How Close Is Close Enough: Public Perceptions of the Risks of Industrial Facilities

Public opinion poll data have consistently shown that the proportion of respondents who are willing to have a nuclear power plant in their own community is smaller than the proportion who agree that more nuclear plants should be built in this country. Respondents' judgments of the minimum safe distance from each of eight hazardous facilities confirmed that this finding results from perceived risk gradients that differ by facility (e.g., nuclear vs. natural gas power plants) and social group (e.g., chemical engineers vs. environmentalists) but are relatively stable over time. Ratings of the facilities on thirteen perceived risk dimensions were used to determine whether any of the dimensions could explain the distance data. Because the rank order of the facilities with respect to acceptable distance was very similar to the rank order on a number of the perceived risk dimensions, it is difficult to determine which of the latter is the critical determinant of acceptable distance if, indeed, there is only one. There were, however, a number of reversals of rank order that indicate that the respondents had a differentiated view of technological risk. Finally, data from this and other studies were interpreted as suggesting that perceived lack of any other form of personal control over risk exposure may be an important factor in stimulating public opposition to the siting of hazardous facilities.     

Do Users Ignore Spatial Data Quality? A Decision‐Theoretic Perspective

Risk analysis (RA) has been proposed as a means of assessing fitness for use of spatial data but is only rarely adopted. The proposal is that better decisions can be made by accounting for risks due to errors in spatial data. Why is RA so rarely adopted? Most geographical information science (GISc) literature stresses educational and technical constraints. In this article we propose, based on decision theory, a number of hypotheses for why the user would be more or less willing to spend resources on RA. The hypotheses were tested with a questionnaire, which showed that the willingness to spend resources on RA depends on the presence of feedback mechanisms in the decision‐making process, on how much is at stake, and to a minor extent on how well the decision‐making process can be modeled.     

Risk Management for Hazardous Materials Transportation: A Local Study in Lyons

A probabilistic risk assessment study has been undertaken in the French city of Lyons. The issue was to know whether it was justified to forbid hazardous material lorries in the city center and to divert them through the suburbs. Therefore, two routes, the City Center route and the Suburban route were compared. This paper describes the analysis and shows how the results were used in the decision-making process. It also lists the difficulties that are encountered when trying to incorporate formal risk analysis into actual decision-making processes. The risk analysis showed that rerouting is an effective option with respect to all criteria. The mathematical expectation of the number of deaths is divided by three, the reduction on the annual frequency of catastrophic accidents is even more important (about one order of magnitude for accidents involving more than 50 deaths). The spatial analysis proved that the risk was more evenly distributed along the Suburban route. However, the annual expected number of death is low: 0.5 in the worst case. So traditional decision-making approaches do not indicate the necessity of rerouting. Such a situation is believed to be typical for risk management of major hazards. In Lyons, the use of a very small risk aversion factor is sufficient to justify the rerouting option on a formal decision-aiding basis. This is rather unusual, but it is thought that the recognition of the importance of risk aversion by the decision-makers themselves is a very positive outcome from this study.     

Using Risk Communication to Disclose the Outcome of a Participatory Decision-Making Process: Effects on the Perceived Acceptability of Risk-Policy Decisions

It has been suggested that public participation during decision making about risks can lead to more widely accepted risk policies. This article discusses an experiment to determine if this is true when people are made aware of the fact that a participatory decision-making process has taken place only through information disclosed during a subsequent risk communication effort. The results from this experiment showed that, after receiving information during risk communication that cast risk policies about space exploration as the product of a participatory decision process, participants in the study felt more supportive of the resulting decisions than did participants in a control group. This result coincided with the participants in the study group perceiving the risks associated with the decision to be lower and the benefits higher. Responses from these participants also showed that they were more satisfied with the decision-making process than they were with the outcome of the decision itself Therefore, it may be premature to view the objective of participatory decision-making approaches-and the risk communication efforts that discuss them-as a means of making risk policies more widely acceptable to the public at large. Rather, it may be better to view the benefits of these approaches in terms of their ability to help lead to higher quality decisions that are the product of more widely accepted decision processes.     

How Do People Evaluate Risk Reduction When They Are Told Zero Risk Is Impossible?

