Heterogeneity's Ruses: Some Surprising Effects of Selection on Population Dynamics

As a cohort of people, animals, or machines ages, the individuals at highest risk tend to die or exit first. This differential selection can produce patterns of mortality for the population as a whole that are surprisingly different from the patterns for subpopulations or individuals. Naive acceptance of observed population patterns may lead to erroneous policy recommendations if an intervention depends on the response of individuals. Furthermore, because patterns at the individual level may be simpler than composite population patterns, both theoretical and empirical research may be unnecessarily complicated by failure to recognize the effects of heterogeneity.     

Another Proof of Borel's Strong Law of Large Numbers

Let X be a continuous nonnegative random variable with finite first and second moments and a continuous pdf that is positive on the interior of its support. A nonzero limiting density at the origin and a coefficient of variation (CV) greater than 1 are shown to be sufficient conditions for the distribution truncated below at t > 0 to have a variance greater than the variance of the full distribution. Distributions that satisfy these conditions include those with decreasing hazard rates (e.g., the gamma and Weibull distributions with shape parameters less than 1) and the beta distribution with parameter values p and q for which q > p(p + q + 1). The bound T for which truncation at 0 < t < T increases the variance relative to the full distribution is shown to be greater than the (1 — 1/CV)th percentile of the full distribution.     

Strategies for a sequential selection of the better of two trinomial populations

A sequential procedure for a selection of the better of two trinomial populations has been proposed by ?idók (1988). The present paper shows some Monte Carlo results for 4 different strategies of sequential experimentation in this procedure, on this basis compares the strategies, and gives some practical recommendations for choosing the strategy.     

Multi-response permutation procedures for a priori classifications

An exact permutation test for analyzing and/or dredging multi-response data at the ordinal or higher levels is presented. The associated test statistic is based on the average distance (or any specified norm) between points within a priori disjoint subgroups of a finite population of points in an r-dimensional space (corresponding to r measured responses from each object in a finite population of objects). Alternative approximate tests based on the beta and normal distributions are provided. Two detailed examples utilizing actual social science data are considered, including comparisons of the approximate tests. An additional example describes the behavior of these tests under a variety of conditions, including extreme data configurations     

大规模灾害中基于聚类的医疗物资联合运送优化

应急响应中,往往出现救援物资供应节点与需求节点距离太远、关键道路损毁导致难以及时通过车辆运送物资到灾区等情景,此时直升飞机逐渐被用来运送关键应急资源（如医疗物资及医护人员）。然而,大规模灾害中难以使用直升飞机运送医疗物资到每个医疗救助点,通常考虑灾民的聚集性选择一定数量的应急中转点,以接收直升飞机运送的医疗物资,之后采用车辆运送物资到其覆盖的医疗救助点。针对该问题,提出一种基于聚类的两阶段医疗物资联合运输方法：第一阶段根据医疗救助点分布,采用模糊C-均值算法（FCM）进行应急中转点选择和医疗救助点划分,并针对FCM划分中存在的剩余容量不均衡问题,考虑容量约束提出一种改进划分方法（FCMwCC）,构建“直升飞机-车辆”医疗物资联合运输网络结构;第二阶段建立基于聚类的运送路线优化模型,确定从应急中转点到医疗救助点的具体运送路线。数值实验验证了提出方法和算法的有效性。     

The impact of the Victorian infringements system on disadvantaged groups: findings from a qualitative study

This article focuses on the infringements system currently operating in the state of Victoria, Australia and, in particular, its impact on disadvantaged groups, such as people suffering homelessness, drug and alcohol dependency, mental illness, acquired brain injury, poverty, and domestic violence. The concerns of lawyers working in community legal centres striving to address the needs of people in these disadvantaged groups prompted this qualitative study, which involved in‐depth interviews with key stakeholders in the infringements system. Participants included those who issue and enforce fines, those who represent vulnerable fine recipients, and the fine recipients themselves. The research sought participants' understanding of the system, its aims, and its outcomes. This article presents an overview of the research findings in relation to the complex Victorian infringements system process, net‐widening, proportionality, and the 'special circumstances' process. Our findings suggest that the Victorian infringements system is expedient and efficient when people can promptly pay their fines. However, multiple issues need to be addressed if the system is to be just and fair to people suffering various types of disadvantage. A number of systemic changes and educational initiatives are recommended, along with law reform that addresses the unreasonable and unacceptable impacts on disadvantaged groups in Victoria.     

临时工作人员被侵权之责任认定问题探究

临时工作人员在用人单位受到人身损害,是否存在劳动法律关系,决定其采取请求工伤保险赔偿抑或民事侵 权赔偿两种救济途径。劳动法律关系的确立对劳动者的保护更为全面,而成立劳动法律关系往往需要多种实质条件, 这排除了大量游离于正常用工之外的临时工作人员,临时工作人员被侵权之责任认定问题尤为重要,被视为保护劳动 者的最后一道防线。用人单位对临时工作人员的安全保障义务是法定义务,消极不作为导致他人遭受人身损害是违 反法定义务的行为,若不作为行为与损害结果之间存在因果关系,应就其过错承担相应责任。民事法律关系在现实生 活中表现形式多样,增加了认识侵权之责的难度,探究临时工作人员被侵权之责任认定,有助于在司法实践中对侵权 责任认识的统一。     

Some subset selection problems

Consider that we have a collection of k populations π₁, π₂…,π_k. The quality of the ith population is characterized by a real parameter θ_i and the population is to be designated as superior or inferior depending on how much the θ_i differs from θ_max = max{θ₁, θ₂,…,θ_k}. From the set {π₁, π₂,…,π_k}, we wish to select the subset of superior populations. In this paper we devise rules of selection which have the property that their selected set excludes all the inferior populations with probability at least 1?α, where a is a specified number.     

On the problem of selecting good populations

The problem of selecting good populations out of k normal populations is considered in a Bayesian framework under exchangeable normal priors and additive loss functions. Some basic approximations to the Bayes rules are discussed. These approximations suggest that some well-known classical rules are "approximate" Bayes rules. Especially, it is shown that Gupta-type rules are extended Bayes with respect to a family of the exchangeable normal priors for any bounded and additive loss function. Furthermore, for a simple loss function, the results of a Monte Carlo comparison of Gupta-type rules and Seal-type rules are presented. They indicate that, in general, Gupta-type rules perform better than Seal-type rules