SAS macros for point and interval estimation of area under the receiver operating characteristic curve for non-proportional and proportional hazards Weibull models

Aims and objectives  For prediction of risk of cardiovascular end points using survival models the proportional hazards assumption is often not met. Thus, non-proportional hazards models are more appropriate for developing risk prediction equations in such situations. However, computer program for evaluating the prediction performance of such models has been rarely addressed. We therefore developed SAS macro programs for evaluating the discriminative ability of a non-proportional hazards Weibull model developed by Anderson (1991) and that of a proportional hazards Weibull model using the area under receiver operating characteristic (ROC) curve.

Method  Two SAS macro programs for non-proportional hazards Weibull model using Proc NLIN and Proc NLP respectively and model validation using area under ROC curve (with its confidence limits) were written with SAS IML language. A similar SAS macro for proportional hazards Weibull model was also written.

Results  The computer program was applied to data on coronary heart disease incidence for a Framingham population cohort. The five risk factors considered were current smoking, age, blood pressure, cholesterol and obesity. The predictive ability of the non-proportional hazard Weibull model was slightly higher than that of its proportional hazard counterpart. An advantage of SAS Proc NLP in terms of the example provided here is that it provides significance level for the parameter estimates whereas Proc NLIN does not.

Conclusion  The program is very useful for evaluating the predictive performance of non-proportional and proportional hazards Weibull models.

Oral language competence, young speakers and the Law

Purpose: This paper highlights the forensic implications of language impairment in 2 key (and overlapping) groups of young people: identified victims of maltreatment (abuse and/or neglect) and young offenders.

Method: Two lines of research pertaining to oral language competence and young people's interface with the law are considered: 1 regarding investigative interviewing with children as victims or witnesses in the context of serious allegations of sexual abuse, and the other pertaining to adolescent offenders as suspects, witnesses, or victims. The linguistic demands that forensic interviewing places on these young people are also considered. Literature concerning the impact of early maltreatment on early language acquisition is briefly reviewed, as is the role of theory of mind in relation to the requirements of investigative interviewing of children and adolescents.

Implications: High-risk young people (i.e., those who are subject to child protection orders because of suspected or confirmed maltreatment, and those who are engaged with the youth justice system) face an elevated risk for suboptimal language development but may need to draw on their language skills in high-stakes forensic interviews. Implications for early intervention policy and practice are identified, and the need for greater speech-language pathology advocacy and engagement in forensic interviewing research is emphasized.

Catastrophic loss and the law : a comparison between 2009 Victorian Black Saturday fires and 2011 Queensland floods and Cyclone Yasi

This article explores insurability relating to loss occasioned by catastrophic events in Australia in the context of the current legal regulatory regime. The analysis includes two case studies, in which we juxtapose the Victorian Black Saturday fires in February 2--9 with the Queensland flooding and Cyclone Yasi (December 2010 - February 2011). We argue that the different responses to, and economic losses stemming from, these events illustrate the urgent need for a national regulatory and insurance regime for the prevention and alleviation of disasters and the management of their consequences.