So sánh phương pháp

	Biểu đồ kiểm soát biến Shewhart (X-bar / R)	Six Sigma DMAIC
Lĩnh vực	Thống kê	Quản lý chất lượng
Họ	Process / pipeline	Process / pipeline
Năm ra đời	1931	2014
Người khởi xướng	Walter A. Shewhart	Motorola; Pyzdek & Keller
Loại	Statistical process control chart for variables	Structured process improvement methodology
Công trình gốc	Shewhart, W. A. (1931). Economic Control of Quality of Manufactured Product. D. Van Nostrand Company. ISBN: 978-0-87389-076-2	Pyzdek, T., & Keller, P. (2014). The Six Sigma Handbook (4th ed.). McGraw-Hill. ISBN: 978-0-07-184053-9
Tên gọi khác	X-bar and R chart, Shewhart chart, variables control chart, process control chart	DMAIC Framework, Six Sigma Process Improvement Cycle, Define-Measure-Analyze-Improve-Control, Altı Sigma DMAIC
Liên quan	4	3
Tóm tắt	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.	Six Sigma DMAIC is a data-driven, five-phase process improvement methodology — Define, Measure, Analyze, Improve, and Control — used to reduce defects and process variation to fewer than 3.4 defects per million opportunities. Originating at Motorola in the 1980s and systematized by practitioners including Pyzdek and Keller, it is widely adopted in manufacturing, healthcare, finance, and service industries seeking sustained quality gains.