What is Six Sigma?
Phases and Steps

Phases and Steps in Six Sigma Methodology

The Six Sigma process consists of five phases: define, measure, analyze, improve, and control. What is meant by these phases?

What is the scope of project? What is the defect? Here the project scope and defects are defined. A business case is made to obtain project approval. Team charter is established with a clear goal statement.
A. Identify Project CTQs
B. Develop Team Charter
C. Define Process Map

What is the frequency of defects? Here we select one or more product characteristics, map the process or processes responsible, and make the necessary measurements to estimate the short and long term process capability.
1. Select CTQ Characteristics
2. Define Performance Standards
3. Validate Measurement System

When and where do defects occur? Here key product performance metrics are benchmarked. Then a gap analysis is undertaken to identify the common factors of successful performance.
4. Establish Performance Capability
5. Define Performance Objectives
6. Identify Variation Sources
These first two phases are referred to as characterization phases. They define and quantify the project, characterizing its objectives.

How can we fix the process? Here product performance characteristics are selected for improvement. They are diagnosed to reveal major sources of variation. Then, key process variables are statistically identified and performance specifications are established for their improvement.
7. Screen Potential Causes
8. Discover Variable Relationships
9. Establish Operating Tolerances

Control: :
How can we make the process stay fixed? This phase insures the new process conditions are documented and monitored statistically. After a settling in period, process capability is reassessed and preceding phases are revisited based upon the results of the analysis.
10. Validate Measurement System
11. Determine Process Capability
12. Implement Process Control System


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