Foundations of risk and reliability
assessment
and management
Terje Aven
University of Stavanger, Norway
Kahneman
asserts that we
have a basic
lack of ability to
treat small risks:
we either ignore
them completely
or give them too
much weight.
The main thesis
put forward is
that we grossly
over-estimate
small risks.
Kahneman’
s book
«Thinking
fast and
slow»
Israel 2001-2004: 23 bombings, 236
fatalities. The number of daily bus
riders in Israel was approximately 1.3
million at that time.
For any traveler, the risks were tiny,
but that was not how the public felt
about it. People avoided buses as much
as they could…
I knew that the risk
was truly negligible, and that any effect at
all on my actions would assign an
inordinately high “decision weight” to a
minuscule probability.
In fact, I was more likely to be injured in a driving accident than by
stopping near a bus. But my avoidance of buses was not motivated
by a rational concern for
survival.
Risk
Is not uncertainty a
main component of
risk ?
Foundations of risk and reliability
assessment
and management
Examples of issues
• How to understand and describe risk and reliability
• How to understand and treat model uncertainty
• How to treat uncertainties in risk and reliability
assessments
• How to conceptualise and deal with black swans
• How to use the precautionary principle in risk
management
• How to make use of signals and warnings in risk
assessment and management
• Risk analysis and science
Risk and reliability assessment and management in
different applications
Engineering
Transportation
Finance
Medicine
…
General insights linked to risk and reliability
Generic concepts, theories, frameworks, approaches, principles and methods
for
understanding, assessing, managing and communicating risk, reliability and
uncertainties
Existing frameworks, principles
and concepts
Today
Theories,
frameworks,
principles,
methods,
concepts
Future
Theories,
frameworks,
principles,
methods,
concepts
New types of systems
and risks
Revitalise the focus and enthusiasm for
fundamental issues in the risk and
reliability fields
Specialty Group of SRA (Society of Risk
Analysis)
on
Foundational issues in Risk Analysis
http://www.sra.org/frasg
http://www.sra.org/news/new-sra-specialty-group-created-foundational-issues-risk-analysis
Special issue of Risk Analysis
Special issue of Safety Science on foundations of safety science
Risk Analysis
Aven, T. and Zio, E. (2014) Foundational issues in
risk assessment and management
10 issues that need further focus
Issue 1: Terminology
Society of Risk Analysis
Glossary
Issue 2
The appropriate representation,
characterization, and interpretation of
uncertainty in a risk assessment context
Samson, Reneke and Wiecek (2009)
A review of different perspectives on uncertainty and risk and an alternative
modeling paradigm, Reliability Engineering & System Safety 94, 558–567
Uncertainty
about
Uncertainty
about how tall John is
Uncertainty
about C
C: John’s height
C = outcome
Uncertainty
about C
Activity
C = future consequences
Uncertainty
about C
p = Pf(outcome is 6)
Uncertainty
about p
P(outcome is 6 |K ) = 0.1
Uncertainty
about P?
No, but imprecision
K:
background
knowledge
Activity
C = unknown quantity
Model g(X)
Model uncertainty?
Activity
C = unknown quantity
Error g(X)-C
Model uncertainty:
uncertainty about this error
«Uncertainty about a
phenomenon»
The link between cancer
and smoking
C = unknown quantity
(number of deaths)
g(X) = model of the number of
deaths as a function of smoking rates
etc.
Error g(X)-C
Model uncertainty:
uncertainty about this error
Expressing the uncertainty
Probability
Probability
Frequentist
probability
Pf
Variation
Jugdmental/
knowledge-based,
subjective
probabilities P
Assessor’s
expression of
uncertainty – a
degree of belief
Knowledge-based probability
• P(A|K) = 0.1
• The assessor compares his/her uncertainty (degree og
belief) about the occurrence of the event A with
drawing a specific ball from an urn that contains 10
balls (Kaplan and Garrick 1981, Lindley, 2000).
K: background knowledge
Youtube: Aven streaming about probability:
http://www.youtube.com/watch?v=wp6iIdxHf_Q&list=PLNFAW9iar
Hu_kP9n34CSPRoUM8h1hBojp&index=3
Expressing the uncertainty
Probability
Knowledge supporting P
Expressing the uncertainty
Imprecise probabilities
Knowledge supporting these
Issue 10
The science of risk assessment
• Hansson and Aven (2014) Is risk analysis
scientific? Risk analysis
Science
• The practice that provides as with the most
reliable statements at the time being on the
subject matter covered by the knowledge
disciplines
Risk and black swans
Risk and reliability assessment and management in
different applications
Engineering
Transportation
Finance
Medicine
…
General insights linked to risk and reliability
Generic concepts, theories, frameworks, approaches, principles and methods
for
understanding, assessing, managing and communicating risk, reliability and
uncertainties
Foundations of risk and reliability
assessment
and management
terje.aven@uis.no
Black Swan
A surprising, extreme event relative
to present knowledge/beliefs
Aven (2013) On the
meaning of a black swan in
a risk context. Safety
Science, 57, 44-51
Risk management implication
Risk analysis
Robustness, resilience,
cautious policies …