Estimation of the Proportion of Defective Units by Using Group Testing Under the Existence of a Threshold of Detection

Group testing procedures, in which groups containing several units are tested without testing each unit, are widely used as cost-effective procedures in estimating the proportion of defective units in a population. A problem arises when we apply these procedures to the detection of genetically modified organisms (GMOs), because the analytical instrument for detecting GMOs has a threshold of detection. If the group size (i.e., the number of units within a group) is large, the GMOs in a group are not detected due to the dilution even if the group contains one unit of GMOs. Thus, most people conventionally use a small group size (which we call conventional group size) so that they can surely detect the existence of defective units if at least one unit of GMOs is included in the group. However, we show that we can estimate the proportion of defective units for any group size even if a threshold of detection exists; the estimate of the proportion of defective units is easily obtained by using functions implemented in a spreadsheet. Then, we show that the conventional group size is not always optimal in controlling a consumer's risk, because such a group size requires a larger number of groups for testing.     

Bad Probability,Good Statistics,and Group Testing for Binomial Estimation

This article examines some improperly stated but often used textbook probability problems. Moving from a probabilistic to a statistical setting provides insight into group testing (i.e., observing only whether one or more of a group responds and not the response of each individual). Exact methods are used to construct tables showing (i) that group testing n times to estimate p can be more efficient than n individual tests even for small n and large p, (ii) optimal grouping strategies for various (n, p) combinations, and (iii) the efficiencies and biases achieved.     

Group Variable Selection with Oracle Property by Weight-Fused Adaptive Elastic Net Model for Strongly Correlated Data

This paper is the generalization of weight-fused elastic net (Fu and Xu, 2012 Fu, G., Xu, Q. (2012). Grouping variable selection by weight fused elastic net for multi-collinear data. Communications in Statistics-Simulation and Computation 41(2):205–221.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]), which performs group variable selection by combining weight-fused LASSO(wfLasso) and elastic net (Zou and Hastie, 2005 Zou, H., Hastie, T. (2005). Regularization and variable selection via the elastic net. Journal of the Royal Statistical Society: Series B (Statistical Methodology) 67(2):301–320.[Crossref], [Web of Science ®] , [Google Scholar]) penalties. In this study, the elastic net penalty is replaced by adaptive elastic net penalty (AdaEnet) (Zou and Zhang, 2009 Zou, H., Zhang, H. (2009). On the adaptive elastic-net with a diverging number of parameters. Annals of Statistics 37(4):1733–1751.[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]), and a new group variable selection algorithm with oracle property (Fan and Li, 2001 Fan, J., Li, R. (2001). Variable selection via nonconcave penalized likelihood and its oracle properties. Journal of the American Statistical Association 96(456):1348–1360.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]; Zou, 2006 Zou, H. (2006). The adaptive lasso and its oracle properties. Journal of the American Statistical Association 101(476):1418–1429.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) is obtained.     

Two-Step Estimation of Incomplete Information Social Interaction Models With Sample Selection

ABSTRACT

This article considers linear social interaction models under incomplete information that allow for missing outcome data due to sample selection. For model estimation, assuming that each individual forms his/her belief about the other members’ outcomes based on rational expectations, we propose a two-step series nonlinear least squares estimator. Both the consistency and asymptotic normality of the estimator are established. As an empirical illustration, we apply the proposed model and method to National Longitudinal Study of Adolescent Health (Add Health) data to examine the impacts of friendship interactions on adolescents’ academic achievements. We provide empirical evidence that the interaction effects are important determinants of grade point average and that controlling for sample selection bias has certain impacts on the estimation results. Supplementary materials for this article are available online.     

