Medical Surveillance, Frequent Sets, and Closure Operations

Surveillance of hospital-acquired infections, especially those caused by antibiotic resistant bacteria, is an important component of hospital infection control. A computer program for this purpose experienced a combinatorial computational explosion in time and space when processing data describing certain multi-drug resistant organisms. The blowup occurred while the program was generating frequent sets, a common phase in data mining algorithms. We present a modified algorithm for computing frequent sets that more efficiently handles the computational burden. The algorithm's proof of correctness involves the concepts of closure, independent sets, and circuits in a space more general than a matroid. Of central concern in the theory are inferences about a closure operation that can be obtained from limited information about the circuits.     

Risk-Based Objectives for the Allocation of Chemical, Biological, and Radiological Air Emissions Sensors

This article addresses the problem of allocating devices for localized hazard protection across a region. Each identical device provides only local protection, and the devices serve localities that are exposed to nonidentical intensities of hazard. A method for seeking the optimal allocation Policy Decisions is described, highlighting the potentially competing objectives of maximizing local risk reductions and coverage risk reductions. The metric for local risk reductions is the sum of the local economic risks avoided. The metric for coverage risk reductions is adapted from the p-median problem and equal to the sum of squares of the distances from all unserved localities to their closest associated served locality. Three graphical techniques for interpreting the Policy Decisions are presented. The three linked graphical techniques are applied serially. The first technique identifies Policy Decisions that are nearly Pareto optimal. The second identifies locations where sensor placements are most justified, based on a risk-cost-benefit analysis under uncertainty. The third displays the decision space for any particular policy decision. The method is illustrated in an application to chemical, biological, and/or radiological weapon sensor placement, but has implications for disaster preparedness, transportation safety, and other arenas of public safety.     

Priority Setting for the Distribution of Localized Hazard Protection

We address the problem of distributing safety-enhancing devices across a region, where each identical device provides for only local protection of the population. The devices protect nonidentical sectors of the population. The sectors of population are exposed to nonidentical intensities of hazard. A method for the screening and prioritizing of needs for the protective devices is described. An approach of risk-benefit-cost analysis under uncertainty is recommended as follows. Measures of hazard intensity and population exposure are identified. Exogenous parameters that influence assessments of risks, benefits, and costs are identified. Uncertainties of the exogenous parameters are propagated by interval analysis. Several tiers of the plausibility of need for protection are identified. The tiers are useful in setting priorities for the distribution of the safety devices. The method is demonstrated in an engineering application to roadway lighting, but has implications for disaster preparedness, anti-terrorism, transportation safety, and other arenas of public safety.     

Risk Ranking for Foodborne Microbial Hazards in New Zealand: Burden of Disease Estimates

Priority setting for food safety management at a national level requires risks to be ranked according to defined criteria. In this study, two approaches (disability‐adjusted life years (DALYs) and cost of illness (COI)) were used to generate estimates of the burden of disease for certain potentially foodborne diseases (campylobacteriosis, salmonellosis, listeriosis (invasive, perinatal, and nonperinatal), infection with Shiga toxin‐producing Escherichia coli (STEC), yersiniosis, and norovirus infection) and their sequelae in New Zealand. A modified Delphi approach was used to estimate the food‐attributable proportion for these diseases. The two approaches gave a similar ranking for the selected diseases, with campylobacteriosis and its sequelae accounting for the greatest proportion of the overall burden of disease by far.     

A Comparative Pharmacokinetic Estimate of Mercury in U.S. Infants Following Yearly Exposures to Inactivated Influenza Vaccines Containing Thimerosal

The use of thimerosal preservative in childhood vaccines has been largely eliminated over the past decade in the United States because vaccines have been reformulated in single‐dose vials that do not require preservative. An exception is the inactivated influenza vaccines, which are formulated in both multidose vials requiring preservative and preservative‐free single‐dose vials. As part of an ongoing evaluation by USFDA of the safety of biologics throughout their lifecycle, the infant body burden of mercury following scheduled exposures to thimerosal preservative in inactivated influenza vaccines in the United States was estimated and compared to the infant body burden of mercury following daily exposures to dietary methylmercury at the reference dose established by the USEPA. Body burdens were estimated using kinetic parameters derived from experiments conducted in infant monkeys that were exposed episodically to thimerosal or MeHg at identical doses. We found that the body burden of mercury (AUC) in infants (including low birth weight) over the first 4.5 years of life following yearly exposures to thimerosal was two orders of magnitude lower than that estimated for exposures to the lowest regulatory threshold for MeHg over the same time period. In addition, peak body burdens of mercury following episodic exposures to thimerosal in this worst‐case analysis did not exceed the corresponding safe body burden of mercury from methylmercury at any time, even for low‐birth‐weight infants. Our pharmacokinetic analysis supports the acknowledged safety of thimerosal when used as a preservative at current levels in certain multidose infant vaccines in the United States.     

