Subjective risk

Risk tolerability is a complex subject. Risk tolerance in society generally has changed over time and will continue to do so. Tolerance criteria may vary from company to company. Further, the reasons for the variations can differ from company to company. Many companies, in fact, have not developed explicit risk tolerance criteria. 

In a society in which democratic principles dominate, the perceptions of the public must be weighed. Instead of objective and subjective risks, the experts sometimes refer to real and imaginary risk. There is a certain arrogance in this — an elitism that has ill served us in the past. Rather than decry the ignorance of the public and seek to ignore their concerns, our governmental... 

Kniesner and Leeth (1991), who indeed included these rates as independent variables, noted that wage allowances for hazardous jobs may be formalised as a result of government or union action. Such action clearly causes wage differentials, but the problem ofworkers actual perception of job risks remains. This latter problem is related directly to the general issue of objective versus subjective risks, an issue which is not discussed further here. 

Mary Douglas s main publications on the subject (Risk and Culture and Risk and Blame) are presented in Richard Farndon, Mary Douglas An Intellectual Biography (London Routledge, 1999), pp. 144-67. 

The Canadian approach to Road Safety Audits includes the traditional aspects of identifying the safety issues and also includes a subjective risk rating as well as a few suggested solutions. The subjective risk rating was requested by the recipients of the Road Safety Audits so that they could apply a priority hierarchy in addressing the issues. The inclusion of a few potential solutions was to fully utilise the expertise of the auditors who have a professional engineer on the team with expertise in road safety. 

In connection with road traffic, with its special condition of self-determination of the rate of work, studies by Taylor [6-40] and Wilde [6-41] have indicated that there is an adequate awareness of the risk content in particular situations. Both authors carried out field experiments which showed that drivers regulate their behavior within the MME-system so that the risk they experience fluctuates only between narrow limits. Thus Taylor reported that drivers tend to increase the speed of the vehicle in situations in which low risk is perceived, and to reduce speed if the perceived risk increases again. The perceived risk was determined in these experiments using the psycho-physiological measure of the galvanic skin response. In a similar experiment Galton and Wilde [6-42] showed that the subjective risk was determined on the basis of a verbally formulated risk scale. The test route consisted of 11 sections with heterogeneous traffic... 

The risk compensation hypothesis derives from the results of field experiments in which drivers performed their tasks under observation. Wilde expresses ii as follows The level of perceived risk minus the driver s effort to reduce subjective risk—i.e., the degree of caution—is a constant. This constant represents the degree of tolerated risk. 

It was found, however, that application of the model method to data of the past shows model-contrary inconsistencies in the population s attitude toward risks. This was explained by means of the difference between objective risk, which is the deciding quantity in Starr s model, and perceived risk. Neither does the risk perception remain constant for the old risks nor can the difference between objective risk and subjective risk perception be neglected in the case of new risks . Though the revealed reference model is therefore subject to criticism as an acceptance-prediction model, the risk-acceptance comparison which can be obtained with the help of this model is suited as an argumentum ad hominem in public discussion. 

The problem of the difference between objective risk and subjective risk perception is avoided by the so-called psychometric models which aim to directly record subjective evaluations as a basis for decision-making processes. The expressed preference method [9-10], which uses opinion polls, did, however, show the change in the way the population evaluates technical developments. 

Although the items on the list represent the same level of numerical or objective risk, they do not represent the same level of subjective risk. If that was the case, then a person who is willing to go for a 10-mile bicycle ride should be equally willing to undertake any of the other activities, for instance eat 100... 

Overall, it was concluded that the effect of the feedback loop was to counteract the benefits of safety countermeasures [t]he present model demonstrates a manner how the expected gain may be lost—the subjective risk is attenuated by, e.g. changes in the traffic environment which make it appear safer. Under such circumstances, the driver can drive faster and overtake other cars more frequently before subjective risk is experienced (p. 257). On the other hand, if a treatment increased subjective risk, then benefits might accrue. Here, we have a proposition of risk compensation. 

The tendency to make propositions at a very high level of generality and without fully specified mechanisms continued. Thus, Jiang, Underwood, and Howarth (1992), in their theoretical model for adaptations to change , tell us that objective risk is not the same as subjective risk and that cognition of risk depends on the possibility of perception of risk. In other words, drivers can only evaluate risks if they perceive them. They go on to state that road users responses to subjective risk will be affected by motivations that can be expressed in the form of a utility maximisation function, but they also state that road users usually have no clear quantitative description of how their actions can affect the benefit they want to maximise (p. 259). We are thus little the wiser in terms of any verifiable predictions. 

