Bias-corrected estimators for dispersion models with dispersion covariates

In this paper we discuss bias-corrected estimators for the regression and the dispersion parameters in an extended class of dispersion models (Jorgensen, 1997b). This class extends the regular dispersion models by letting the dispersion parameter vary throughout the observations, and contains the dispersion models as particular case. General formulae for the O(n(-1)) bias are obtained explicitly in dispersion models with dispersion covariates, which generalize previous results obtained by Botter and Cordeiro (1998), Cordeiro and McCullagh (1991), Cordeiro and Vasconcellos (1999), and Paula (1992). The practical use of the formulae is that we can derive closed-form expressions for the O(n(-1)) biases of the maximum likelihood estimators of the regression and dispersion parameters when the information matrix has a closed-form. Various expressions for the O(n(-1)) biases are given for special models. The formulae have advantages for numerical purposes because they require only a supplementary weighted linear regression. We also compare these bias-corrected estimators with two different estimators which are also bias-free to order O(n(-1)) that are based on bootstrap methods. These estimators are compared by simulation. (C) 2011 Elsevier B.V. All rights reserved.

A note on influence diagnostics in nonlinear mixed-effects elliptical models

This paper provides general matrix formulas for computing the score function, the (expected and observed) Fisher information and the A matrices (required for the assessment of local influence) for a quite general model which includes the one proposed by Russo et al. (2009). Additionally, we also present an expression for the generalized leverage on fixed and random effects. The matrix formulation has notational advantages, since despite the complexity of the postulated model, all general formulas are compact, clear and have nice forms. (C) 2010 Elsevier B.V. All rights reserved.

Reduction of Models in the Presence of Nuisance Parameters

In many statistical inference problems, there is interest in estimation of only some elements of the parameter vector that defines the adopted model. In general, such elements are associated to measures of location and the additional terms, known as nuisance parameters, to control the dispersion and asymmetry of the underlying distributions. To estimate all the parameters of the model and to draw inferences only on the parameters of interest. Depending on the adopted model, this procedure can be both algebraically is common and computationally very costly and thus it is convenient to reduce it, so that it depends only on the parameters of interest. This article reviews estimation methods in the presence of nuisance parameters and consider some applications in models recently discussed in the literature.

Do Different Models of Integration Affect Actual Integration? The Cases of France and Great Britain Revisited

Britain and France adapted two different integration models, namely assimilationist and multiculturalism to integrate their immigrants. These two big models of integration have distinctive characteristics to integrate immigrants. There is a general claim that multiculturalism model is the best for integrating immigrants in terms of actual integration, however, some argue the opposite, that French assimilationist model is ‘better off.’ This study examines these controversial claims by looking at the level to which immigrants are integrated in economic, social, political, cultural dimensions of integration and attitudes towards immigrants in Britain and France. Within a given theoretical framework, this study compares the overall competency level of immigrants’ integration in terms of actual integration between British multiculturalism model and French assimilationist model and validate that both these two big models of integration have reached a comparable level of integration and they do not have any decisive impact on actual integration.

The Dynamics of The Firm : In Search for a General Model

This paper describe a model from system theory that can be used as a base for better understanding of different situations in the firms evolution. This change model is derived from the theory of organic systems and divides the evolution of the system into higher complexity of the system structure in three distinctive phases. These phases are a formative phase, a normative phase and an integrative phase. After a summary of different types of models of the dynamics of the firm the paper makes a theoretical presentation of the model and how this model is adaptable for better understanding of the need for change in strategic orientation, organization form and leadership style over time.

Factors associated with evidence-based practice among registered nurses in Sweden : a national cross-sectional study

Background: Evidence-based practice (EBP) is emphasized to increase the quality of care and patient safety. EBP is often described as a process consisting of distinct activities including, formulating questions, searching for information, compiling the appraised information, implementing evidence, and evaluating the resulting practice. To increase registered nurses' (RNs') practice of EBP, variables associated with such activities need to be explored. The aim of the study was to examine individual and organizational factors associated with EBP activities among RNs 2 years post graduation. Methods: A cross-sectional design based on a national sample of RNs was used. Data were collected in 2007 from a cohort of RNs, included in the Swedish Longitudinal Analyses of Nursing Education/Employment study. The sample consisted of 1256 RNs (response rate 76%). Of these 987 RNs worked in healthcare at the time of the data collection. Data was self-reported and collected through annual postal surveys. EBP activities were measured using six single items along with instruments measuring individual and work-related variables. Data were analyzed using logistic regression models. Results: Associated factors were identified for all six EBP activities. Capability beliefs regarding EBP was a significant factor for all six activities (OR = 2.6 - 7.3). Working in the care of older people was associated with a high extent of practicing four activities (OR = 1.7 - 2.2). Supportive leadership and high collective efficacy were associated with practicing three activities (OR = 1.4 - 2.0). Conclusions: To be successful in enhancing EBP among newly graduated RNs, strategies need to incorporate both individually and organizationally directed factors.

