Likelihood estimation and inference in threshold regression

This paper studies likelihood-based estimation and inference in parametric discontinuous threshold regression models with i.i.d. data. The setup allows heteroskedasticity and threshold effects in both mean and variance. By interpreting the threshold point as a “middle” boundary of the threshold variable, we find that the Bayes estimator is asymptotically efficient among all estimators in the locally asymptotically minimax sense. In particular, the Bayes estimator of the threshold point is asymptotically strictly more efficient than the left-endpoint maximum likelihood estimator and the newly proposed middle-point maximum likelihood estimator. Algorithms are developed to calculate asymptotic distributions and risk for the estimators of the threshold point. The posterior interval is proved to be an asymptotically valid confidence interval and is attractive in both length and coverage in finite samples.     

改进的干扰观察法在光伏系统MPPT中的应用

针对光伏发电系统最大功率跟踪问题,提出了一种改进的干扰观察算法。仿真实验结果表明,在外界环境变化的情况下,改进的方法在保证系统稳定性的前提下,使得光伏阵列能更快速、准确地跟踪最大功率点。     

A note on finite sample breakdown points of projection based multivariate location and scatter statistics

In this note, general results of finite sample breakdown point are obtained for two classes of projection based location and scatter statistics: the Stahel-Donoho statistics and the Maronna-Yohai statistics. It is shown that these projection based location and scatter statistics can achieve the maximum breakdown point of affine equivariant multivariate location and scatter statistics. General relationships between the finite sample breakdown point of these statistics and the uniform finite sample breakdown point of the sample median and a modified sample median absolute deviation are formally established. Received: May 1999     

基于功能区间的价值工程理论在工程中的应用

工程是一个相对复杂的系统,要对其功能进行精准的定位比较难,因为每个工程成本所对应的是一个功能区间,而非功能点。本文结合概率学的相关知识,提出了基于功能区间的价值工程理论模型,并认为工程建设的立足点应该是在可靠性上,而非追求"最低成本"或"最大价值"。     

论品牌包装设计的新理念

现今,品牌文化已经深入群众内心,要想让品牌突出让人耳目一新就得有一个够突出的包装设计。品牌包装设计新理念应从商标,图案,色彩,造型,材料等构成要素入手,在考虑商品特性的基础上,遵循品牌设计的一些基本原则。品牌包装设计的新理念就是让两者之间很好的平衡达到最大的收益,起点依然是包装设计。从而使设计效果更多的影响产品的品牌记忆,达到最大的利益。     

Federal mandates with local agenda setters

This paper investigates the effect of local monopoly agenda setting on federal standards. Federal standards specify a minimum (or maximum) point in policy space which can be raised (or lowered) by local option. Without local agenda setters, this creates incentives for nonmajoritarian outcomes, with a tendency for policies to be too high (low). Local agenda setters may have incentives to distort these outcomes even further. We demonstrate that federal standards can counterbalance the distortions of local agenda setters. We wish to thank LEESP, CNRS, and NSF for financial support. The paper has benefitted from helpful comments by Andy Postlewaite, Howard Rosenthal, Norman Schofield, and an anonymous referee.     

绥宁连接线第43合同段K31+650～K31+770路堑工程地质评述

K31+650～K31+770为路堑段,起点设计路面高程510.60 m,止点设计路面高程507.78 m,设计路面纵坡-1.5%,线路左右两侧均为切坡,切坡最大高度约15.00 m,但是其地质条件较为复杂。文章对其地质条件进行评述,以期为设计和施工提供技术支持。     

Exponential deconvolution: two asymptotically equivalent estimators

Two isotonic estimators for the distribution function in a specific deconvolution model, the exponential deconvolution model, are considered. The first estimator is a least squares projection of a naive estimator for the distribution function on the set of distribution functions. The second estimator is the well known maximum likelihood estimator. The two estimators are shown to be first order asymptotically equivalent at a fixed point.     

Breakdown concepts for contingency tables

Loglinear Poisson models are commonly used to analyse contingency tables. So far, robustness of parameter estimators as well as outlier detection have rarely been treated in this context. We start with finite-sample breakdown points. We yield that the breakdown point of mean value estimators determines a lower bound for a masking breakdown point of a class of one-step outlier identification rules. Within a more refined breakdown approach, which takes account of the structure of the contingency table, a stochastic breakdown function is defined. It returns the probability that a given proportion of outliers is randomly placed at such a pattern, where breakdown is possible. Finally, the introduced breakdown concepts are applied to characterise the maximum likelihood estimator and a median-polish estimator.     

The bias of least squares polynomial interpolants

The fitting of a straight line — or more generally of a low degree polynomial — to a point cloud in the plane is a commonly performed statistical technique. This paper discusses the bias of such a procedure and in particular generalizes the well-known remainder formula for polynomial interpolation to the regression setting. Designs minimizing the maximum bias are discussed as well.     

The two faces of development

An intrinsic connection exists between mission and money. As both are extended to their maximum point, the institution can role through its life effectively.     

