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BACKGROUND Regression to the mean (RTM) is a statistical phenomenon that can make natural variation in repeated data look like real change. It happens when unusually large or small measurements tend to be followed by measurements that are closer to the mean. METHODS We give some examples of the phenomenon, and discuss methods to overcome it at the design(More)
As usually understood in survival analysis, frailty models are extensions of the proportional hazards model that incorporate unobserved random multiplicative components into the hazard function. Frailty models have become quite popular in recent years both as a way of modeling otherwise unexplained heterogeneity in survival data and as an approach to(More)
Strong social support is associated with lower mortality and morbidity and better self-rated health in later life. The aim of this study was to compare social network size and satisfaction in men (N = 2589) and women (n = 3152), aged 72-78 years. Women reported significantly larger networks (Difference 1.36, 95% CI 0.89, 1.83) than men. However, being(More)
OBJECTIVE To measure the effectiveness of the quadrivalent human papillomavirus (HPV) vaccine against cervical abnormalities four years after implementation of a nationally funded vaccination programme in Queensland, Australia. DESIGN Case-control analysis of linked administrative health datasets. SETTING Queensland, Australia. PARTICIPANTS Women(More)
BACKGROUND The recent emergence of leptospirosis has been linked to many environmental drivers of disease transmission. Accurate epidemiological data are lacking because of under-diagnosis, poor laboratory capacity, and inadequate surveillance. Predictive risk maps have been produced for many diseases to identify high-risk areas for infection and guide(More)
Missing data is a common problem in survey based research. There are many packages that compensate for missing data but few can easily compensate for missing longitudinal data. WinBUGS compensates for missing data using multiple imputation, and is able to incorporate longitudinal structure using random effects. We demonstrate the superiority of longitudinal(More)
BACKGROUND There are well-established risk factors, such as lower education, for attrition of study participants. Consequently, the representativeness of the cohort in a longitudinal study may deteriorate over time. Death is a common form of attrition in cohort studies of older people. The aim of this paper is to examine the effects of death and other forms(More)
BACKGROUND Currently, we are not aware of a method to assess graphically on one simple plot agreement between more than two observers making continuous measurements on the same subjects. METHODS We aimed to develop a simple graphical method to assess agreement between multiple observers using continuous measurements. The Bland-Altman graphical method for(More)
BACKGROUND Estimates of the absolute risk of death based on the combined effects of sex, age and health behaviours are scarce for elderly people. The aim of this paper is to calculate population based estimates and display them using simple charts that may be useful communication tools for public health authorities, health care providers and policy makers.(More)