Global kernel estimator and test of varying‐coefficient autoregressive model

We propose a varying‐coefficient autoregressive model that contains additive models, varying‐ coefficient models, partially linear models and low‐dimensional interaction models as special cases. A global kernel backfitting method is proposed for the estimation and inference of parameters and unknown functions in this model. Key large‐sample results are established, including estimation consistency, asymptotic normality and the generalized likelihood ratio test for parameters and non‐parametric functions. The proposed methodology is examined by simulation studies and applied to examine the relationship between suicide news reports in the three leading newspapers and the daily number of suicides in Taiwan. The relationship between the media reporting and suicide incidence has been established and explored. The Canadian Journal of Statistics 47: 487–519; 2019 © 2019 Statistical Society of Canada     

Modelling repeated insurance claim frequency data using the generalized linear mixed model

Most of the methods used to estimate claim frequency rates in general insurance have assumed that data are independent. However, it is not uncommon for information stored in the database of an insurance company to contain previous years' claim data from each policyholder. We consider the application of the generalized linear mixed model approach to the analysis of repeated insurance claim frequency data in which a conditionally fixed random effect vector is incorporated explicitly into the linear predictor to model the inherent correlation. A motor insurance data set is used as the basis for simulation to demonstrate the advantages of the method. Ignoring the underlying association for observations within the same policyholder results in an underestimation of the standard error of the parameter estimates and a remarkable reduction in the prediction accuracy. The method provides a viable alternative for incorporating repeated claim experience that enables the revision of rates in general insurance.     

An exploratory study to conceptualize press engagement behavior with public relations practitioners

This study addresses how journalists respond to public relations (PR) practitioners in co-creating value for their audiences. The co-creation perspective is conceptualized by synthesizing extant literature from public relations and relationship marketing, including cultivation strategies in organization-public relationships studies, two-way symmetrical model in excellence theory, intereffication model, service-dominant (S-D) logic of co-creation in marketing, and customer engagement theories. Using long-interview technique with 18 journalists, the study investigates how journalists perceive media relations activities of PR practitioners from a value co-creation dimension. A new theoretical model titled press engagement behavior (PEB) with sub-dimensions in press participation behavior (PPB) and press citizenship behavior (PCB) is proposed. A thirty-item scale is proposed to guide future study on scale development and validation. The proposed new model can explain the context of journalist engagement, enriching the operational value of cultivation strategies in dyadic relationship settings.     

OPTIMAL PORTFOLIO SELECTION WITH UPPER BOUNDS FOR INDIVIDUAL SECURITIES*

In this paper, we consider optimal portfolio selection with no short sales and with upper bounds for individual securities. The solution is reached by directy revising the optimal portfolio without upper bounds. Specifically, our analysis is based on the single-index model, as well as the general multi-index model that provides the return generating process for securities in the arbitrage pricing theory. As demonstrated in a simulation study, the proposed algorithm for optimal portfolio selection usually requires very few iterations. Also, since our approach is developed using intuitive reasoning and simple linear algebra, we are able to provide direct and intuitive justifications for the resulting portfolio choice. Therefore this paper should be of interest to both finance academics and practitioners in portfolio management.     

High‐order Corrected Estimator of Asymptotic Variance with Optimal Bandwidth

Estimation of time‐average variance constant (TAVC), which is the asymptotic variance of the sample mean of a dependent process, is of fundamental importance in various fields of statistics. For frequentists, it is crucial for constructing confidence interval of mean and serving as a normalizing constant in various test statistics and so forth. For Bayesians, it is widely used for evaluating effective sample size and conducting convergence diagnosis in Markov chain Monte Carlo method. In this paper, by considering high‐order corrections to the asymptotic biases, we develop a new class of TAVC estimators that enjoys optimal ‐convergence rates under different degrees of the serial dependence of stochastic processes. The high‐order correction procedure is applicable to estimation of the so‐called smoothness parameter, which is essential in determining the optimal bandwidth. Comparisons with existing TAVC estimators are comprehensively investigated. In particular, the proposed optimal high‐order corrected estimator has the best performance in terms of mean squared error.     

