About this lesson
Six Sigma Principles
The Six Sigma methodology seeks to reduce and ultimately eliminate variation within a process. It applies a five-phase project management approach and uses the standard deviation (sigma) as the controlling attribute for the process.
When to use
The Six Sigma methodology is both a principle-based and a tool-based methodology. The principles should guide the project team through the process and assist with the selection of tools.
The Six Sigma methodology has several key principles that are embodied within it. These principles were tested and proven at Motorola on the manufacturing product lines.
The measures of Defects per Million Opportunities (DPMO) and process sigma are used to measure the level of variation and out-of-specification conditions of the result from the business process. Variation is the enemy of process control and the Six Sigma analysis first measures this variation and then strives to reduce or eliminate the sources of variation. This is the overarching goal and organizing principle of the Six Sigma methodology.
Another key principle is that of an orderly and structured problem solving process that is based upon the analysis of data. The five phases of Define, Measure, Analyze, Improve and Control guide the team though this approach.
The first two phases, Define and Measure, are used to articulate the real problem. The first phase determines the problem from a business and customer perspective. The second phase then collects data about the product or process in order to determine what is actually happening and where the problem really occurs. The third phase is the statistical analysis of the problem. Data is used to statistically validate the real problem that is causing the variation and out-of-specification conditions. The final two phases are associated with the problem solution. The Improve phase designs the solution and validates that it is effective. The Control phase implements that solution and changes all associated processes, procedures, and systems that must change to ensure the improvement becomes the new standard operation.
Six Sigma strives to create processes where the normal variation is much less than the allowed variation based upon the process specification limits. Understanding the sources and magnitude of variation are essential elements of the Six Sigma methodology.
Hints & tips
- The DMAIC process guides the team through the analysis and ensures they don’t jump to the wrong conclusion.
- Variation is the enemy of process control. Stay focused on sources of variation and don’t get lost in the statistical analysis.
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