Digital Commons Network^™

Design And Estimation For Split Questionnaire Surveys, James O. Chipperfield, David G. Steel

Professor David Steel

When sampling from a finite population to estimate the means or totals of K population characteristics of interest, survey designs typically impose the constraint that information on all K characteristics (or data items) is collected from all units in the sample. Relaxing this constraint means that information on a subset of the K data items may be collected from any given unit in the sample. Such a design, called a split questionnaire design (SQD), has three advantages over the typical design: increased efficiency with which design objectives can be met, by allowing the number of sample units from which information …

Conditional And Unconditional Models In Model-Assisted Estimation Of Finite Population Totals, David Steel, Robert Clark

Professor David Steel

The well known Godambe-Joshi lower bound for the anticipated variance of design unbiased estimators of population totals treats the auxiliary variables as constants. We extend the result to models where these variables are random and show that the generalized difference estimator using the expected values conditional on all auxiliary values is optimal. This has several implications including the fact that collecting multiple survey variables does not reduce the lower bound.

Scales, Levels And Processes: Studying Spatial Patterns Of British Census Variables, David Manley, Robin Flowerdew, David Steel

Professor David Steel

No abstract provided.

Measuring And Analysing Homogeneity Of Geographical Areas For A Categorical Variable, David Steel, Mark Tranmer

Professor David Steel

Many Variables have within group homogeneity (similarity of values for the individual units that comprise the groups). Measures of within group homogeneity are useful for the sample design and statistical analysis of datasets for populations that contain groups, such as individuals in geographical areas. Homogeneity measures can easily be defined for continuous or dichotomous variables. Here we propose a homogeneity measure for a multi-category variable and show how this measure can be calculated without access to individual level data. We apply the measure to data from the UK census and show how this measure can be related to the homogeneity …

Person-Level And Household-Level Regression Estimation In Household Surveys, David G. Steel, Robert Graham Clark

Professor David Steel

A common class of survey designs involves selecting all people within selected households. Generalized regressionestimators can be calculated at either the person or household level. Implementing the estimator at the household level has the convenience of equal estimation weights for people within households. In this article the two approaches are compared theoretically and empirically for the case of simple random sampling of households and selection of all persons in each selected household. We find that the household level approach is theoretically more efficient in large samples and any empirical inefficiency in small samples is limited.

The 2003 Australian Breast Health Survey: Survey Design And Preliminary Results, Elmer V. Villanueva, Sandra C. Jones, Caroline Nehill, Simone K. Favelle, David G. Steel, Don Iverson, Helen Zorbas

Professor David Steel

The Breast Health Surveys, conducted by the National Breast Cancer Centre (NBCC) in 1996 and 2003, are designed to gain insight into the knowledge, attitudes and behaviours of a nationally representative sample of Australian women on issues relevant to breast cancer. In this article, we focus on major aspects of the design and present results on respondents' knowledge about mammographic screening. Methods: The 2003 BHS surveyed English-speaking Australian women aged 3069 without a history of breast cancer using computer-assisted telephone interviewing. Questions covered the following themes: knowledge and perceptions about incidence, mortality and risk; knowledge and behaviour regarding early detection, …

Contextual Effects In Modeling For Small Domain Estimation, Mohammad-Reza Namazi-Rad, David G. Steel

Professor David Steel

Many different Small Area Estimation (SAE) methods have been proposed to overcome the challenge of findingreliable estimates for small domains. Often, the required data for various research purposes are available at differentlevels of aggregation. Based on the available data, individual-level or aggregated-level models are used in SAE.However, parameter estimates obtained from individual and aggregated level analysis may be different, in practice.This may happen due to some substantial contextual or area-level effects in the covariates which may be misspecifiedin individual-level analysis. If small area models are going to be interpretable in practice, possible contextualeffects should be included. Ignoring these effects leads …

Understanding Ageing In Older Australians: The Contribution Of The Dynamic Analyses To Optimise Ageing (Dynopta) Project To The Evidence Base And Policy, Kaarin Anstey, Allison Blelak, Carole Birrell, Colette Browning, Richard Burns, Julie Byles, Kim Kiely, Binod Nepal, Lesley Ross, David Steel, Timothy Windsor

Professor David Steel

Aim:  To describe the Dynamic Analyses to Optimise Ageing (DYNOPTA) project and illustrate its contributions to understanding ageing through innovative methodology, and investigations on outcomes based on the project themes. DYNOPTA provides a platform and technical expertise that may be used to combine other national and international datasets. Methods:  The DYNOPTA project has pooled and harmonised data from nine Australian longitudinal studies to create the largest available longitudinal dataset (n= 50652) on ageing in Australia. Results:  A range of findings have resulted from the study to date, including methodological advances, prevalence rates of disease and disability, and mapping trajectories of …

Estimates Of Probable Dementia Prevalence From Population-Based Surveys Compared With Dementia Prevalence Estimates Based On Meta-Analyses, Kaarin J. Anstey, Richard A. Burns, Carole Birrell, David G. Steel, Kim M. Kiely, Mary A. Luszcz

Professor David Steel

Background: National data on dementia prevalence are not always available, yet it may be possible to obtain estimates from large surveys that include dementia screening instruments. In Australia, many of the dementia prevalence estimates are based on European data collected between 15 and 50 years ago. We derived populationbased estimates of probable dementia and possible cognitive impairment in Australian studies using the Mini-Mental State Examination (MMSE), and compared these to estimates of dementia prevalence from meta-analyses of European studies.

Methods: Data sources included a pooled dataset of Australian longitudinal studies (DYNOPTA), and two Australian Bureau of Statistics National …

Measuring And Analyzing The Within Group Homogeneity Of Multi-Category Variables, David Steel, Mark Tranmer

Professor David Steel

No abstract provided.

Unravelling Ecological Analysis, David Steel, Mark Tranmer, D Holt

Professor David Steel

No abstract provided.

Investigation Of Relative Risk Estimates From Studies Of The Same Population With Contrasting Response Rates And Designs, Nicole M. Mealing, Emily Banks, Louisa R. Jorm, David G. Steel, Mark S. Clements, Kris D. Rogers

Professor David Steel

Background: There is little empirical evidence regarding the generalisability of relative risk estimates from studies which have relatively low response rates or are of limited representativeness. The aim of this study was to investigate variation in exposure-outcome relationships in studies of the same population with different response rates and designs by comparing estimates from the 45 and Up Study, a population-based cohort study (self-administered postal questionnaire, response rate 18%), and the New South Wales Population Health Survey (PHS) (computer-assisted telephone interview, response rate ~60%). Methods: Logistic regression analysis of questionnaire data from 45 and Up Study participants (n = 101,812) …