Two studies examined how people evaluate risk reduction when they believe zero risk to be impossible. Measures collected were willingness to pay (WTP) for risk reduction, and degree of trust in the risk management agency. The findings from the combined studies are: (1) participants were more willing to pay a higher amount for the same reduction in risk in the "zero risk possible" than in the "zero risk impossible" condition; and (2) people's trust in the risk management agency did not differ between the "zero risk impossible" and "zero risk possible" conditions. These results suggest that it might be viable for agencies to accurately communicate the unattainability of zero risk without suffering a loss in public faith or trust, and thus that excessive expenditure for risk reduction might be prevented.     

Designing Graphs to Communicate Risks: Understanding How the Choice of Graphical Format Influences Decision Making

Previous research suggests that the choice of graphical format for communicating risk information affects both understanding of the risk magnitude and the likelihood of acting to decrease risk. However, the mechanisms through which these effects work are poorly understood. To explore these mechanisms using a real‐world scenario, we examined the relative impact of two graphical displays for depicting the risk of exposure to unexploded ammunition during potential land redevelopment. One display depicted only the foreground information graphically (a bar graph of the number of people harmed), and a second depicted the foreground and background graphically (a stacked bar graph representing both the number harmed and at risk). We presented 296 participants with either the foreground‐only or the foreground and background graphical display and measured a broad set of outcome variables, examining (1) the graphical display effect on each of the outcome measures and (2) the pathways by which any display effects work to influence decision making. We found that the foreground‐only graphical display increased perceived likelihood and experienced fear, which produced greater worry, which in turn increased risk aversion. In addition, a positive evaluation of the communication materials increased support for policies related to land redevelopment, whether those policies were risk taking or risk mitigating. Finally, the foreground‐only graphical display decreased understanding of the risk magnitude, showing that approaches to accomplish one risk communication goal (promoting risk‐averse decisions) may do so at the expense of another goal (increasing understanding).     

Consumers’ Risk Perception of Household Cleaning and Washing Products

A large share of accidental and nonaccidental poisonings are caused by household cleaning and washing products, such as drain cleaner or laundry detergent. The main goal of this article was to investigate consumers’ risk perception and misconceptions of a variety of cleaning and washing products in order to inform future risk communication efforts. For this, a sorting task including 33 commonly available household cleaning and washing products was implemented. A total of 60 female consumers were asked to place the cleaning and washing products on a reference line 3 m in length with the poles “dangerous” and “not dangerous.” The gathered data were analyzed qualitatively and by means of multidimensional scaling, cluster analysis, and linear regression. The dimensionality of the sorting data suggests that both analytically (i.e., written and graphical hazard notes and perceived effectiveness) and intuitively driven risk judgments (i.e., eco vs. regular products) were applied by the participants. Furthermore, results suggest the presence of misconceptions, particularly related to consumers’ perceptions of eco cleaning products, which were generally regarded as safer than their regular counterparts. Future risk communication should aim at dispelling these misconceptions and promoting accurate risk perceptions of particular household cleaning and washing products.     

Risk Assessment for Aflatoxin: III. Modeling the Relative Risk of Hepatocellular Carcinoma

Estimates have been made of the cancer potency of aflatoxin exposure among the U.S. population. Risk modeling is used to assess the dose-response relationship between aflatoxin exposure and primary liver cancer, controlling for hepatitis B virus (HBV), based on data provided by the Yeh et al. study in China. A relative risk model is proposed as a more appropriate alternative to the additive ("absolute" risk) model for transportation of risk coefficients between populations with different baseline rates. Several general relative risk models were examined; the exponential model provided the best fit. The Poisson regression method was used to fit the relative risk model to the grouped data. The effects of exposure to aflatoxin (AFB1) and hepatitis B infection were both found to be statistically significant. The risk of death from liver cancer for those exposed to AFB1 relative to the unexposed population, increases by 0.05% per ng/kg/day exposure of AFB1 (p less than 0.001). The results also indicated a 25-fold increase in the risk of death from liver cancer among those infected with hepatitis B virus, relative to noncarriers (p less than 0.0001). With a hepatitis prevalence rate of 1%, the aflatoxin intake level associated with liver cancer lifetime excess risk of 1 x 10(-5) for the U.S. population was estimated as 253 ng/day, based on a liver cancer baseline rate of 3.4/100,000/yr.     

