Non-smooth optimization methods for computation of the conditional value-at-risk and portfolio optimization

We examine numerical performance of various methods of calculation of the Conditional Value-at-risk (CVaR), and portfolio optimization with respect to this risk measure. We concentrate on the method proposed by Rockafellar and Uryasev in (Rockafellar, R.T. and Uryasev, S., 2000, Optimization of conditional value-at-risk. Journal of Risk, 2, 21-41), which converts this problem to that of convex optimization. We compare the use of linear programming techniques against a non-smooth optimization method of the discrete gradient, and establish the supremacy of the latter. We show that non-smooth optimization can be used efficiently for large portfolio optimization, and also examine parallel execution of this method on computer clusters.

A conditional probability approach to risk assessment for child sexual offenders with different classes of victim

Specific scales were developed for discriminating child sexual offenders with different classes of victim. The project demonstrates a method of individualising scores on actuarial risk assessment measured in a way that makes them more meaningful for those involved in decision-making about individual child sexual offenders. At present, the only quantifiable approach to specific decision-making relies on a general prediction of future behaviour, based on group data. The Bayesian approach is one method that can be used to assist decision-makers to use this information in ways that lead to the more appropriate management of risk. Ultimately, the better management of known child sexual offenders will lead to fewer offences and a reduction in the number of children who lives are profoundly affected by sexual victimisation.

Deterministic versus stochastic quantitative microbial Risk Assessment models for wastewater irrigation of food crops

Reuse of wastewater to irrigate food crops is being practiced in many parts of the world and is becoming more commonplace as the competition for, and stresses on, freshwater resources intensify. But there are risks associated with wastewater irrigation, including the possibility of transmission of pathogens causing infectious disease, to both workers in the field and to consumers buying and eating produce irrigated with wastewater. To manage these risks appropriately we need objective and quantitative estimates of them. This is typically achieved through one of two modelling approaches: deterministic or stochastic. Each parameter in a deterministic model is represented by a single value, whereas in stochastic models probability functions are used. Stochastic models are theoretically superior because they account for variability and uncertainty, but they are computationally demanding and not readily accessible to water resource and public health managers. We constructed models to estimate risk of enteric virus infection arising from the consumption of wastewater-irrigated horticultural crops (broccoli, cucumber and lettuce), and compared the resultant levels of risk between the deterministic and stochastic approaches. Several scenarios were tested for each crop, accounting for different concentrations of enteric viruses and different lengths of environmental exposure (i.e. the time between the last irrigation event and harvest, when the viruses are liable to decay or inactivation). In most situations modelled the two approaches yielded similar estimates of risk (within 1 order-of-magnitude). The two methods diverged most markedly, up to around 2 orders-of-magnitude, when there was large uncertainty associated with the estimate of virus concentration and the exposure period was short (1 day). Therefore, in some circumstances deterministic modelling may offer water resource managers a pragmatic alternative to stochastic modelling, but its usefulness as a surrogate will depend upon the level of uncertainty in the model parameters.

Quantitative microbial risk assessment modelling for the use of reclaimed water in irrigated horticulture

Reuse of treated sewage effluent for the irrigation of horticultural crops is being propounded and practiced as a means of alleviating pressure on freshwater resources. Concerns have been raised. however, as to the risk to human health, primarily disease, associated with this practice. Quantitative Microbial Risk Assessment (QMRA) is a useful tool for estimating this risk. We describe how QMRA works and the current state of knowledge of the components of QMRA models for the horticultural reuse scenario.

Risk assessment in child protection: problem rather than solution?

Risk assessment in child protection services has been promoted as the most reliable way to ensure that maltreatment to children is prevented and has become central to practice with children and families. However, recent research in Australia has suggested that children are being left in unsafe situations, leading to further maltreatment, by the very agencies responsible for their protection. The present article explores the reasons why child protection has become central to child protection practice and presents a wide ranging critical appraisal of risk assessment and its application. It is argued that risk assessment is a flawed process and, as a central tenet of practice, is implicated in any problems that children's protective services face. Consequently, any future reconfiguration of services for children in need of protection needs to include a re-evaluation of the efficacy of risk  assessment.

Quantitative microbial risk assessment models for consumption of raw vegetables irrigated with reclaimed water

Quantitative microbial risk assessment models for estimating the annual risk of enteric virus infection associated with consuming raw vegetables that have been overhead irrigated with nondisinfected secondary treated reclaimed water were constructed. We ran models for several different scenarios of crop type, viral concentration in effluent, and time since last irrigation event. The mean annual risk of infection was always less for cucumber than for broccoli, cabbage, or lettuce. Across the various crops, effluent qualities, and viral decay rates considered, the annual risk of infection ranged from 10–3 to 10–1 when reclaimed-water irrigation ceased 1 day before harvest and from 10–9 to 10–3 when it ceased 2 weeks before harvest. Two previously published decay coefficients were used to describe the die-off of viruses in the environment. For all combinations of crop type and effluent quality, application of the more aggressive decay coefficient led to annual risks of infection that satisfied the commonly propounded benchmark of ≤10–4, i.e., one infection or less per 10,000 people per year, providing that 14 days had elapsed since irrigation with reclaimed water. Conversely, this benchmark was not attained for any combination of crop and water quality when this withholding period was 1 day. The lower decay rate conferred markedly less protection, with broccoli and cucumber being the only crops satisfying the 10–4 standard for all water qualities after a 14-day withholding period. Sensitivity analyses on the models revealed that in nearly all cases, variation in the amount of produce consumed had the most significant effect on the total uncertainty surrounding the estimate of annual infection risk. The models presented cover what would generally be considered to be worst-case scenarios: overhead irrigation and consumption of vegetables raw. Practices such as subsurface, furrow, or drip irrigation and postharvest washing/disinfection and food preparation could substantially lower risks and need to be considered in future models, particularly for developed nations where these extra risk reduction measures are more common.

