Drug dependency and HIV testing among state prisoners

HIV and drug use are higher among prisoners than the general US population. This study examines drug dependency/use and differences between prisoners who volunteered for HIV testing and those who did not in a less densely populated state. It was hypothesized that prisoners who volunteered for an HIV test were engaged in more drug use and other risky behaviors than those who did not. Survey data were collected from 600 randomly selected inmates (567 males and 33 females) from 15 state prisons. Subjects were male (95%), white (63%), never married (43%), and 44% volunteered for an HIV test since entering prison. Ninety-two percent of inmates met DSM criteria for drug dependence in their lifetime. Those who volunteered for HIV testing were 2.6 times more likely to ever have used PCP; 1.5 times more likely to ever have used cocaine; 1.4 times more likely to ever have had a problem with drugs; 1.3 times more likely to have used opiates, and 1.6 times more likely to report having been sexually or physically abused. Implications for interventions are discussed.     

THE CHOICE BETWEEN SETS OF REGRESSORS

This paper examines the choice of critical values for testing both non-sequential and nested sequential sets of constraints in the standard linear regression model. Modest increases in (e.g.) t-ratio critical values relative to their one-off values are often sufficient to maintain proper size. A Bayesian decision-theoretic approach, highlighted by the Schwarz (1978) criterion, provides a framework for deriving consistency and asymptotic local power properties of both forms of testing (data mining) algorithms.     

Conditional interval estimation of the mean following rejection of a two sided test

The effect of rejecting a two-sided preliminary test of significance for the mean of a normal distribution upon subsequent interval estimation of the mean is examined. For the case where the variance is known, conditional confidence intervals may be shorter than unconditional intervals, in contrast to the one-sided preliminary test case examined by Meeks and D’Agostino (1983, The American Statistician, 7, 134-136) . For the case where the variance is unknown and must be estimated by the sample variance, it is shown that customary intervals do not offer uniformly greater or lesser coverage than the nominal level.     

中国C2C电子商务网站的用户体验

通过学生用户试用在两个不同文化背景下设计出来的C2C电子商务网站——淘宝网和Ebay易趣,并进行初次网上购物体验活动,以及对测试后满意度问卷的分析,结果显示:在用户决定购买的过程中,网站概念/功能的传递和表达对用户的影响最大,它们会影响到用户的初次购买决定;而流程的跳转以及交互行为的不平衡会对用户的购买过程造成影响;对用户初次购物总体评价影响最大的是功能满足。两个网站的系统可用性与界面设计不能决定用户的总体评价,但却会影响到用户对网站的感觉。因此,创建一个对用户有用、好用和想用的购物网站就必须要满足功能、交互以及冲击三个层次的要求。     

参数假设检验教学中的几个问题

在概率统计教学的基础上,对参数假设检验教学中出现的学生难于理解的几个问题做了系统的总结,主要包括决策的依据,拒绝域的选择以及决策可靠性的判断,其中对做出"接受零假设"决策的可靠性给出了解释。     

边限检验理论及几点讨论

检验经济变量之间长期关系的协整技术要求变量是同阶单整的,这不可避免地涉及一定程度的预检验问题,而预检验问题会增加变量间长期关系分析的不确定性。当不能确定变量的单整类型时,边限检验理论提出了一个可以直接检验一个变量和一组解释变量之间长期关系的新方法。在介绍了边限检验方法中基本的VAR模型和假设及边限检验方法中用到的重要统计量——Wald统计量和T统计量及它们各自的渐近分布形式后,说明了边限检验理论在理论和实际运用当中需要注意的几个问题,最后通过实例分析说明了边限检验理论的运用。     

Robust pairwise multiple comparisons under short-tailed symmetric distributions

In one-way ANOVA, most of the pairwise multiple comparison procedures depend on normality assumption of errors. In practice, errors have non-normal distributions so frequently. Therefore, it is very important to develop robust estimators of location and the associated variance under non-normality. In this paper, we consider the estimation of one-way ANOVA model parameters to make pairwise multiple comparisons under short-tailed symmetric (STS) distribution. The classical least squares method is neither efficient nor robust and maximum likelihood estimation technique is problematic in this situation. Modified maximum likelihood (MML) estimation technique gives the opportunity to estimate model parameters in closed forms under non-normal distributions. Hence, the use of MML estimators in the test statistic is proposed for pairwise multiple comparisons under STS distribution. The efficiency and power comparisons of the test statistic based on sample mean, trimmed mean, wave and MML estimators are given and the robustness of the test obtained using these estimators under plausible alternatives and inlier model are examined. It is demonstrated that the test statistic based on MML estimators is efficient and robust and the corresponding test is more powerful and having smallest Type I error.     

On False Discovery and Non‐discovery Proportions of the Dynamic Adaptive Procedure

This paper studies the asymptotic behaviour of the false discovery and non‐discovery proportions of the dynamic adaptive procedure under some dependence structure. A Bahadur‐type representation of the cut point in simultaneously performing a large scale of tests is presented. The asymptotic bias decompositions of the false discovery and non‐discovery proportions are given under some dependence structure. In addition to existing literatures, we find that the randomness due to the dynamic selection of the tuning parameter in estimating the true null rate serves as a source of the approximation error in the Bahadur representation and enters into the asymptotic bias term of the false discovery proportion and those of the false non‐discovery proportion. The theory explains to some extent why some seemingly attractive dynamic adaptive procedures do not outperform the competing fixed adaptive procedures substantially in some situations. Simulations justify our theory and findings.     

无机化学实验教学改革探索

分析了高校化工、生物技术、环境保护及食品工程等相关专业的专业基础课程《无机化学》实验教学改革的必要性,探索并实施了一系列有效的改革方案,取得了良好的实验教学效果.