New recursive estimators of the time-average variance constant

Estimation of the time-average variance constant (TAVC) of a stationary process plays a fundamental role in statistical inference for the mean of a stochastic process. Wu (2009) proposed an efficient algorithm to recursively compute the TAVC with \(O(1)\) memory and computational complexity. In this paper, we propose two new recursive TAVC estimators that can compute TAVC estimate with \(O(1)\) computational complexity. One of them is uniformly better than Wu’s estimator in terms of asymptotic mean squared error (MSE) at a cost of slightly higher memory complexity. The other preserves the \(O(1)\) memory complexity and is better then Wu’s estimator in most situations. Moreover, the first estimator is nearly optimal in the sense that its asymptotic MSE is \(2^{10/3}3^{-2} \fallingdotseq 1.12\) times that of the optimal off-line TAVC estimator.     

On Bartlett correction of empirical likelihood for regularly spaced spatial data

Bartlett correction constitutes one of the attractive features of empirical likelihood because it enables the construction of confidence regions for parameters with improved coverage probabilities. We study the Bartlett correction of spatial frequency domain empirical likelihood (SFDEL) based on general spectral estimating functions for regularly spaced spatial data. This general formulation can be applied to testing and estimation problems in spatial analysis, for example testing covariance isotropy, testing covariance separability as well as estimating the parameters of spatial covariance models. We show that the SFDEL is Bartlett correctable. In particular, the improvement in coverage accuracies of the Bartlett‐corrected confidence regions depends on the underlying spatial structures. The Canadian Journal of Statistics 47: 455–472; 2019 © 2019 Statistical Society of Canada     

Child Poverty Among Hong Kong Ethnic Minorities

This paper analyzes the data from the Population Census of 2011 to identify the characteristics of poor ethnic minority groups in Hong Kong and the factors that are associated with child poverty among these ethnic minorities. The results show that the child poverty level varies between different ethnic groups and that ethnic minorities from developing nations are likely to have a higher poverty level. In particular, Pakistani children have the highest poverty rate among all ethnic groups. The results also show that Pakistani, Nepalese, and Mixed (Chinese and Asian) nationalities have a higher child poverty rate than that of Chinese individuals who constitute the majority of the Hong Kong population. The main reason for this is that, unlike their Chinese counterparts, some of these ethnic minority households have not benefited from their own human capital or their length of exposure in the local society in Hong Kong. And even if they have benefited, the positive impact of these factors on ethnic minority households was much weaker compared to that of Chinese households. These results suggest that ethnic minorities need to be categorized as a separate group in order to assess their specific needs, and assimilation policies, especially support on Chinese language learning, need to be an integral part of the government’s poverty reduction strategy to reduce child poverty among ethnic minorities.     

Assessing the devolution revolution: How accurate are state-level estimates from the current population survey

The devolution of many social policy responsibilities from the Federal government to states has prompted increased interest in state-level measures of need. One data source that could be used to provide more state-level information on a variety of topics is the Current Population Survey (CPS). During the past ten years the CPS has been used to produce state-level estimates on a variety of measures. However, there has been little systematic evaluation of these data. This paper provides measures of accuracy for several state-level estimates derived from the CPS. These include standard errors for single-year estimates, three-year averages, and five-year averages of the March CPS measures; standard errors for three-year averages of 12-month CPS files; and comparison of CPS-based estimates to data from the Decennial Census. The paper also examines the relative accuracy of CPS estimates based on states' size. The information in this study will help analysts better understand the tradeoffs between timeliness and accuracy to be considered when using state-level estimates derived from the CPS.     

Bayesian Nonparametric Hidden Markov Models with application to the analysis of copy-number-variation in mammalian genomes

We consider the development of Bayesian Nonparametric methods for product partition models such as Hidden Markov Models and change point models. Our approach uses a Mixture of Dirichlet Process (MDP) model for the unknown sampling distribution (likelihood) for the observations arising in each state and a computationally efficient data augmentation scheme to aid inference. The method uses novel MCMC methodology which combines recent retrospective sampling methods with the use of slice sampler variables. The methodology is computationally efficient, both in terms of MCMC mixing properties, and robustness to the length of the time series being investigated. Moreover, the method is easy to implement requiring little or no user-interaction. We apply our methodology to the analysis of genomic copy number variation.     

The psychosocial needs of the Chinese elderly

Changing Chinese family patterns caused by immigration have contributed to the breakdown of traditional community and familial control in Chinese-American families. As a result, the Chinese-American elderly are faced with unique psychosocial problems that workers must consider when providing services to this population.     

Does Australia Have a Filipina Brides Problem?

This paper challenges the assumption that Australian-Filipina marriages are prone to high rates of marital breakdown; and the belief that the incidence of Australian-Filipina marriages is sufficiently large to warrant the introduction of restrictive immigration policies for Filipinas. First we set the problem of Filipina bride migration in perspective by viewing it in the wider context of Australian immigration patterns — something that has been largely neglected in the discussion so far. Then we review the evidence on marital breakdown and show that Filipina-Australian marriages have been more successful than is commonly assumed. Finally, we consider the standard explanation of the breakdown of Filipina-Australian marriages in terms of ‘cultural differences’. Our conclusion is that much of the discussion has been based on implicit racial and sexual prejudices, rather than factual evidence.     

The functional capacity of healthcare workers with history of severe acute respiratory distress syndrome (SARS) complicated with avascular necrosis--case report

Two years after the SARS outbreak in Hong Kong, 128 healthcare workers continued to present with musculoskeletal complaints and 38 workers were diagnosed with avascular necrosis (AVN) in different joints. 13 healthcare workers were referred to six designated Physiotherapy Departments of the Hospital Authority for a tailor-made standardized Functional Capacity Evaluation (FCE) from 2004 to 2005 on a voluntary basis. Job analysis, workers' self-perceived disability and functional capacity, non-material handling tests, and the cardiopulmonary fitness test were performed. Retrospective review of the FCE data showed that there were 17 AVN of hips, 16 AVN of knees, 3 AVN of shoulders. All patients had AVN of lower limb joints. Nearly full ranges of movement (ROM) were observed in the knees involved, but the hip range was decreased for most subjects suffering from hip AVNs. Most workers (n=12) could not complete the cardiopulmonary test due to intolerable joint pain. Six workers' self-perceived physical demands level (PDC) matched with the physical demands level identified by the FCE. 12 healthcare workers attained a sedentary physical demands level and were unable to match with their previous job demands. One staff was classified as light physical demands and managed his original duty. Four workers had returned to work at the time FCE was performed. The tailor-made FCE added information to facilitate the return-to-work planning for the staff. Four more workers returned to work with modified duties one year after the FCE.     

Testing for zero-inflation in count series: application to occupational health

Count data series with extra zeros relative to a Poisson distribution are common in many biomedical applications. A score test is presented to assess whether the zero-inflation problem is significant to warrant the analysis by the more complex zero-inflated Poisson autoregression model. The score test is implemented as a computer program in the Splus platform. For illustration, the test procedure is applied to a workplace injury series where many zero counts are observed due to the heterogeneity in injury risk and the dynamic population involved.