The Multiple Comfort Zone, or Safety Margin, Model (Summala, 2005, 2007) is a hierarchical model of driver behaviour that could be described as a modem evolution of Naatanen and Summala s (1974) zero risk theory and Summala s (1997) hierarchical and motivational model of behavioural adaptation. Much like TDH/RAT and the RMM, it also mentions the SMH (Damasio, 1994, 2003), but only to point out that emotion and feelings have long played a role in zero-risk theory (Naatanen and Summala, 1974) via the subjective risk monitor (Summala, 2007). The multiple comfort zone model also incorporates some parts of TDH and the RMM, while at the same time taking a somewhat different approach in terms of how driver decision making and behavioural adaptation is viewed. Also, like TDH, it has been proposed as an attempt to create a model that produces testable hypotheses (Summala, 2005). 

Moran, A. 1982. Drivers mental load and subjective risk estimates while driving road sections of different accident histories. Proceedings, 15th Annual Meeting of the Human Factors Association of Canada, Toronto, pp. 72-75. 

In addition to avoiding accidents, drivers seek a certain target feeling that can be realized in addition to a subjective risk of zero. This feeling is not experienced in the same way in all drivers. Rather, each driver has a unique target, which is not necessarily experienced consciously. Targets that drivers seek have to be defined and characterized by an emotional dimension. 

A corrosion index for pipeline risk evaluation. A risk assessment technique is described in much detail in the second edition of a popular book on pipeline risk management. The technique proposed in that book is based on subjective risk assessment, a method that is particularly well adapted to situations in which knowledge is perceived to be incomplete and judgment is often based on opinion, experience, intuition, and other nonquantifiable resources. A detailed schema relating an extensive description of all the elements involved in creating risk compensates for the fuzziness associated with the manipulation of nonquantifiable data. Figure 4.12 illustrates the basic pipeline risk assessment model or tool proposed in that book. 

Research also exists which addresses directly the proposition of behavioral decision theory that bounded rationality leads people to use heuristics which in turn cause systematic error in traffic safety decisions. Max Hammerton and his colleagues specifically mvestigate the seriousness of bounds when people are asked to deal with traffic safety. They performed psychological laboratory experiments presenting situations which tested for willingness to deal with traffic risks, ability to rank traffic risks, accuracy of subjective risk relative to objective estimates of risk, and monetary valuation of reductions in traffic risks. The results show that people are willing and able to answer questions about traffic safety, there is no evidence of mendacity, people were coherent in that they were consistent in choices involving different bets and they were... 

Risk Perception Experimental results indicate people s subjective risk estimates differ from objective estimates Slovic and Fischloff Survey results indicate that people are good at ranking risks associated with traffic Hammerton et al... 

The accident analysis presented up to this point has concentrated on individual characteristics of accidents related to persons, objects and work places. In order to arrive at more exact indications for preventive measures, it is necessary to ascertain the special work activities or individual types of work places, at which the involved occupational groups are especially liable to accidents. Such an analysis based on official accident records is possible for various types of elevated work places. The analysis simultaneously provides the reference data for the comparisons between objective risk data and subjective risk estimates, which will be described later. 

The results of this study support the hypothesis that there is a mis-match between subjective risk estimates and objective risks. Some misfits between the risk distributions seem to be due to special problems of the technique applied. Slovic et al. (1978) have demonstrated that irrespective of the object... 

Misfits of subjective risk estimates and objective risks call for adjustments and improvements. Traditionally, this was thought to be a matter of safety posters, safety publications, accident reports in particular, and activities of safety officiers. Four approaches seem important ... 

Risks are by nature subjective, therefore, the AHP method may be suited for risk assessment in many situations. This technique allows subjective and objective factors to be considered in risk analysis and also provides a flexible and easily understood way to annualise subjective risk factors. The elements in each level are compared pair-wise with respect to their importance in making the decision under consideration. The verbal scale used in AHP enables the decisionmaker to incorporate subjectivity, experience and knowledge in an intuitive and natural way. 

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