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Six Sigma vs. Lean Six Sigma: Which Methodology Is Right for Your Business?

six sigma vs lean six sigma

Six Sigma and Lean Six Sigma both strive to accomplish similar goals: to create more efficient processes that produce greater value. However, they approach the process in slightly different ways.

We will explain the difference between Six Sigma and Lean Six Sigma, identify the processes each methodology uses to improve efficiency, the factors to consider when choosing a methodology, and where to get Lean Six Sigma training to hone your skills.

What is Six Sigma?

The Six Sigma methodology uses statistical analysis to streamline processes, reduce variations, and lower defect rates in production for continuous improvement.

Six Sigma focuses on five core principles, known by the acronym DMAIC. DMAIC stands for:

  • Define
  • Measure
  • Analyze
  • Improve
  • Control


In the first phase of Six Sigma, you define the project scope and existing process you are trying to improve by answering these questions:

  • What is the problem?
  • How often does the problem occur?
  • What is the impact of the problem?

You must also define the project management team, who will participate, how you will undertake the analysis, and the key stakeholders involved.

Also Read: What is Quality Management? A Complete Guide


The measurement phase ensures we can quantify the problem and accurately assess improvement. Before starting a project, it’s essential to set benchmarks to measure the impact of changes. During this phase, Six Sigma teams must answer questions such as:

  • How can we measure the problem?
  • What data do we need to collect?
  • What is the performance of the current process?


The next step in DMAIC is to analyze the root cause of system problems that impact productivity and efficiency. Questions during this phase include:

  • How does the process work?
  • What is our knowledge of the process?
  • What does the data tell us about the root cause?
  • How does this root cause impact the output?


With data in hand and an understanding of the root cause, it’s time to examine potential solutions. Team members will research and detail the answers to these questions:

  • What are all of the possible solutions?
  • Which solutions achieve optimal results?
  • When, where, and how do we implement the optimal solution?


The final step is the control phase, which includes the implementation of the solution and assurance that goals are achieved. Teams will monitor progress and answer these questions:

  • What are the outcomes of process changes?
  • Were initial goals achieved?
  • Have we standardized improvements to become standard operating procedures?

Six Sigma is designed for continuous improvement, so once all five phases are complete, the cycle starts anew to drive even better outcomes by identifying and resolving additional bottlenecks in processes.

Also Read: Six Sigma Green Belt Salary: Here’s Everything You Should Know

What is Lean Six Sigma?

Six Sigma is designed to reduce process variation and enhance process control. Lean Six Sigma focuses more on eliminating waste, such as processes and procedures that do not add value. While both methodology target process improvements, Lean Six Sigma uses five lean principles:

  1. Identify Value
  2. Map the Value Stream
  3. Create Flow
  4. Establish Pull
  5. Seek Perfection

Identify Value

To improve performance, Lean Six Sigma focuses on the value defined by customer or client needs. For example, Lean Six Sigma teams will want to understand timelines for producing and delivering goods or services, the appropriate price points versus costs, and project requirements or expectations that must be met.

This process helps establish the value of improvements, the impact of changes, and the end goal.

Map the Value Stream

Mapping the value stream requires documenting every step in the process, from customer requests to deliveries. Sometimes called process re-engineering, each incremental step in the flow is detailed. A typical value stream map might include the customer ordering process, project acceptance and design, procurement of raw materials through supply chains, production, administration, billing, and delivery.

At each step in the process, the goal is to identify areas that do not create value and find ways to eliminate wasteful steps.

Create Flow

The remaining steps must flow smoothly without bottlenecks once the waste has been eliminated from the value stream. Often, removing waste in one step can create additional bottlenecks in subsequent steps. As such, teams need to think cross-functionally when creating a flow to employ a holistic approach.

Establish Pull

Improving process flow shortens the time to market for product delivery, making it easier for customers to “pull” products from you when needed. This reduces the lead time for product delivery and can eliminate waste, such as inventory holding costs for excess raw materials. This can produce cost-saving efficiencies to benefit companies and customers.

Seek Perfection

The goal of Lean Six Sigma is to seek perfection by constantly reviewing processes and continuing to eliminate non-value. Teams often find that achieving truly lean processes requires starting through the entire value stream mapping process multiple times to create ever-increasing improvements.