First-exit times for compound poisson processes for some types of positive and negative jumps

We consider the one-sided and the two-sided first-exit problem for a compound Poisson process with linear deterministic decrease between positive and negative jumps. This process (X(t)) _t≥0 occurs as the workload process of a single-server queueing system with random workload removal, which we denote by M/G _u /G _d /1, where G _u (G _d ) stands for the distribution of the upward (downward) jumps; other applications are to cash management, dams, and several related fields. Under various conditions on G _u and G _d (assuming e.g. that one of them is hyperexponential, Erlang or Coxian), we derive the joint distribution of τ _y =inf{t≥0|X(t)?(0,y)}, y>0, and X(τ _y ) as well as that of T=inf{t≥0|X(t)≤0} and X(T). We also determine the distribution of sup{X(t)|0≤t≤T}.     

Communicating intersectionality through creative claims making: the queer undocumented immigrant project

ABSTRACT

Social movements confronting overlapping inequalities face the unique challenge of elucidating the heretofore invisible experiences of those whose identities lie at the intersection of existing movements. Social media platforms provide a direct outlet for intersectional social movements to make political claims visually by illuminating these complexities creatively with discursive resources such as symbols, text, and narratives. Using content analysis of images posted to the organization’s Facebook, we examine how lesbian, gay, bisexual, transgender, and queer (LGBTQ) immigration activists – as embodied by the Queer Undocumented Immigrant Project (QUIP) – attempt to communicate intersectionality online. Images posted by QUIP demonstrate how the existing ideas and values of separate established immigrant and LGBTQ movements can be reformulated and repackaged. However, the available discursive resources may compartmentalize identities, which then requires movements to generate new symbols, text, and narratives. By leveraging extant discursive resources and innovating new expressions, activists aim to communicate intersectional experiences and unite multiple struggles.     

The multiethnic state-building dilemma: national and ethnic minorities' identities in the Crimea

This article examines the process of national identity formation among ethnic minorities in the Crimea – specifically, how a new common identity develops in the system of existing identities, what meaning group identities have for different minorities group and how this process influences attitudes and stereotypes toward the ingroup and outgroup. Based on surveys in the Crimea, results show that formation of a common national and regional identity leads to developing of positive stereotypes toward members of other groups, who now are involved in a new group identity, but also is connected with formation of negative attitudes and stereotypes toward other groups. The meaning of identity depends on its position in the system of identities and can be used as a criterion for early warning of conflicts.     

“无直接利益冲突”的网络发生机制

近年来,“无直接利益冲突”现象在我国似乎形成一种所谓“涟漪效应”,其产生的深层根源在于社会分配的不公平及与之相联系的群体异质不公平感的普遍存在;其次也与利益表达机制的不畅通有关。在其产生的过程中,事件触发与演化的关联性往往是通过驱动机制、认同机制、社会比较与自我展示机制和说服争辩机制交互作用表现出来的。在信息时代,“无直接利益冲突”的这些相关发生机制往往与网络极化效应直接相关,即“无直接利益冲突”极易导致网络极化效应的产生,而网络极化效应也促使了“无直接利益冲突”的扩散。而这种双向互动的过程,正是“无直接利益冲突”网络发生机制的作用过程。由此,应给予充分重视。     

Exposure to occupational violence and the buffering effects of intra-oranizational support

This paper presents a conceptually distinct analysis of the data first reported by Leather et al. Specifically, it investigates the effects of exposure to a variety of forms of work-related violence upon work attitudes and general well-being within a sample of UK public house licensees—individuals who manage public houses and hold the licence permitting the sale of alcoholic drinks on the premises. In addition, it examines the role of social support in moderating such effects. Based upon a sample of 242 licensees, it reports a consistent interaction between exposure to such violence and the availability of perceived intra-organizational support in determining the size of any negative effects upon individual well-being, job satisfaction and organizational commitment. It is argued that exposure to all forms of work-related violence, including intimidation, verbal abuse and threat, should be seen as a potential stressor within the work environment, the negative effects of which are buffered by perceived support from within the organization, but not by that perceived to be available from informal sources such as family and friends.     

组织信息资源管理论纲

本文在简要分析现代组织管理环境基本特点的基础上,对社会组织的信息资源管理的功能、原则及其运作等若干问题进行了认真的探讨,以期进一步完善现代组织管理理论。