24 resultados para predictor endogeneity

em Deakin Research Online - Australia


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While the literature concerned with the predictability of stock returns is huge, surprisingly little is known when it comes to role of the choice of estimator of the predictive regression. Ideally, the choice of estimator should be rooted in the salient features of the data. In case of predictive regressions of returns there are at least three such features; (i) returns are heteroskedastic, (ii) predictors are persistent, and (iii) regression errors are correlated with predictor innovations. In this paper we examine if the accounting of these features in the estimation process has any bearing on our ability to forecast future returns. The results suggest that it does.

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A survey of almost 8,000 season ticket holders of Australian Football League clubs suggests that a combination of tangible (ticketing arrangements) and intangible (feelings of personal involvement) aspects have the greatest influence on the satisfaction of members and their intentions regarding future membership.

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Purpose
Cross-sectional evidence has demonstrated the importance of motor skill proficiency to physical activity participation, but it is unknown whether skill proficiency predicts subsequent physical activity.

Methods
In 2000, children's proficiency in object control (kick, catch, throw) and locomotor (hop, side gallop, vertical jump) skills were assessed in a school intervention. In 2006/07, the physical activity of former participants was assessed using the Australian Physical Activity Recall Questionnaire. Linear regressions examined relationships between the reported time adolescents spent participating in moderate-to-vigorous or organized physical activity and their childhood skill proficiency, controlling for gender and school grade. A logistic regression examined the probability of participating in vigorous activity.

Results
Of 481 original participants located, 297 (62%) consented and 276 (57%) were surveyed. All were in secondary school with females comprising 52% (144). Adolescent time in moderate-to-vigorous and organized activity was positively associated with childhood object control proficiency. Respective models accounted for 12.7% (p = .001), and 18.2% of the variation (p = .003). Object control proficient children became adolescents with a 10% to 20% higher chance of vigorous activity participation.

Conclusions
Object control proficient children were more likely to become active adolescents. Motor skill development should be a key strategy in childhood interventions aiming to promote long-term physical activity.

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This study investigated the pretend play of mother—toddler dyads in relation to later child IQ. Twenty-one toddlers were videotaped in monthly play sessions with their mothers, from age 8 to 17 months, and later assessed at 5 years of age on the Stanford-Binet IV. Children's and mothers' pretend play levels and frequencies were measured using Brown's (1997) Pretend Play Observation Scale. Dyadic play activity was analyzed using the conceptual frameworks of scaffolding and Vygotsky's Zone of Proximal Development (ZPD). Toddlers later assessed as having higher IQ demonstrated more rapid learning in the ZPD for pretend play and experienced earlier maternal transfer of responsibility for play. These findings support other evidence on the differential early development of high ability or gifted children and the role of caregiver interactions in that development.

Putting the Research to Use: This study provides evidence that gifted children show differential development, in this case more rapid learning, from the first year of life. It also demonstrates how responsive parental interactions can support this advanced development. For family and professional caregivers, the findings imply that optimum caregiving for the young gifted child involves interactions that are both responsive to individual potential and appropriately challenging. In regard to the methodological challenges of researching early giftedness, the study demonstrated that the constructs of the ZPD and scaffolding were useful frameworks for investigating early gifted development and caregiver influences on that development. Pretend play activity was also shown to be an effective measure and a useful context for the study of gifted development in infants and toddlers. It would be valuable for future researchers in this area to utilize similar approaches that are grounded in the unique developmental characteristics of young children, and that aim to account for the interactive contexts that are so important in children's lives. The field of gifted education, in general, would also benefit from an increased awareness and exploration of the role of play in the development of intellect, imagination and creativity.

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Aims : To assess the utility of the metabolic syndrome (MetS) and a Diabetes Predicting Model as predictors of incident diabetes.

