Diagnostics For Mixture Regression Models: Applications To Public Health
Funder
National Health and Medical Research Council
Funding Amount
$128,250.00
Summary
In many public health studies, finite mixture regression models are often used to analyse data arising from heterogeneous populations. It is important to assess the stability of parameter estimates and the validity of statistical inferences when the underlying assumptions appear to be violated, but appropriate diagnostics are lacking in the literature. This research aims to develop effective diagnostic methods for assessing the adequacy of mixture regression models and the sensitivity of accompa ....In many public health studies, finite mixture regression models are often used to analyse data arising from heterogeneous populations. It is important to assess the stability of parameter estimates and the validity of statistical inferences when the underlying assumptions appear to be violated, but appropriate diagnostics are lacking in the literature. This research aims to develop effective diagnostic methods for assessing the adequacy of mixture regression models and the sensitivity of accompanying test statistics. The methodology developed will enable health care professionals to focus on substantive issues and to draw accurate and valid conclusions inferred from correlated and over-dispersed outcomes. In the presence of anomalous observations, the influence diagnostics can provide insights into the source of heterogeneity and the apparent over-dispersion, while accommodating the inherent correlation due to the longitudinal study design or nested data structure. Significance of the research lies in its scientific novelty and the breadth of its practical applications. The benefits to public health will accrue both nationally and internationally. For the empirical studies that motivated and are linked to this research, evaluation of health outcomes has significant implications in the prevention and control of recurrent urinary tract infections, hospital strategic planning, and post-stroke care and rehabilitation management. Moreover, appropriate assessment of a physical activity intervention for older adults is pertinent to falls prevention and reduction of musculoskeletal disorders among sedentary seniors.Read moreRead less
Hierarchical Finite Mixture Modelling Of Health Outcomes: A Risk-adjusted Random Effects Approach
Funder
National Health and Medical Research Council
Funding Amount
$117,000.00
Summary
In medical and health studies, finite mixture regression models have been used to analyze data arising from heterogeneous populations. Traditionally, the application of mixture models is mainly concerned with finite normal mixtures. Recent computational advances and methodological developments have enhanced the extension of the method to non-normal finite mixtures, such as the modelling of discrete responses in finite mixture of generalized linear models and overlapping phases of failure time da ....In medical and health studies, finite mixture regression models have been used to analyze data arising from heterogeneous populations. Traditionally, the application of mixture models is mainly concerned with finite normal mixtures. Recent computational advances and methodological developments have enhanced the extension of the method to non-normal finite mixtures, such as the modelling of discrete responses in finite mixture of generalized linear models and overlapping phases of failure time data in the context of survival analysis. However, due to the hierarchical study design or the data collection procedure, the inherent correlation structure and-or clustering effects present may contribute to extra variations and violation of the independence assumption, resulting in spurious associations and misleading inferences based on the finite mixture model. This project aims to present a unified approach to accommodate both heterogeneity and dependency of observations, by incorporating random effects into finite mixture regression models. The new methodology will provide an integrated framework to analyze heterogeneous and correlated health outcomes. Three empirical studies are considered, namely, evaluation of an occupational injury reduction intervention, length of hospital stay modeling, and analysis of survival times of patients after cardiac surgery. The long term benefits to bioscience are accurate and valid conclusions inferred from medical and health studies, as well as the correct identification of high-risk subgroups. For the three application areas of this project, the improved analyses will specifically enable the evaluation of a participatory ergonomics intervention, the assessment of hospital efficiency and factors influencing length of hospitalization, and the determination of effectiveness of treatments prescribed pre- and post- operation, respectively.Read moreRead less
NATIONAL TRENDS IN SUICIDE BY AGE, GENDER, GEOGRAPHY, SOCIO-ECONOMIC AND MIGRANT STATUS AND MENTAL HEALTH
Funder
National Health and Medical Research Council
Funding Amount
$148,690.00
Summary
Suicide in Australia has become an increasingly important public health problem, chiefly because of increasing rates in some population sub-groups, and to a lesser extent because declines in other external causes of death have increased the prominence of suicide. Since the 1970s suicide rates have increased in young males and have eclipsed motor vehicle accidents as the dominant cause of death in this group. Suicide in the young produces a significant impact on years of life lost from premature ....Suicide in Australia has become an increasingly important public health problem, chiefly because of increasing rates in some population sub-groups, and to a lesser extent because declines in other external causes of death have increased the prominence of suicide. Since the 1970s suicide rates have increased in young males and have eclipsed motor vehicle accidents as the dominant cause of death in this group. Suicide in the young produces a significant impact on years of life lost from premature mortality. Suicide rates have been shown to vary by socio-economic status, ethnicity, area of residence, age and sex. In NSW for example, suicide rates in young males have been found to have increased by 50% in urban areas, and by 5-6 times in isolated rural areas. Another study has shown suicide rates to vary by country-of-birth which in turn has an effect on its relationship with socio-economic status. However, not all studies have replicated findings in NSW. In Queensland, for example, it has been shown that male youth suicide rates in rural areas have not substantially exceeded those in urban areas. There have been very few studies at the national level of variations in suicide in Australia. Most studies of Australian suicide to date have been confined to state-level analyses or to very limited nation-level analyses. An additional spur to a whole-nation approach to suicide has been the nation-wide Australian Bureau of Statistics Mental Health and Wellbeing Profile of Adults and a similar mental health survey of youth. Thus for the first time it will be possible to relate population prevalence of self-reported mental illness to suicide rates. In short, the current proposal addresses the two major gaps in Australia in population suicide research: examining suicide at the national level with regard to geographic location, immigrant and socio-economic status; and correlating surveyed prevalence of mental illness with suicide rates.Read moreRead less
Melanoma is the 4th most common cancer diagnosed in Australia. Advanced melanoma frequently spreads to other organs and can acquire resistance to anti-melanoma treatments, making it fundamentally incurable. I am focused on investigating the mechanisms underlying melanoma disease progression. I will achieve this by comparing the biological nature of melanoma cells at different stages of disease and therapy-resistance to identify new targets for the more effective treatment of patients with melano ....Melanoma is the 4th most common cancer diagnosed in Australia. Advanced melanoma frequently spreads to other organs and can acquire resistance to anti-melanoma treatments, making it fundamentally incurable. I am focused on investigating the mechanisms underlying melanoma disease progression. I will achieve this by comparing the biological nature of melanoma cells at different stages of disease and therapy-resistance to identify new targets for the more effective treatment of patients with melanoma.Read moreRead less
Synthetic DNA Standards For Clinical Genome Sequencing
Funder
National Health and Medical Research Council
Funding Amount
$870,005.00
Summary
Genome sequencing can diagnose a wide range of mutations that cause human disease. However, errors during sequencing and analysis can lead to incorrect diagnosis. We propose to develop synthetic representations of genetic mutations that are then added to a patient’s DNA sample and act as internal controls throughout the clinical sequencing workflow. These controls improve the accuracy and reliability of mutation detection, resulting in improved diagnosis and better-informed patient care.
Diagnosis Of Inherited Genetic Disorders Using DNA Reference Standards
Funder
National Health and Medical Research Council
Funding Amount
$690,820.00
Summary
Whole genome sequencing can diagnose mutations that cause inherited disease, however, errors during sequencing and analysis can result in incorrect diagnosis. We propose to develop synthetic DNA standards that mirror important disease-associated mutations. These DNA standards are then added directly of a patient DNA sample and act as internal controls during sequencing and analysis to provide more accurate and reliable diagnosis.