Inflammation, oxidative stress, glomerular filtration rate, and albuminuria in elderly men : a cross-sectional study

BACKGROUND: The role of inflammation and oxidative stress in mild renal impairment in the elderly is not well studied. Accordingly, we aimed at investigating the associations between estimated glomerular filtration rate (eGFR), albumin/creatinine ratio (ACR), and markers of different inflammatory pathways and oxidative stress in a community based cohort of elderly men. FINDINGS: Cystatin C-based GFR, ACR, and biomarkers of cytokine-mediated inflammation (interleukin-6, high-sensitivity C-reactive protein[CRP], serum amyloid A[SAA]), cyclooxygenase-mediated inflammation (urinary prostaglandin F2alpha [PGF2alpha]), and oxidative stress (urinary F2 isoprostanes) were assessed in the Uppsala Longitudinal Study of Adult Men(n = 647, mean age 77 years). RESULTS: In linear regression models adjusting for age, BMI, smoking, blood pressure, LDL-cholesterol, HDL-cholesterol, triglycerides, and treatment with statins, ACE-inhibitors, ASA, and anti-inflammatory agents, eGFR was inversely associated with CRP, interleukin-6, and SAA (beta-coefficient -0.13 to -0.19, p < 0.001 for all), and positively associated with urinary F2-isoprostanes (beta-coefficient 0.09, p = 0.02). In line with this, ACR was positively associated with CRP, interleukin-6, and SAA (beta- coefficient 0.09-0.12, p < 0.02 for all), and negatively associated with urinary F2-isoprostanes (beta-coefficient -0.12, p = 0.002). The associations were similar but with lower regression coefficients in a sub-sample with normal eGFR (>60 ml/min/1.73 m2, n = 514), with the exception that F2-isoprostane and SAA were no longer associated with eGFR. CONCLUSION: Our data indicate that cytokine-mediated inflammation is involved in the early stages of impaired kidney function in the elderly, but that cyclooxygenase-mediated inflammation does not play a role at this stage. The unexpected association between higher eGFR/lower albuminuria and increased F2-isoprostanes in urine merits further studies.

Australian women`s experiences of living with hepatitis C virus: results from a cross-sectional survey

Background: Of the estimated 160 000 Australians currently infected with the hepatitis C virus (HCV), over one-third are women and very few have received clinical treatment, with most managing their illness in non-specialist settings. Little is known about the experiences of women living with HCV in the general community. The present study provides the results from the first comprehensive social survey of Australian women's experiences of living with HCV.

Methods: In 2000, a questionnaire was administered to a largely non-clinical sample of women with HCV (n = 462) living in the state of Victoria and the Australian Capital Territory, Australia. The questionnaire was self-administered with a return rate of 75%. The mean age was 35 years and 83% were 'current' or 'past' injecting drug users. The mean time since diagnosis was 4.6 years (SD = 4.0) and the mean time since infection was 10.5 years (SD = 8.2).

Results: Fifty-eight percent of women reported experiencing symptoms related to their HCV, the most common being tiredness (78%) and nausea (44%). Of the sample, 56% currently saw a doctor for their HCV, and while 52% had ever been referred to a specialist, only 17% of the total sample had ever begun interferon-based combination or monotherapy. Forty-eight percent of women reported experiencing less favorable treatment by a health professional because of their HCV. Age-related self-assessed health status was significantly lower than Australian norms, as were SF-12 physical and mental health scores. The SF-12 physical and mental health scores were highly correlated, indicating a significant physical and mental health burden associated with HCV.

Conclusion: The social, physical and mental health needs of women living with HCV are considerable. Most women had not accessed specialist treatment and the response of the primary health care system to HCV-related women's health issues requires improvement.