Also Read: What Is Lean Management? Principles & Everything You Need to Know

The Differences Between Six Sigma and Lean Six Sigma

While the goals are essentially the same—streamlining process for efficiency—the differences between Lean vs. Six Sigma lie in focus. Six Sigma focuses on reducing defects, while Lean Six Sigma focuses on reducing waste.

While Six Sigma focuses mostly on manufacturing, the Lean Six Sigma methodology can often be applied to any business process. The lines between the two blur frequently, and, in reality, both methods can be adapted to different business cases.

When to Use Six Sigma vs. Lean Six Sigma

Six Sigma is highly effective with mature processes with higher than acceptable defect rates. It is often used in manufacturing, quality control, and industries where defects are measurable and quantifiable. Examples include:

  • Manufacturing defects: Identifying root causes of product defects in the production line.
  • Quality control: Improving the consistency and reliability of products.
  • Process inefficiencies: Removing waste and improving process flow.
  • Customer complaints: Investigating and resolving customer complaints to improve satisfaction and retention.

Lean Six Sigma effectively eliminates waste, reduces cycle times, and enhances customer value. It is most effective when process inefficiencies result in delays or waste effort. Examples include:

  • Process bottlenecks: Eliminating unnecessary steps that create delays or inefficiency.
  • Inventory management: Optimization of inventory levels to reduce waste and improve cash flow.
  • Value stream mapping: Identifying and eliminating non-value-adding activity in the workflow.
  • Service delivery: Streamlining processes to reduce lead time and drive greater customer value.

The decision of whether to use Lean vs. Six Sigma will depend on the specific project and its complexity. Additionally, Six Sigma and Lean Six Sigma methodologies can often be applied in conjunction to achieve optimal results.

Factors to Consider about Six Sigma vs. Lean Six Sigma

When comparing Six Sigma vs. Lean Six Sigma, the methodology you choose to employ will depend on various factors, most notably your organization’s strategic goals and what you are trying to achieve. Here are some of the critical factors to consider.

Problem TypeGoal: Reducing defects or process variation, improving quality.Goal: Eliminating inefficiencies and waste, improving overall processes.
Process ComplexityBetter for well-defined and stable processes.Better for complex processes or processes that have multiple interdependencies.
Customer RequirementsEffective to achieve high levels of quality control and defect reduction.Effective at creating more efficient time-to-market, responsiveness, and efficiency.
Available ResourcesTeams need a strong focus on statistical analysis and data-driven decision-making.Teams require expertise in Lean principles and techniques.
Time ConstraintsSix Sigma can significantly reduce defects but often takes longer to uncover and mitigate root causes.Lean Six Sigma often focuses on rapid improvements and quick wins where time is of the essence.

Whether you choose to deploy Six Sigma or Lean Six Sigma, you must carefully evaluate these factors in light of your company’s goals and culture. Change management requires a commitment from employees at every level and a continuous focus on improvement.

The Different Sigma Levels

You will also need to consider the Sigma level you want to achieve.

The Six Sigma methodology has different levels, from one to six. Each level has an acceptable error rate in terms of statistical deviation. For example, comparing 3 Sigma vs. 6 Sigma, three Sigma requires 93.3 percent of outcomes to be defect-free, allowing up to 66,800 per one million products. Some operations require a higher level of accuracy. Six Sigma strives for near-perfect production with 99.99966 percent accuracy, which equates to just 3.4 defects per one million.

Read More: Understanding Six Sigma Belt Levels: A Comprehensive Guide

How to Get a Lean Six Sigma Certification

Now that you know the difference between Lean and Six Sigma, you may be interested in exploring a career in quality management. Luckily, we have an option to share. You can fast-track your career by taking an IASSC-accredited, post graduate Lean Six Sigma Certification course. Attend live interactive classes and solve real-world business problems through case studies and projects. With this program, you will earn a certificate of completion from UMass Amherst and SImplilearn and gain skills including:

  • Agile Management
  • Lean Management
  • Digital Transformation
  • Lean Six Sigma Black Belt
  • Lean Six Sigma Green Belt
  • Minitab
  • Quality Management

Learn more and apply to the Lean Six Sigma Certification course.

You might also like to read:

Six Sigma Certification Cost: A Comprehensive Guide to Understanding the Expenses

Lean Six Sigma Green Belt Exam Questions and Answers

How to Get Lean Six Sigma Certification? A Complete Guide

How Lean Six Sigma Belts Can Increase Your Value and Salary?

Mastering Lean Six Sigma Principles for Exceptional Quality Management

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