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9 Societal Dialogue on Risks and Benefits
9.3.1 Considering Risk Aversion
Many individuals dislike accidents with high impact potential, even if the probability of occurrence is very low. To help with assessing this risk aversion on both the
technical and perceptive levels, it can be considered, for example, by introducing an
aversion factor into the product formula for calculating risk:
R = p × I
α
(9.1)
• R: risk
• p: probability
• I : impact
• α: empirically determined risk aversion factor (α > 1, i.e., risks that are less
likely but of high impact are weighted more heavily)
In considering a risk and preparing for risk communication with stakeholders,
this calculation can help to consider the subjective societal perception of risk
alongside the technically-based criteria. A greater α means a steeper acceptability
line in the risk diagram discussed in the following section and presented in Fig. 9.2.
9.3.2 Using Risk Diagrams
A helpful way to illustrate protection goals and map the limits of societal acceptance
(as defined on the decision-making level) to support dialogue is through the use
of a risk diagram. This is very similar to the use of a risk matrix as introduced
in Chap. 7. An example of such a diagram for the operation of a hypothetical
chemical production plant is shown in Fig. 9.2. The diagram plots the probability
of an accident (shown here as cumulative frequency) against the impact of an event
(shown here normalized as the number of resulting fatalities). Cumulative frequency
can be understood as the probability that an event occurs with an impact that is equal
to or less than a specific level of impact. The impact value along the x-axis could also
be represented by, for example, a category such as the number of humans injured,
contaminated surface waters (in m 3 or km 2 ), soil with impaired fertility (in km 2 ×
years), or property damage in millions of US dollars, etc.
The acceptability line divides the space into an acceptable and an unacceptable
region, with a transition area in between. These acceptability boundaries should be
defined during the dialogue, although they are of course not always so simple to
set given the different patterns of perception and evaluation between groups and
individual stakeholders. The steepness of the line itself is a reflection of society’s
comfort with risk and can be related to the risk aversion factor (α) in Eq. 9.1.
Once the diagram is established, potential events can then be plotted onto it
based on their impact and probability of occurrence. Events that are partially in the
transition area between acceptable and not acceptable require careful consideration
of the trade-offs at stake. If the event is in the unacceptable region, safety measures
9 Societal Dialogue on Risks and Benefits
9.3.1 Considering Risk Aversion
Many individuals dislike accidents with high impact potential, even if the probability of occurrence is very low. To help with assessing this risk aversion on both the
technical and perceptive levels, it can be considered, for example, by introducing an
aversion factor into the product formula for calculating risk:
R = p × I
α
(9.1)
• R: risk
• p: probability
• I : impact
• α: empirically determined risk aversion factor (α > 1, i.e., risks that are less
likely but of high impact are weighted more heavily)
In considering a risk and preparing for risk communication with stakeholders,
this calculation can help to consider the subjective societal perception of risk
alongside the technically-based criteria. A greater α means a steeper acceptability
line in the risk diagram discussed in the following section and presented in Fig. 9.2.
9.3.2 Using Risk Diagrams
A helpful way to illustrate protection goals and map the limits of societal acceptance
(as defined on the decision-making level) to support dialogue is through the use
of a risk diagram. This is very similar to the use of a risk matrix as introduced
in Chap. 7. An example of such a diagram for the operation of a hypothetical
chemical production plant is shown in Fig. 9.2. The diagram plots the probability
of an accident (shown here as cumulative frequency) against the impact of an event
(shown here normalized as the number of resulting fatalities). Cumulative frequency
can be understood as the probability that an event occurs with an impact that is equal
to or less than a specific level of impact. The impact value along the x-axis could also
be represented by, for example, a category such as the number of humans injured,
contaminated surface waters (in m 3 or km 2 ), soil with impaired fertility (in km 2 ×
years), or property damage in millions of US dollars, etc.
The acceptability line divides the space into an acceptable and an unacceptable
region, with a transition area in between. These acceptability boundaries should be
defined during the dialogue, although they are of course not always so simple to
set given the different patterns of perception and evaluation between groups and
individual stakeholders. The steepness of the line itself is a reflection of society’s
comfort with risk and can be related to the risk aversion factor (α) in Eq. 9.1.
Once the diagram is established, potential events can then be plotted onto it
based on their impact and probability of occurrence. Events that are partially in the
transition area between acceptable and not acceptable require careful consideration
of the trade-offs at stake. If the event is in the unacceptable region, safety measures