This month’s NSW Statistical Society talk is on Tuesday May 20 and is being given by Professor Judy Simpson from the School of Public Health at the University of Sydney. There will be light refreshments from 6pm, and the talk is scheduled to run from 6.30 to 7.30. The venue is the Gregg Lecture Theatre, Level 2, Edward Ford Building (A27), School of Public Health, University of Sydney. The title, abstract and a short bio appear below. Cheers, Michael -- Analysis of Linked Data in Perinatal Population Health Research Perinatal researchers study what happens to mothers and babies before, during and after birth. This research has been greatly facilitated by the availability of data linkage, enabling hospital records of mothers to be linked to those of their babies (including twins) and of their own previous and subsequent pregnancies and other hospital admissions and registries. The NSW Perinatal Data Collection (PDC) is a legislated population-based surveillance system which monitors patterns of pregnancy care, services and pregnancy outcomes. It covers all births in NSW, i.e., live born babies regardless of gestational age and stillbirths of at least 20 weeks gestation or 400 grams birth weight. For multiple births, a separate record is completed for each baby. Each record contains details of the mother, her previous pregnancies, this pregnancy, labour and delivery, the baby, and postnatal care. Examples will be described of the use of linked PDC data to address different types of research question. These include: examining the impact of the baby bonus on birth rate by age, parity, socioeconomic status and geography; explaining increases over time in adverse maternal and infant outcomes using logistic regression; estimating the risk of complications in a second pregnancy following caesarean section in the first pregnancy; using longitudinally linked data to validate cross-sectional reporting of previous caesarean section; using linked data to obtain outcomes for a randomised trial; examining risk factors for late preterm singleton birth, taking into account multiple observations for the same mother using generalised estimating equation (GEE) methods; and investigating variations in outcomes among hospitals. Biography of Prof. Judy Simpson: Judy Simpson is Professor of Biostatistics in the School of Public Health at the University of Sydney with 30 years’ postdoctoral experience in applying biostatistical techniques to the design and analysis of research in public health and clinical medicine. During her career as a biostatistician, she has published extensively both nationally and internationally, including over 200 articles in peer-reviewed journals. Her main research interests are: design and analysis of randomised controlled trials, especially cluster-randomised trials; statistical modelling, including hierarchical (multilevel) modeling; survival analysis, especially analysis of multiple failure time data; and analysis of linked data sets. She has been collaborating for several years in the analysis of linked data with Associate Professors Christine Roberts and Jane Ford, perinatal epidemiologists.