Modelling Under Risk and Uncertainty An Introduction to Statistical, Phenomenological and Computational Methods
, by De Rocquigny, Etienne- ISBN: 9780470695142 | 0470695145
- Cover: Hardcover
- Copyright: 4/30/2012
Preface | p. xv |
Acknowledgements | p. xvii |
Introduction and reading guide | p. xix |
Notation | p. xxxiii |
Acronyms and abbreviations | p. xxxvii |
Applications and practices of modelling, risk and uncertainty | p. 1 |
Protection against natural risk | p. 1 |
The popular 'initiator/frequency approach' | p. 3 |
Recent developments towards an 'extended frequency approach' | p. 5 |
Engineering design, safety and structural reliability analysis (SRA) | p. 7 |
The domain of structural reliability | p. 8 |
Deterministic safety margins and partial safety factors | p. 9 |
Probabilistic structural reliability analysis | p. 10 |
Links and differences with natural risk studies | p. 11 |
Industrial safety, system reliability and probabilistic risk assessment (PRA) | p. 12 |
The context of systems analysis | p. 12 |
Links and differences with structural reliability analysis | p. 14 |
The case of elaborate PRA (multi-state, dynamic) | p. 16 |
Integrated probabilistic risk assessment (IPRA) | p. 17 |
Modelling under uncertainty in metrology, environmental/sanitary assessment and numerical analysis | p. 20 |
Uncertainty and sensitivity analysis (UASA) | p. 21 |
Specificities in metrology/industrial quality control | p. 23 |
Specificities in environmental/health impact assessment | p. 24 |
Numerical code qualification (NCQ), calibration and data assimilation | p. 25 |
Forecast and time-based modelling in weather, operations research, economics or finance | p. 27 |
Conclusion: The scope for generic modelling under risk and uncertainty | p. 28 |
Similar and dissimilar features in modelling, risk and uncertainty studies | p. 28 |
Limitations and challenges motivating a unified framework | p. 30 |
References | p. 31 |
A generic modelling framework | p. 34 |
The system under uncertainty | p. 34 |
Decisional quantities and goals of modelling under risk and uncertainty | p. 37 |
The key concept of risk measure or quantity of interest | p. 37 |
Salient goals of risk/uncertainty studies and decision-making | p. 38 |
Modelling under uncertainty: Building separate system and uncertainty models | p. 41 |
The need to go beyond direct statistics | p. 41 |
Basic system models | p. 42 |
Building a direct uncertainty model on variable inputs | p. 45 |
Developing the underlying epistemic/aleatory structure | p. 46 |
Summary | p. 49 |
Modelling under uncertainty - the general case | p. 50 |
Phenomenological models under uncertainty and residual model error | p. 50 |
The model building process | p. 51 |
Combining system and uncertainty models into an integrated statistical estimation problem | p. 55 |
The combination of system and uncertainty models: A key information choice | p. 57 |
The predictive model combining system and uncertainty components | p. 59 |
Combining probabilistic and deterministic settings | p. 60 |
Preliminary comments about the interpretations of probabilistic uncertainty models | p. 60 |
Mixed deterministic-probabilistic contexts | p. 61 |
Computing an appropriate risk measure or quantity of interest and associated sensitivity indices | p. 64 |
Standard risk measures or q.i. (single-probabilistic) | p. 65 |
A fundamental case: The conditional expected utility | p. 67 |
Relationship between risk measures, uncertainty model and actions | p. 68 |
Double probabilistic risk measures | p. 69 |
The delicate issue of propagation/numerical uncertainty' | p. 71 |
Importance ranking and sensitivity analysis | p. 71 |
Summary: Main steps of the studies and later issues | p. 73 |
Exercises | p. 74 |
References | p. 75 |
A generic tutorial example: Natural risk in an industrial installation | p. 77 |
Phenomenology and motivation of the example | p. 77 |
The hydro component | p. 78 |
The system's reliability component | p. 80 |
The economic component | p. 83 |
Uncertain inputs, data and expertise available | p. 84 |
A short introduction to gradual illustrative modelling steps | p. 86 |
Step one: Natural risk standard statistics | p. 87 |
Step two: Mixing statistics and a QRA model | p. 89 |
Step three: Uncertainty treatment of a physical/engineering model (SRA) | p. 91 |
Step four: Mixing SRA and QRA | p. 91 |
Step five: Level-2 uncertainty study on mixed SRA-QRA model | p. 94 |
Step six: Calibration of the hydro component and updating of risk measure | p. 96 |
Step seven: Economic assessment and optimisation under risk and/or uncertainty | p. 97 |
Summary of the example | p. 99 |
Exercises | p. 101 |
References | p. 101 |
Understanding natures of uncertainty, risk margins and time bases for probabilistic decision-making | p. 102 |
Natures of uncertainty: Theoretical debates and practical implementation | p. 103 |
Defining uncertainty - ambiguity about the reference | p. 103 |
Risk vs. uncertainty - an impractical distinction | p. 104 |
The aleatory/epistemic distinction and the issue of reducibility | p. 105 |
Variability or uncertainty - the need for careful system specification | p. 107 |
Other distinctions | p. 109 |
Understanding the impact on margins of deterministic vs. probabilistic formulations | p. 110 |
