Examples of the use of an equivalence theorem in constructing optimum experimental designs for random-effects nonlinear regression models

The problem considered is that of finding an optimum measurement schedule to estimate population parameters in a nonlinear model when the patient effects are random. The paper presents examples of the use of sensitivity functions, derived from the General Equivalence Theorem for D-optimality, in the construction of optimum population designs for such schedules. With independent observations, the theorem applies to the potential inclusion of a single observation. However, in population designs the observations are correlated and the theorem applies to the inclusion of an additional measurement schedule. In one example, three groups of patients of differing size are subject to distinct schedules. Numerical, as opposed to analytical, calculation of the sensitivity function is advocated. The required covariances of the observations are found by simulation.     

Investigating the Structural Validity of Ryff’s Psychological Well-Being Scales Across Two Samples

Ryff’s (1989b) Psychological Well-Being (PWB) scales measure six related constructs of human functioning. The present paper examined the validity of Ryff’s 6-factor PWB model, using data from a life events study (N = 401) and an organisational climate study (N = 679). Previous validation studies, using Confirmatory Factor Analysis (CFA), have identified alternative PWB models, but limitations include the use of shorter scale versions with items relating to a number of life domains within the same PWB factor, and failure to examine the influence of participants’ socio-demographic characteristics on PWB. In this study, Exploratory Factor Analysis (EFA) mostly found consistency in the PWB items and structure between the two studies whereby a 3-factor model delineated between items relating to Autonomy, Positive Relations and a super-ordinate factor comprising the other PWB factors. Using CFA, Goodness of Fit indices reached acceptable levels for the adjusted PWB model identified by the EFA, whilst differences between adjusted models of PWB previously identified in the literature were hardly evident. Post-hoc analysis by gender demonstrated socio-demographic effects on the structure and items that comprise PWB. Further development of PWB measures is needed to reflect its hierarchical and multi-dimensional nature. In the scales’ current form, the construct validation of the PWB factors will continue to be problematic and will fail to adequately evaluate the nature and impact of PWB.     

Robustness evaluation of multisite distributed schedule with perturbed virtual jobshops

A method for evaluating the robustness of medium term multisite distributed schedule is presented. The method of robustness evaluation is based on steps and tools associated with the conceptual model of a MultiSite Reactive Production Activity Control (MSR-PAC). The MSR-PAC makes it possible to study the sensitivity of the scheduled plans in presence of perturbations. These must be evaluated before being dispatched to the shop-floors. At present, to the best of the authors' knowledge, there is no means to make this evaluation in the distributed systems such as extended enterprise. The monitoring of errors is based on the discrepancy between the two flow-shape functions that model respectively the dynamics of the scheduled manufacturing orders and the state of the perturbed production. The MSR-PAC is based on a multisite agent system and on the monitoring of the perturbed virtual jobshops. The method can also be used for controlling short term distributed production activities.     

Effect of perceived cost on judgments regarding the efficacy of investment

Three experiments examined the effect of costs associated with investments on the judgments of the causal effectiveness of those investments, and on the type of information utilised when making those judgements. Using operant conditioning technology, in an experimental analogue of making economic investments, it was found that greater costs associated with an investment reduced the judgement about the effectiveness of the response (Experiment 1). Greater investment costs tended to bias the subject toward using information integrated over a longer period of time; whereas low costs tended to produce judgements made on the basis of the conditions prevailing immediately prior to the return being acquired (Experiments 1–3). The effect of cost was modulated by the subjects' own financial background. The same absolute cost being treated as “greater” by those from less wealthy backgrounds compared to those from more affluent backgrounds (Experiments 2 and 3). These results suggest that as well as the nature of the schedule relating investment to return, the perceived cost of the investment determines the manner in which it is judged with respect to its efficacy.     

子代情感支持选择对农村老年妇女主观幸福感的影响——基于安徽省的问卷调查分析

根据2011年“安徽省老年妇女养老问题农村地区调查”数据,应用Logistic回归方法,对农村地区老年妇女在情感支持方面不同子代角色的选择对其主观幸福感的影响进行了分析研究.研究结果显示:在情感支持方面选择儿媳和女儿的农村老年妇女主观幸福感发生比较高,选择儿子和女婿的则对其主观幸福感有负面影响.     