A retail supply chain risk assessment conceptual model

Supply chains are increasingly relying on information and communications technologies and in particular electronic commerce to facilitate transactions between supply chain partners. The adoption of these enabling technologies brings several enhancements to the conduct of business including gains in efficiency. However there are also drawbacks inherent in these technologies that include threats that are imposed on businesses that use them. This paper presents a study on retail supply chains and the risks and vulnerabilities that cooperating supply chain partners are exposed to when adopting these technologies. In particular, the paper discusses the various threats and vulnerabilities of retail supply and presents a conceptual model of such risks.

The mental health Risk Assessment and Management Process (RAMP) for schools: II. Process evaluation

The Risk Assessment and Management Process (RAMP) is a whole-school process for the assessment and management of student’s mental health and wellbeing in primary and secondary schools. A process evaluation revealed that RAMP was implemented as intended across six primary and three secondary schools in Melbourne, Australia. Using the RAMP risk and protective factors monitoring form and screening processes, each school identified ‘at-risk’ students who had not previously been identified or received assistance from welfare staff at the school. School staff and mental health workers from local agencies reported improvements in their knowledge of risk and protective factors, and their ability to identify at-risk students following RAMP. They also reported satisfaction in outcomes for at-risk students managed within the school using RAMP. All the primary schools and one of the
secondary schools continued to use some RAMP processes in their school up to 6 months after the initial implementation of the program.

Child protection, risk assessment and blame ideology

In this article we use qualitative data drawn from a sample of child protection cases 10 demonstrate holV the process of al1ributing blame to parents and carers for child maltreatment is a sign!ficanr influence 011 decisionmaking,
sometimes to the detriment of assessing the flltllre safety of children. We foctls on two cases which both demonstrate how the process of apportioning blame can lead to decisions which might not be considered 10 be in the best interests of the children concerned. We conceptualise blame as an 'ideology' with its roots in the discourse of the 'risk society', pelpetuated and sustained by the technology of risk assessment. The concept of blame ideology is offered as an addition to theOlY which seeks 10 explain the influences on decision making in child protection practice.

The effects of time pressure and experience on nurses' risk assessment decisions : a signal detection analysis

Background: Time pressure and, occasionally, suboptimal assessment decisions are features of nursing in acute care.

Objectives: To explore the effect of generic and specialist clinical experience on the ability to detect the need to take action in acute care and the impact of time pressure on nurses' decision-making performance.

Methods: Experienced acute care registered nurses (n = 241) were presented with 50 vignettes of real clinical risk assessments. Each vignette contained seven information cues. In response to these vignettes, nurses had to decide whether to intervene or not. The 26 vignettes were time limited and mixed randomly into the 50 cases. Signal detection analysis was used to establish nurses' performance, personal decision thresholds ([beta]), and their abilities (d') to distinguish a signal of clinical risk from the clinical noise of noncontributory information.

Results: Nurses had significantly lower d' and were significantly less likely to indicate intervening under time pressure. For ability-but not threshold-there was a significant interaction of time pressure and years of experience in acute care. With no time pressure, d' increased in line with years of experience. Under time pressure, there was no effect.

Discussion: Time pressure reduced nurses' ability to detect the need and the tendency to report intervening. Thus, there were more failures to report appropriate intervention under time pressure, and the positive effects of clinical experience were negated under time pressure. More and larger scale research on the effect on clinical outcomes of time pressured nursing choices is required.

Risk assessment of child-victim sex offenders for extended supervision in New Zealand

Recently enacted legislation in New Zealand, the Parole (Extended Supervision) Amendment Act 2004, allows for the imposition of up to 10 years of supervision in the community for child-victim sex offenders following their release from prison. The Act requires reports to be written specifically assessing the risk of sexual re-offending against children. This study examined the application of actuarial measures used by the New Zealand Department of Corrections in these assessments, including a computer-scored instrument based on static factors (the Automated Sexual Recidivism Scale; ASRS) and a clinically-based judgement of dynamic risk factors (the SONAR). It was expected that a conservative approach would be taken in making recommendations for or against extended periods of supervision, such that a high score on either measure would predict a recommendation for extended supervision. It was found, however, that a more individualized approach was often taken, whereby a baseline assessment of risk as predicted by the ASRS was adjusted by clinicians based on SONAR ratings. Implications for the practice of risk assessment in sexual re-offending are discussed.