手法を比較

	根本原因分析	フォールトツリー解析 (FTA)
分野	品質管理	信頼性
系統	Process / pipeline	Process / pipeline
提唱年	1986	1981
提唱者	Kaoru Ishikawa	Vesely et al. (US NRC Fault Tree Handbook)
種類	Structured causal-inference tool	Deductive top-down failure analysis
原典	Ishikawa, K. (1986). Guide to Quality Control (2nd ed.). Asian Productivity Organization. ISBN: 978-92-833-1036-7	Vesely, W. E., Goldberg, F. F., Roberts, N. H., & Haasl, D. F. (1981). Fault Tree Handbook (NUREG-0492). U.S. Nuclear Regulatory Commission.
別名	Cause-and-Effect Analysis, Fishbone Analysis, Ishikawa Diagram, Kök Neden Analizi	FTA, Fault Tree Method, Top-Down Reliability Analysis, Hata Ağacı Analizi
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.	Fault Tree Analysis (FTA) is a top-down, deductive reliability method that begins with an undesired top-level failure event and systematically traces backward through chains of contributing causes using Boolean logic gates (AND, OR). First formalized by Watson at Bell Telephone Laboratories in 1961 and later standardized by Vesely, Goldberg, Roberts, and Haasl in the landmark 1981 NRC Fault Tree Handbook, FTA has become a cornerstone of quantitative risk assessment in nuclear, aerospace, and industrial safety engineering.