Estimation of the parameters of symmetric stable ARMA and ARMA–GARCH models

In this article, we first propose the modified Hannan–Rissanen Method for estimating the parameters of autoregressive moving average (ARMA) process with symmetric stable noise and symmetric stable generalized autoregressive conditional heteroskedastic (GARCH) noise. Next, we propose the modified empirical characteristic function method for the estimation of GARCH parameters with symmetric stable noise. Further, we show the efficiency, accuracy and simplicity of our methods with Monte-Carlo simulation. Finally, we apply our proposed methods to model the financial data.     

Proportional odds model – a quantile approach

The paper discusses a quantile-based definition for the well-known proportional odds model. We present various reliability properties of the model using quantile functions. Different ageing properties are derived. A generalization for the class of distributions with bilinear hazard quantile function is established and the practical application of this model is illustrated with a real-life data set.     

Assessment of an e-training tool for college students to improve accuracy and reduce effort associated with reading nutrition labels

Objective: Nutrition labels are often underutilized due to the time and effort required to read them. We investigated the impact of label-reading training on effort, as well as accuracy and motivation. Participants: Eighty college students (21 men and 59 women). Methods: The training consisted of a background tutorial on nutrition followed by three blocks of practice reading labels to decide which of two foods was the relatively better choice. Label-reading effort was assessed using an eye tracker and motivation was assessed using a 6-item scale of healthy food-choice empowerment. Results: Students showed increases in label-reading accuracy, decreases in label-reading effort, and increases in empowerment. Conclusions: The nutrition label e-training tool presented here, whether used alone or as part of other wellness and health programs, may be an effective way to boost students’ label-reading skills and healthy food choices, before they settle into grocery shopping habits.     

Estimation of population mean in successive sampling under super-population model in presence of random non response situations

The present work is an attempt to estimate the population mean on the current occasion in two-occasion successive (rotation) sampling in presence of random non response situations. The estimation strategy has been constructed under a super-population model design approach with the help of imputation technique. The estimators proposed on the current occasion cover the cases of occurrences random non responses on either of the occasions. Detail behaviors of the proposed class of estimators have been studied and its performance has been examined with the sample mean estimator. The results are demonstrated through empirical studies which establish the effectiveness of the proposed class of estimators. Suitable recommendations have been put forward to the survey statisticians for its practical application.     

The multiple faces of tension: dualities in decision-making

Review of Managerial Science - In making decisions about strategic and operational actions, managers commonly need to consider dualities such as long-term versus short-term, innovation versus...     

‘The world they’ve been born into’: Black male teachers on Blackness,masculinities and leadership

ABSTRACT

In this article, life history methodology and principles of counterstorytelling are used to examine moments when one Black male preservice social studies teacher and three Black male social studies teachers challenge Black masculinist visions of leadership, and moments when they seem complicit in perpetuating these visions. Findings indicate that these educators’ understandings of Blackness, maleness, and the pursuit of Black masculine recognition are fluid, developing and sometimes contradictory. We argue that while necessary across disciplines, interrogations of Black masculinity are uniquely imperative in social studies teacher education due to how assumptions about Blackness and maleness have shaped struggles for Black civic recognition.     

Identification of Protective Actions to Reduce the Vulnerability of Safety-Critical Systems to Malevolent Intentional Acts: An Optimization-Based Decision-Making Approach

An empirical classification model based on the Majority Rule Sorting (MR-Sort) method has been previously proposed by the authors to evaluate the vulnerability of safety-critical systems (in particular, nuclear power plants [NPPs]) with respect to malevolent intentional acts. In this article, the model serves as the basis for an analysis aimed at determining a set of protective actions to be taken (e.g., increasing the number of monitoring devices, reducing the number of accesses to the safety-critical system) in order to effectively reduce the level of vulnerability of the safety-critical systems under consideration. In particular, the problem is here tackled within an optimization framework: the set of protective actions to implement is chosen as the one minimizing the overall level of vulnerability of a group of safety-critical systems. In this context, three different optimization approaches have been explored: (i) one single classification model is built to evaluate and minimize system vulnerability; (ii) an ensemble of compatible classification models, generated by the bootstrap method, is employed to perform a “robust” optimization, taking as reference the “worst-case” scenario over the group of models; (iii) finally, a distribution of classification models, still obtained by bootstrap, is considered to address vulnerability reduction in a “probabilistic” fashion (i.e., by minimizing the “expected” vulnerability of a fleet of systems). The results are presented and compared with reference to a fictitious example considering NPPs as the safety-critical systems of interest.     

Differences in Adolescent Experiences of Polyvictimization and Suicide Risk by Sexual Minority Status

Sexual minority adolescents (SMA) report more suicide risk behaviors than heterosexual adolescents. Polyvictimization (co‐occurrence of multiple types of victimization) may be an important, underresearched correlate of this disparity. With the 2017 national Youth Risk Behavior Survey (N = 13,179), national estimates of polyvictimization and suicide risk were assessed among high school students by sexual minority status (SM vs. heterosexual), and multivariate relationships between sexual minority status, polyvictimization, and suicide risk were tested. Additionally, risk profiles of those who experienced polyvictimization (2 + types of victimization; n = 1,932) were compared across sexual minority status. Results confirm that SMA are more likely to experience polyvictimization than heterosexual adolescents (31.8% v. 12.9%, respectively); however, also indicate that polyvictimization does not fully explain elevated suicide risk among SMA.