A Comparison of Approaches to Interval Estimation of Mediated Effects in Linear Regression Models

A novel approach based on the concepts of a generalized pivotal quantity (GPQ) is developed to construct confidence intervals for the mediated effect. Thereafter, its performance is compared with six interval estimation approaches in terms of empirical coverage probability and expected length via simulation and two real examples. The results show that the GPQ-based and bootstrap percentile methods outperform other methods when mediated effects exist in small and medium samples. Moreover, the GPQ-based method exhibits a more stable performance in small and non-normal samples. A discussion on how to choose the best interval estimation method for mediated effects is presented.     

Confidence intervals for the difference in paired Youden indices

Comparison of accuracy between two diagnostic tests can be implemented by investigating the difference in paired Youden indices. However, few literature articles have discussed the inferences for the difference in paired Youden indices. In this paper, we propose an exact confidence interval for the difference in paired Youden indices based on the generalized pivotal quantities. For comparison, the maximum likelihood estimate‐based interval and a bootstrap‐based interval are also included in the study for the difference in paired Youden indices. Abundant simulation studies are conducted to compare the relative performance of these intervals by evaluating the coverage probability and average interval length. Our simulation results demonstrate that the exact confidence interval outperforms the other two intervals even with small sample size when the underlying distributions are normal. A real application is also used to illustrate the proposed intervals. Copyright © 2012 John Wiley & Sons, Ltd.     

Approximate MLEs of the parameters of location-scale models under type II censoring

Log-location-scale distributions are widely used parametric models that have fundamental importance in both parametric and semiparametric frameworks. The likelihood equations based on a Type II censored sample from location-scale distributions do not provide explicit solutions for the para-meters. Statistical software is widely available and is based on iterative methods (such as, Newton Raphson Algorithm, EM algorithm etc.), which require starting values near the global maximum. There are also many situations that the specialized software does not handle. This paper provides a method for determining explicit estimators for the location and scale parameters by approximating the likelihood function, where the method does not require any starting values. The performance of the proposed approximate method for the Weibull distribution and Log-Logistic distributions is compared with those based on iterative methods through the use of simulation studies for a wide range of sample size and Type II censoring schemes. Here we also examine the probability coverages of the pivotal quantities based on asymptotic normality. In addition, two examples are given.     

存在议价能力和副产品协同生产的制造商最优产量决策

考虑由环保型制造商和处理厂构成的两级供应链结构，其中上游制造商进行主产品的生产，而下游处理厂通过对废料加工进行副产品的生产。基于供应链成员之间存在不同议价能力的情形，构建了上游制造商将产生的废料给下游进行处理的协同生产模式，给出了主产品的均衡产量决策和废料的最优交易价格以及制造商关于废料的最优处理策略。研究结果表明，制造商的废料处理策略取决于消费者对副产品产量的敏感程度。当消费者对副产品产量较敏感（不敏感）时，制造商会选择自己处理废料（给处理厂进行加工）。此外，随着制造商议价能力的上升，制造商的均衡利润上升，而处理厂的均衡利润下降。最后发现本文的基本结论在随机产出环境下依然稳健。     

基于数量柔性契约的双源应急物资采购定价模型

针对灾害事件发生的不确定性以及灾害发生后应急物资需求量的爆发式增长，本文设计了一个政府主导的基于数量柔性契约的双源应急物资采购模型。在存在一个现货市场的情况下，政府除了常规采购外，还会与供应方签订一份数量柔性契约，用以建立政企联合储备应急物资的合作关系。通过数理推导，本文发现灾害事件发生概率，政府自身储备量，现货市场采购价格会对双方决策产生重要影响，并给出三个影响因素在满足不同条件时政企双方的最优决策，同时进一步分析了这三个因素对政府采购成本与供应方利润的影响。最后，通过数值模拟的方式对所得结论进行了验证。本文的研究为政府与企业构建联合储备应急物资的合作关系提供了指导与依据。     

考虑订货协调成本与数量折扣的改良品供应链水平协调

在单个供应商与多个销售商构成的二级改良品供应链中，销售商们采用联合补货方式不仅可以分摊订货成本，而且由于订货批量的增加从而更易获得供应商提供的数量折扣合同。建立多个销售商在独立补货与联合补货中的利润水平函数，推导联合补货优于独立补货的充要条件。将销售商之间的联合补货行为转化成多人合作博弈问题，证明博弈具有的基本性质，设计基于博弈核心的利润分配方法。通过数值算例和敏感性分析验证了文中所构建模型的正确性。     

委婉语与合作原则的违背

合作原则,作为人际交流沟通的指导原则之一以及语用学的理论基石,对于委婉语的研究有着至关重要的作用。作为一种语用现象,委婉语的使用应遵循合作原则阐述的准则,但人们在使用委婉语进行实际交际时,经常在一定程度上故意违背合作原则,要求听者探测说者的弦外之意,领会其真正意图。主要从合作原则的量、质、关联、方式准则四个方面论述委婉语对合作原则的违背。委婉语虽然违背了合作原则,但是不妨碍对话的流畅进行。为了增强理解、欣赏以及运用语言的能力,应正确看待委婉语对合作原则的违背这一现象。     

还原论及其历史发展

在考察西方不同学者关于还原论定义的基础上合理重建了还原论概念,并据此加以综合分类。接着着重追溯了还原论的历史发展,指出它经历了由萌芽（ 古希腊原子论与中国古代元气说） 到确立（ 近代机械还原论） 再到成熟（ 目标理论多元化的现代还原论） 的三个历史发展阶段     

机械制图课程的CDIO教学初探

按照CDIO教学对人才培养的基本要求,通过精选教学内容、强化实践教学、引入思维导图、改进教学方法和考核方法等有效措施,对机械制图课程开展CDIO教学进行了改革和实践,受到了学生的欢迎,取得了较好的教学效果。     

基于CDIO理念的新机械制图教学模式研究

为了改变传统的机械制图课程教学模式,更好地培养学生的实践能力、创新意识和团队精神,不断提高该课程的教育教学质量,基于CDIO理念,对该课程的教学内容、教学方法、教学体系等方面进行了深入的改革与创新,从而构建了新的机械制图课程的教学模式。