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Risk analysis can be defined in many different ways, and much of the definition depends on how risk analysis relates to other concepts. Risk analysis can be "broadly defined to include risk assessment, risk characterization, risk communication, risk management, and policy relating to risk, in the context of risks of concern to individuals, to public- and private-sector organizations, and to society at a local, regional, national, or global level."〔Society for Risk Analysis, '(About the Society for Risk Analysis )'〕 A useful construct is to divide risk analysis into two components: (1) risk assessment (identifying, evaluating, and measuring the probability and severity of risks) and (2) risk management (deciding what to do about risks).〔Y. Y. Haimes, ''Risk Modeling, Assessment, and Management'' (2004).〕 Some books〔D. W. Hubbard, ''The Failure of Risk Management: Why It's Broken and How to Fix It'' (2009).〕 take a slightly different approach and define risk management as the overarching concept, where risk analysis is the component that seeks to identify and measure the risks and risk mitigation is determining what to do about the risks. Risk analysis can be qualitative or quantitative.〔M. Rausand, ''Risk Assessment: Theory, Methods, and Applications'' (2011).〕 Qualitative risk analysis uses words or colors to identify and evaluate risks or presents a written description of the risk, and quantitative risk analysis (QRA) calculates numerical probabilities over the possible consequences. ==Quantitative risk analysis== QRA seeks to numerically assess probabilities for the potential consequences of risk, and is often called probabilistic risk analysis or probabilistic risk assessment (PRA). The analysis often seeks to describe the consequences in numerical units such as dollars, time, or lives lost. PRA often seeks to answer three questions:〔S. Kaplan and B. J. Garrick, 'On the quantitative definition of risk,' Risk Analysis, Vol. 1, No. 1, 1981, doi/10.1111/j.1539-6924.1981.tb01350.x〕 #What can happen? (i.e., what can go wrong?) #How likely is it that it will happen? #If it does happen, what are the consequences? Thus, risk ''R'' can be described as a set of triplets, ''R''=, ''i''=1,2,...,''N'' where ''si'' is scenario ''i'', ''pi'' is the probability of scenario ''i'', ''ci'' are the consequences if scenario ''i'' occurs, and ''N'' is the total number of scenarios. This type of analysis typically results in a probability distribution over the consequences. Although actuarial science has used probabilities to measure risk for more than a hundred years,〔 P. L. ''Against the Gods: The Remarkable Story of Risk'' (1998)〕 PRA as a specific mode of inquiry was initially developed to analyze engineering risks such as nuclear power plants and the space shuttle.〔T. Bedford and R. Cooke, ''Probabilistic Risk Analysis: Foundations and Methods'' (2001)〕 More recently, it has also been applied to other areas, such as business, climate change, health risks, food safety and security. Especially with the increasing importance of terrorism, game theory has become a quantitative tool to analyze the risks of intelligent adversaries who seek to do harm against a system or people. These game-theoretic techniques may be probabilistic or deterministic. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「risk analysis」の詳細全文を読む スポンサード リンク
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