手法を比較

	根本原因分析	シックスシグマDMAIC
分野	品質管理	品質管理
系統	Process / pipeline	Process / pipeline
提唱年	1986	2014
提唱者	Kaoru Ishikawa	Motorola; Pyzdek & Keller
種類	Structured causal-inference tool	Structured process improvement methodology
原典	Ishikawa, K. (1986). Guide to Quality Control (2nd ed.). Asian Productivity Organization. ISBN: 978-92-833-1036-7	Pyzdek, T., & Keller, P. (2014). The Six Sigma Handbook (4th ed.). McGraw-Hill. ISBN: 978-0-07-184053-9
別名	Cause-and-Effect Analysis, Fishbone Analysis, Ishikawa Diagram, Kök Neden Analizi	DMAIC Framework, Six Sigma Process Improvement Cycle, Define-Measure-Analyze-Improve-Control, Altı Sigma DMAIC
関連	3	3
概要	Root Cause Analysis (RCA) is a structured, systematic method for identifying the fundamental causes of defects, failures, or undesirable outcomes rather than treating surface-level symptoms. Popularised by Japanese quality engineer Kaoru Ishikawa in the 1960s–1980s, and formally codified in his 1986 Guide to Quality Control, RCA combines the Ishikawa (fishbone) diagram with the iterative 5 Whys questioning technique to trace causal chains back to their origin.	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.