behavioural studies may provide what are commonly denoted to as revealed preferences.
Finally, preferences which are expressed on the basis of a full understanding of the possible
consequences of the preferences are called informed preferences. Many specific techniques
have been developed for the purpose of assessing and modelling the preferences of
individuals. Stated preferences have proven to be very problematic in the sense that they may
depend completely on the way with which the information has been collected, e.g. the
formulation of the questions in an interview. Revealed preferences form a much better basis
for understanding and modelling preferences, however, there is no guarantee that such
preferences will comply with basic pre-requisites such as the Universal Declaration of Human
Rights. The so-called informed preferences are generally preferred as a basis for the
modelling of preferences; however, also these are associated with problems. It may not be
possible to provide information in an unbiased way about the consequences which will follow
from given preferences and again the manner in which the consequences of preferences are
explained may have a significant effect on the informed preferences. In a societal decision
making context there is, however, no doubt that informed preferences must be strived for. The
role of the engineer in this is to help to provide information to societal decision makers such
as politicians and authorities in regard to risks and the efficiency of different options for
managing risks. Furthermore, an important task is to clearly communicate to the societal
decision makers as well as the general public the assumptions underlying risk results as well
as the implications of these for the identified optimal decision options. If all aspects of the
societal management of risks are appropriately communicated the means of a well functioning
democracy should provide the basis for invoking informed preferences into the societal
decision making process.
In the following first commonly applied formats for enforcing acceptable life risks in
engineering are summarized. Thereafter the aspects of revealed risks for individuals of the
society are discussed and it is shown that it is possible to get an indication of acceptable life
risks simply based on statistical information. Following this the problem of risk acceptance is
considered in a societal or socio-economical perspective, and it is shown that it is possible to
develop a more rich and informative basis for decisions on optimal societal investments into
life safety.
13.2 Commonly Applied Formats of Risk Acceptance
The most commonly used format for representing acceptable risks is the so-called Farmer
diagram or FN-diagrams, see Figure 13.1.