t-Latinized Designs

A variety trial sometimes requires a resolvable block design in which the replicates are set out next to each other. The long blocks running through the replicates are then of interest. A t -latinized design is one in which groups of these t long blocks are binary. In this paper examples of such designs are given. It is shown that the algorithm described by John & Whitaker (1993) can be used to construct designs with high average efficiency factors. Upper bounds on these efficiency factors are also derived.     

Robustness to non-normality and autocorrelation of individuals control charts

This paper studies the effects of non-normality and autocorrelation on the performances of various individuals control charts for monitoring the process mean and/or variance. The traditional Shewhart X chart and moving range (MR) chart are investigated as well as several types of exponentially weighted moving average (EWMA) charts and combinations of control charts involving these EWMA charts. It is shown that the combination of the X and MR charts will not detect small and moderate parameter shifts as fast as combinations involving the EWMA charts, and that the performana of the X and MR charts is very sensitive to the normality assumption. It is also shown that certain combinations of EWMA charts can be designed to be robust to non-normality and very effective at detecting small and moderate shifts in the process mean and/or variance. Although autocorrelation can have a significant effect on the in-control performances of these combinations of EWMA charts, their relative out-of-control performances under independence are generally maintained for low to moderate levels of autocorrelation.     

The effect of autocorrelation on the ewma maxmin tolerance limits

Amin et al. (1999) developed an exponentially weighted moving average (EWMA) control chart, based on the smallest and largest observations in each sample. The resulting plot of the extremes suggests that the MaxMin EWMA may also be viewed as smoothed tolerance limits. Tolerance limits are limits that include a specific proportion of the population at a given confidence level. In the context of process control, they are used to make sure that production will not be outside specifications. Amin and Li (2000) provided the coverages of the MaxMin EWMA tolerance limits for independent data. In this article, it is shown how autocorrelation affects the confidence level of MaxMin tolerance limits, for a specified level of coverage of the population, and modified smoothed tolerance limits are suggested for autocorrelated processes.     

Computing optimal adjustment schemes for the general tool-wear problem

An important problem in process adjustment using feedback is how often to sample the process and when and by how much to apply an adjustment. Minimum cost feedback schemes based on simple, but practically interesting, models for disturbances and dynamics have been discussed in several particular cases. The more general situation in which there may be measurement and adjustment errors, deterministic process drift, and costs of taking an observation, of making an adjustment, and of being off target, is considered in this article. Assuming all these costs to be known, a numerical method to minimize the overall expected cost is presented. This numerical method provides the optimal sampling interval, action limits, and amount of adjustment; and the resulting average adjustment interval, mean squared deviation from target, and minimum overall expected cost. When the costs of taking an observation, of making an adjustment, and of being off target are not known, the method can be used to choose a particular scheme by judging the advantages and disadvantages of alternative options considering the mean squared deviation they produce, the frequency with which they require observations to be made, and the resulting overall length of time between adjustments. Computer codes that perform the required computations are provided in the appendices and applied to find optimal adjustment schemes in three real examples of application.     

产业集群持续竞争优势的动态能力分析视角

传统理论对于产业集群持续竞争优势的研究多是基于稳定或渐变的环境来分析的,因而在动态复杂环境下很难适用。动态能力理论是战略管理领域研究的一个前沿理论,它为我们解释动态复杂环境下的产业集群持续竞争优势问题提出了一个新的分析视角。     

女性人口文化程度对其婚育状况的影响探析

本文以1995年全国1％人口抽样调查资料为基础,对女性人口文化程度与其早婚状况、平均初婚年龄．以及女性初婚年龄与其平均活产子女数间的相关关系进行了深入的定量分析．     

Violence Against African American Women in Prisons and Jails

Abstract

The United States prison population is bulging and in recent years, the percentage of African American women being incarcerated far outnumber any other group. As the Black women in jails and prisons grow, so do the whispers about sexual abuse and labor abuse inside these institutions. This article discusses the nature of violence directed against incarcerated Black women and why it is important to direct national attention to this problem. It argues that though the violence may be individually directed, it is institutionally founded. Strategies are proposed for humanizing local jails and federal and state prisons.     

The Hobo Anomalous: Class,minorities and political invention in the Industrial Workers of the World

This article is an analysis of minority political invention in the Industrial Workers of the World (IWW). Against the tendency in recent social and cultural theory to dichotomize class and difference, it argues that it was in and through the IWW's formulation of class that minority political and cultural invention occurred. Using the framework of Deleuze and Guattari's minor politics, the article shows how the IWW's composition in the simultaneously diffuse and cramped plane of work operated against the major political identities and subjects of worker, immigrant, American, citizen and 'people', and towards the creation of minority political knowledges, tactics and cultural styles premised on the condition that 'the people are missing'. Seeking to understand the IWW's modes and techniques of invention, the article explores the general plane of IWW composition, its particular political and cultural expressions (in songs, manifestos, cartoons and tactics), and its minor mode of authorship. The article focuses in particular on two aspects of IWW minority composition, the itinerant worker, or hobo, and the politics of sabotage.     

Comparison of estimators of the location parameter using pitman's closeness criterion

Necessary and sufficient conditions for a linear estimator to dominate another linear estimator of a location parameter under the Pitman's criterion of comparison are discussed. Consequently it is demonstrated that a linear biased estimator can not dominate a linear unbiased estimator under Pitman's criterion and that the sample mean is the Closest Linear Unbiased Estimator (CLUE). It is also shown that the ridge regression estimator with a known biasing constant can not dominate the ordinary least squares estimator. If an estimator δdominates an estimator δin the average loss sense then sufficient conditions are obtained under which δis also preferred over δunder Pitman's criterion. Further we obtain sufficient conditions under which preference under the Pitman's criterion will lead to preference under the mean squared error sense.     

Is regression adjustment supported by the Neyman model for causal inference?

This paper examines both theoretically and empirically whether the common practice of using OLS multivariate regression models to estimate average treatment effects (ATEs) under experimental designs is justified by the Neyman model for causal inference. Using data from eight large U.S. social policy experiments, the paper finds that estimated standard errors and significance levels for ATE estimators are similar under the OLS and Neyman models when baseline covariates are included in the models, even though theory suggests that this may not have been the case. This occurs primarily because treatment effects do not appear to vary substantially across study subjects.