Methods :
A longitudinal survey was conducted in Mauritius in 1987 (n = 4972; response 80%) and 1992 (n = 3685; follow-up 74.2%). Diabetes status was retrospectively determined using 1999 World Health Organization (WHO) criteria. MetS was determined according to four definitions and sensitivity, positive predictive value (PPV), specificity and the association with incident diabetes before and after adjustment for MetS components calculated.

Results : Of the 3198 at risk, 297 (9.2%) developed diabetes between 1987 and 1992. The WHO MetS definition had the highest prevalence (20.3%), sensitivity (42.1%) and PPV (26.8%) for prediction of incident diabetes, the strongest association with incident diabetes after adjustment for age and sex [odds ratio 4.6 (3.5–6.0)] and was the only definition to show a significant association after adjustment for its component parts (in men only). The low prevalence and sensitivity of the International Diabetes Federation (IDF) and ATPIII MetS definitions resulted from waist circumference cut-points that were high for this population, particularly in men, and both were not superior to a diabetes predicting model on receiver operating characteristic analysis.

Conclusions : Of the MetS definitions tested, the WHO definition best identifies those who go on to develop diabetes, but is not often used in clinical practice. If cut-points or measures of obesity appropriate for this population were used, the IDF and ATPIII MetS definitions could be recommended as useful tools for prediction of diabetes, given their relative simplicity.

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Research has suggested that effective leadership, specifically the utilisation of transformational leadership behaviours, is heavily entrenched in a leader’s interpersonal skills. However, few studies have investigated the interpersonal factors that drive appropriate use of transformational and transactional leadership in leader-follower settings. Attachment theory provides a robust framework in which to chart the developmental precursors of effective leadership that underpin positive leader-follower relationships and potential organisational outcomes. In this study, 46 manager-non manager dyads recruited from a Victorian education institution, a national telecommunications company and a Victorian real-estate business (managers – Mean age = 48.5 years, SD = 7.78, non-managers – Mean age 43.92 years, SD = 8.72) took part in an online questionnaire. Participants completed measures of attachment, leadership behaviour and organisational citizenship behaviour. Path analysis revealed that manager’s attachment style significantly predicted follower ratings of transformational and transactional leadership behaviours. Additionally, follower ratings of leadership were associated with organisational citizenship behaviour. Thus, it is concluded that attachment theory provides a valid framework in which to understand follower perceptions of leadership behaviour and subsequent organisational outcomes. These findings are discussed within the context of attachment theory and the leadership literature.

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Objective: To determine whether the processes of task performance as measured by the Assessment of Motor and Process Skills (AMPS) would discriminate between the employment levels of adults with schizophrenia. Participants: Twenty adults with schizophrenia who were engaged either in competitive employment, supported employment, prevocational training, or nonvocational activities, participated in this exploratory study. Methods: Each participant completed the AMPS, the Positive and Negative Syndrome Scale (PANSS), the Addiction Severity Index (ASI), and theWorker Role Interview (WRI) to gather data about their occupational performance, symptoms, drug / alcohol use, and psychosocial / environmental factors that might influence their work related outcomes. Results: Analysis revealed a moderate correlation between the level of employment and the global scores of the process skills scale in the AMPS. Conclusions: This should be seen as preliminary evidence that beyond the basic cognitive functions, processes of task performance may also be a predictor of work related outcomes for this population. The results also highlighted the importance of considering personal causation and worker roles when assessing the work capacities of these clients. Finally, findings supported the four levels of employment used in this study, which appeared to form a continuum from nonvocational activities, prevocational training, supported employment, through to competitive employment.

