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What is Lean Six Sigma? How is it Different from Six Sigma?

Lean Six Sigma is a project management methodology that gained traction due to its efficiency-boosting and defect-reducing capabilities. It combines two powerful project management methodologies: Lean and Six Sigma.

In this article, we'll talk about the definition of Lean Six Sigma, its history, methodology, and importance.

What is Lean Six Sigma Methodology?

What is Lean Six Sigma Methodology?

As the name suggests, Lean Six Sigma blends Lean and Six Sigma principles. Six Sigma is a data-centric approach which improves processes by minimising defects and variations. 

Originating from Motorola in the 1980s, "Six Sigma" refers to a statistical concept representing a process with an extremely low defect rate, equating to 3.4 defects per million opportunities (DPM). Utilising statistical tools, Six Sigma identifies and addresses the root causes of defects, ensuring processes operate at the highest level of quality and precision

If Six Sigma focuses on minimising variations and defects, Lean focuses on enhancing efficiency and quality by eliminating waste. Waste, in the Lean context, refers to anything that does not add value from the customer's perspective. Key elements of Lean include minimising inventory, reducing waiting times, optimising workflows, and improving overall process flow

Together, these two managerial processes form Lean Six Sigma. In simplest terms, the Lean Six Sigma Approach improves organisational processes by minimising variations and defects and removing waste.

History of Lean Six Sigma

History of Lean Six Sigma

Lean Six Sigma started with the development of Lean. Lean principles, originating from the Toyota Production System (TPS) in the 1950s by Taiichi Ohno and Shigeo Shingo, focused on minimising waste and optimising manufacturing processes. Key principles like Just-In-Time production and the Kanban system aim for efficiency and resource optimisation.

In the 1980s, Six Sigma emerged at Motorola under the guidance of engineer Bill Smith. Introducing statistical methods, the objective was to enhance manufacturing quality to achieve only 3.4 defects per million opportunities. Motorola's success promoted Six Sigma, establishing its reputation for improving quality.

The formal integration of Lean and Six Sigma in the 1990s resulted in the creation of Lean Six Sigma. Adopting the DMAIC framework from Six Sigma and incorporating Lean tools for waste elimination, this integration aimed to provide a comprehensive approach to process improvement.

Why Use Lean Six Sigma?

Why Use Lean Six Sigma?

Lean Six Sigma benefits your organisation in various ways. Firstly, it offers a structured, data-driven problem-solving approach through its DMAIC (Define, Measure, Analyse, Improve, Control) process. This ensures decisions are based on objective analysis, leading to effective and lasting solutions.

Secondly, Lean Six Sigma cultivates a culture of continuous improvement, encouraging organisations to evolve and adapt. Implementing Lean Six Sigma has proven to enhance operational efficiency, cut costs, and heighten customer satisfaction. 

Boeing, a leading aircraft manufacturing company, has successfully implemented Lean Six Sigma principles in its production process. As a result, they have increased the production rate of commercial planes by a staggering 60%. The time taken to assemble a 737 aircraft has been reduced by 50%, while warehouse utilisation has increased by 132%.

The methodology's adaptability across industries further solidifies its appeal, making it an invaluable asset for businesses striving for sustained success.

Lean Six Sigma Phases and Steps

Lean Six Sigma Phases and Steps

As previously mentioned, Lean Six Sigma follows Lean’s systematic approach known as DMAIC (Define, Measure, Analyse, Improve, Control).

  • Define

    Begin by precisely outlining the project goals, scope, and objectives. Identify key stakeholders and customer requirements to understand the project's parameters clearly.

  • Measure

    Proceed to quantify and assess the current state of the business processes. Collect relevant data to establish baseline metrics, allowing for a comprehensive evaluation of the existing conditions.

  • Analyse

    Delve into the gathered data to pinpoint the root causes of issues. Utilise statistical tools to gain valuable insights into the factors influencing performance, facilitating a thorough analysis.

  • Improve

    Move forward by developing and implementing solutions to address the identified problems. Apply Lean principles for waste reduction and integrate Six Sigma techniques specifically designed for defect reduction. This step involves actively enhancing the process based on the insights gained during the analysis phase.

  • Control

    Finish the process by establishing measures and monitoring systems to sustain the implemented improvements. This step is crucial for ensuring the stability of the process and confirming that it consistently meets the defined goals over time. Implement control mechanisms to uphold the achieved enhancements and prevent the reoccurrence of identified issues.

Lean Six Sigma vs Six Sigma

Lean Six Sigma vs Six Sigma

While Lean Six Sigma and Six Sigma aim for process improvement, they differ in focus and application. Here's a summary of their differences and similarities.


  • Focus on Process Improvement:Lean Six Sigma and Six Sigma are dedicated to improving organisational processes. They are committed to enhancing efficiency, reducing defects, and delivering higher-quality products or services.

  • Rooted in Data and Analysis:Data-driven decision-making is a fundamental aspect of both methodologies. They emphasise using statistical analysis to identify the root causes of issues, measure performance, and drive informed improvements.

  • DMAIC Framework:Lean Six Sigma and Six Sigma follow the DMAIC (Define, Measure, Analyse, Improve, Control) framework as a structured approach for guiding improvement projects. This common structure provides a systematic and disciplined methodology.



Organisations must understand these differences and similarities to choose the most suitable methodology based on the specific goals, industry, and organisational culture. While Lean Six Sigma integrates principles from both methods, Six Sigma focuses more on defect reduction and process stability using statistical methods. Organisations often choose based on the nature of their processes and the extent to which waste reduction is a priority alongside defect reduction.