Bayesian Inference for a Stochastic Epidemic Model with Uncertain Numbers of Susceptibles of Several Types

A stochastic epidemic model with several kinds of susceptible is used to analyse temporal disease outbreak data from a Bayesian perspective. Prior distributions are used to model uncertainty in the actual numbers of susceptibles initially present. The posterior distribution of the parameters of the model is explored via Markov chain Monte Carlo methods. The methods are illustrated using two datasets, and the results are compared where possible to results obtained by previous analyses.     

A study of sexual satisfaction and frequency of sex among Hong Kong Chinese couples

There have been several studies in Western societies on the causes and consequences of sexual satisfaction within marriage. Little is known, however about the marital sexual relationship in Chinese societies. Moreover, most published studies used married individuals rather than married couples as participants. The present study examined data from a well-established knowledge, attitude, and practice (KAP) survey of 1,124 Hong Kong Chinese couples on martial sexual relationship. A conceptual model was tested using structural equation modeling (SEM). Interest in sex was found to be the strongest predictor of both sexual satisfaction and frequency of sex for both husbands and wives. Among the sociodemographic variables, the following two were significantly associated with lower frequencies of sex: for wives, that of having a full-time job; and for husbands, the factor of age. Theoretical implications for research on the interplay among culture, marriage, and sex in non-Western societies are discussed.     

A Strengths Perspective in Working with an Adolescent with Dual Diagnosis

Dual diagnosis has gradually become a problem among adolescents in Hong Kong. In working with persons with dual diagnosis, professionals are accustomed to use a disease model in diagnosis, treatment, and rehabilitation. By means of a case illustration, the writer tries to contrast a disease orientation and a strengths perspective in working with persons with dual diagnosis. The disease orientation stresses: addiction and mental illness; intoxication and dependence; symptoms and diagnosis; detoxification and treatment; confusion and control as well as resistance and labeling. The strengths perspective focuses on: decoding frustration and emptiness from addiction; searching for strengths to satisfy normal needs; establishing social support and encouraging participation in a healthy environment; re-anchoring self-confidence and capability development as well as maintaining empathetic trust. In this case, with the strengths perspective, the writer successfully helped an adolescent to re-build his self-confidence and re-establish a healthy social support system to live a normal life.     

Neighbourhood in a high rise, high density city: some observations on contemporary Hong Kong

Most of the contemporary literature on the neighbourhood comes from US or European sources where there are sharp contrasts with East Asian cities in terms of the physical form, residential densities and in relation to ideas of community and kinship. This paper reports on a study carried out in Hong Kong which was designed to explore the extent to which western preoccupations with neighbourhood resonate in a high rise, high density Chinese city. As a precursor to a larger scale study interviews were carried out with fifteen individuals in three contrasting locations: a New Town estate, an older, inner city area and a middle class housing estate. The interviews explored inter alia neighbourhood perceptions, ideas of community, sense of belonging and sense of place among contemporary Hong Kong residents. When Yuan Ssu became Confucius' steward he was given nine hundred measures of grain, which he declined. The Master said, ‘Can you not find a use for it in helping the people in your neighbourhood?’ (The Analects, Book VI).     

Non-parametric Back-projection of HIV Positive Tests using Multinomial and Poisson Settings

Back-projection is a commonly used method in reconstructing HIV incidence. Instead of using AIDS incidence data in back-projection, this paper uses HIV positive tests data. Both multinomial and Poisson settings are used. The two settings give similar results when a parametric form or step function is assumed for the infection curve. However, this may not be true when the HIV infection in each year is characterized by a different parameter. This paper attempts to use simulation studies to compare these two settings by constructing various scenarios for the infection curve. Results show that both methods give approximately the same estimates of the number of HIV infections in the past, whilst the estimates for HIV infections in the recent past differ a lot. The multinomial setting always gives a levelling-off pattern for the recent past, while the Poisson setting is more sensitive to the change in the shape of the HIV infection curve. Nonetheless, the multinomial setting gives a relatively narrower point-wise probability interval. When the size of the epidemic is large, the narrow probability interval may be under-estimating the true underlying variation.