CEO duality and firm performance: The moderating roles of other executives and blockholding outside directors

This study examines how the effect of CEO duality on firm performance is affected by two internal governance forces – namely other executives in the top management team and blockholding outside directors. Results based on a longitudinal dataset from the U.S. computer industry were consistent with my hypotheses. Specifically, I found that the effect of CEO duality was negative when the CEO had dominant power relative to other executives and when the board had a blockholding outside director, but was nonsignificant otherwise. This study enriches our understanding of the effect of CEO duality, and helps reinforce the call for the nonduality structure as the default choice and put the burden of proof on those who wish to justify otherwise on special grounds.     

Mitigating Sports Injury Risks Using Internet of Things and Analytics Approaches

Sport injuries restrict participation, impose a substantial economic burden, and can have persisting adverse effects on health‐related quality of life. The effective use of Internet of Things (IoT), when combined with analytics approaches, can improve player safety through identification of injury risk factors that can be addressed by targeted risk reduction training activities. Use of IoT devices can facilitate highly efficient quantification of relevant functional capabilities prior to sport participation, which could substantially advance the prevailing sport injury management paradigm. This study introduces a framework for using sensor‐derived IoT data to supplement other data for objective estimation of each individual college football player's level of injury risk, which is an approach to injury prevention that has not been previously reported. A cohort of 45 NCAA Division I‐FCS college players provided data in the form of self‐ratings of persisting effects of previous injuries and single‐leg postural stability test. Instantaneous change in body mass acceleration (jerk) during the test was quantified by a smartphone accelerometer, with data wirelessly transmitted to a secure cloud server. Injuries sustained from the beginning of practice sessions until the end of the 13‐game season were documented, along with the number of games played by each athlete over the course of a 13‐game season. Results demonstrate a strong prediction model. Our approach may have strong relevance to the estimation of injury risk for other physically demanding activities. Clearly, there is great potential for improvement of injury prevention initiatives through identification of individual athletes who possess elevated injury risk and targeted interventions.     

The Precautionary Principle Is Incoherent

This article argues that no version of the precautionary principle can be reasonably applied to decisions that may lead to fatal outcomes. In support of this strong claim, a number of desiderata are proposed, which reasonable rules for rational decision making ought to satisfy. Thereafter, two impossibility theorems are proved, showing that no version of the precautionary principle can satisfy the proposed desiderata. These theorems are directly applicable to recent discussions of the precautionary principle in medicine, biotechnology, environmental management, and related fields. The impossibility theorems do not imply, however, that the precautionary principle is of no relevance at all in policy discussions. Even if it is not a reasonable rule for rational decision making, it is possible to interpret the precautionary principle in other ways, e.g., as an argumentative tool or as an epistemic principle favoring a reversed burden of proof.     

Safety Management and Public Spaces: Restoring Balance

Since 2000, the reputation of health and safety in the United Kingdom has been tarnished, so much so that it has become the subject of both a media circus and a government inquiry. This not only threatens the worthy goals of health and safety, but also impacts upon the associated tool of risk assessment itself such that "risk assessment" is increasingly seen by the public at large as a term inviting ridicule, even abuse. The main thrust of the government's examination of health and safety has been its concern that safety requirements were placing a disproportionate burden on business. However, there is another source of discontent, which is public chagrin over the impact of injury control measures upon life beyond the conventional workplace, in particular upon the public spaces that people frequent in their leisure time and on the activities they engage in there. This article provides a perspective on this second dimension of the crisis in confidence. It describes how many U.K. agencies with responsibilities for a wide portfolio of public amenities ranging from the provision of play spaces for the young to the management of publicly accessible countryside, the maintenance of urban and rural trees, the stewardship of sites of cultural heritage, and the pursuit of outdoor educational activities have responded to some conflicts posed to their services by the new safety culture. It concludes with a discussion of implications for the management of public space and for risk assessment itself.     

Managerial support for basic psychological needs,somatic symptom burden and work-related correlates: A self-determination theory perspective

Somatic symptom burden, or the experience of physical symptomatology without a medical explanation, is related to functional disability and poor quality of life. The consequences of somatic symptom burden extend beyond the individual and affect society, as manifested in higher medical utilization and lower job productivity. Using self-determination theory, we posited that employees' perceptions of managerial support for basic psychological needs may be associated with lower levels of somatic symptom burden among employees, in part because such contexts promote autonomous self-regulation (a type of motivation) at work. Also, we posited that somatic symptom burden among employees would explain some of the relations of managerial need support and autonomous self-regulation at work to indices of work-related functioning, namely emotional exhaustion, turnover intention and absenteeism. Results from 287 Norwegian employees confirmed these hypotheses. These findings not only identify a theoretical mechanism that may explain (in part) the origin of somatic symptoms, but also offer a model by which social-contextual and motivational factors affect important work-related outcomes. These findings also bespeak the importance of developing workplace interventions that provide support for satisfaction of the basic psychological needs.     