The dynamics of business ethics: a function of time and culture-cases and models

Examines the construct of ethics in general and of business ethics in particular. Provides a conceptual discussion of the dynamics of ethics in society and the dynamics of business ethics in the marketplace. Ethics and business ethics constructs are dependent upon two principal parameters – time and culture. Eventually, ethics and business ethics are about what is perceived as acceptable or unacceptable at a specific time and in a specific cultural setting. What was ethical yesterday may not be ethical today, and what is ethical today may not be ethical tomorrow. Furthermore, both the company’s view and the views of others may determine what is acceptable or unacceptable in business ethics. This is a social construction that may differ between the parties involved in a specific context. The discussion is supported by two brief and different cases from the automobile industry. This research contributes a set of generic models that examine business ethics dynamics.

Can Australain general practitioners tackle chidhood overweight/obesity? Methods and processes from the LEAP (live, eat, and play) randomized controlled trial

Background: General practitioners (GPs) could make an important contribution to management of childhood overweight. However, there are no efficacy data to support this, and the feasibility of this approach is unknown.

Objectives: To determine if GPs and families can be recruited to a randomized controlled trial (RCT), and if GPs can successfully deliver an intervention to families with overweight/obese 5- to 9-year-old children.

Methods: A convenience sample of 34 GPs from 29 family medical practices attended training sessions on management of childhood overweight. Practice staff trained in child anthropometry conducted a cross-sectional body mass index (BMI) survey of 5- to 9-year-old children attending these practices. The intervention focused on achievable goals in nutrition, physical activity and sedentary behaviour, and was delivered in four solution-focused behaviour change consultations over 12 weeks.

Results: General practitioners were recruited from across the sociodemographic spectrum. All attended at least two of the three education sessions and were retained throughout the trial. Practice staff weighed and measured 2112 children in the BMI survey, of whom 28% were overweight/obese (17.5% overweight, 10.5% obese), with children drawn from all sociodemographic quintiles. Of the eligible overweight/obese children, 163 (40%) were recruited and retained in the LEAP RCT; 96% of intervention families attended at least their first consultation.

Conclusions: Many families are willing to tackle childhood overweight with their GP. In addition, GPs and families can participate successfully in the careful trials that are needed to determine whether an individualized, family-based primary care approach is beneficial, harmful or ineffective.

Parent-reported health status of overweight and obese Australian primary school children: a cross-sectional population survey

Introduction: Childhood overweight/obesity is associated with poor physical and psychosocial health in clinical samples. However, there is little information on the health status of overweight and obese children in the community, who now represent a large proportion of the child population. We examined parent-reported child health and well-being and parent concern about child weight by body mass index (BMI) category in a population sample of primary school children.

Design: A stratified two-stage random cluster sample of 24 primary schools representative of the state of Victoria, Australia.

Measures: BMI (weight/height2) transformed to normalised Z-scores using the 1990 UK Growth Reference; the Child Health Questionnaire (CHQ), a 13-scale 50-item parent-completed measure of health and well-being; parent self-reported height and weight; parent concern about child's weight.

Results: Data were available for 2863 children aged 5-13 y (50.5% male), of whom 17% were overweight and 5.7% obese. Using logistic regression analyses with 'normal weight' as the referent category, obese boys were at greater risk of poor health (ie <15th centile) on seven of the 12 CHQ scales: Physical Functioning (odds ratio (OR) 2.8), Bodily Pain (OR 1.8), General Health (OR 3.5), Mental Health (OR 2.8), Self Esteem (OR 1.8), Parent Impact¾Emotional (OR 1.7) and Parent Impact¾Time (OR 1.9). Obese girls were at greater risk of poor health on only two scales: General Health (OR 2.1) and Self Esteem (OR 1.8). Forty-two percent of parents with obese children and 81% with overweight children did not report concern about their child's weight. Parents were more likely to report concern if the child was obese (OR 21.3), overweight (OR 3.5) or underweight (OR 5.4) than normal weight (P<0.05). Concern was not related to child gender, parental BMI or parental education after controlling for child BMI. Perceived health and well-being of overweight/obese children varied little by weight category of the reporting parent (overweight vs non-overweight).

