Comparing and Improving the Accuracy of Nonprobability Samples: Profiling Australian Surveys

There has been a great deal of debate in the survey research community about the accuracy of nonprobability sample surveys. This work aims to provide empirical evidence about the accuracy of nonprobability samples and to investigate the performance of a range of post-survey adjustment approaches (calibration or matching methods) to reduce bias, and lead to enhanced inference. We use data from five nonprobability online panel surveys and com­pare their accuracy (pre- and post-survey adjustment) to four probability surveys, including data from a probability online panel. This article adds value to the existing research by assessing methods for causal inference not previously applied for this purpose and dem­onstrates the value of various types of covariates in mitigation of bias in nonprobability online panels. Investigating different post-survey adjustment scenarios based on the avail­ability of auxiliary data, we demonstrated how carefully designed post-survey adjustment can reduce some bias in survey research using nonprobability samples. The results show that the quality of post-survey adjustments is, first and foremost, dependent on the avail­ability of relevant high-quality covariates which come from a representative large-scale probability-based survey data and match those in nonprobability data. Second, we found little difference in the efficiency of different post-survey adjustment methods, and inconsis­tent evidence on the suitability of 'webographics' and other internet-associated covariates for mitigating bias in nonprobability samples

Two Novel Techniques of Drying Silica Aerogel at Ambient Pressure

二氧化硅气凝胶因其优异的性能广泛应用于各个行业，成为多孔材料研究的热点之一。然而，工业化生产时往往受限于干燥技术，主要的影响因素包括成本、生产效率、安全性和对环境的影响程度等。本工作开发两种方法来解决这些问题。 第一种方法采用一种可变换亲水溶剂(SHS)溶解于二氧化硅水凝胶的间隙中，之后将间隙中的水萃取出来，其中二氧化硅水凝胶采用加压碳化溶胶-凝胶过程制得。引入常压CO2与该SHS反应，发现快速反应（反应时间1分钟）就能使滤液内水的最大溶解度达到72.8%。滤液是单相溶液，并可以循环使用。滤渣是二氧化硅湿凝胶，可用常压干燥得到二氧化硅气凝胶。用氮气吸附-脱附仪测试可知，该气凝胶产品具有较大的...The exceptional properties of silica aerogel make it one of the intensely investigated porous materials obviously because of its multiple and diverse applications. However, its commercial-scale production is often limited by a drying technique that critically embodies considerations such as cost, safety, time for production and effects on the environment. In an attempt to address these challenges ...学位：工学硕士院系专业：化学化工学院_化学工程学号：2042015115469

Ethnic differences in the quality of the interview process and implications for survey analysis: The case of Indigenous Australians

Comparable survey data on Indigenous and non-Indigenous Australians are highly sought after by policymakers to inform policies aimed at closing ethnic socio-economic gaps. However, collection of such data is compromised by group differences in socio-economic status and cultural norms. We use data from the Household, Income and Labour Dynamics in Australia Survey and multiple-membership multilevel regression models that allow for individual and interviewer effects to examine differences between Indigenous and non-Indigenous Australians in approximate measures of the quality of the interview process. We find that there are both direct and indirect ethnic effects on different dimensions of interview process quality, with Indigenous Australians faring worse than non-Indigenous Australians in all outcomes ceteris paribus . This indicates that nationwide surveys must feature interview protocols that are sensitive to the needs and culture of Indigenous respondents to improve the quality of the survey information gathered from this subpopulation

Subsequent Migration of Immigrants Within Australia, 1981-2016

Australia is a major immigration country and immigrants currently represent around 28% of the total population. The aim of this research is to understand the long-term consequences of this immigration and, particularly, how migrants respond to opportunities within the country after arriving through the process of subsequent (internal) migration. The focus is on major immigrant groups in Australia, including persons born in the United Kingdom, New Zealand, China and India, and how their patterns differ from persons born in Australia. To conduct this analysis, we have gathered data for a 35-year period based on quinquennial census data. We also obtained birthplace-specific mortality data for constructing multiregional life tables for the immigrant populations. Subsequent migration is important for understanding population redistribution, and the relative attractiveness of destinations within host countries. Our results highlight the importance of subsequent migration and the diversity of migration behaviours amongst different immigrant groups in the context of overall declines in internal migration since 1981

Prevalence of child undernutrition measures and their spatio-demographic inequalities in Bangladesh: an application of multilevel Bayesian modelling

Micro-level statistics on child undernutrition are highly prioritized by stakeholders for measuring and monitoring progress on the sustainable development goals. In this regard district-representative data were collected in the Bangladesh Multiple Indicator Cluster Survey 2019 for identifying localised disparities. However, district-level estimates of undernutrition indicators - stunting, wasting and underweight - remain largely unexplored. This study aims to estimate district-level prevalence of these indicators as well as to explore their disparities at sub-national (division) and district level spatio-demographic domains cross-classified by children sex, age-groups, and place of residence. Bayesian multilevel models are developed at the sex-age-residence-district level, accounting for cross-sectional, spatial and spatio-demographic variations. The detailed domain-level predictions are aggregated to higher aggregation levels, which results in numerically consistent and reasonable estimates when compared to the design-based direct estimates. Spatio-demographic distributions of undernutrition indicators indicate south-western districts have lower vulnerability to undernutrition than north-eastern districts, and indicate significant inequalities within and between administrative hierarchies, attributable to child age and place of residence. These disparities in undernutrition at both aggregated and disaggregated spatio-demographic domains can aid policymakers in the social inclusion of the most vulnerable to meet the sustainable development goals by 2030.Australia National Health and Medical Research Council (NHMRC), APP118472

A dyadic approach to the study of perceived subfecundity and contraceptive use

Background: There is an increasing literature on women's perception of subfecundity and contraceptive use, with studies showing that women with perceived difficulties conceiving are more likely to have an unintended pregnancy because of a lower reliance on contraception. There is little research investigating the correlates of perceived subfecundity, and quantitative investigation of couple-level perceived subfecundity appears absent from the literature, which is somewhat surprising, as the inability to have a child is a couple-level outcome. Furthermore, most studies that relate to perceived subfecundity and the use of contraception, or lack thereof, are typically limited to young adults. Objective: The aim of this study is to explore the couple-level correlates of perceived subfecundity and to investigate the relationship between perceived subfecundity and contraceptive use among a nationally representative sample of couples. Methods: Drawing on data from the Household Income and Labour Dynamics in Australia (HILDA) survey, binary and multinomial logistic regression models are estimated using the couple-dyad as the unit of analysis. Results: Both biological and life-course interference factors are strong predictors of perceived subfecundity at the couple level, with women's characteristics more influential than their partner's characteristics. Additionally, couples in which at least one partner perceives subfecundity are less likely to use contraception, regardless of their short-term intentions or desire to have a child. Contribution: Men's and women's characteristics differently influence the likelihood of perceiving subfecundity at the couple level and the perception of subfecundity is a relevant reason why couples do not use contraception