Historically, both the Six Sigma and Lean methodologies have existed to serve the purpose of improving the operational effectiveness in a variety of businesses. In the past, they have stood alone as methodologies. The current trend is to combine Six Sigma and Lean, providing a greater toolset from which operational waste can be identified, measured, and improved. Though the concepts behind Six Sigma and Lean are different, the two can, and arguably should, be used jointly.

Six Sigma Reduces Variability

The goal of Six Sigma is to reduce the variability in a process in order to deliver practically defect-free products and services. Six Sigma relies heavily on statistical analysis to achieve gains in quality and typically has a direct impact to the bottom line. The Six Sigma methodology has a ‘scientific method-like' approach called DMAIC, which stands for:

  • Define the goals of the improvement activity
  • Measure the existing system/process
  • Analyze the system/process to identify ways to eliminate the gap between the current performance of the system or process and the desired goal
  • Improve the system/process
  • Control the new system/process

In theory, Six Sigma is a fairly simple concept, but implementing a successful Six Sigma project requires immense training, proper sponsorship, and sound statistical measures. While Six Sigma projects can be challenge to implement, the rewards can be substantial. Organizations that adopt the Six Sigma methodology can reach better than a Six Sigma quality, as defects become so rare, that more time can be spent on addressing the root cause. Though the rewards can be significant, the same characteristics that make Six Sigma a success can also be hindrances. Six Sigma requires a level of management commitment that can be daunting to executives. Additionally, the cost and effort required to obtain ‘defect free' may not be appropriate for some industries.

Lean Eliminates Waste

Lean techniques utilize certain tools and ways of thinking, which are all centered on the elimination of wastes. Lean focuses on the idea of continuous flow manufacturing and pull systems to make the input to a process only available when it is needed. The eight forms of waste include:

  • Overproduction
  • Waiting
  • Transportation
  • Non-value-added processing
  • Inventory
  • Underutilizing Resources/People
  • Defects
  • Motion

Included in Lean are 5S, Poka-yoke, and Standard work, which are all ways to maintain organization, order, and streamlined activities. Lean can be easier to implement than Six Sigma, and the benefits include lower production costs, fewer required resources, more efficient product development, higher quality, and larger profits. Once Lean is implemented, there should be a constant focus towards improvement. Though Lean is commonly used in manufacturing environments, it is not in any way limited in its use, as it is applicable to any process or system.

The Lean-Six Sigma Methodology

Both Lean and Six Sigma are very customer-driven. They utilize different tools, but look to accomplish the same goal of improvement. There is tremendous value to integrating Lean and Six Sigma, as it gives the change agent more tools in their process engineering tool belt. Both seek to create a culture of continuous improvement. They utilize some of the same problem solving techniques, including FMEAs, Pareto analyses, cause-and-effect diagrams, and 5 ‘whys'. Problem definition is a key component to both Lean and Six Sigma. Ron Crabtree, a twenty year veteran in implementing Lean and Six Sigma, and author of "Driving Operational Excellence: Successful Lean Six Sigma Secrets to Improve the Bottom Line", further explains the need for a Lean-Six Sigma approach. Mr. Crabtree would ask leadership what type of problem they had. There are certain problems that are identified as needing a Lean solution, and others that required a Six Sigma solution, but Mr. Crabtree would find that most executives would recognize that they had multiple problems, which required both Lean and Six Sigma Solutions.

A company taking a true Lean-Six Sigma approach recognizes a mixed use of tools in various stages of their process engineering methodology. The table below represents the mixture of Lean and Six Sigma tools, which can be leveraged as part of the CapTech's process engineering. Though these tools can be used in various stages, I have included their most applicable use.


Analyze Current State

Qualify Opportunities, and Define Vision

Model Future State

Simulate, Implement, and Control

Value Stream Mapping

Prioritization Matrices

Regression Analysis

Design of Experiments

Statistical Process Control

Charter-Problem Statement

MSA Studies


Kaizen Events

Visual Controls

Voice of the Customer

Capability Studies

Cause-Effect Diagrams

Theory of Constraints

Control Plans

Communication Plans


Root Cause Analysis

Pull Systems

Total Productive Maintenance

Critical to Quality Issues

Time Studies



Standard Work

Business Results


Multi-Vari Analysis


Procedures and Work Instructions


Collecting Data

Hypothesis Testing

Work Flow Improvement

Training Requirements

Lean and Six Sigma are different, but seek to accomplish the same goals. Proper utilization of these tools can increase the positive impacts of the improvements, and create a better chance for success.