Comparison of methods of estimation of parameters of the weibull distribution

The generalised least squares, maximum likelihood, Bain-Antle 1 and 2, and two mixed methods of estimating the parameters of the two-parameter Weibull distribution are compared. The comparison is made using (a) the observed relative efficiency of parameter estimates and (b) themean squared relative error in estimated quantiles, to summarize the results of 1000 simulated samples of sizes 10 and 25. The results are that: generalised least squares is the best method of estimating the shape parameter ß the best method of estimating the scale parameter a depends onthe size of ß for quantile estimation maximum likelihood is best Bain-Antle 2 is uniformly the worst of the methods.     

Formative evaluation of a motivational intervention for increasing physical activity in underserved youth

The present study was designed to develop an innovative motivational intervention (based on Self-Determination Theory and Social Cognitive Theory) to increase physical activity (PA) in underserved adolescents. Sixty-four adolescents (35 females, 29 males; 50% minority; 65% on reduced lunch program; ages 11-13 yr) participated in either an 8-week motivational intervention after-school (n = 32) or a typical after-school program (n = 32). The conceptual framework for the intervention targeted the social environment (perceived autonomy, perceived social support, participation, fun), cognitive mediators (perceived choice, self-efficacy, and relatedness/belongingness), and motivational orientation (intrinsic motivation, commitment, positive self-concept). Formative evaluation data was collected by staff through daily forms throughout the 8-week program and through observational data completed by independent objective observers during 2 weeks of the program. The major themes that were identified addressed theoretical concepts regarding the intervention and logistical issues in delivering the intervention. The data revealed information regarding the importance of the cognitive appropriateness of the PA and motivational activities, the environmental climate for promoting nurturing relationships, developing specific strategies for increasing intrinsic rather than extrinsic reinforcement, and developing methods for preventing social "cliques" and gender conflicts to maintain an appropriate level of support in the social climate. Themes for training staff included focusing on team building, leadership, and nurturing. This formative evaluation is being used to formalize a randomized trial to test the effects of a student-centered motivational intervention on increasing PA in underserved 6th graders.     

Adolescents at risk of mental health problems in the COVID-19 pandemic: A prospective population-based study of the effects of government mandates and school closures

There is increasing evidence that the COVID-19 pandemic has had substantial mental health impacts for adolescents. Yet, few definitive studies have investigated which adolescents were at higher risk of poor mental health and well-being during the pandemic. Data were drawn from the Childhood to Adolescence Transition Study, a prospective cohort study of students in Australia (N = 1211). Prevalence of mental health outcomes (depressive symptoms, anxiety symptoms, self-harm and good subjective well-being) was estimated in school Years 5–12, where Years 11 (2020) and 12 (2021) coincided with the pandemic. The age- and sex-adjusted relative risk of each mental health outcome for each priority group during the pandemic were estimated. During the pandemic, over 50% of study participants reported depressive symptoms, and one quarter reported anxiety symptoms. There was a decrease in good subjective well-being compared with pre-pandemic years, while self-harm prevalence remained similar. History of mental health problems, school disengagement and frequent peer victimisation increased the risk of experiencing mental health problems during the pandemic. Schools play a central role in maintaining the mental health and good subjective well-being of students, and this is particularly important during periods of social disruption, such as the COVID-19 pandemic.     

A New Multiperiod Multiple Traveling Salesman Problem with Heuristic and Application to a Scheduling Problem

A new multiperiod variation of the M-traveling salesman problem is introduced. The problem arises in efficient scheduling of optimal interviews among tour brokers and vendors at conventions of the tourism and travel industry. In classical traveling salesman problem vocabulary, a salesman is a tour broker at the convention and a city is a vendor's booth. In this problem, more than one salesman may be required to visit a city, but at most one salesman per time period can visit each city. The heuristic solution method presented is polynomial and is guaranteed to produce a nonconflicting set of salesmen's tours. The results of an implementation of the method for a recent convention are also reported.     

Moving from ‘what we know works’ to ‘what we do in practice’: An evidence overview of implementation and diffusion of innovation in transition to adulthood for care experienced young people

Global research has shown that most young people who are care experienced are not prepared to transition to independent living at 18 years of age and require support into early adulthood. We used rigorous systematic methods to identify English-based peer reviewed and grey literature describing innovations relevant to care experienced young people as they transition into adulthood, with a focus upon lessons for their implementation and diffusion. We synthesised the evidence narratively and organise data linked to seven key areas important to the transition to adulthood: (1) Health and well-being; (2) relationships; (3) education and training; (4) employment; (5) participation in society; (6) accommodation; (7) other. Twenty-five papers met our inclusion criteria. This review has found that, whilst there are a broad spectrum of innovations taking place within the social care environment for care experienced young people to support their transition into adulthood, there exists limited insight into how best to support implementation and diffusion of evidence-based innovation. We drew upon the ‘Consolidated Framework for Implementation Research’, developed in the setting of clinical service delivery, to highlight challenges in implementing and diffusing evidence-based innovation for care experienced young people transitioning into adulthood.     

An Empirical Estimation of the Investor Loss Function Associated with the Use of Analysts' Forecasts of Earnings

The aggregate investor loss function associated with the use of analysts' forecasts of earnings expresses the relation between loss and prediction error. Prior research suggested that the shape of this loss function should provide guidance in decision rules for investors. This study empirically estimates the investor loss function and finds an asymmetry in the relation between loss and analysts' prediction error. For overestimates of earnings, loss is a quadratic function of error; while for underestimates of earnings, loss is a linear function of error.