Does Communicating (Flood) Risk Affect (Flood) Risk Perceptions? Results of a Quasi‐Experimental Study

People's risk perceptions are generally regarded as an important determinant of their decisions to adjust to natural hazards. However, few studies have evaluated how risk communication programs affect these risk perceptions. This study evaluates the effects of a small-scale flood risk communication program in the Netherlands, consisting of workshops and focus group discussions. The effects on the workshop participants' ( n  = 24) and focus group participants' ( n  = 16) flood risk perceptions were evaluated in a pretest-posttest control group ( n  = 40) design that focused on two mechanisms of attitude change—direct personal experience and attitude polarization. We expected that (H1) workshop participants would show greater shifts in their flood risk perceptions compared with control group participants and that (H2) focus groups would rather produce the conditions for attitude polarization (shifts toward more extreme attitudinal positions after group discussion). However, the results provide only modest support for these hypotheses, perhaps because of a mismatch between the sessions' contents and the risk perception measures. An important contribution of this study is that it examined risk perception data by both conventional tests of the mean differences and tests for attitude polarization. Moreover, the possibility that attitude polarization could cause people to confirm their preexisting (hazard) beliefs could have important implications for risk communication.     

Probability Size Matters: The Effect of Foreground-Only versus Foreground+Background Graphs on Risk Aversion Diminishes with Larger Probabilities

Graphs are increasingly recommended for improving decision-making and promoting risk-avoidant behaviors. Graphs that depict only the number of people affected by a risk (“foreground-only” displays) tend to increase perceived risk and risk aversion (e.g., willingness to get vaccinated), as compared to graphs that also depict the number of people at risk for harm (“foreground+background” displays). However, previous research examining these “foreground-only effects” has focused on relatively low-probability risks (<10%), limiting generalizability to communications about larger risks. In two experiments, we systematically investigated the moderating role of probability size on foreground-only effects, using a wide range of probability sizes (from 0.1% to 40%). Additionally, we examined the moderating role of the size of the risk reduction, that is, the extent to which a protective behavior reduces the risk. Across both experiments, foreground-only effects on perceived risk and risk aversion were weaker for larger probabilities. Experiment 2 also revealed that foreground-only effects were weaker for smaller risk reductions, while foreground-only displays decreased understanding of absolute risk magnitudes independently of probability size. These findings suggest that the greater effectiveness of foreground-only versus foreground+background displays for increasing perceived risk and risk aversion diminishes with larger probability sizes and smaller risk reductions. Moreover, if the goal is to promote understanding of absolute risk magnitudes, foreground+background displays should be used rather than foreground-only displays regardless of probability size. Our findings also help to refine and extend existing theoretical accounts of foreground-only effects to situations involving a wide range of probability sizes.     

A Diversity Index for Model Space Selection in the Estimation of Benchmark and Infectious Doses via Model Averaging

In chemical and microbial risk assessments, risk assessors fit dose‐response models to high‐dose data and extrapolate downward to risk levels in the range of 1–10%. Although multiple dose‐response models may be able to fit the data adequately in the experimental range, the estimated effective dose (ED) corresponding to an extremely small risk can be substantially different from model to model. In this respect, model averaging (MA) provides more robustness than a single dose‐response model in the point and interval estimation of an ED. In MA, accounting for both data uncertainty and model uncertainty is crucial, but addressing model uncertainty is not achieved simply by increasing the number of models in a model space. A plausible set of models for MA can be characterized by goodness of fit and diversity surrounding the truth. We propose a diversity index (DI) to balance between these two characteristics in model space selection. It addresses a collective property of a model space rather than individual performance of each model. Tuning parameters in the DI control the size of the model space for MA.     

Assessing Risk in Graphically Presented Financial Series

It has been argued that traders use their natural sensitivity to the fractal properties of price graphs to assess risk and that they are better able to do this when given price change as well as price level information. This approach implies that risk assessments should be higher when the Hurst exponents are lower, that this relationship should be stronger in the presence of price change information and that risk assessment should depend more strongly on the Hurst exponent than on the standard deviation of the series. Participants in Experiment 1 decided which of two assets was riskier by inspecting graphs of their price series. Graphs with lower Hurst exponents were selected only by those who were less emotionally stable and hence more sensitive to risk. However, when both price series and price change series were presented, the assets with lower Hurst exponents were selected by all participants. In a second experiment, participants were given both price level and price change series for a number of assets and rated the risk of trading in each one. Ratings depended more strongly on Hurst exponents than on other measures of volatility. They also depended on indicators of potential loss. Human risk assessment deviates from the way that risk is measured in modern finance theory: it requires integration of information relevant to both uncertainty and loss aversion, thereby imposing high attentional demands on traders. These demands may impair risk assessment but they can be eased by adding displays of price change information.     

