Shewhart Control Chart
The Shewhart control chart, invented by Walter Shewhart at Bell Labs in the 1920s and set out in his 1931 book, is the foundational tool of statistical process control. It plots a process statistic — typically the subgroup mean (X-bar) and range (R) — over time against a center line and three-sigma control limits, distinguishing the natural common-cause variation inherent in a stable process from special-cause variation that signals something has changed and warrants investigation.
Source record
Citations copied verbatim from the method’s source record. No claim-level verification is inferred from them.
- Shewhart, W. A. (1931). Economic Control of Quality of Manufactured Product. D. Van Nostrand Company. · ISBN 978-0-87389-076-2
- Montgomery, D. C. (2009). Introduction to Statistical Quality Control (6th ed.). John Wiley & Sons. · ISBN 978-0-470-16992-6
Curated claims
Claims persisted in the evidence ledger, each with its own assessment.
This view does not invent a claim assessment when the ledger has none.
Related methods
Generated from the method graph and shown as machine-suggested relations — no evidence claim is inferred.