Understanding probabilistic averaging, dependence issues and deterministic maximisation and in the linear case | p. 110 |
Understanding safety factors and quantiles in the monotonous case | p. 114 |
Probability limitations, paradoxes of the maximal entropy principle | p. 117 |
Deterministic settings and interval computation û uses and limitations | p. 119 |
Conclusive comments on the use of probabilistic and deterministic risk measures | p. 120 |
Handling time-cumulated risk measures through frequencies and probabilities | p. 121 |
The underlying time basis of the state of the system | p. 121 |
Understanding frequency vs. probability | p. 124 |
Fundamental risk measures defined over a period of interest | p. 126 |
Handling a time process and associated simplifications | p. 128 |
Modelling rare events through extreme value theory | p. 130 |
Choosing an adequate risk measure - decision-theory aspects | p. 135 |
The salient goal involved | p. 135 |
Theoretical debate and interpretations about the risk measure when selecting between risky alternatives (or controlling compliance with a risk target) | p. 136 |
The choice of financial risk measures | p. 137 |
The challenges associated with using double-probabilistic or conditional probabilistic risk measures | p. 138 |
Summary recommendations | p. 140 |
Exercises | p. 140 |
References | p. 141 |
Direct statistical estimation techniques | p. 143 |
The general issue | p. 143 |
Introducing estimation techniques on independent samples | p. 147 |
Estimation basics | p. 147 |
Goodness-of-fit and model selection techniques | p. 150 |
A non-parametric method: Kernel modelling | p. 154 |
Estimating physical variables in the flood example | p. 157 |
Discrete events and time-based statistical models (frequencies, reliability models, time series) | p. 159 |
Encoding phenomenological knowledge and physical constraints inside the choice of input distributions | p. 163 |
Modelling dependence | p. 165 |
Linear correlations | p. 165 |
Rank correlations | p. 168 |
Copula model | p. 172 |
Multi-dimensional non-parametric modelling | p. 173 |
Physical dependence modelling and concluding comments | p. 174 |
Controlling epistemic uncertainty through classical or Bayesian estimators | p. 175 |
Epistemic uncertainty in the classical approach | p. 175 |
Classical approach for Gaussian uncertainty models (small samples) | p. 177 |
Asymptotic covariance for large samples | p. 179 |
Bootstrap and resampling techniques | p. 185 |
Bayesian-physical settings (small samples with expert judgement) | p. 186 |
Understanding rare probabilities and extreme value statistical modelling | p. 194 |
The issue of extrapolating beyond data û advantages and limitations of the extreme value theory | p. 194 |
The significance of extremely low probabilities | p. 201 |
Exercises | p. 203 |
References | p. 204 |
Combined model estimation through inverse techniques | p. 206 |
Introducing inverse techniques | p. 206 |
Handling calibration data | p. 206 |
Motivations for inverse modelling and associated literature | p. 208 |
Key distinctions between the algorithms: The representation of time and uncertainty | p. 210 |
One-dimensional introduction of the gradual inverse algorithms | p. 216 |
Direct least square calibration with two alternative interpretations | p. 216 |
Bayesian updating, identification and calibration | p. 223 |
An alternative identification model with intrinsic uncertainty | p. 225 |
Comparison of the algorithms | p. 227 |
Illustrations in the flood example | p. 229 |
The general structure of inverse algorithms: Residuals, identifiability, estimators, sensitivity and epistemic uncertainty | p. 233 |
The general estimation problem | p. 233 |
Relationship between observational data and predictive outputs for decision-making | p. 233 |
Common features to the distributions and estimation problems associated to the general structure | p. 236 |
Handling residuals and the issue of model uncertainty | p. 238 |
Additional comments on the model-building process | p. 242 |
Identifiability | p. 243 |
Importance factors and estimation accuracy | p. 249 |
Specificities for parameter identification, calibration or data assimilation algorithms | p. 251 |
The BLUE algorithm for linear Gaussian parameter identification | p. 251 |
An extension with unknown variance: Multidimensional model calibration | p. 254 |
Generalisations to non-linear calibration | p. 255 |
Bayesian multidimensional model updating | p. 256 |
Dynamic data assimilation | p. 257 |
Intrinsic variability identification | p. 260 |
A general formulation | p. 260 |
Linearised Gaussian case | p. 261 |
Non-linear Gaussian extensions | p. 263 |
Moment methods | p. 264 |
Recent algorithms and research fields | p. 264 |
Conclusion: The modelling process and open statistical and computing challenges | p. 267 |
Exercises | p. 267 |
References | p. 268 |
Computational methods for risk and uncertainty propagation | p. 271 |
Classifying the risk measure computational issues | p. 272 |
Risk measures in relation to conditional and combined uncertainty distributions | p. 273 |
Expectation-based single probabilistic risk measures | p. 275 |
Simplified integration of sub-parts with discrete inputs | p. 277 |
