Tests for a simple tree order restriction with application to dose–response studies

Summary.  We propose 'Dunnett-type' test procedures to test for simple tree order restrictions on the means of p independent normal populations. The new tests are based on the estimation procedures that were introduced by Hwang and Peddada and later by Dunbar, Conaway and Peddada. The procedures proposed are also extended to test for 'two-sided' simple tree order restrictions. For non-normal data, nonparametric versions based on ranked data are also suggested. Using computer simulations, we compare the proposed test procedures with some existing test procedures in terms of size and power. Our simulation study suggests that the procedures compete well with the existing procedures for both one-sided and two-sided simple tree alternatives. In some instances, especially in the case of two-sided alternatives or for non-normally distributed data, the gains in power due to the procedures proposed can be substantial.     

Beyond Assessment: Social Work Intervention in Family Court Enquiries

Most parents or carers who separate or divorce are able to makearrangements themselves about where their children will resideand how the children’s contact with the non-resident parentwill be managed. A further group of parents or carers are ableto come to agreement with the assistance of community- or court-baseddispute resolution/ mediation services. There are times, however,when disputes cannot be resolved without recourse to the courtsand, when this happens, the court will normally request thata welfare report be prepared by a CAFCASS (Children and FamilyCourt Advisory and Support Service) practitioner. While theboundary between assessment and intervention in social workis often less than clear, the commissioning of a court welfarereport in family proceedings strongly suggests an assessmentfocus and appears to carry little expectation that the practitionershould intervene in order to meet the needs of the childrenor adults involved. This article presents recent research findingsthat illustrate ways in which CAFCASS practitioners do go beyondthe assessment role expected of them in the course of the enquiriesthey undertake. Implications for policy and practice in thisarea of social work are then discussed.     

Welfare benefits,economic opportunities,and out-of-wedlock births among black teenage girls

This article presents a model of teenage out-of-wedlock births that incorporates the effects of both welfare and nonwelfare economic opportunities. We construct measures of the likely "medium-run" income available to a teenage girl in the event of an out-of-wedlock birth and in the absence of a birth and then estimate a logit model to determine their importance in influencing fertility behavior. The model is estimated with data from the Panel Study of Income Dynamics on nearly 900 black teenagers. We find weak and statistically insignificant positive effects of Aid to Families With Dependent Children (AFDC) benefit levels and stronger and significant negative effects of economic opportunities on the probability of AFDC-related out-of-wedlock teen births.     

What are the economic consequences of divorce?

Our analysis suggests that Weitzman's finding concerning the precipitous decline in the economic status of women following divorce is likely to be incorrect. Her findings not only imply improbably large changes in income but are also inconsistent with the information she reports on changes in income and in income per capita. Corrected estimates suggest a decline in economic status of about one-third, rather than the widely cited 73 percent figure. It remains the case that the economic status of men and women diverge substantially in the years after divorce. That difference, however, is not nearly as dramatic as suggested by Weitzman's findings.     

Simulation to enhance care of patients with psychiatric and behavioral issues: use in clinical settings

Nurses with a medical-surgical clinical focus often care for patients with psychiatric and behavioral issues in acute care hospitals. This article describes how hospital staff and nursing and theater department faculty joined forces to develop realistic simulated psychiatric scenarios for use by practicing nurses.     

Restrictiveness and guidance in support systems

Restrictiveness and guidance have been proposed as methods for improving the performance of users of support systems. In many companies computerized support systems are used in demand forecasting enabling interventions based on management judgment to be applied to statistical forecasts. However, the resulting forecasts are often ‘sub-optimal’ because many judgmental adjustments are made when they are not required. An experiment was used to investigate whether restrictiveness or guidance in a support system leads to more effective use of judgment. Users received statistical forecasts of the demand for products that were subject to promotions. In the restrictiveness mode small judgmental adjustments to these forecasts were prohibited (research indicates that these waste effort and may damage accuracy). In the guidance mode users were advised to make adjustments in promotion periods, but not to adjust in non-promotion periods. A control group of users were not subject to restrictions and received no guidance. The results showed that neither restrictiveness nor guidance led to improvements in accuracy. While restrictiveness reduced unnecessary adjustments, it deterred desirable adjustments and also encouraged over-large adjustments so that accuracy was damaged. Guidance encouraged more desirable system use, but was often ignored. Surprisingly, users indicated it was less acceptable than restrictiveness.     

Habitat selection by an arboreal lizard in an urban parkland: not just any tree will do

The nocturnal, arboreal Marbled Gecko, Christinus marmoratus, is a common reptile in urban areas in southern Australia. This study compared the demographics and the distribution of geckos occupying different tree species in a modified urban park, the Adelaide Parklands, with those of a population occurring in Ferguson Conservation Park, a nearby native vegetation remnant surrounded by suburbia. The geckos in the modified urban and native remnant parks demonstrated different demographic characteristics. These differences were explained by tree circumference and the amount and type of bark cover on the tree trunk. In the Parkland, geckos were limited by the availability of thick exfoliating bark, its clearly preferred microhabitat as demonstrated by a laboratory choice experiment. The preference for trees with larger circumference, more cover, and thick bark were probably linked to thermoregulation, predator avoidance, and food resources. This study supports the premise that to support populations of urban animals, tree species selection needs careful consideration with regard to its microhabitat capabilities as well as food provision and other resource supports it can provide.     

Causation Analysis of Risk Coupling of Gas Explosion Accident in Chinese Underground Coal Mines

The coal mine production industry is a complex sociotechnical system with interactive relationships among several risk factors. Currently, causation analysis of gas explosion accidents is mainly focused on the aspects of human error and equipment fault, while neglecting the interactive relationships among risk factors. A new method is proposed through risk coupling. First, the meaning of risk coupling of a gas explosion is defined, and types of risk coupling are classified. Next, the coupled relationship and coupled effects among risk factors are explored through combining the interpretative structural modeling (ISM) and the NK model. Twenty‐eight representative risk factors and 16 coupled types of risk factors are obtained through analysis of 332 gas explosion accidents in coal mines in China. Through the application of the combined ISM–NK model, an eight‐level hierarchical model of risk coupling of a gas explosion accident is established, and the coupled degrees of different types of risk coupling are assessed. The hierarchical model reveals that two of the 28 risk factors, such as state policies, laws, and regulations, are the root risk factors for gas explosions; nine of the 28 risk factors, such as flame from blasting, electric spark, and local gas accumulation, are direct causes of gas explosions; whereas 17 of the risk factors, such as three‐violation actions, ventilation system, and safety management, are indirect ones. A quantitative analysis of the NK model shows that the probability of gas explosion increases with the increasing number of risk factors. Compared with subjective risk factors, objective risk factors have a higher probability of causing gas explosion because of risk coupling.     

Remarriage patterns among recent widows and widowers

Remarriage is one of the most important determinants of physical and economic well-being among the widowed. The goal of this study is to estimate how hazard rates for remarriage vary among widows and widowers on the basis of both observable and unobservable characteristics. The remarriage estimates rely on nationally representative samples of widows and widowers from the Panel Study of Income Dynamics. Continuous-time hazard rate regressions indicate strong age and duration dependence effects for middle-aged widows and widowers and for older widowers. Among middle-aged widows, blacks and those with dependent children in the home have lower rates of remarriage. For middle-aged widowers, living in urbanized areas limits the prospects of remarriage. For older widowers, education and, to some extent, economic status appear to have positive effects on the remarriage rates. Overall, age and time since widowhood have the strongest and most consistent effects on remarriage rates for different widowed groups.