Standard voting power indices work : an experimental investigation of pure voting power

We evaluate power indices by experimentally measuring the political power embodied in blocks of votes per se. Subjects with differing votes divide a fixed purse by majority rule in online chat rooms under supermision. Chat rooms and processes for selecting subjects reduce or eliminate extraeous political forces leaving logrolling as the primary political force. Results show that various power indices bracket voting power which is more than proportionally concentrated in large players.

The effects of clustered data on standard error estimates in covariance structure analysis : a field data application

Purpose – The purpose of this article is to present an empirical analysis of complex sample data with regard to the biasing effect of non-independence of observations on standard error parameter estimates. Using field data structured in the form of repeated measurements it is to be shown, in a two-factor confirmatory factor analysis model, how the bias in SE can be derived when the non-independence is ignored.

Design/methodology/approach – Three estimation procedures are compared: normal asymptotic theory (maximum likelihood); non-parametric standard error estimation (naïve bootstrap); and sandwich (robust covariance matrix) estimation (pseudo-maximum likelihood).

Findings – The study reveals that, when using either normal asymptotic theory or non-parametric standard error estimation, the SE bias produced by the non-independence of observations can be noteworthy.

Research limitations/implications – Considering the methodological constraints in employing field data, the three analyses examined must be interpreted independently and as a result taxonomic generalisations are limited. However, the study still provides “case study” evidence suggesting the existence of the relationship between non-independence of observations and standard error bias estimates.

Originality/value – Given the increasing popularity of structural equation models in the social sciences and in particular in the marketing discipline, the paper provides a theoretical and practical insight into how to treat repeated measures and clustered data in general, adding to previous methodological research. Some conclusions and suggestions for researchers who make use of partial least squares modelling are also drawn.

COSMOS: COmparing standard maternity care with one-to-one midwifery support: a randomised controlled trial

Background: In Australia and internationally, there is concern about the growing proportion of women giving birth by caesarean section. There is evidence of increased risk of placenta accreta and percreta in subsequent pregnancies as well as decreased fertility; and significant resource implications. Randomised controlled trials (RCTs) of continuity of midwifery care have reported reduced caesareans and other interventions in labour, as well as increased maternal satisfaction, with no statistically significant differences in perinatal morbidity or mortality. RCTs conducted in the UK and in Australia have largely measured the effect of teams of care providers (commonly 6–12 midwives) with very few testing caseload (one-to-one) midwifery care. This study aims to determine whether caseload (one-to-one) midwifery care for women at low risk of medical complications decreases the proportion of women delivering by caesarean section compared with women receiving 'standard' care. This paper presents the trial protocol in detail.

Methods/design: A two-arm RCT design will be used. Women who are identified at low medical risk will be recruited from the antenatal booking clinics of a tertiary women's hospital in Melbourne, Australia. Baseline data will be collected, then women randomised to caseload midwifery or standard low risk care. Women allocated to the caseload intervention will receive antenatal, intrapartum and postpartum care from a designated primary midwife with one or two antenatal visits conducted by a 'back-up' midwife. The midwives will collaborate with obstetricians and other health professionals as necessary. If the woman has an extended labour, or if the primary midwife is unavailable, care will be provided by the back-up midwife. For women allocated to standard care, options include midwifery-led care with varying levels of continuity, junior obstetric care and community based general medical practitioner care. Data will be collected at recruitment (self administered survey) and at 2 and 6 months postpartum by postal survey. Medical/obstetric outcomes will be abstracted from the medical record. The sample size of 2008 was calculated to identify a decrease in caesarean birth from 19 to 14% and detect a range of other significant clinical differences. Comprehensive process and economic evaluations will be conducted.

Trial registration: Australian New Zealand Clinical Trials Registry ACTRN012607000073404.

Family physical activity and sedentary environments and weight change in children

Objective. To examine associations between family physical activity and sedentary environment and changes in body mass index (BMI) z-scores among 10-12-year-old children over three years.
Method. Design. Longitudinal (three-year follow-up). Subjects. In total, 152 boys and 192 girls aged 10-12 years at baseline.
Measurements. Measured height and weight at baseline and follow-up (weight status, BMI z-scores); aspects of the family physical activity and sedentary environment (parental and sibling modelling, reinforcement, social support, family-related barriers, rules/restrictions, home physical environment) measured with a questionnaire completed by parents at baseline.
Results. At baseline, 29.6% of boys and 21.9% of girls were overweight or obese, and mean (standard deviation, SD) BMI z-scores were 0.44 (0.99) and 0.28 (0.89), respectively. There was a significant change in BMI z-score among girls (mean change=0.19, SD=0.55, p<0.001), but not boys. Among boys, the number of items at home able to be used for sedentary behaviour (B=0.11, p=0.037) was associated with relatively greater increases in BMI z-score. Among girls, sibling engagement in physical activity at least three times/wk (B=-0.17, p=0.010) and the number of physical activity equipment items at home (B=-0.05, p=0.018) were associated with relatively greater decreases in BMI z-score.
Conclusion. Sibling physical activity and environmental stimuli for sedentary behaviours and physical activity within the home may be important targets for prevention of weight gain during the transition from childhood to adolescence.

