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.     

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。     

价格持续期、信息传递与市场微观结构——基于非对称ACD模型的实证分析

本文建立两状态价格持续期的非对称对数自回归条件持续期模型,引入买卖价差、交易量、交易规模、指令流等信息交易间接度量变量,在刻画条件期望价格持续期对价格上升和下降两种状态的不对称依赖关系的同时,探讨价格持续期的信息传递机制并检验微观结构相关假说。实证分析表明,在选取样本中,滞后买卖价差与滞后交易量与条件期望价格持续期显著负相关;滞后买一(卖一)指令申报数量与条件期望价格持续期具有显著相关性,其符号由当期价格状态决定;大规模交易比中等规模交易对条件期望价格持续期有着更加显著的影响。即实证结果支持信息交易增加导致交易持续期减小的观点,不支持隐藏交易假说。     

略谈亚健康

健康是人类追求和探索的永恒主题,是人类最大的财富,渴望健康是人类唯一没有时间与疆界藩蓠的共同理想,对无往不胜的人类来说,唯一无法征服和打败的,大概也是健康了。在新的世纪里,人们有能力为自己的健康负起更大的责任,不断地改善自己的健康水平。本文主要通过对亚健康的成因,检测、预防和消除的研究,使我们更全面,更科学的认知亚健康,预防亚健康,走出亚健康.     

A product-limit estimator for use with length-biased data

The following life-testing situation is considered. At some time in the distant past, n objects, from a population with life distribution F, were put in use; whenever an object failed, it was promptly replaced. At some time τ, long after the start of the process, a statistician starts observing the n objects in use at that time; he knows the age of each of those n objects, and observes each of them for a fixed length of time? ∞, or until failure, whichever occurs first. In the case where T is finite, some of the observations may be censored; in the case where T =∞, there is no censoring. The total life of an object in use at time ∞ is a length-biased observation from F. A nonparametric estimator of the (cumulative) hazard function is proposed, and is used to construct an estimator of F which is of the product-limit type. Strong uniform consistency results (for n → ∞) are obtained. An “Aalen-Johansen” identity, satisfied by any pair of life distributions and their (cumulative) hazard functions, is used in obtaining rate-of-convergence results.     

The stalactite plot for the detection of multivariate outliers

Detection of multiple outliers in multivariate data using Mahalanobis distances requires robust estimates of the means and covariance of the data. We obtain this by sequential construction of an outlier free subset of the data, starting from a small random subset. The stalactite plot provides a cogent summary of suspected outliers as the subset size increases. The dependence on subset size can be virtually removed by a simulation-based normalization. Combined with probability plots and resampling procedures, the stalactite plot, particularly in its normalized form, leads to identification of multivariate outliers, even in the presence of appreciable masking.     

Radon Testing Behavior in a Sample of Individuals with High Home Radon Screening Measurements

Although radon exposure has been identified as the second leading cause of lung cancer, fewer than 6% of U.S. homeowners test their homes for radon. This report examines participants'follow-up radon testing behavior subsequent to receiving an initial screening radon level greater than 20 pCi/L. Sixty-two participants in the Iowa State-Wide Rural Radon Screening Survey who had radon screening measurements over 20 pCi/L were questioned by phone survey 3 months after receipt of their radon screening result to assess: whether participants were aware of radon's health risk; if participants recalled the radon screening results; how participants perceived the relative health risk of radon and whether participants planned follow-up radon testing. Only 19% of the respondents specifically identified lung cancer as the possible adverse health outcome of high radon exposure, and the majority of participants underestimated the health risks high radon levels pose when compared to cigarettes and x-rays. In addition, less than one third (29%)of the participants actually remembered their radon screening level within 10 pCi/L 3 months after receiving their screening results. Only 53% of the individuals correctly interpreted their screening radon level as being in the high range, and only 39% of the participants planned follow-up radon measurements. Receipt of radon screening test results indicating high radon levels was not an adequate motivational factor in itself to stimulate further radon assessment or mitigation. Our findings suggest that free radon screening will not result in a dramatic increase in subsequent homeowner initiated remediation or further recommended radon testing.     

Performance evaluation of normal distribution software

Methods are developed to test the performance of software for calculating the standard normal distribution function. The accuracy and implementation details of the tests are described. Results are presented on a selection of available codes, showing a wide variation in performance. At least one published code is shown to have severe defects.     

我国和西欧地区机床工业企业管理的抽样比较研究

本文通过抽样数据分析对我国和西欧地区的机床工业企业的生产管理进行评价比较。文中首先应用多集合的数据包络分析(DEA)方法,选用3个投入变量和2个产出变量对之进行相对有效性的综合评价。然后,应用t检验和Kolmogorov-Smirnov检验对生产管理的诸方面作显著性差异的检验。指出差距所在,并提出了一些改进管理的参考意见。