手法を比較

	イベントツリー解析 (ETA)	フォールトツリー解析 (FTA)
分野	信頼性	信頼性
系統	Process / pipeline	Process / pipeline
提唱年	2002	1981
提唱者	Andrews & Moss	Vesely et al. (US NRC Fault Tree Handbook)
種類	Forward inductive logic tree	Deductive top-down failure analysis
原典	Andrews, J. D., & Moss, T. R. (2002). Reliability and Risk Assessment (2nd ed.). Professional Engineering Publishing. ISBN: 978-1-86058-290-5	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	ETA, Event Sequence Diagram Analysis, Initiating Event Analysis, Olay Ağacı Analizi	FTA, Fault Tree Method, Top-Down Reliability Analysis, Hata Ağacı Analizi
関連	2	3
概要	Event Tree Analysis (ETA) is a forward inductive technique used in reliability and risk engineering to model the possible outcomes that follow an initiating event. Starting from a single undesired event, ETA traces all subsequent event sequences through a binary branching tree representing the success or failure of safety barriers and protective systems. Introduced formally in reliability and risk literature by Andrews and Moss (2002), it is widely applied in nuclear, chemical, and aerospace industries to quantify accident sequence probabilities and guide safety decision-making.	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.