Conclusions: Parents were more likely to report poorer health and well-being for overweight and obese children (particularly obese boys). Parental concern about their child's weight was strongly associated with their child's actual BMI. Despite this, most parents of overweight and obese children did not report poor health or well-being, and a high proportion did not report concern. This has implications for the early identification of such children and the success of prevention and intervention efforts.

Depression : an important comorbidity with metabolic syndrome in a general population

OBJECTIVE—There is a recognized association among depression, diabetes, and cardiovascular disease. The aim of this study was to examine in a sample representative of the general population whether depression, anxiety, and psychological distress are associated with metabolic syndrome and its components.

RESEARCH DESIGN AND METHODS—Three cross-sectional surveys including clinical health measures were completed in rural regions of Australia during 2004–2006. A stratified random sample (n = 1,690, response rate 48%) of men and women aged 25–84 years was selected from the electoral roll. Metabolic syndrome was defined by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults, Adult Treatment Panel III (NCEP ATP III), and International Diabetes Federation (IDF) criteria. Anxiety and depression were assessed by the Hospital Anxiety and Depression Scale and psychological distress by the Kessler 10 measure.

RESULTS—Metabolic syndrome was associated with depression but not psychological distress or anxiety. Participants with the metabolic syndrome had higher scores for depression (n = 409, mean score 3.41, 95% CI 3.12–3.70) than individuals without the metabolic syndrome (n = 936, mean 2.95, 95% CI 2.76–3.13). This association was also present in 338 participants with the metabolic syndrome and without diabetes (mean score 3.37, 95% CI 3.06–3.68). Large waist circumference and low HDL cholesterol showed significant and independent associations with depression.

CONCLUSIONS—Our results show an association between metabolic syndrome and depression in a heterogeneous sample. The presence of depression in individuals with the metabolic syndrome has implications for clinical management.

Haptically enabled interactive virtual reality prototype for general assembly

Desktop computers based virtual training systems are attracting paramount attention from manufacturing industries due to their potential advantages over the conventional training practices. Significant cost savings can be realized due to the shorter training-scenarios development times and reuse of existing engineering models. In addition, by using computer based virtual reality (VR) training systems, the time span from the product design to commercial production can be shortened due to non-reliance on hardware parts. Within the aforementioned conceptual framework, a haptically enabled interactive and immersive virtual reality (HIIVR) system is presented. Unlike existing VR systems, the presented idea tries to imitate real physical training scenarios by providing comprehensive user interaction, constrained within the physical limitations of the real world imposed by the haptics devices within the virtual environment. As a result, in contrast to the existing VR systems, capable of providing knowledge generally about assembly sequences only, the proposed system helps in procedural learning and procedural skill development as well, due to its high physically interactive nature.

Market makers v's the general public : a first look at S & P500 futures trade data

This paper considers 15 minute records of trading volume and traded prices coinciding with the reporting intervals required by the Commodity Futures Trading Commission. Records are extracted from trade records for market trade and also two way trade between market makers (CT1) and the general public (CT4) from January 1994 to June 2004. Futures price records are matched with S&P500 cash index price records. Simultaneous volatility models are specified and estimated to test trading volume to futures volatility lead/lag effects and also futures volatility to cash index volatility lead/lag effects. As we disaggregate from the market records to CT1 and CT4 records and further into year to year samples volume to futures volatility leading effects and also futures volatility to cash volatility leading effects dominate. The results raise important issues for risk management and dynamic hedging models employing intra-day trader data. A number of important issues for further analysis are also raised in this paper.

Changing violent behaviour : forensic mental health and criminological models compared

Evidence-based interventions designed to reduce the risk of re-offending, particularly violent re-offending, are commonly offered in correctional systems around the world. The interventions are often based upon the application of several principles of service delivery that have become widely known as the 'what works' approach to offender rehabilitation. The applicability of these principles to forensic psychiatric services has yet to be determined. The aims are to examine the possible application of the 'what works' approach and its implications for forensic mental health practice. The method used was a review of relevant research from both the general offender and forensic psychiatry literature. The principles underlying the 'what works' approach are likely to have utility in service delivery in forensic psychiatry, particularly when a treatment target is a reduction in risk of harm to others. The individualized models of patient care practiced in forensic psychiatry are also likely to have utility in improving treatment outcomes in correctional settings. The conclusion is that an increased interchange of ideas and interventions between the two areas of practice is likely to be of mutual benefit. This is an area that requires significant development.