Quantitative Risk Assessment: The Scientific Platform

Cover......Page 1
Half-title......Page 3
Title......Page 5
Copyright......Page 6
Contents......Page 7
Preface......Page 9
Acknowledgments......Page 13
1.1 General features of risk management and risk assessments......Page 15
Quantitative risk assessment......Page 16
The risk assessment process (planning, execution and use of risk assessments)......Page 20
ALARP principle......Page 22
Cautionary and precautionary principles......Page 24
Defence-in-depth, robustness and resilience......Page 26
1.2 Challenges......Page 27
2.1 Risk equals expected value......Page 30
2.2 Risk is defined through probabilities......Page 31
2.4 Other definitions of risk......Page 34
2.5 Comparison of some common risk definitions and the (A,C,U) perspective......Page 35
2.6 The ontological status of the various risk concepts......Page 36
2.7 A risk assessment perspective based on the (A,C,Pf) definition......Page 37
Vulnerability and resilience......Page 39
2.8 A risk assessment perspective based on the (A,C,U) definition......Page 41
Vulnerability and resilience......Page 42
2.9 Example Offshore diving activities......Page 43
2.10 Summary of concepts and perspectives......Page 45
3.1 Reflections on risk assessment being a scientific method......Page 46
Natural sciences......Page 49
Mathematics and probability theory......Page 50
Other sciences......Page 51
3.3 Risk assessment as a scientific method. The reliability and validity requirements......Page 52
Validity......Page 53
4.1 Working accidents......Page 55
4.2 An LNG plant in an urban area......Page 58
4.3 The design of a safety system......Page 63
5.1 Scientific basis\n......Page 65
5.2 Case 1: Statistical inference of accident data\n......Page 66
5.2.1 No trend\n......Page 68
5.2.2 Linear trend. Regression analysis......Page 72
5.3 Case 2: QRA of the LNG plant\n......Page 75
Hazard identification......Page 76
Cause analysis (including a hazard frequency analysis)......Page 77
Consequence analysis......Page 78
5.4 Case 3: Design of a safety system\n......Page 81
5.5 Discussion\n......Page 82
5.5.1 Validity criterion V1: Accurate risk estimations......Page 83
5.5.2 Validity criterion V4: Addressing the right quantities\n......Page 85
5.5.3 The reliability criteria R – the same results with repetition\n......Page 87
5.5.4 Summary of assessments and final remarks\n......Page 88
I: Risk is defined through chances (frequentist probabilities)......Page 90
6.2.1 Risk is defined through chances (frequentist probabilities)......Page 91
6.2.2 Risk is defined through uncertainties......Page 95
6.3.1 Risk is defined through frequentist probabilities (chances)......Page 99
6.3.2 Risk is defined through uncertainties......Page 103
6.5 Discussion......Page 108
6.5.1 Validity criteria V2-V4......Page 109
Model uncertainties......Page 112
6.5.3 Summary of assessments and final remarks......Page 115
7.1 The use of predefined risk criteria......Page 117
7.2 The use of the ALARP principle and cost-benefit type of analyses......Page 121
7.2.1 Welfare economic theory......Page 124
7.2.2 Applying the ALARP principle to terrorist risk management......Page 127
7.3 The role of the cautionary and precautionary principles......Page 129
7.3.1 The objective of risk assessment is uncertainty description......Page 130
7.3.2 The objective of the risk assessment is to accurately estimate the risk (probabilities)......Page 131
7.3.3 An alternative classification system......Page 135
7.4 Risk communication......Page 138
Low uncertainty......Page 141
Medium uncertainty......Page 142
7.5 The content and purpose of managerial review and judgement......Page 143
7.5.1 How the risk perspective affects the managerial review and judgement......Page 145
7.5.2 Climate Change example......Page 149
7.5.3 Different decision settings......Page 150
8 Towards a holistic scientific approach to risk assessment......Page 152
8.1 What is risk? A structure for conceptualising and describing risk......Page 153
8.2 A model-based framework for risk assessments......Page 158
The quantities X and Z are well-defined......Page 161
Probabilities are knowledge-based probabilities with reference to an uncertainty standard......Page 162
Assessments of uncertainty factors......Page 163
The decision-making context......Page 164
Reliability example......Page 165
8.2.3 Value of information......Page 166
8.3 Probability and alternative approaches for representing (expressing) epistemic uncertainties......Page 168
8.3.1 Objective 3 (subjective analyst/expert judgements)......Page 171
Propagating the uncertainties through the model......Page 174
The reliability and validity requirements......Page 175
Validity......Page 176
8.3.2 Objectives 1 (inter-subjective descriptions) and 2 (faithful uncertainty representation)......Page 177
Example: Two prospects with different chance distributions......Page 180
Possibility theory......Page 182
The scientific criteria reliability and validity......Page 183
8.3.3 Discussion......Page 184
9 Conclusions......Page 188
A.1.1 The meaning of a probability......Page 192
A.1.2 Probability calculus......Page 194
A.1.3 Random variables (quantities) and probability distributions......Page 196
Expected value and variance......Page 197
The strong law of large numbers......Page 198
Binomial and Poisson distributions......Page 199
Exponential distribution......Page 200
Gamma distribution......Page 201
Beta-binomial distribution......Page 202
Student (t) distribution......Page 203
Estimation of distribution parameters......Page 204
Confidence interval......Page 205
Testing hypothesis......Page 206
Regression analysis......Page 207
A.2.2 Bayesian statistics......Page 209
Appendix B: Terminology......Page 211
References......Page 214
Index......Page 224