Local polynomial estimation of Poisson intensities in the presence of reporting delays

Summary.  The system for monitoring suicides in Hong Kong has considerable delays in reporting as the cause of death needs to be determined by a coroner's investigation. However, timely estimates of suicide rates are desirable to assist in the formulation of public health policies. This motivated us to develop a non-parametric procedure to estimate the intensity function of a Poisson process in the presence of reporting delays. We give closed form estimators of the Poisson intensity and the delay distribution, conduct simulation studies to evaluate the method proposed and derive their asymptotic properties. The method proposed is applied to estimate the intensity of suicide in Hong Kong.     

Nonparametric Estimation of the Number of Drug Users in Hong Kong Using Repeated Multiple Lists

We update a previous approach to the estimation of the size of an open population when there are multiple lists at each time point. Our motivation is 35 years of longitudinal data on the detection of drug users by the Central Registry of Drug Abuse in Hong Kong. We develop a two‐stage smoothing spline approach. This gives a flexible and easily implemented alternative to the previous method which was based on kernel smoothing. The new method retains the property of reducing the variability of the individual estimates at each time point. We evaluate the new method by means of a simulation study that includes an examination of the effects of variable selection. The new method is then applied to data collected by the Central Registry of Drug Abuse. The parameter estimates obtained are compared with the well known Jolly–Seber estimates based on single capture methods.     

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.     

‘Actually There is a Brain in There’: Uncovering Complexity in Pathways Through Education for Young Adults Who Have Been in Care

Internationally, research has highlighted disruption to the educational trajectories of young people in care, documenting concern about upheaval and poor educational outcomes. We present findings from English data arising from qualitative longitudinal research with care experienced people (16–32 years) who were also in education, employment or training. The analysis extends understanding of the experiences of those who achieve educational ‘success’, including those who followed non‐linear trajectories. The need for a flexible education system, and leaving care entitlements, which take into account the disruption experienced by young people in care and the consequent possibility of delayed educational pathways, is discussed.     

Stakeholder Perspectives on Children's Mental Health Needs and Supports in Six Low‐ and Middle‐Income Countries

Low‐ and middle‐income countries (LMIC) are faced with disproportionately high levels of unmet child mental health needs. This study explored through interviews the perspectives of 17 inter‐agency service stakeholders from Brazil, Indonesia, Kenya, Pakistan, Rwanda and Turkey on existing supports and challenges. Four themes emerged on the holistic nature of children's mental health needs linked with disadvantage; limited resources and skilled workforce; stigma; and strategies for future implementation, including awareness, parental engagement, skills‐based programmes and cultural adaptation. Stakeholder input is essential in conceptualising, developing and evaluating culturally appropriate interventions for vulnerable children in LMIC.     

No One Is Immune: A Community Education Partnership Addressing HIV/AIDS and Older Adults

There has been a dramatic increase in the number of new HIV diagnoses among people aged 50 to 64 in the United States, and according to the Centers for Disease Control and Prevention (CDC), in just 7 years (by 2015) 50% of those living with AIDS will be aged 50 or older. To address this public health concern, viable HIV/AIDS prevention and treatment options for individuals over the age of 50 are necessary. This article discusses the No One Is Immune initiative that planned, implemented, and coordinated evidence- based HIV/AIDS prevention and education programs specifically tailored for middle-aged and older adults. Guided by the health belief model, an educational conference entitled "Sexuality, Medication, and HIV/AIDS in Middle and Later Adulthood" was conducted along with research activities that assessed HIV/AIDS knowledge gained using both qualitative and quantitative measures. This project can be replicated by other providers within the aging network.     

Estimation in capture–recapture models when covariates are subject to measurement errors and missing data

For capture–recapture models when covariates are subject to measurement errors and missing data, a set of estimating equations is constructed to estimate population size and relevant parameters. These estimating equations can be solved by an algorithm similar to the EM algorithm. The proposed method is also applicable to the situation when covariates with no measurement errors have missing data. Simulation studies are used to assess the performance of the proposed estimator. The estimator is also applied to a capture–recapture experiment on the bird species Prinia flaviventris in Hong Kong. The Canadian Journal of Statistics 37: 645–658; 2009 © 2009 Statistical Society of Canada