Estimating population size in proportional trapping-removal models

We examine the inference problem of a proportional trapping model introduced by Good, Lewis, Gaskins and Howell (1979), and consider a similar removal model in continuous time. The existence and uniqueness of the maximum likelihood estimates of the parameters are studied. Corresponding variance estimates are also given. Martingale theory is used to obtain the asymptotic properties, and simulations are conducted to examine the performance of the estimation procedure.published_or_final_versio

Modelling the severe acute respiratory syndrome epidemic [3]

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A comparison of seasonal variation between suicide deaths and attempts in Hong Kong SAR

Background: Seasonal variations in suicide deaths and attempted suicides have been reported for many countries. Recent research has suggested that seasonal patterns of suicide deaths have diminished considerably. The seasonality pattern between attempts and completed ones are not the same. This paper is the first one to examine seasonal variation between suicide deaths and attempts simultaneously. Method: Census and Statistics Department and the Hospital Authority provided mortality and morbidity data on suicides for the period 1997-2001 in Hong Kong SAR, respectively. Seasonal patterns of suicide deaths and attempts were examined by a harmonic analysis and a non-parametric chi-square test. Results: A significant seasonal variation was detected in suicide attempts with a markedly bi-seasonal pattern was found amongst females with a peak in May and October; only a cyclic pattern was observed for males with a peak in summer. The female attempters who used non-violent suicide methods contributed to the second peak in October. On the other hand, there was no evidence of significant differences in the seasonal distribution among the suicide deaths for males and females. Only a mild pattern was found amongst females involving in violent suicide deaths, while others can be treated as a random event and no significantly pattern was observed in our study. Overall, a significant difference in seasonal variation existed between suicide deaths and attempts (p-value<0.01). Conclusions: This study reinforces the findings that seasonal variation in suicide appears to be diminishing. Also, suicide attempters and completed suicides in Hong Kong seem to arise from two non-identical but overlapping groups in the community. © 2003 Elsevier B.V. All rights reserved.postprin

Workplace violence towards nurses in Hong Kong : prevalence and correlates

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Acute care service utilisation and the possible impacts of a user-fee policy in Hong Kong

OBJECTIVES: To examine the utilisation pattern of accident and emergency services and to study the possible impact of a user-fee policy on non-emergency attendances in Hong Kong. DESIGN: Retrospective study. METHODS: Four different scenarios are postulated to examine the impact on the number of accident and emergency attendances of a user-fee policy from 2000 to 2029. Patient volume data of accident and emergency attendances for 2000 were made available by the Hospital Authority of Hong Kong. RESULTS: Non-emergency use of the accident and emergency services is the main cause of over-utilisation and contributes to more than 70.0% of its use. Only 22.0% of patients attending accident and emergency departments were admitted to a ward for further treatment. By 2029, the number of accident and emergency attendances would increase by more than 47.0% if the present utilisation pattern prevails. However, if patients at triage levels 3, 4, and 5 were discouraged from using the accident and emergency services, the number of attendances would decrease by 76.4%. CONCLUSION: The proposed user-fee policy would act as a deterrent by preventing unnecessary use of accident and emergency services. However, the use of out-patient services may be increased as a result and attendance should be carefully monitored. Community health education and civic education relating to abuse of accident and emergency services would be effective in reducing over-utilisation of these services.published_or_final_versio

Viability of the Health Protection Account in Hong Kong: Authors' reply

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Workplace Violence toward Physicians and Nurses: Prevalence and Correlates in Macau

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Validation of the Chinese version of the Reynolds' suicidal ideation questionnaire: psychometric properties and its short version

BACKGROUND: This study aims to validate the Chinese version of the Reynolds' Suicidal Ideation Questionnaire (SIQ) in a Chinese society and explore a convenient short version. METHODS: A sample of 711 cases was derived from two territory-wide surveys of Hong Kong adolescents aged between 15 and 19 years old. RESULTS: The SIQ and the Suicidal Ideation Questionnaire-Junior (SIQ-JR) demonstrated good reliability and concurrent validity among Hong Kong adolescents. However, the factor structure for both SIQ and SIQ-JR appeared to be unclear. A four-item short form of the SIQ-JR, namely, SIQ-JR-4, was proposed. CONCLUSION: The SIQ-JR-4 is an ideal substitute of the SIQ/SIQ-JR for future quick assessment of suicidal ideation in Chinese young adolescents

A Gibbs-sampler approach to estimate the number of faults in a system using capture-recapture sampling

A new recapture debugging model is suggested to estimate the number of faults in a system, ν, and the failure intensity of each fault, φ. The Gibbs sampler and the Metropolis algorithm are used in this inference procedure. A numerical illustration suggests a notable improvement on the estimation of ν and φ compared with that of a removal debugging model.published_or_final_versio