时变Copula模型的非参数推断

运用Copula模型研究金融变量之间的相关结构,是近年来金融分析中的一个热点,如何估计Copula模型中的时变参数则是一个重点和难点问题。本文从非参数建模思想为切入点,提出经验分布函数—局部极大似然法(ECDF-LML)估计Copula函数中的时变参数,研究了Copula模型参数是否时变的统计假设检验问题。最后通过大量随机模拟研究验证了本文所提出的方法较DCC-MGARCH方法在刻画随机变量动态相关性方面更具优越性且很稳健。     

易变质产品双边定价库存模型研究

本文研究易变质产品库存模型中供货阶段和订货阶段之间的价格差异,引进双边定价的概念,提出一种新的基于易变质产品的双边定价库存模型。新模型以利润最大化为目标,寻求供货阶段和订货阶段的价格均衡条件和时间均衡条件。文中通过严格的数学推导,证明了目标函数最优解的存在性和唯一性。在这基础上,提出一种基于利润最大化的求解最优价格和最优时间比例系数的数值优化算法。实验结果证明了该数值算法具有快速收敛的特性,同时说明了该模型的合理性和有效性。     

Estimation and testing of crossing‐points in fixed design regression

Many phenomena in the life sciences can be analyzed by using a fixed design regression model with a regression function m that exhibits a crossing‐point in the following sense: the regression function runs below or above its mean level, respectively, according as the input variable lies to the left or to the right of that crossing‐point, or vice versa. We propose a non‐parametric estimator and show weak and strong consistency as long as the crossing‐point is unique. It is defined as maximizing point arg max of a certain marked empirical process. For testing the hypothesis H₀ that the regression function m actually is constant (no crossing‐point), a decision rule is designed for the specific alternative H₁ that m possesses a crossing‐point. The pertaining test‐statistic is the ratio max/argmax of the maximum value and the maximizing point of the marked empirical process. Under the hypothesis the ratio converges in distribution to the corresponding ratio of a reflected Brownian bridge, for which we derive the distribution function. The test is consistent on the whole alternative and superior to the corresponding Kolmogorov–Smirnov test, which is based only on the maximal value max. Some practical examples of possible applications are given where a certain study about dental phobia is discussed in more detail.     

Parametric links for binary choice models: A Fisherian–Bayesian colloquy

The familiar logit and probit models provide convenient settings for many binary response applications, but a larger class of link functions may be occasionally desirable. Two parametric families of link functions are investigated: the Gosset link based on the Student t latent variable model with the degrees of freedom parameter controlling the tail behavior, and the Pregibon link based on the (generalized) Tukey λ family, with two shape parameters controlling skewness and tail behavior. Both Bayesian and maximum likelihood methods for estimation and inference are explored, compared and contrasted. In applications, like the propensity score matching problem discussed below, where it is critical to have accurate estimates of the conditional probabilities, we find that misspecification of the link function can create serious bias. Bayesian point estimation via MCMC performs quite competitively with MLE methods; however nominal coverage of Bayes credible regions is somewhat more problematic.     

Highway traffic flow and the uneconomic region of production

In this paper highway traffic flow is formulated as a short-run production function in which traffic volume is the output and traffic density is the variable input. Given this formulation, the ‘uneconomic’ region of production is relevant. Often it is the case that traffic density will exceed the point at which traffic volume is at a maximum; i.e., the marginal product of the variable input is negative.     

A contingent claims analysis of optimal investment subsidy

This paper uses contingent claims analysis to answer two questions: (i) why are some subsidy markets apparently slow in attracting an optimal subsidy when others are not, and (ii) what can be done about it? The lack of activity in the green investment subsidy markets has been a concern as it appears optimal that countries should offer such support from a welfare point of view but progress has nonetheless been stalling, which motivates this paper. We show that free riding (which is likely to affect the green subsidy market) cools down the subsidy market with harmful welfare effects, and preemption (which is likely to affect the more active FDI subsidy market) overheats the subsidy market with similarly harmful effects. The theory dictates a taxation scheme that offsets these effects to restore the welfare to its maximum point.     

长宁区医用X射线装置周围环境辐射监测及分析

为了了解长宁区医用射线装置辐射防护现状,论文提出了两种快速判别泄露点位的方法并验证其可行性。依据相关要求,论文对29家单位共52台X射线装置周围环境辐射水平进行了监测。结果显示,测点最大年有效剂量估算值在8.6×10^-3~1.41×10^-1mSv,对探头屏蔽与否的监测结果相差较大。监测结果均满足GB 18871—2002对公众剂量的限制要求,因此,论文提出的探头屏蔽准直判别法和旋转视线法可行并有效。     

武警部队应急保障资源调度优化模型研究

文中针对武警部队跨区执行任务过程中多点保障、多目标资源调度的问题,建立了一种以时间最短、保障点最少、运输路径安全性最高为优化目标的数学模型,运用理想点法进行求解,并通过构造算例,验证了所建立模型的合理性以及理想点法的可行性,为武警部队跨区装备保障决策提供了一种新方法。     

A minimum chi-squared method for indirect parameter estimation from Poisson data

In this paper, we introduce a new algorithm for estimating non-negative parameters from Poisson observations of a linear transformation of the parameters. The proposed objective function fits both a weighted least squares (WLS) and a minimum χ² estimation framework, and results in a convex optimization problem. Unlike conventional WLS methods, the weights do not need to be estimated from the datas, but are incorporated in the objective function. The iterative algorithm is derived from an alternating projection procedure in which "distance" is determined by the chi-squared test statistic, which is interpreted as a measure of the discrepancy between two distributions. This may be viewed as an alternative to the Kullback-Leibler divergence which corresponds to the maximum likelihood (ML) estimation. The algorithm is similar in form to, and shares many properties with, the expectation maximization algorithm for ML estimation. In particular, we show that every limit point of the algorithm is an estimator, and the sequence of projected (by the linear transformation into the data space) means converge. Despite the similarities, we show that the new estimators are quite distinct from ML estimators, and obtain conditions under which they are identical.