Understanding the older food consumer, present day behaviours and future expectations

The main aim of this study was to determine whether Baby boomers know how they would manage to maintain a healthy diet on lower incomes in retirement. A cross-sectional survey was conducted at two shopping centres in Melbourne, Australia with 352 respondents. Contingency table analyses (using chi-square tests) were used to examine differences in present and future cooking habits between gender, age and socio-economic groups as well as anticipated changes to food shopping if they had less money in the future. The findings suggest that the most common food preparation behaviours were making meals from scratch ingredients (80% of participants) or using a combination of fresh and convenience foods (55% of participants), with socio-economic and demographic factors significantly influencing specific behaviours. Nearly 50% responded that if they had reduced income they would make a change to their food shopping habits. The most common changes were to the types of food purchased and seeking out special offers or cheaper brands. The results suggest that when faced with a lower standard of living, people will make changes to their food consumption habits. The challenge facing health promotion practitioners, is to ensure that these changes are well informed, leading to healthy options.

A new instrument for targeting falls prevention interventions was accurate and clinically applicable in a hospital setting

Background and Objective: To describe the diagnostic accuracy and practical application of the Peter James Centre Falls Risk Assessment Tool (PJC-FRAT), a multidisciplinary falls risk screening and intervention deployment instrument.

Methods: In phase 1, the accuracy of the PJC-FRAT was prospectively compared to a gold standard (the STRATIFY) on a cohort of subacute hospital patients (n = 122). In phase 2, the PJC-FRAT was temporally reassessed using a subsequent cohort (n = 316), with results compared to those of phase 1. Primary outcomes were falls (events), fallers (patients who fell), and hospital completion rates of the PJC-FRAT.

Results: In phase 1, PJC-FRAT accuracy of identifying fallers showed  sensitivity of 73% (bootstrap 95% confidence interval CI = 55, 90) and specificity of 75% (95% CI = 66, 83), compared with the STRATIFY (cutoff ≥ 2/5) sensitivity of 77% (95% CI = 59, 92) and specificity of 51% (95% CI = 41, 61). This difference was not significant. In phase 2, accuracy of nursing staff using the PJC-FRAT was lower. PJC-FRAT completion rates varied among disciplines over both phases: nurses and physiotherapists, ≥90%; occupational therapists, ≥82%; and medical officers, ≥57%.

Conclusion: The PJC-FRAT was practical and relatively accurate as a predictor of falls and a deployment instrument for falls prevention interventions, although continued staff education may be necessary to maintain its accuracy.

Effects of sublethal fenitrothion ingestion on cholinesterase inhibition, standard metabolism, thermal preference, and prey-capture ability in the Australian central bearded dragon (Pogona vitticeps, Agamidae)

The central bearded dragon (Pogona vitticeps) is a medium-sized lizard that is common in semiarid habitats in Australia and that potentially is at risk of fenitrothion exposure from use of the chemical in plague locust control. We examined the effects of single sublethal doses of this organophosphate (OP; low dose = 2.0 mg/kg; high dose = 20 mg/kg; control = vehicle alone) on lizard thermal preference, standard metabolic rate, and prey-capture ability. We also measured activities of plasma total cholinesterase (ChE) and acetylcholinesterase before and at 0, 2, 8, 24, 120, and 504 h after OP dosing. Predose plasma total ChE activity differed significantly between sexes and averaged 0.66 ± 0.06 and 0.45 ± 0.06 μmol/min/ml for males and females, respectively. Approximately 75% of total ChE activity was attributable to butyrylcholinesterase. Peak ChE inhibition reached 19% 2 h after OP ingestion in the low-dose group, and 68% 8 h after ingestion in high-dose animals. Neither OP doses significantly affected diurnal body temperature, standard metabolic rate, or feeding rate. Plasma total ChE levels remained substantially depressed up to 21 d after dosing in the high-dose group, making this species a useful long-term biomonitor of OP exposure in its habitat.

An examination of the 'gold standard' diagnosis of major depression in aged-care settings

Objectives: Individual clinical interviews are typically viewed as the “gold standard” when diagnosing major depressive disorder (MDD) and when examining the validity of self-rated questionnaires. However, this approach may be problematic with older people, who are known to underreport depressive symptomatology. This study examined the effect of including an informant interview on prevalence estimations of MDD in an aged-care sample.

Design: The results of an individual clinical interview for MDD were compared with those obtained when an informant interview was incorporated into the assessment. Results from each diagnostic approach were compared with scores on a self-rated depression instrument.

Setting: Low-level aged-care residential facilities in Melbourne (equivalent to “residential homes,” “homes for the elderly,” or “assisted living facilities” in other countries).

Participants: One hundred and sixty-eight aged-care residents (mean age: 84.68 years; SD: 6.16 years) with normal cognitive functioning.

Measurements: Individual clinical interviews were conducted using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition Axis I Disorders. This interview was modified for use with staff informants. Self-reported depression was measured using the Geriatric Depression Scale-15 (GDS-15).

