Factor screening in nonregular two-level designs based on projection-based variable selection

In this paper, we focus on the problem of factor screening in nonregular two-level designs through gradually reducing the number of possible sets of active factors. We are particularly concerned with situations when three or four factors are active. Our proposed method works through examining fits of projection models, where variable selection techniques are used to reduce the number of terms. To examine the reliability of the methods in combination with such techniques, a panel of models consisting of three or four active factors with data generated from the 12-run and the 20-run Plackett–Burman (PB) design is used. The dependence of the procedure on the amount of noise, the number of active factors and the number of experimental factors is also investigated. For designs with few runs such as the 12-run PB design, variable selection should be done with care and default procedures in computer software may not be reliable to which we suggest improvements. A real example is included to show how we propose factor screening can be done in practice.     

“共享员工”制度常态化可行性研究

新冠疫情期间,企业为了缓解各方面压力,探索出"共享员工"新型用工形式,具体表现为企业间共享模式、用工单位直接与劳动者签订劳务合同以及在第三方介入下实现员工共享。中央及地方政府也纷纷推出鼓励"共享员工"发展的政策。但是"共享员工"制度是否能在常时条件下成为一种用工形式仍存在一系列问题。"共享员工"制度常态化的可能性应从其对劳务派遣制度"三性"的突破、对传统员工借调主体范围的扩大以及对共享经济用工模式的补充等方面分析。"共享员工"制度实现常态化需要以平台经济为依托,借助政府监督机构,对其他用工制度的不足进行修复式移用。     

贵州城乡经济一体化现状、问题及对策研究

本文首先分析了城乡经济一体化的基本内涵,同时主要采用城乡居民收入差异系数、城乡居民恩格尔系数差异系数、二元对比系数以及城乡居民收入差异倍数、城乡居民积累差异倍数五个基本指标分析了贵州省1978年-2006年城乡差异的现状。分析得出贵州省存在较显著的城乡二元经济结构,城乡经济一体化任重而道远。     

人口老龄化：进程模拟和政策机制分析

以人口老龄化系数分析为主线,对相关统计数据从生育率、死亡率、老龄化系数、跨期队列人口四个方面进行模拟分析,推算出中国人口老龄化进程在1976年开始出现;计划生育政策是老龄化进程加速的关键因素,并导致我国步入老龄化国家行列的时间提前了12年;面对老龄化和高龄化浪潮,应当实行由国家主导、社会与家庭广泛参与的多元化的老龄化应对举措。     

应用同伦正则化算法反演二维溶质运移模型中的弥散系数

利用同伦正则化算法探讨了二维对流弥散方程的依赖空间变量的弥散系数反演问题.讨论了初始迭代值、数值微分步长、以及收敛精度对算法实现的影响.数值模拟表明,同伦正则化算法对于此类参数反演问题是一种有效的方法.     

On deaf ears: anti-black police terror,multiracial protest and white loyalty to the state

In this essay, we explore the racialised dimensions of policing practices in Brazil. To do so, we look not at the police, their administrative organisation, and practices, but rather we examine the modes of sociality reflected in and produced by police violence. Drawing from a statistics-based analysis of the social and political outcomes produced by the state in its preparation of mega-sports events – evictions, incarceration, and police violence, for example – we identify a nexus between, on the one hand, racialised violence against black bodies and, on the other hand, white loyalty to the state, despite, or precisely because of, a specific type of violence perpetrated by the state on white bodies. Our primary contention is that we cannot understand white victimisation by the police – and the outrage it produces – without taking into consideration two foundational, dialectical aspects of the regime of rights: complicity and disavowal. White vulnerability to this specific form of state violence – a form of violence that is contingent and produces collective horror – reflects not only the disavowal of black suffering, but also the strengthening of the white public sphere.     

Approximate confidence intervals for the weighted kappa coefficient of a binary diagnostic test subject to a case–control design

Case–control design to assess the accuracy of a binary diagnostic test (BDT) is very frequent in clinical practice. This design consists of applying the diagnostic test to all of the individuals in a sample of those who have the disease and in another sample of those who do not have the disease. The sensitivity of the diagnostic test is estimated from the case sample and the specificity is estimated from the control sample. Another parameter which is used to assess the performance of a BDT is the weighted kappa coefficient. The weighted kappa coefficient depends on the sensitivity and specificity of the diagnostic test, on the disease prevalence and on the weighting index. In this article, confidence intervals are studied for the weighted kappa coefficient subject to a case–control design and a method is proposed to calculate the sample sizes to estimate this parameter. The results obtained were applied to a real example.     

Unified Inference for Sparse and Dense Longitudinal Data in Time‐varying Coefficient Models

Time‐varying coefficient models are widely used in longitudinal data analysis. These models allow the effects of predictors on response to vary over time. In this article, we consider a mixed‐effects time‐varying coefficient model to account for the within subject correlation for longitudinal data. We show that when kernel smoothing is used to estimate the smooth functions in time‐varying coefficient models for sparse or dense longitudinal data, the asymptotic results of these two situations are essentially different. Therefore, a subjective choice between the sparse and dense cases might lead to erroneous conclusions for statistical inference. In order to solve this problem, we establish a unified self‐normalized central limit theorem, based on which a unified inference is proposed without deciding whether the data are sparse or dense. The effectiveness of the proposed unified inference is demonstrated through a simulation study and an analysis of Baltimore MACS data.     

Computational approach test for inference about several correlation coefficients: Equality and common

In this article, we consider inference about the correlation coefficients of several bivariate normal distributions. We first propose computational approach tests for testing the equality of the correlation coefficients. In fact, these approaches are parametric bootstrap tests, and simulation studies show that they perform very satisfactory, and the actual sizes of these tests are better than other existing approaches. We also present a computational approach test and a parametric bootstrap confidence interval for inference about the parameter of common correlation coefficient. At the end, all the approaches are illustrated using two real examples.     

用二元n维序列证明一些组合系数恒等式

通过建立“二元集上n维序列”概念,用组合分析的新方法证明了一些组合恒等式.