Multiple event times in the presence of informative censoring: modeling and analysis by copulas

Motivated by a breast cancer research program, this paper is concerned with the joint survivor function of multiple event times when their observations are subject to informative censoring caused by a terminating event. We formulate the correlation of the multiple event times together with the time to the terminating event by an Archimedean copula to account for the informative censoring. Adapting the widely used two-stage procedure under a copula model, we propose an easy-to-implement pseudo-likelihood based procedure for estimating the model parameters. The approach yields a new estimator for the marginal distribution of a single event time with semicompeting-risks data. We conduct both asymptotics and simulation studies to examine the proposed approach in consistency, efficiency, and robustness. Data from the breast cancer program are employed to illustrate this research.

     

优选方案定量评价模型研究

在确定评价指标体系的基础上，如何对若干事物或方案进行选优是一个十分有意义的问题．作者利用模糊多目标决策对此进行研究，并通过实例说明该方法的有效性与实用性．     

Risk,trust and knowledge networks in farmers’ learning

This study reports on New Zealand dairy farmers’ access to and use of information as mediated through conditions of risk and trust within the context of their interpersonal social networks. We located participants’ reports of their information use within their perceived environments of trust and risk, following Giddens's [1990. The consequences of modernity. Polity Press, Stanford, CA] typology of trust and risk in pre-modernity and modernity. The research participants were constant users of interpersonal and print information from numerous sources, and monitored their incoming data in the light of strategic needs, reflecting their roles as both farming practitioners and business owners. Socio-spatial knowledge networks (SSKNs) combine individuals’ explanatory cognitive models of information acquisition and use with a micro-geographical analysis of their interpersonal networks. The participants showed characteristics of pre-modern, modern and even post-modern society in respect of their use of complex interactional forms, as well as a blending of individualistic and communitarian practices and concerns in their professional and personal lives.     

A case study of the labour market status of recent mainland Chinese immigrants,metropolitan Toronto

"This article focuses on an analysis of the labour market status of recent MCIs [mainland Chinese immigrants to Canada], taking into account such factors as gender, educational attainment, language proficiency and period of arrival (or length of residence in Canada), and uses Metropolitan Toronto as a case study. The effect of each factor on MCIs' labour market status will be analysed separately, followed by two logit models examining the simultaneous effects of the factors and their relative importance." (SUMMARY IN FRE AND SPA)     

On changes in the age composition of the population and policy options for population planning

This analysis, based on 1978 data from official household registers, suggests that the 1983-2000 period will be critical for China's efforts to control population growth. If declines in the fertility rate are maintained, the possibility of stabilizing China's population at 800-900 million in the next century is feasible. If the population is to be kept under 1.2 billion by the year 2000, the general fertility rate must be lowered to 1.8 in 1985 and must decline 0.1 each 5 years thereafter until it reaches 1.5 in the year 2000. Once population growth is brought under control, it will be necessary to address consequent increases in the median age of the population. Those over 65 years of age will comprise 7.1-7.8% of the population in the year 2000, depending on whether fertility rates are low or high. The medium projection includes a population of 1.211 billion in the year 2000, approaching the peak value but allowing the fertility rate to rise slowly to guard against excessive aging of the population. The proportion of those over 65 years of age reaches a peak value of 20.2% in the year 2040. Overall, these projections suggest a "golden age" continuing until about 2020 in which the proportion of those both over 65 years and under 15 years will be rather low. The dependency ratio should begin to climb after 2020, reaching a peak in 2040 and stabilizing by 2070 at a level slightly higher than that existing today in developed countries. Since a rational age composition and a suitable decrease in the proportion of dependents are essential for economic growth, future analyses should focus on the quality of the population and not just population size. As long as birth rates continue to fall, the proportion of the dependent population will also fall and have a beneficial effect on China's economic development.     

A gold key to initiate a new situation in family planning work]

Because of the popularization of a responsible agricultural production system, the livilihood of peasants has been improving greatly, while the demands and needs of the general public are also increasing at the same time. Still under the influence of the traditional belief of carrying on one's family line and emphasis on having male children, married people prefer to have more childre, and the birth rate is now rising again. In order to solve this new problem, we need to teach the peasants national policies on population, land utilization, and food supply. In order to initiate a new situation in family planning work, we need to control this "gold key" of ideological education and propaganda. The emphasis should be placed on ideological education for cadres at all levels as well as the general public in order that they may understand the Party's strategy. Education on the national strategy should be combined with material interests of the peasants, and reward and punishment in production should also be linked up with that of family planning. Social measures are needed to reduce economic burdens of the peasants, offer better treatment for single-child households, and provide adequate care for old and retired people. Family planning projects should be consolidated and improved. Scientific management, facilities and techniques for birth control, compensation for working personnel in family planning, and other practical problems deserve immediate attention and solution.     

Finie mixures of canonical fundamenal skew $$$$-disribuions

This paper introduces a finite mixture of canonical fundamental skew \(t\) (CFUST) distributions for a model-based approach to clustering where the clusters are asymmetric and possibly long-tailed (in: Lee and McLachlan, arXiv:1401.8182 [statME], 2014b). The family of CFUST distributions includes the restricted multivariate skew \(t\) and unrestricted multivariate skew \(t\) distributions as special cases. In recent years, a few versions of the multivariate skew \(t\) (MST) mixture model have been put forward, together with various EM-type algorithms for parameter estimation. These formulations adopted either a restricted or unrestricted characterization for their MST densities. In this paper, we examine a natural generalization of these developments, employing the CFUST distribution as the parametric family for the component distributions, and point out that the restricted and unrestricted characterizations can be unified under this general formulation. We show that an exact implementation of the EM algorithm can be achieved for the CFUST distribution and mixtures of this distribution, and present some new analytical results for a conditional expectation involved in the E-step.     

Power analysis for clustered non-continuous responses in multicenter trials

Power analysis for multi-center randomized control trials is quite difficult to perform for non-continuous responses when site differences are modeled by random effects using the generalized linear mixed-effects model (GLMM). First, it is not possible to construct power functions analytically, because of the extreme complexity of the sampling distribution of parameter estimates. Second, Monte Carlo (MC) simulation, a popular option for estimating power for complex models, does not work within the current context because of a lack of methods and software packages that would provide reliable estimates for fitting such GLMMs. For example, even statistical packages from software giants like SAS do not provide reliable estimates at the time of writing. Another major limitation of MC simulation is the lengthy running time, especially for complex models such as GLMM, especially when estimating power for multiple scenarios of interest. We present a new approach to address such limitations. The proposed approach defines a marginal model to approximate the GLMM and estimates power without relying on MC simulation. The approach is illustrated with both real and simulated data, with the simulation study demonstrating good performance of the method.     

An elastic-net penalized expectile regression with applications

To perform variable selection in expectile regression, we introduce the elastic-net penalty into expectile regression and propose an elastic-net penalized expectile regression (ER-EN) model. We then adopt the semismooth Newton coordinate descent (SNCD) algorithm to solve the proposed ER-EN model in high-dimensional settings. The advantages of ER-EN model are illustrated via extensive Monte Carlo simulations. The numerical results show that the ER-EN model outperforms the elastic-net penalized least squares regression (LSR-EN), the elastic-net penalized Huber regression (HR-EN), the elastic-net penalized quantile regression (QR-EN) and conventional expectile regression (ER) in terms of variable selection and predictive ability, especially for asymmetric distributions. We also apply the ER-EN model to two real-world applications: relative location of CT slices on the axial axis and metabolism of tacrolimus (Tac) drug. Empirical results also demonstrate the superiority of the ER-EN model.