8 Types of Wastes in Lean and Lean Six Sigma

8 Types of Wastes in Lean and Lean Six Sigma

In Lean methodology, waste is any activity or resource that doesn't contribute value to the final product or service as perceived by the customer. The core principles of Lean thinking revolve around recognising and getting rid of this waste, aiming to simplify processes, cut down on expenses, and improve overall efficiency.

1. Overproduction

This waste happens when more items are produced than the actual demand or before they are needed for the next phase. This results in the tying up resources such as materials and labour, leading to unnecessary costs. In the context of Lean and Lean Six Sigma, reducing overproduction is critical for optimising efficiency and cutting down on excess inventory, enabling better allocation of resources.

2. Waiting

This waste occurs when processes or individuals are inactive and awaiting the next step in the production or workflow. This idle time contributes to inefficiency. Lean identifies and eliminates these waiting periods to maintain a continuous flow and maximise overall productivity.

3. Transportation

This involves unnecessary movement or handling of materials or products. Excessive transportation consumes time and resources and heightens the risk of damage or defects. In the Lean framework, emphasis is placed on streamlining transportation to essential steps to reduce waste and enhance overall efficiency.

4. Overprocessing

Overprocessing means conducting more work than necessary according to the customer's specifications. This may include using higher-grade materials or employing more complex processes than required. Lean and Lean Six Sigma recognise and eliminate to maximise resources and reduce costs without compromising quality.

5. Inventory

Inventory waste includes excess raw materials, work-in-progress, or finished goods beyond immediate necessity. This ties up capital, occupies space, and may lead to obsolescence or deterioration. Lean and Lean Six Sigma advocate for minimising inventory to enhance cash flow, cut holding costs, and improve responsiveness to customer demand.

6. Motion

This waste pertains to the unnecessary movement of people or equipment within a workspace. This can result in inefficiency, an increased risk of accidents, and decreased worker productivity. In Lean principles, the emphasis is on minimising unnecessary motion to create a more ergonomic and efficient work environment.

7. Defects

Defect waste involves producing products or delivering services that exceed customer specifications. This waste leads to rework, heightened costs, and potentially damages the organisation's reputation. Lean Six Sigma strongly emphasises identifying and eliminating defects through thorough analysis and improvement processes.

8. Underutilised Talent

Underutilised talent waste occurs when employees' skills, knowledge, and creativity are not fully leveraged. This represents a missed opportunity for innovation and improvement. Through Lean and Lean Six Sigma, organisations empower employees in the improvement process by tapping into their full potential to contribute to the organisation's success.


In conclusion, Lean Six Sigma is a comprehensive methodology beyond mere defect reduction. Its integration of Lean principles enriches the approach, ensuring the quality enhancement of products or services and optimising business processes for efficiency. 

If you're ready to take the next level of your project management career, enrol on Lean Six Sigma courses through e-Careers. With over 625,000 trained professionals worldwide, you can trust us to deliver excellent Lean Six Sigma training. Start your success by contacting us today. Connect with us by calling us at (+44 (0) 20 3198 7700) or by emailing us at ask@e-careers.com.


Why is it called Lean Six Sigma?

A: The term "Lean Six Sigma" comes from combining two powerful methodologies: Lean and Six Sigma. "Lean" originated from Toyota's production system, focusing on waste reduction and efficient flow. "Six Sigma," introduced by Motorola, concentrates on reducing defects and variations. By integrating these two methodologies, Lean Six Sigma offers a holistic approach to process improvement, addressing efficiency and quality concerns.

What is the difference between Lean and Lean Six Sigma?

A: Lean focuses exclusively on waste reduction and process efficiency, while Lean Six Sigma combines Lean principles with Six Sigma methodologies. While retaining Lean's emphasis on efficiency, Lean Six Sigma broadens its scope to include Six Sigma's defect-reduction techniques. This integration results in a method that optimises efficiency and quality improvement processes.

How to use Lean Six Sigma?

A: Lean Six Sigma is applied through a structured approach known as DMAIC (Define, Measure, Analyse, Improve, Control). 

What are some of the most common Lean Six Sigma tools?

A: Six Sigma projects use tools like SIPOC, Value Stream Mapping, 5 Whys, Fishbone Diagram, Kaizen, Pareto Analysis, Control Charts, Histogram, 5S, Kanban, DMAIC, Root Cause Analysis, Control Plan, and Regression Analysis.

Which is better, Lean or Six Sigma?

A: This depends on your organisational needs. Lean is suitable for those focusing on process efficiency and waste reduction. Six Sigma is ideal for those prioritising defect reduction and process stability.

Are Lean Six Sigma certifications worth it?

A: Lean Six Sigma certifications are greatly valuable, especially if you want better career opportunities. Lean Six Sigma Certification enhances career prospects and will broaden your expertise.

Which jobs can I qualify for if I am Lean Six Sigma certified?

A: Lean Six Sigma certifications open doors to various roles, including Process Improvement Specialist, Quality Assurance Manager, Operations Manager, Project Manager, Business Analyst, Supply Chain Manager, and Continuous Improvement Manager.

How much do Lean Six Sigma black belts make?

A: The salary of Lean Six Sigma Black Belts varies based on factors like experience, industry, and location. On average, Black Belts often command higher salaries due to their expertise in leading complex improvement projects. Annual salaries can range from £50,000 to £90,000 or more, depending on your qualifications and the organisation.

Which Lean Six Sigma certification is best?

A: Several organisations offer Lean Six Sigma certifications. Here at e-Careers, we offer Lean Six Sigma Green Belt ISO 18404, Lean Six Sigma Yellow Belt, and Lean Six Sigma Black Belt ISO 18404 through interactive virtual classrooms.

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