Exact likelihood inference for Laplace distribution based on Type-II censored samples

We develop exact inference for the location and scale parameters of the Laplace (double exponential) distribution based on their maximum likelihood estimators from a Type-II censored sample. Based on some pivotal quantities, exact confidence intervals and tests of hypotheses are constructed. Upon conditioning first on the number of observations that are below the population median, exact distributions of the pivotal quantities are expressed as mixtures of linear combinations and of ratios of linear combinations of standard exponential random variables, which facilitates the computation of quantiles of these pivotal quantities. Tables of quantiles are presented for the complete sample case.     

量的概念与王充的无神论学说

王充是东汉杰出的无神论思想家.他通过对当时社会上流行的各种神学思想的批判,建立了自己无神论的理论体系.在进行这种批判的过程中,他特别注意考查不同物体同一属性在大小、多少等方面的差异,注意物体的尺度、重量等属性以及物体间相互作用范围、远近距离变化等因素,以此来揭露批判对象的荒谬,这使他形成了注重量的概念的独特思想方法,使得量的概念成了他建立自己的无神论学说的一个重要出发点.王充这一思想方法的形成是由他所处的时代及其学术取向所决定的.     

工程量清单计价模式下财政投资审核方法探讨

中国2003年7月已经正式实施工程量清单计价模式,财政性投资项目的招标标底、投标报价的编制、合同价款的确定与调整、工程结算等都必须执行工程量清单计价。笔者认真分析了工程量清单计价模式的特点,结合财政性投资项目的工程造价控制的要求,从工程量、分项工程单价、取费标准、工程合同、设计变更等方面探讨了开展财政性投资项目工程预结算审核工作的方法。     

工程量清单招标中利与弊的分析

针对我国在建设工程招投标中实施工程量清单这种计价模式的利与弊进行了分析,从工程量清单招标的合理性、符合国际惯例、促进建设市场有序竞争和企业健康发展等几个方面阐述了工程量清单招标的优越性,同时提出了工程量清单招标存在企业定额不完善、投标人的造价人员还不能符合工程量清单计价模式的要求、工程量清单招标投标的项目其评标标准和方法不完善等问题和解决办法。     

The interpretation of maximum-likelihood estimation

Maximum-likelihood estimation is interpreted as a procedure for generating approximate pivotal quantities, that is, functions u(X;θ) of the data X and parameter θ that have distributions not involving θ. Further, these pivotals should be efficient in the sense of reproducing approximately the likelihood function of θ based on X, and they should be approximately linear in θ. To this end the effect of replacing θ by a parameter ϕ = ϕ(θ) is examined. The relationship of maximum-likelihood estimation interpreted in this way to conditional inference is discussed. Examples illustrating this use of maximum-likelihood estimation on small samples are given.     

Transformed Logit Confidence Intervals for Small Populations in Single Capture–Recapture Estimation

The good performance of logit confidence intervals for the odds ratio with small samples is well known. This is true unless the actual odds ratio is very large. In single capture–recapture estimation the odds ratio is equal to 1 because of the assumption of independence of the samples. Consequently, a transformation of the logit confidence intervals for the odds ratio is proposed in order to estimate the size of a closed population under single capture–recapture estimation. It is found that the transformed logit interval, after adding .5 to each observed count before computation, has actual coverage probabilities near to the nominal level even for small populations and even for capture probabilities near to 0 or 1, which is not guaranteed for the other capture–recapture confidence intervals proposed in statistical literature. Thus, given that the .5 transformed logit interval is very simple to compute and has a good performance, it is appropriate to be implemented by most users of the single capture–recapture method.     

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.     

考虑学习效应的可复用物流容器供应链的最优运作决策研究

本文研究了单个制造商通过可复用物流容器将产品送至单个零售商的闭环供应链,在可复用物流容器回收处理后得到的数量小于发出时数量的条件下,本文考虑可以通过工人操作过程中存在的学习效应来降低可复用物流容器的丢弃率。本文构建了两个模型：模型1未考虑维修中心工人操作过程中存在的学习效应,可复用容器的丢弃率为随机变量;模型2考虑维修中心工人在操作过程中存在学习效应,使得可复用物流容器的丢弃率不断降低。通过定量分析确定了最小联合库存总成本下的最优运行周期、货物配送次数以及可复用容器配送次数。结果表明,在任一供应链参与者不采取降本措施的情况下,仅考虑工人在操作过程中存在的学习效应就可以起到降低容器丢弃率、节约总成本的效果。此外,本文还分析了制造商可以支付给工人的最大维修费用,为企业的成本投入预算提供决策依据。     

Confidence intervals for variance components in unbalanced one-way random effects model using non-normal distributions

In scenarios where the variance of a response variable can be attributed to two sources of variation, a confidence interval for a ratio of variance components gives information about the relative importance of the two sources. For example, if measurements taken from different laboratories are nine times more variable than the measurements taken from within the laboratories, then 90% of the variance in the responses is due to the variability amongst the laboratories and 10% of the variance in the responses is due to the variability within the laboratories. Assuming normally distributed sources of variation, confidence intervals for variance components are readily available. In this paper, however, simulation studies are conducted to evaluate the performance of confidence intervals under non-normal distribution assumptions. Confidence intervals based on the pivotal quantity method, fiducial inference, and the large-sample properties of the restricted maximum likelihood (REML) estimator are considered. Simulation results and an empirical example suggest that the REML-based confidence interval is favored over the other two procedures in unbalanced one-way random effects model.     

行政案例分析在行政学原理中的应用探讨

行政案例分析在行政学原理教学中具有不可替代的作用。坚持和完善讲授式教学方法,是搞好案例分析课程的首要环节;行政案例分析课程组织实施中的关键环节主要由选择案例、学生分组、课前准备、班级发言、提交小组案例分析报告与教师总结多个步骤所组成;目前我国在行政案例教学中虽然还存在诸多问题,但我们坚信行政管理专业教育一定会在不断革新中发展,行政案例教学的春天一定会到来。