologies emphasize collaboration, data-driven decision-making, customer value and a culture of continuous improvement

The methodology encourages employees to constantly look for ways to improve processes, reduce waste and increase efficiency by promoting collaboration across teams. By breaking down silos and encouraging teamwork, it fosters a more positive and collaborative work environment.

Lean Six Sigma promotes data-driven decision making as it helps to establish a culture of continuous improvement. By regularly collecting and analyzing data on process performance, companies can identify trends and patterns that indicate areas for improvement. 


Competitive Advantage 

By improving quality, efficiency and customer satisfaction, Lean Six Sigma can help organizations gain a competitive advantage in the marketplace. This can lead to increased market share, revenue growth and improved profitability.

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Lean Six Sigma Phases

1. Define 

In this phase, we establish a project team. The team then works to define the project goals and objectives as well as identify the process to be improved. The team also clarifies the problem and the customer’s requirements.


2. Measure 

In this phase, teams measure and baseline the current performance of the process, collect data and develop a process map (or flowchart) to understand the process steps and potential areas for improvement.


3. Analyze 

In this phase, teams analyze data to identify the root cause of problems and process variations. The team may use statistical analysis and other tools to help them identify the most significant causes of process problems.


4. Improve 

In this phase, the team develops and implements process improvements by using the information gathered in the previous phases. The team may use lean tools to reduce waste, improve flow and make the process more efficient. The team may also use Six Sigma tools to reduce variation and improve quality.


5. Control 

Finally, the team monitors and sustains process improvements over time. During the control phase, teams focus on monitoring and sustaining the improvements achieved in the previous phase. The team also develops a control plan to monitor the process and take corrective action when necessary.

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DMAIC in Lean Six Sigma vs. Six Sigma

The DMAIC process in Six Sigma and Lean Six Sigma is essentially the same. However, there are some key differences in how we apply DMAIC in the context of Six Sigma versus Lean Six Sigma.

In Six Sigma, DMAIC is typically focused on improving the quality of a process by reducing defects and minimizing variability. The emphasis is on achieving statistical process control and improving process capability. The team may use statistical tools such as hypothesis testing, design of experiments and control charts to identify and eliminate sources of variation and improve process performance.

In Lean Six Sigma, we use the DMAIC process to improve both the quality and efficiency of a process by reducing waste and improving flow. The team may use lean tools such as value stream mapping, 5S and kaizen events to identify and eliminate non-value-added activities and streamline the process flow. The team may also use Six Sigma tools to reduce variability and defects and improve quality.

Another key difference is that Lean Six Sigma places a greater emphasis on the customer and their needs throughout the DMAIC process. Teams identify and analyze customer needs in the define phase, then monitor and measure customer satisfaction throughout the process. This helps ensure the process improvements are aligned with the needs of the customer and deliver value to the organization.

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Lean Six Sigma Belt Levels

Lean Six Sigma uses a belt system to denote different levels of expertise and responsibilities within the organization. The belt system is based on the martial arts belt system, where darker belts indicate a greater level of expertise. Each belt level has its own set of responsibilities and requirements for certification.

There are five levels of Lean Six Sigma belts.


White Belt 

This is the introductory level of Lean Six Sigma training and provides an overview of the basic concepts and principles of Lean Six Sigma.


Yellow Belt 

Yellow belt training provides a more detailed understanding of the Lean Six Sigma methodology and prepares individuals to participate in improvement projects.


Green Belt 

Green belt training provides a comprehensive understanding of Lean Six Sigma tools and techniques and prepares individuals to lead improvement projects.


Black Belt 

Black belt training provides advanced training in Lean Six Sigma tools and techniques and prepares individuals to lead complex improvement projects and manage improvement programs.


Master Black Belt 

Master black belt training provides the highest level of training in Lean Six Sigma and prepares individuals to be experts in the methodology and lead strategic improvement initiatives while mentoring and training others.

In addition to these belt levels, there are also Lean Six Sigma Champions who provide executive sponsorship and leadership for improvement initiatives, as well as Lean Six Sigma Facilitators who provide training and support for improvement projects.

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Lean Six Sigma vs. Six Sigma

Lean Six Sigma and Six Sigma are two related methodologies that share the goal of improving business processes and reducing defects. However, there are some key differences between the two.

Six Sigma is a methodology that focuses on reducing defects and improving quality by using statistical analysis to measure and improve process performance. 

Lean Six Sigma, on the other hand, combines the principles of lean manufacturing and Six Sigma. In addition to the DMAIC process, Lean Six Sigma also includes lean manufacturing principles such as value stream mapping, 5S and Kanban to improve process efficiency.

The main difference between Lean Six Sigma and Six Sigma is that Lean Six Sigma places a greater emphasis on the reduction of waste and non-value-added activities, while Six Sigma focuses more on reducing defects and improving process quality. 

Another difference is that Lean Six Sigma is more focused on continuous improvement and cultural change, while Six Sigma is more focused on solving specific problems and implementing process improvements.

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