Results: The estimated point prevalence of MDD rose from 16% to 22% by including an informant clinical interview in the diagnostic procedure. Overall, 27% of depressed residents failed to disclose symptoms in the clinical interview. The concordance of the GDS-15 with a diagnosis of MDD was substantially lower when an informant source was included in the diagnostic procedure.

Conclusion: Individual interviews and self-report questionnaires may be insufficient to detect depression among older adults. This study supports the use of an informant interview as an adjunct when diagnosing MDD among cognitively intact aged-care residents.

The impact of study design on prevalence estimates of female sexual dysfunction

Introduction, objectives Despite increasing research, the true prevalence of Female Sexual Dysfunction (FSD) remains a contentious issue. Previous research suggests that aspects of study design affect the reported prevalence of FSD. We compare commonly used instruments for assessing FSD. Methods A random sample of 240 Australian women aged 20-70 participated in this population based, cross-sectional study. A questionnaire mailed to women across Australia included four instruments for assessing FSD. The Sexual Function Questionnaire combined with the Female Sexual Distress Scale (SFQ-FSDS) was employed as a standard, validated instrument. Alternative instruments were the SFQ alone and two modified versions of a set of questions originally developed by Laumann et al. Results When assessed by the SFQ-FSDS, prevalence estimates (and 95% confidence intervals) of Hypoactive Sexual Desire Disorder, Female Sexual Arousal Disorder (genital subtype), Female Orgasmic Disorder, and Dysparunia were 16%(11-20%), 8%(4-11%), 9%(6-13%), 2%(0.1-3%) respectively. The prevalence estimates of these same disorders obtained using alternative instruments were 32-55%, 17-35%, 17-33% and 3-25% respectively. The sensitivity of alternative instruments varied widely (0 to 1.0). Specificities ranged from 0.51 to 0.99. Positive predictive values ranged from 0 to 0.57. Negative predictive values were all above 0.90. Changing the time span for recalling sexual experiences in an instrument altered the prevalence estimates, sensitivity and specificity. 32% of women with low desire, 31% with low genital arousal, 36% with orgasm difficulty and 57% with sexual pain were sexually distressed. Conclusion Over a third of women who were classified as suffering FSD by alternative instruments did not have FSD when assessed by SFQ-FSDS. Alternative instruments produced substantially higher prevalence estimates of FSD and identified different groups of women. Consequently, the instruments researchers choose to assess FSD may affect both the prevalence estimates and risk factors they report.

Getting your life back on track after stroke : a phase II multi-centered, single-blind, randomized, controlled trial of the Stroke Self-Management Program vs. the Stanford Chronic Condition Self-Management Program or standard care in stroke survivors

Background Self-management is seen as a primary mechanism to support the optimization of care for people with chronic diseases such as symptomatic vascular disease. There are no established and evidence-based stroke-specific chronic disease self-management programs. Our aim is to evaluate whether a stroke-specific program is safe and feasible as part of a Phase II randomized-controlled clinical trial.
Methods Stroke survivors are recruited from a variety of sources including: hospital stroke services, local paper advertisements, Stroke South Australia newsletter (volunteer peer support organization), Divisions of General Practice, and community service providers across Adelaide, South Australia. Subjects are invited to participate in a multi-center, single-blind, randomized, controlled trial. Eligible participants are randomized to either;
• standard care,
• standard care plus a six week generic chronic condition self-management group education program, or,
• standard care plus an eight week stroke specific self-management education group program.
Interventions are conducted after discharge from hospital. Participants are assessed at baseline, immediate post intervention and six months.
Study Outcomes The primary outcome measures determine study feasibility and safety, measuring, recruitment, participation, compliance and adverse events.
Secondary outcomes include:
• positive and active engagement in life measured by the Health Education Impact Questionnaire,
• improvements in quality of life measured by the Assessment of Quality of Life instrument,
• improvements in mood measured by the Irritability, Depression and Anxiety Scale,
• health resource utilization measured by a participant held diary and safety.

Conclusion The results of this study will determine whether a definitive Phase III efficacy trial is justified.

Non-standard work schedules and health outcomes in Australia : some evidence from the HILDA Panel

What does the around-the-clock economic activity mean for workers' health? Despite the fact that non-standard work accounts for an increasing share of the job opportunities, relatively little is known about the potential consequences for health and the existing evidence is ambiguous. In this paper I examine the associations between non-standard job schedules and workers' physical and mental health outcomes using longitudinal data from the Household, Income and Labour Dynamics in Australia (HILDA). Specifically, the four health indicators considered are self-rated health and the SF-36 health indices for general health, mental health and physical functioning. Overall results generally suggest a negative relationship between non-standard work schedules and better health for both males and females. Regarding the statistical significance and magnitudes of the associations, however, we observe apparent differences between males and females. Among females, most of the coefficients in all models are statistically insignificant, which implies very small magnitudes in terms of the correlation between non-standard working hours and health. These results apply uniformly to all health measures investigated. Among males, on the other hand, the negative relationship is more noticeable for self-rated health, general health and physical functioning than for mental health. The pooled OLS and random effects coefficients are usually larger in magnitude and more significant than the fixed effects parameters. Nonetheless, even the more significant coefficients do not imply large effects in absolute terms.