9.4. PRINCIPLES OF STATISTICAL PROCESS CONTROL
9.4.1. Terms and concepts
9.4.1.1. DISTRIBUTIONS
A central concept in statistical process control (SPC) is that every measurable phenomenon is a statistical distribution. In other words, an observed set of data constitutes a sample of the effects of unknown common causes. It follows that, after we have done everything to eliminate special causes of variations, there will still remain a certain amount of variability exhibiting the state of control. Figure 9.25 illustrates the relationships between common causes, special causes, and distributions.
Figure 9.25. Distributions.
From Continuing Process ...
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