Does a Reactor Need a Safety Backfit? Case Study on Communicating Decision and Risk Analysis Information to Managers

An approach to communicating decision and risk analysis findings to managers is illustrated in a real case context. This article consists essentially of a report prepared for senior managers of the Nuclear Regulatory Commission to help them make a reactor safety decision. It illustrates the communication of decision analysis findings relating to technical risks, costs, and benefits in support of a major risk management decision: whether or not to require a safety backfit. Its focus is on the needs of decision makers, and it introduces some novel communication devices.     

Linking Decision Theory and Quantitative Microbial Risk Assessment: Tradeoffs Between Compliance and Efficacy for Waterborne Disease Interventions

Achieving health gains from the U.N. Sustainable Development Goals of universal coverage for water and sanitation will require interventions that can be widely adopted and maintained. Effectiveness—how an intervention performs based on actual use—as opposed to efficacy will therefore be central to evaluations of new and existing interventions. Incomplete compliance—when people do not always use the intervention and are therefore exposed to contamination—is thought to be responsible for the lower‐than‐expected risk reductions observed from water, sanitation, and hygiene interventions based on their efficacy at removing pathogens. We explicitly incorporated decision theory into a quantitative microbial risk assessment model. Specifically, we assume that the usability of household water treatment (HWT) devices (filters and chlorine) decreases as they become more efficacious due to issues such as taste or flow rates. Simulations were run to examine the tradeoff between device efficacy and usability. For most situations, HWT interventions that trade lower efficacy (i.e., remove less pathogens) for higher compliance (i.e., better usability) contribute substantial reductions in diarrheal disease risk compared to devices meeting current World Health Organization efficacy guidelines. Recommendations that take into account both the behavioral and microbiological properties of treatment devices are likely to be more effective at reducing the burden of diarrheal disease than current standards that only consider efficacy.     

Mechanism Design with Collusion and Correlation

In a public good environment with positively correlated types, we characterize optimal mechanisms when agents have private information and can enter collusive agreements. First, we prove a weak‐collusion‐proof principle according to which there is no restriction for the principal in offering weak‐collusion‐proof mechanisms. Second, with this principle, we characterize the set of allocations that satisfy individual and coalitional incentive constraints. The optimal weakly collusion‐proof mechanism calls for distortions away from first‐best efficiency obtained without collusion. Allowing collusion restores continuity between the correlated and the uncorrelated environments. When the correlation becomes almost perfect, first‐best efficiency is approached. Finally, the optimal collusion‐proof mechanism is strongly ratifiable.     

Commitment,Flexibility, and Optimal Screening of Time Inconsistency

This paper develops a theory of optimal provision of commitment devices to people who value both commitment and flexibility and whose preferences differ in the degree of time inconsistency. If time inconsistency is observable, both a planner and a monopolist provide devices that help each person commit to the efficient level of flexibility. However, the combination of unobservable time inconsistency and preference for flexibility causes an adverse‐selection problem. To solve this problem, the monopolist and (possibly) the planner curtail flexibility in the device for a more inconsistent person at both ends of the efficient choice range; moreover, they may have to add unused options to the device for a less inconsistent person and also distort his actual choices. This theory has normative and positive implications for private and public provision of commitment devices.     

Risk-Perception Studies and Policy Priorities

The current fascination with risk acceptability, risk benefit analysis and other devices for relating risk to social gain is a manifestation of the loss of faith amongst certain groups in modern western society with the honesty and competence of those who assess and finally make judgements about public safety. The problem lies as much in a suspicion over the motives of leading personalities and the fidelity of assessment procedures as it does with the collective psychology of individual beliefs and judgements. "Real world" studies involving carefully sampled households monitored over a period of time may well reveal better information on the complexities of risk cognition and evaluation than laboratory investigation of the views of individuals responding in isolation.     

