How does Six Sigma work?

Identify Business Problem
At the beginning of a Six Sigma project, the Business Problem is defined. Questions such as What, When, Where are addressed in a problem statement. Magnitude and Consequence of the problem is also discussed. Project Scope is identified.

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Identify Statistical Problem
Potential causes of the business problem are identified and turned into statistical questions for investigation. Hypothesis tests can help evaluate them when the data and assumptions support the chosen test.
Trivial Many Causes: Begin with all plausible causes. After analysis, the “trivial many” are the causes with relatively small individual contributions to the problem.
Vital Few Causes: These are the few critical causes which cause maximum impact over the problem.

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Identify Statistical Solution
Statistical analysis helps identify the vital root causes with the greatest impact. An illustration may narrow the list to 3–4 causes, but the number depends on the evidence. The Pareto principle often describes a pattern in which roughly 80% of effects come from 20% of causes; it is a useful guide, not a law that every problem must follow. Study solutions to the verified causes and determine suitable operating values.

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Identify Business Solution
These statistical solutions are then converted to implementable practical solutions. Implementation of these business solutions is carried out in the process. Improvements are observed and sustained.

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