An emotion-based model of risk perception and stigma susceptibility: cognitive appraisals of emotion, affective reactivity, worldviews, and risk perceptions in the generation of technological stigma.

A study (N=198) was conducted to examine hypotheses derived from an emotion-based model of stigma responses to radiation sources. A model of stigma susceptibility is proposed in which affective reactions and cognitive worldviews activate predispositions to appraise and experience events in systematic ways that result in the generation of negative emotion, risk perceptions, and stigma responses. Results of structural equation modeling supported the hypotheses. Radiation sources that scored higher on a measure of stigma were included in the analyses (i.e., nuclear power plants, radioactive waste from nuclear power plants, radiation from nuclear weapons testing). Individual differences in negative reactivity and worldviews were associated with the strength of emotional appraisals that were associated, in turn, with negative emotion toward stigmatized radiation sources. As hypothesized, the model fit better with perceived risk as a function of negative emotion rather than vice versa. Finally, a measure of stigma was associated with negative emotion and, to a lesser extent, with risk perceptions. Risk communication about stigmatized objects may benefit from a more complete understanding of how affective and emotional reactions are constructed and the routes through which they affect responses and behaviors.     

Understanding the Positive Effects of Graphical Risk Information on Comprehension: Measuring Attention Directed to Written,Tabular, and Graphical Risk Information

Risk communications are an integral aspect of health education and promotion. However, the commonly used textual risk information is relatively difficult to understand for the average recipient. Consequently, researchers and health promoters have started to focus on so‐called decision aids, such as tables and graphs. Although tabular and graphical risk information more effectively communicate risks than textual risk information, the cognitive mechanisms responsible for this enhancement are unclear. This study aimed to examine two possible mechanisms (i.e., cognitive workload and attention). Cognitive workload (mean pupil size and peak pupil dilation) and attention directed to the risk information (viewing time, number of eye fixations, and eye fixation durations) were both measured in a between‐subjects experimental design. The results suggest that graphical risk information facilitates comprehension of that information because it attracts and holds attention for a longer period of time than textual risk information. Graphs are thus a valuable asset to risk communication practice for two reasons: first, they tend to attract attention and, second, when attended to, they elicit information extraction with relatively little cognitive effort, and finally result in better comprehension.     

The Interplay of Science, Values, and Experiences Among Scientists Asked to Evaluate the Hazards of Dioxin, Radon, and Environmental Tobacco Smoke

To investigate the extent to which personal values and experiences among scientists might affect their assessment of risks from dioxin, radon, and environmental tobacco smoke (ETS), we conducted an experiment through a telephone survey of 1461 epidemiologists, toxicologists, physicians, and general scientists. Each participant was read a vignette designed to reflect the mainstream scientific thinking on one of the three substances. For half of the participants (group A) the substance was named. For the other half (group B), the substance was not named but was identified only as Substance X, Y, or Z. Knowing the name of the substance had little effect on the scientists' evaluation of dioxin, although those who knew the substance to be dioxin were more likely to rate the substance as a serious environmental health hazard (51% vs. 42%, p = 0.062). For radon, those who knew the substance by name were significantly more likely to consider it an environmental health hazard than were those who knew it as substance Z (91% vs. 78%, p less than 0.001). Participants who knew they were being asked about ETS rather than substance X were significantly more likely to consider the substance an environmental health hazard (88% vs. 66%, p less than 0.001), to consider the substance a serious environmental health hazard (70% vs. 33%, p less than 0.001), to believe that background exposure required public health intervention (85% vs. 41%, p less than 0.001), and to believe that above-background exposure required public health intervention (90% vs. 74%, p less than 0.001). These findings suggest that values and experiences may be influencing health risk assessments for these substances, and indicate the need for more study of this phenomenon.     

