An admissible minimax estimator of a bounded scale-parameter in a subclass of the exponential family under scale-invariant squared-error loss

A subclass of the scale-parameter exponential family is considered and for the rth power of the scale parameter, which is lower bounded, an admissible minimax estimator under scale-invariant squared-error loss is presented. Also, an admissible minimax estimator of a lower-bounded parameter in the family of transformed chi-square distributions is given. These estimators are the pointwise limits of a sequence of Bayes estimators. Some examples are given.     

关于有限论域上模糊度定理的一个注记

设F（U）为有限论域U={u1,u2,…,un}上的模糊幂集.令D：F（U）→[0,1],AaD（A）=g（∑i=1^n ci fi（A（ui）））,其中ci〉0,fi：[0,1]→[0,＋∞）满足（1）fi（x）=fi（1-x）,（2）fi（0）=0,（3）fi在[0,0.5]上严格递增.又设a=∑i=1^n ci fi（0,5）,且g：[0,a]→[0,1]严格递增,g（0）=0,g（a）=1.某教材中的定理断定具有上述性质的映射D为F（U）上的模糊度函数.本文构造出具有上述性质的D,但D不满足模糊度函数定义中的可加性条件,故不为F（U）上的模糊度函数.本文进一步指出,若将g的定义域扩展为[0,2a],并再假定g是可加的,则可使D为F（U）上的模糊度函数.     

多环芳烃结构致癌性关系的模糊数学模型

综合考虑了多环芳烃 (PAH s)分子中诸致癌活性区的作用 ,对这些活性区的 H MO或 PMO计算特性指标作了模糊数学的权衡软处理 ,从而构造出致癌 PAH s的模糊集 ,此模糊集的隶属函数即为 PAH s致癌性强弱的判据 .根据本文提出的数学模型对 PAH s致癌活性的计算结果与实验结果比较 ,符合率达 10 0 % .     

The distribution of the likelihood ratio for mixtures of densities from the one-parameter exponential family

We here consider testing the hypothesis ofhomogeneity against the alternative of a two-component mixture of densities. The paper focuses on the asymptotic null distribution of 2 log _n , where _n is the likelihood ratio statistic. The main result, obtained by simulation, is that its limiting distribution appears pivotal (in the sense of constant percentiles over the unknown parameter), but model specific (differs if the model is changed from Poisson to normal, say), and is not at all well approximated by the conventional ₍₂₎ ² -distribution obtained by counting parameters. In Section 3, the binomial with sample size parameter 2 is considered. Via a simple geometric characterization the case for which the likelihood ratio is 1 can easily be identified and the corresponding probability is found. Closed form expressions for the likelihood ratio _n are possible and the asymptotic distribution of 2 log _n is shown to be the mixture giving equal weights to the one point distribution with all its mass equal to zero and the ²-distribution with 1 degree of freedom. A similar result is reached in Section 4 for the Poisson with a small parameter value (0.1), although the geometric characterization is different. In Section 5 we consider the Poisson case in full generality. There is still a positive asymptotic probability that the likelihood ratio is 1. The upper precentiles of the null distribution of 2 log _n are found by simulation for various populations and shown to be nearly independent of the population parameter, and approximately equal to the (1–2)100 percentiles of ₍₁₎ ² . In Sections 6 and 7, we close with a study of two continuous densities, theexponential and thenormal with known variance. In these models the asymptotic distribution of 2 log _n is pivotal. Selected (1–) 100 percentiles are presented and shown to differ between the two models.     

An estimator for the mean of an exponential distribution with random right-censoring

Let (Y₁, Z₁),…,(Y_N, Z_N) be i.i.d. pairs of independent random variables such that Y_i is exponentially distributed with unknown mean 1/λ and Z_i has an unknown distribution function F. Let X_i ≔ min(Y_i, Z_i). Under certain assumptions on F an estimator T_N(X₁,…,X_N) for 1/λ is constructed which is consistent and asymptotically normal.     

Fuzzy真凸集的公理化定义

本文以基本Ｆｕｚｚｙ点、Ｆｕｚｚｙ点为基础，给出Ｆｕｚｚｙ真凸集的公理化定义，并对其性质进行了讨论     

中介数学系统已建立,为什么还会产生模糊数学危机

构造了两个例子,当试图用扎德的＂隶属函数＂的定义去表述例子中的模糊信息时发现,对于列举的例子,＂隶属函数＂的定义根本＂无法确切表达＂甚至根本＂无法表达＂其中所蕴含的模糊信息.进而发现,模糊数学危机产生的原因不是因为其基础理论不完善,而是因为某些定义在当初人们定义它时,定义的不准确造成的.所以要从根本上解决模糊数学的危机...     

