Estimation in a bivariate integer-valued autoregressive process

ABSTRACT

A bivariate integer-valued autoregressive time series model is presented. The model structure is based on binomial thinning. The unconditional and conditional first and second moments are considered. Correlation structure of marginal processes is shown to be analogous to the ARMA(2, 1) model. Some estimation methods such as the Yule–Walker and conditional least squares are considered and the asymptotic distributions of the obtained estimators are derived. Comparison between bivariate model with binomial thinning and bivariate model with negative binomial thinning is given.     

Fast Random Number Generation Using 128-Bit Multimedia Extension Registers on Pentium Class Machines

In this article, it is shown how 128-bit SSE2 multimedia extension registers, present in Pentium IV class 32-bit processors, may be used to generate random numbers at several times greater speed then when regular general purpose registers are used. In particular, a 128-bit algorithm is presented for the Marsaglia MWC1616 generator from the DIEHARD battery of random number generator tests, and its performance is compared to that of the conventional approach.     

Goodness of fit assessment of an alcohol intervention program and the underlying theories of change

The authors conducted an investigation of The Pennsylvania State University's Alcohol Intervention Program Level 2 (AIP2) to determine goodness of fit of the program components and its underpinning theories. They determined that the Health Belief Model, Social Norms Theory, Social Learning Theory, and the Transtheoretical Model Stages of Change and Process of Change are associated with AIP2's program elements. Although elements of AIP2 fit with these theories, gaps did exist within the program. The authors put forth recommendations for additional program elements that would strengthen the fit with these theories and enhance the program. In addition, upon examining the Transtheoretical Model Stages of Change and Process of Change in terms of sequence, the authors found that information from the readiness to change assessment was not being used to tailor the program elements to individual participant needs. Moreover, the postreadiness-to-change measure adapted by a prereadiness-to-change assessment was not useful in determining behavior change.     

Suicide and documentation: don't let the pen kill your career

1. Nurses' notes must reflect the assessment performed regarding their patients' risk factors, red flags, and protective supports, especially for suicidal patients. 2. Nursing interventions range from the least-restrictive methods to full restraints, if necessary to prevent patients from harming themselves. 3. Medications, such as antidepressant, antipsychotic, and antimanic agents, as well as benzodiazepines, have been shown to help psychiatric patients cope with depression, psychosis, and mood stability.     

Integrating a family-centered approach into social work practice with families of children and adolescents with disabilities

This article identifies a family-centered practice construct for working with children and adolescents with disabilities and their families. The experiences of these families have shifted considerably over the past 30 years. A legislative and historical context provides the basis for an understanding of present policies and practices that influence current approaches to service delivery. Though family-centered practice is emphasized in various practice settings, there is still a need to integrate this philosophy into social work practice with children and adolescents with disabilities and their families. In order to enhance the ability of the social worker to integrate this construct into practice, a framework for exploring the experiences of children, adolescents and families is provided. This framework provides an overview of factors related to the individual child, the family and siblings for the social worker to consider when working with these families. The social worker's role as collaborator, advocate, team member and family resource is highlighted.     

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.     

A generalized semi-Pareto minification process

In this paper a generalization of the semi-Pareto autoregressive minification process of the first order is given. The necessary and sufficient condition for stationarity of the process is determined. It is shown that the process is ergodic and uniformly mixing. The joint survival function and the joint density function of the random variables X _n+h and X _n are determined. The extremes of the random variables X ₁, X ₂, ..., X _n and the geometric extremes of random variables X ₁, X ₂, ..., X _N are derived and their asymptotic distributions are discussed. The estimation of the parameters is discussed and some numerical results are given.