基于时变Copula函数的下偏矩最优套期保值效率测度方法研究

由于下偏矩测度方法具有明显优于最小方差风险度量方法的特征,因此是更为合理的套期保值效率测度准则。本文针对已有的计算最小下偏矩套期保值比率的非参数方法与参数方法存在的局限性问题,提出使用时变Copula函数来估计现货与期货收益率的联合密度函数,然后通过数值方法计算最小下偏矩套期保值比率的新方法。并且运用上海期货交易所交易的铜期货合约价格与上海金属网公布的铜现货价格数据进行实证检验,发现使用具有随时间变化的相关系数的Copula函数,与非参数方法相比,可以得到更小下偏矩的套期保值率。     

Reflections on Risk Perception and Policy1,2

This paper looks critically at the emergence and present status of risk analysis with the aim of assessing its usefulness for policy decisions on risk regulation and the acceptability of risk-bearing innovations. The authors adopt a personal narrative to illustrate their own involvement in risk research and to comment on empirical trends that have resulted in the current fashion for risk workshops. The second part of the paper confronts specific issues in risk research. These are not new problems-indeed several of the questions asked have been taken directly from a list used to structure a recent risk seminar; but the stand taken here is rather less conciliatory than is usual when these issues are discussed. The pessimistic message of this paper is that risk research, especially in the area of risk perception, is being used as a panacea with which to attempt to remedy what are essentially societal and political matters. Risk research is being used as a tool in a discourse which is not concerned with risks per se, nor with the cognitive processes by which people misperceive the risks of new technologies, but whose hidden agenda is the legitimacy of decision-making institutions and the equitable distribution of hazards and benefits. The authors take a subjectivist view, not just of risk but in general, and query the natural science approach to risk perception, with its assumption that universal dimensions of risk perception can be discovered and used in policy-making and setting regulatory standards. Although it is possible to collect subjective data on the wider meanings that risks and benefits associated with technological innovations have for lay publics, the interpretation and recombination of these data into useful policy guidelines is seen as fraught with technical and, above all, political problems.     

Institutionalized Ignorance as a Precondition for Rational Risk Expertise

The present case study seeks to explain the conditions for experts’ rational risk perception by analyzing the institutional contexts that constitute a field of food safety expertise in Denmark. The study highlights the role of risk reporting and how contextual factors affect risk reporting from the lowest organizational level, where concrete risks occur, to the highest organizational level, where the body of professional risk expertise is situated. The article emphasizes the role of knowledge, responsibility, loyalty, and trust as risk‐attenuation factors and concludes by suggesting that the preconditions for the expert's rationality may rather be a lack of risk‐specific knowledge due to poor risk reporting than a superior level of risk knowledge.     

A Deliberative Method for Ranking Risks (II): Evaluation of Validity and Agreement among Risk Managers

A deliberative method for ranking risks was evaluated in a study involving 218 risk managers. Both holistic and multiattribute procedures were used to assess individual and group rankings of health and safety risks facing students at a fictitious middle school. Consistency between the rankings that emerged from these two procedures was reasonably high for individuals and for groups, suggesting that these procedures capture an underlying construct of riskiness. Participants reported high levels of satisfaction with their groups' decision-making processes and the resulting rankings, and these reports were corroborated by regression analyses. Risk rankings were similar across individuals and groups, even though individuals and groups did not always agree on the relative importance of risk attributes. Lower consistency between the risk rankings from the holistic and multiattribute procedures and lower agreement among individuals and groups regarding these rankings were observed for a set of high-variance risks. Nonetheless, the generally high levels of consistency, satisfaction, and agreement suggest that this deliberative method is capable of producing risk rankings that can serve as informative inputs to public risk-management decision making.     

Risk Perceptions and Food Choice: An Exploratory Analysis of Organic- Versus Conventional-Produce Buyers

Consumer choice between organically (without pesticides) and conventionally grown produce is examined. Exploratory focus-group discussions and questionnaires (N = 43) suggest that individuals who purchase organically grown produce believe it is substantially less hazardous than the conventional alternative and are willing to pay significant premiums to obtain it (a median 50% above the cost of conventional produce). The value of risk reduction implied by this incremental willingness to pay is not high relative to estimates for other risks, since the perceived risk reduction is relatively large. Organic-produce consumers also appear more likely than conventional-produce consumers to mitigate other ingestion-related risks (e.g., contaminated drinking water) but less likely to use automobile seatbelts.