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The Perfect Companion to SQC Online
Practical Acceptance Sampling (2nd Edition) is a hands-on introduction to the inspection of products and services for quality assurance using statistically-based sampling plans.
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Download first chapter (PDF)
Download first chapter (PDF)
Methods are illustrated using SQC Online, Microsoft Excel, and online calculators.
From the Glossary
The zones in an ordinary 3-sigma control chart are beyond the upper control limit (3,∞), and below the lower control limit (-∞, -3).
- To specify the alarm zone as the area between the warning limits and control limits, enter a=2, b=3.
- In a control chart with 0.001 probability control limits (3.09 "sigma") and 0.025 warning limits (2.24 "sigma"), the rule "two consecutive points between the control and warning limits" is given by: k=2, a=2.24, b=3.09.
- The zones are usually symmetric around the center line. For example: [-3,-2] and [2,3].