# Data Mining - Variation (Change?)

## 2 - Type

As defined in the statistical thinking and methods of Walter A. Shewhart and W. Edwards Deming., Common and special causes are the two distinct origins of variation in a process:

• common causes, also called Natural patterns, are the usual, historical, quantifiable variation in a system,
• while special causes are unusual, not previously observed, non-quantifiable variation.

Shewhart conclude that while every process displays variation:

• some processes display controlled variation that is natural to the process,
• while others display uncontrolled variation that is not present in the process causal system at all times

Same as:

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