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Background: Risk prediction for CVD events has been shown to vary according to current smoking status, pack-years smoked over a lifetime, time since quitting and age at quitting. The latter two are closely and inversely related. It is not known whether the age at which one quits smoking is an additional important predictor of CVD events. The aim of this study was to determine whether the risk of CVD events varied according to age at quitting after taking into account current smoking status, lifetime pack-years smoked and time since quitting.
Findings.
We used the Cox proportional hazards model to evaluate the risk of developing a first CVD event for a cohort of participants in the Framingham Offspring Heart Study who attended the fourth examination between ages 30 and 74 years and were free of CVD. Those who quit before the median age of 37 years had a risk of CVD incidence similar to those who were never smokers. The incorporation of age at quitting in the smoking variable resulted in better prediction than the model which had a simple current smoker/non-smoker measure and the one that incorporated both time since quitting and pack-years. These models demonstrated good discrimination, calibration and global fit. The risk among those quitting more than 5 years prior to the baseline exam and those whose age at quitting was prior to 44 years was similar to the risk among never smokers. However, the risk among those quitting less than 5 years prior to the baseline exam and those who continued to smoke until 44 years of age (or beyond) was two and a half times higher than that of never smokers.
Conclusions:
Age at quitting improves the prediction of risk of CVD incidence even after other smoking measures are taken into account. The clinical benefit of adding age at quitting to the model with other smoking measures may be greater than the associated costs. Thus, age at quitting should be considered in addition to smoking status, time since quitting and pack-years when counselling individuals about their cardiovascular risk.

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Background Depression often coexists with myocardial infarction (MI) and has been found to impede recovery through reduced functioning in key areas of life such as work. In an era of improved survival rates and extended working lives, we review whether depression remains a predictor of poorer work outcomes following MI by systematically reviewing literature from the past 15 years.

Methods Articles were identified using medical, health, occupational and social science databases, including PubMed, OVID, Medline, Proquest, CINAHL plus, CCOHS, SCOPUS, Web of Knowledge, and the following pre-determined criteria were applied: (i) collection of depression measures (as distinct from 'psychological distress') and work status at baseline, (ii) examination and statistical analysis of predictors of work outcomes, (iii) inclusion of cohorts with patients exhibiting symptoms consistent with Acute Coronary Syndrome (ACS), (iv) follow-up of work-specific and depression specific outcomes at minimum 6 months, (v) published in English over the past 15 years. Results from included articles were then evaluated for quality and analysed by comparing effect size.

Results Of the 12 articles meeting criteria, depression significantly predicted reduced likelihood of return to work (RTW) in the majority of studies (n = 7). Further, there was a trend suggesting that increased depression severity was associated with poorer RTW outcomes 6 to 12 months after a cardiac event. Other common significant predictors of RTW were age and patient perceptions of their illness and work performance.

Conclusion Depression is a predictor of work resumption post-MI. As work is a major component of Quality of Life (QOL), this finding has clinical, social, public health and economic implications in the modern era. Targeted depression interventions could facilitate RTW post-MI.

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The purpose of the present study was to determine the validity of the 20-meter multistage shuttle run (MSR) for predicting peak VO2 in Hong Kong Chinese students, ages 12-15 years. Fifty-five subjects, 27 boys and 28 girls, performed the MSR in the school environment and had peak VO2 determined in the laboratory. A correlation of 0.72 (p is less than 0.001) was found between peak VO2 and predicted peak VO2 using an equation previously developed with Canadian children (6). However, maximal shuttle run speed alone was a better predictor in this group (r=0.74, SEE=4.6 ml.kg-1.min-1, p is less than 0.001). Multiple-regression analysis (best-subsets) was performed and the best predictor variables were maximal speed and sex with either triceps skinfold or weight. For practical application in the school setting, the equation peak VO2=24.2-5.0(sex) minus 0.8(age) plus 3.4(maximal speed) (r=0.82, SEE=4.0), where for sex, male = 0 and female = 1, is suggested.

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In this paper, we test whether oil price uncertainty predicts credit default swap (CDS) returns for eight Asian countries. We use the Westerlund and Narayan, 2011 and Westerlund and Narayan, 2012 predictability test that accounts for any persistence in and endogeneity of the predictor variable. The estimator also accounts for any heteroskedasticity in the regression model. In-sample evidence reveals that oil price uncertainty predicts CDS returns for three Asian countries, whereas out-of-sample evidence suggests that oil price uncertainty predicts CDS returns for six countries.