What is the Structure of South African Happiness Equations? Evidence from Quality of Life Surveys

The issue of what determines subjective well-being has been at the centre of a recent flurry of research in the economics field. A necessary part of this understanding is the role relative positions (economic, social, geographic) of economic agents, particularly individuals, play in life (commonly referred to in the literature as rivalry). In this paper, we concentrate on whether the structure of happiness equations of South Africa are the same/similar to those of developed countries. The analysis uses three of the Durban Quality of Life Studies. Firstly these three data series are pooled and a variety of covariates are tested for their significance on happiness. These include age, marital status, employment status, household income and relative household income. Next we estimate yearly cross-sectional models to see if there are consistent findings of what determines happiness across the period considered. Our findings indicate there may be some structural differences between results from the Durban studies and those of international findings. Age appears to play no role in happiness likelihood, nor does marital status. Being unemployed does significantly and negatively effect happiness as does the size of household income, relative household income and whether living in a formal dwelling place. When we distinguish between employment categories we find that being self-employed negatively affects happiness, contradicting findings for developed countries. The authors wish to thank members of the Department of Economics, University of the Witwatersrand, participants at the 10th African Econometric Conference, Nairobi 2005 and International Society of Quality of Life Studies, Grahamstown South Africa 2006 as well as one anonymous referee for helpful comments on earlier drafts of this paper.     

The many meanings of sleep

Reductions in sleep are concomitant with night shift work. Data are presented showing that these robust differences in sleep are even present in experienced permanent night shift workers who most prefer to work nights. A model is presented which relates these reductions to chronic sleep deprivation. This, in turn, may be associated with performance decrements, and lead to accidents and illness. Better work schedule selection, worker training programs, and preventive medical action are unproven but promising approaches to overturning this model.     

Preenrollment Immunization Policies of American Colleges: An Assessment of the Need for Policy Implementation

Abstract

Alcohol abuse among college students is prevalent, yet few instruments with sound reliability and validity are available to assess these problems in this population. As part of a large, baseline assessment battery for a prospective study of offspring of alcoholics, the 27-item Young Adult Alcohol Problems Screening Test (YAAPST) was given to 490 freshmen at a large mid western university; approximately 9 months later, 482 subjects completed the scale again. In addition to asking about such traditional problems as experiencing blackouts and driving while intoxicated, the YAAPST included specific items relating to college experiences (eg, getting into sexual situations that were later regretted, missing classes, and receiving lower grades than usual). The YAAPST was designed to assess these drinking consequences over two different time frames, lifetime and past year, and also to indicate the frequency of occurrence during the past year. Results indicated that the YAAPST is a unidimensional scale with good psychometric properties (good internal consistency and test-retest reliability). Three different approaches were used to demonstrate the validity of the YAAPST. Findings supported criterion validity (with interview-based alcohol abuse/dependence diagnoses as the criterion), concurrent validity (comparing the YAAPST with other drinking measures), and construct validity (correlating the YAAPST with etiologically relevant personality, motivational, and peer influence variables). The YAAPST is a promising screening instrument for alcohol problems in college students. It has excellent psychometric properties and the potential to provide a range of useful information to the clinician or researcher.     

Lost in transition: Illicit substance use and services receipt among at-risk youth in the child welfare system

This study examined the use of mental health and substance abuse services among adolescents in the child welfare system (CWS) who reported use of illicit substances. 1004 adolescents age 11–15 years at baseline were followed for 5–7 years, over five waves of data collection. Shortly after the investigation for maltreatment (baseline), 69.1% of youths using illicit substances received mental health and/or substance abuse outpatient specialty services. By the last follow-up, during the transition to adulthood, only 21.5% of young adults using illicit substances received outpatient specialty services. Youth who used illicit substances were more likely to receive outpatient and inpatient specialty services than non-users at the time of contact with the CWS (mostly baseline), but this difference faded over the follow-up period. By 5–7 years follow-up, there was no significant difference in specialty services receipt for illicit substances users versus non-users. Predictors of outpatient service use at most waves were having Medicaid, mental health needs, and having recently seen a school counselor or primary care physician. Among illicit substance users transitioning to adulthood, African American youths were less likely to receive outpatient specialty services than White youths. These findings reveal a need for more attention to illicit substances use among youth in the CWS, better cross agency integration, and special attention to the needs of transition-age youth to better connect them with services as they age out of the CWS.     

农村留守儿童主观幸福感现状调查报告

农村留守儿童主观幸福感状况不容乐观,农村留守儿童的主观幸福感显著低于非留守儿童,留守儿童中,非独生子女的主观幸福感显著低于独生子女,父母感情不和的留守儿童其主观幸福感显著低于感情融洽的留守儿童。并有针对性地提出了提高留守儿童主观幸福感水平的建议。