Sandy Burden

Spatio-temporal Analysis of Acute Admissions for Ischemic Heart Disease in NSW, Australia

The recently funded Spatial Environmental Epidemiology in New South Wales (SEE NSW) project aims to use routinely collected data in NSW Australia to investigate risk factors for various chronic diseases. In this paper, we present a case study focused on the relationship between social disadvantage and ischemic heart disease to highlight some of the methodological challenges that are likely to arise.

The impact of complex survey design on prevalence estimates of intakes of food groups in the Australian National Children's Nutrition and Physical Activity Survey

OBJECTIVE To assess the impact of the complex survey design used in the 2007 Australian National Childrens Nutrition and Physical Activity Survey (ANCNPAS07) on prevalence estimates for intakes of groups of foods in the population of children. DESIGN The impacts on prevalence estimates were determined by calculating design effects for values for food group consumption. The implications of ignoring elements of the sample design including stratification, clustering and weighting are discussed. SETTING The ANCNPAS07 used a complex sample design involving stratification, a high degree of clustering and estimation weights. SUBJECTS Australian children aged 2-16 years. RESULTS Design effects ranging from <1 to 5 were found for the values of mean consumption and proportion of the population consuming the food groups. When survey weights were ignored, prevalence estimates were also biased. CONCLUSIONS Ignoring the complex survey design used in the ANCNPAS07 could result in underestimating the width of confidence intervals, higher mean square errors and biased estimators. The magnitude of these effects depends on both the parameter under consideration and the chosen estimator.