Statistical methods for clinical studies in the presence of surrogate end points

The use of surrogate end points has become increasingly common in medical and biological research. This is primarily because, in many studies, the primary end point of interest is too expensive or too difficult to obtain. There is now a large volume of statistical methods for analysing studies with surrogate end point data. However, to our knowledge, there has not been a comprehensive review of these methods to date. This paper reviews some existing methods and summarizes the strengths and weaknesses of each method. It also discusses the assumptions that are made by each method and critiques how likely these assumptions are met in practice.     

The Perceived Role of ICTs in Quality of Life in Three Chinese Cities

This study assesses the perceived role of information and communication technologies (ICTs) including the Internet, mobile telephone, CD/MD/MP3, television and VCR/VCD/DVD in raising quality of life (QoL). A comparison is made between three Chinese cities, namely, Beijing, Taipei and Hong Kong, to see if differences exist in the perceived value of various forms of ICTs in the three cities, which share Chinese culture but different levels of development. Household interviews with probability samples were conducted in the three cities in 2002–2003. The findings show that the Internet and mobile phone are considered as the most and second most important medium respectively in raising quality of life in all three cities, while television ranks third and other ICTs trail behind. Based on the findings, the authors advance four propositions for the perceived role of ICTs in QoL. First, there are four basic needs related to ICT’s role in QoL. These “ICT-QoL” needs are the need for interaction, need for being in touch, need for instantaneous communication, and need for entertainment. Second, people’s assessment of an ICT’s value in raising their QoL varies with the penetration rate of that ICT—the higher the penetration, the more positive is the assessment of that ICT’s role in QoL. Third, the perceived value of an ICT in QoL declines with time—the longer the ICT has been around after reaching full penetration rate, the lower the value is attached to its contribution to QoL. Finally, education has strong influences on the assessment of the Internet’s role in QoL. Highly educated people tend to value the Internet most as a QoL raiser irrespective of the city they reside in. As a QoL raiser, the Internet is favored more by highly educated while mobile and fixed phone are favored more by lowly educated people.     

Two-period pricing and ordering policy for the dominant retailer in a two-echelon supply chain with demand uncertainty

Retailing channels are increasingly being dominated by ‘power’ retailers who are in a position to dictate prices and ordering schedules to manufacturers and suppliers. A dominant retailer, such as Wal-Mart, has the ‘power’ to decide retail prices of products because there are so many manufacturers who are keen to sell their products through or to such a large and powerful retailer. Several products, such as electronic products, can be sold in the market for some periods during their lifecycles before they retreat, except when they are not popular with consumers after been introduced. Therefore, in case of such products, the retailer should not just consider a single-period pricing and ordering policy. It should make dynamic pricing and ordering decisions based on market demand forecast, in order to obtain maximum cumulative profit from the product during its lifecycle. In this study, we consider this scenario and construct a two-period model to discuss pricing and ordering problems for a dominant retailer with demand uncertainty in a declining price environment. We show that the maximum expected profit function is continuous concave, so the optimal solution to pricing and ordering policy exists and it is the one and only. We also analyze sensitivity of retailer's expected profit to the effects of parameters of price-discount sharing scheme and market demand.     

Asymptotic Comparison of Two Discriminants Used in Normal Covariate Classification

In this paper, we examine the performance of Anderson's classification statistic with covariate adjustment in comparison with the usual Anderson's classification statistic without covariate adjustment in a two-population normal covariate classification problem. The same problem has been investigated using different methods of comparison by some authors. See the bibliography. The aim of this paper is to give a direct comparison based upon the asymptotic probabilities of misclassification. It is shown that for large equal sample size of a training sample from each population, Anderson's classification statistic with covariate adjustment and cut-off point equal to zero, has better performance.     

Sequential selectiok procedures based on confidence sequences for normal populations

In this paper confidence sequences are used to construct sequential procedures for selecting the population with the a common variance. These procedures are shown to provide substantial saving, particularly in the expected samplw sizes of the inferior populations,over various procedures in the literature. A new “indifference zone” formulation is given for the correct selection probability requirement, and confidence sequences are also applied to construct sequential procedures for this new selection goal.     

The studentized location linear discriminant function

The location linear discriminant function is used in a two-population classification problem when the available data are generated from both binary and continuous random variables. Asymptotic distribution of the studentized location linear discriminant function is derived directly without the inversion of the corresponding characteristic function. The resulting plug-in estimate of the overall error of misclassification consists of the estimate based on the limiting distribution of the discriminant plus a correction term up to the second order. By comparison, our estimate avoids exact knowledge of the Mahalanobis distances which is necessary when the expansions of Vlachonikolis (1985) are used in the case of an arbitrary cut-off point. An example is re-examined and analysed in the present context.     

A stochastic programming model for production planning of perishable products with postponement

This study addresses the production planning problem for perishable products, in which the cost and shortage of products are minimised subject to a set of constraints such as warehouse space, labour working time and machine time. Using the concept of postponement, the production process for perishable products is differentiated into two phases to better utilise the resources. A two-stage stochastic programming with recourse model is developed to determine the production loading plan with uncertain demand and parameters. A set of data from a toy company shows the benefits of the postponement strategy: these include lower total cost and higher utilisation of resources. The impact of unit shortage cost under different probability distribution of economic scenarios on the total cost is analyzed. Comparative analysis of solutions with and without postponement strategies is also performed.     

So near and yet so far - socio-spatial factors affecting service accessibility

ABSTRACT

Conventionally, social service planners conduct statistical analyses on service data for future planning. However, the limitations are their neglect of the spatial characteristics of these social data and their effects. All human activities have social and spatial dimensions. Social service provision is no exception. In this study, the authors suggest a socio-spatial framework in term of understanding service accessibility. A questionnaire survey was conducted and 491 participants, users and non-users, were interviewed. The results show that both spatial and social capital factors affect service accessibility. The study can help better service planning in densely-populated Asian metropolis like Hong Kong.     

Gender Matters: Rethinking the Childcare Model in Hong Kong

This study aims to reveal the gendered practices in childcare under the family care model and the effects of these practices on carers in Hong Kong. Familial ideology remains a dominant welfare principle in childcare policy in Hong Kong, which assumes that family care is the best form of care provision. However, this policy assumption fails to respond to the needs in childcare arising from the social changes and development. The suggested possible solution for this issue is the shifting of the family care model to the social care model, in which childcare responsibilities are shared between the family and the state.     

Are Liberal Studies teachers ready to prepare human rights respecting students? A portrait of teachers’ attitudes towards human rights

As in most countries, human rights education (HRE) in Hong Kong has never been high on the educational agenda. In 2009, a compulsory subject, Liberal Studies (LS), which could be used as a platform for HRE, was introduced. The Hong Kong Institute of Education launched a research and development project which, as one of its objectives, studied LS teachers’ attitudes towards human rights and Rule of Law. This article first provides a brief overview of HRE. Then, the potential of HRE in LS will be discussed, followed by an introduction of the research project. Subsequently, the research design and findings will be presented. The findings reveal that there is a large gap between teachers’ understandings of human rights and international human rights standards. Since LS teachers’ attitudes are crucial for effective HRE, the findings are quite striking. The paper ends with recommendations for further research, policy formulations, and teacher preparation.