Risk, Statistical Inference, and the Law of Evidence: The Use of Epidemiological Data in Toxic Tort Cases

Toxic torts are product liability cases dealing with alleged injuries due to chemical or biological hazards such as radiation, thalidomide, or Agent Orange. Toxic tort cases typically rely more heavily than other product liability cases on indirect or statistical proof of injury. There have been numerous theoretical analyses of statistical proof of injury in toxic tort cases. However, there have been only a handful of actual legal decisions regarding the use of such statistical evidence, and most of those decisions have been inconclusive. Recently, a major case from the Fifth Circuit, involving allegations that Benedectin (a morning sickness drug) caused birth defects, was decided entirely on the basis of statistical inference. This paper examines both the conceptual basis of that decision, and also the relationships among statistical inference, scientific evidence, and the rules of product liability in general.     

Deciding with Thresholds: Importance Measures and Value of Information

Risk‐informed decision making is often accompanied by the specification of an acceptable level of risk. Such target level is compared against the value of a risk metric, usually computed through a probabilistic safety assessment model, to decide about the acceptability of a given design, the launch of a space mission, etc. Importance measures complement the decision process with information about the risk/safety significance of events. However, importance measures do not tell us whether the occurrence of an event can change the overarching decision. By linking value of information and importance measures for probabilistic risk assessment models, this work obtains a value‐of‐information‐based importance measure that brings together the risk metric, risk importance measures, and the risk threshold in one expression. The new importance measure does not impose additional computational burden because it can be calculated from our knowledge of the risk achievement and risk reduction worth, and complements the insights delivered by these importance measures. Several properties are discussed, including the joint decision worth of basic event groups. The application to the large loss of coolant accident sequence of the Advanced Test Reactor helps us in illustrating the risk analysis insights.     

Probabilistic Reliability Analysis, Quantitative Safety Goals, and Nuclear Licensing in the United Kingdom

Although unpublicized, the use of quantitative safety goals and probabilistic reliability analysis for licensing nuclear reactors has become a reality in the United Kingdom. This conclusion results from an examination of the process leading to the licensing of the Sizewell B PWR in England. The licensing process for this reactor has substantial implications for nuclear safety standards in Britain, and is examined in the context of the growing trend towards quantitative safety goals in the United States.     

Perceived Risks of Conventional and Organic Produce: Pesticides, Pathogens, and Natural Toxins

Public risk perceptions and demand for safer food are important factors shaping agricultural production practices in the United States. Despite documented food safety concerns, little attempt has been made to elicit consumers' subjective risk judgments for a range of food safety hazards or to identify factors most predictive of perceived food safety risks. In this study, over 700 conventional and organic fresh produce buyers in the Boston area were surveyed for their perceived food safety risks. Survey results showed that consumers perceived relatively high risks associated with the consumption and production of conventionally grown produce compared with other public health hazards. For example, conventional and organic food buyers estimated the median annual fatality rate due to pesticide residues on conventionally grown food to be about 50 per million and 200 per million, respectively, which is similar in magnitude to the annual mortality risk from motor vehicle accidents in the United States. Over 90% of survey respondents also perceived a reduction in pesticide residue risk associated with substituting organically grown produce for conventionally grown produce, and nearly 50% perceived a risk reduction due to natural toxins and microbial pathogens. Multiple regression analyses indicate that only a few factors are consistently predictive of higher risk perceptions, including feelings of distrust toward regulatory agencies and the safety of the food supply. A variety of factors were found to be significant predictors of specific categories of food hazards, suggesting that consumers may view food safety risks as dissimilar from one another. Based on study findings, it is recommended that future agricultural policies and risk communication efforts utilize a comparative risk approach that targets a range of food safety hazards.     

The Effect of Graphics on Environmental Health Risk Beliefs, Emotions, Behavioral Intentions, and Recall

Lay people have difficulty understanding the meaning of environmental health risk information. Visual images can use features that leverage visual perception capabilities and semiotic conventions to promote meaningful comprehension. Such evidence-based features were employed to develop two images of a color-coded visual scale to convey drinking water test results. The effect of these images and a typical alphanumeric (AN) lab report were explored in a repeated measures randomized trial among 261 undergraduates. Outcome measures included risk beliefs, emotions, personal safety threshold, mitigation intentions, the durability of beliefs and intentions over time, and test result recall. The plain image conveyed the strongest risk message overall, likely due to increased visual salience. The more detailed graded image conveyed a stronger message than the AN format only for females. Images only prompted meaningful risk reduction intentions among participants with optimistically biased safety threshold beliefs. Fuzzy trace theory supported some findings as follow. Images appeared to promote the consolidation of beliefs over time from an initial meaning of safety to an integrated meaning of safety and health risk; emotion potentially shaped this process. Although the AN report fostered more accurate recall, images were related to more appropriate beliefs and intentions at both time points. Findings hinted at the potential for images to prompt appropriate beliefs independent of accurate factual knowledge. Overall, results indicate that images facilitated meaningful comprehension of environmental health risk information and suggest foci for further research.