Non-expectation based single probabilistic risk measures | p. 280 |
Other risk measures (double probabilistic, mixed deterministic-probabilistic) | p. 281 |
The generic Monte-Carlo simulation method and associated error control | p. 283 |
Undertaking Monte-Carlo simulation on a computer | p. 283 |
Dual interpretation and probabilistic properties of Monte-Carlo simulation | p. 285 |
Control of propagation uncertainty: Asymptotic results | p. 290 |
Control of propagation uncertainty: Robust results for quantiles (Wilks formula) | p. 292 |
Sampling double-probabilistic risk measures | p. 298 |
Sampling mixed deterministic-probabilistic measures | p. 299 |
Classical alternatives to direct Monte-Carlo sampling | p. 299 |
Overview of the computation alternatives to MCS | p. 299 |
Taylor approximation (linear or polynomial system models) | p. 300 |
Numerical integration | p. 305 |
Accelerated sampling (or variance reduction) | p. 306 |
Reliability methods (FORM-SORM and derived methods) | p. 312 |
Polynomial chaos and stochastic developments | p. 316 |
Response surface or meta-models | p. 316 |
Monotony, regularity and robust risk measure computation | p. 317 |
Simple examples of monotonous behaviours | p. 317 |
Direct consequences of monotony for computing the risk measure | p. 319 |
Robust computation of exceedance probability in the monotonous case | p. 322 |
Use of other forms of system model regularity | p. 329 |
Sensitivity analysis and importance ranking | p. 330 |
Elementary indices and importance measures and then-equivalence in linear system models | p. 330 |
Sobol sensitivity indices | p. 336 |
Specificities of Boolean input/output events û importance measures in risk assessment | p. 339 |
Concluding remarks and further research | p. 341 |
Numerical challenges, distributed computing and use of direct or adjoint differentiation of codes | p. 342 |
Exercises | p. 342 |
References | p. 343 |
Optimising under uncertainty: Economics and computational challenges | p. 347 |
Getting the costs inside risk modelling - from engineering economics to financial modelling | p. 347 |
Moving to costs as output variables of interest û elementary engineering economics | p. 347 |
Costs of uncertainty and the value of information | p. 351 |
The expected utility approach for risk aversion | p. 353 |
Non-linear transformations | p. 355 |
Robust design and alternatives mixing cost expectation and variance inside the optimisation procedure | p. 356 |
The role of time - cash flows and associated risk measures | p. 358 |
Costs over a time period - the cash flow model | p. 358 |
The issue of discounting | p. 361 |
Valuing time flexibility of decision-making and stochastic optimisation | p. 362 |
Computational challenges associated to optimisation | p. 366 |
Static optimisation (utility-based) | p. 367 |
Stochastic dynamic programming | p. 368 |
Computation and robustness challenges | p. 368 |
The promise of high performance computing | p. 369 |
The computational load of risk and uncertainty modelling | p. 369 |
The potential of high-performance computing | p. 371 |
Exercises | p. 372 |
References | p. 372 |
Conclusion: Perspectives of modelling in the context of risk and uncertainty and further research | p. 374 |
Open scientific challenges | p. 374 |
Challenges involved by the dissemination of advanced modelling in the context of risk and uncertainty | p. 377 |
References | p. 377 |
Annexes | p. 378 |
Annex 1 - refresher on probabilities and statistical modelling of uncertainty | p. 378 |
Modelling through a random variable | p. 378 |
The impact of data and the estimation uncertainty | p. 380 |
Continuous probabilistic distributions | p. 382 |
Dependence and stationarity | p. 382 |
Non-statistical approach of probabilistic modelling | p. 384 |
Annex 2 - comments about the probabilistic foundations of the uncertainty models | p. 386 |
The overall space of system states and the output space | p. 386 |
Correspondence to the Kaplan/Garrick risk analysis triplets | p. 389 |
The model and model input space | p. 389 |
Estimating the uncertainty model through direct data | p. 391 |
Model calibration and estimation through indirect data and inversion techniques | p. 393 |
Annex 3 - introductory reflections on the sources of macroscopic uncertainty | p. 394 |
Annex 4 - details about the pedagogical example | p. 397 |
Data samples | p. 397 |
Reference probabilistic model for the hydro component | p. 399 |
Systems reliability component - expert information on elementary failure probabilities | p. 399 |
Economic component - cost functions and probabilistic model | p. 403 |
Detailed results on various steps | p. 404 |
Annex 5 - detailed mathematical demonstrations | p. 414 |
Basic results about vector random variables and matrices | p. 414 |
Differentiation results and solutions of quadratic likelihood maximisation | p. 415 |
Proof of the Wilks formula | p. 419 |
Complements on the definition and chaining of monotony | p. 420 |
Proofs on level-2 quantiles of monotonous system models | p. 422 |
Proofs on the estimator of adaptive Monte-Carlo under monotony (section 7.4.3) | p. 423 |
References | p. 426 |
Epilogue | p. 427 |
Index | p. 429 |
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