负相伴样本情形连续型单参数指数族参数的经验Bayes检验问题

在加权"线性损失"下讨论了负相伴样本情形连续型单参数指数族参数的经验Bayes(EB)检验问题.利用概率密度函数的核估计构造了参数的经验Bayes检验函数,并获得了它的渐近最优(a.o.)性,在适当的条件下证明了所提出的经验Bayes检验函数的收敛速度可任意接近O(n-1/2).     

Some measures of robustness for unbiased estimators in one-parameter natural exponential families with quadratic variance function

In this paper two measures to highlight the possible effect of an observation on the UMVU estimate are proposed. Our study is based in expansions in terms of orthogonal polynomials for the UMVUE when sampling from a NEF-QVF. We obtain the conditional bias and the asymptotic mean sensitivity curve (AMSC) for the UMVUE. We observe that these measures depend on parametric function under consideration at the true and unknown value of the parameter. We study in detail their properties and relationships as well as to the Hampel's influence function. In fact, we note that the AMSC also verifies for the UMVUE in the NEF-QVF some of most relevant properties of influence function. Also a case-deletion influence diagnostic and some simulations are included to illustrate our results.     

基于模糊理论的机动车辆风险评估

对机动车辆风险进行评估是车险费率厘定的一个重要环节.提出一种基于模糊理论的机动车辆风险评估方法(The Risk Assess of Motor Vehicle Based on Fuzzy Theory,简称RMFT),应用表明该方法在风险评估的精度上取得较好效果.     

军校硕士研究生复试评价指标的科学确定

复试是硕士研究生招生考试的重要组成部分,是保证生源质量的基础环节,因此研究硕士研究生复试评价指标体系具有极其重要的意义。通过构建合理的隶属函数,利用模糊聚类的方法,对军校硕士研究生复试的评价指标进行聚类,并依据相关指数对同类指标进行了筛选,最终确定了精简且具有科学性的指标体系,为军队院校的硕士研究生的选拔提供参考。     

Hesitant fuzzy information aggregation in decision making

As a generalization of fuzzy set, hesitant fuzzy set is a very useful tool in situations where there are some difficulties in determining the membership of an element to a set caused by a doubt between a few different values. The aim of this paper is to develop a series of aggregation operators for hesitant fuzzy information. We first discuss the relationship between intutionistic fuzzy set and hesitant fuzzy set, based on which we develop some operations and aggregation operators for hesitant fuzzy elements. The correlations among the aggregation operators are further discussed. Finally, we give their application in solving decision making problems.     

The fuzzy decision problem: An approach to the point estimation problem with fuzzy information

This paper is devoted to the extension of the Bayesian method for the point estimation, when the available information is ‘vague’.In the nonfuzzy case, the parametric estimation can be approached as a particularization in the statistical decision problem. This motivates us to accomplish the mentioned extension by looking at the parametric estimation in the fuzzy case as a special situation in the fuzzy decision problem (defined by Tanaka, Okuda and Asia).In this way, concepts in the fuzzy decision problem are first ‘expressed’ in the estimation terminology. Then, on the basis of these concepts, we shall introduce some notions and state some interesting results. Finally, several illustrative examples will be exposed.     

The hazard rate of the power-quadratic exponential family of distributions

Among life distributions of exponential-type the power-quadratic distributions form a very versatile family since their hazard rates can have a wide variety of shapes, including the bathtub shape. It is shown in this article that this family can be partially ordered by its hazard rates whose precise expression and asymptotic behavior can also be obtained by using special mathematical functions.     

考虑区间值的相对隶属函数与传统模糊分布函数的比较

通过分析比较,揭示了可变集理论中考虑区间值的相对隶属函数与传统的线性模糊分布函数之间的一些区别与联系,即传统的线性模糊分布函数是考虑区间值的相对隶属函数的一些特例,考虑区间值的相对隶属函数在描述模糊现象的模糊性时更具有普适性;同时指出了应用考虑区间值的相对隶属函数时应当注意的问题.     

An exponential inequality for the distribution function of the kernel density estimator, with applications to adaptive estimation

It is shown that the uniform distance between the distribution function $F_n^K(h)$ of the usual kernel density estimator (based on an i.i.d. sample from an absolutely continuous law on ${\mathbb{R}}$ ) with bandwidth h and the empirical distribution function F _n satisfies an exponential inequality. This inequality is used to obtain sharp almost sure rates of convergence of $\|F_n^K(h_n)-F_n\|_\infty$ under mild conditions on the range of bandwidths h _n , including the usual MISE-optimal choices. Another application is a Dvoretzky–Kiefer–Wolfowitz-type inequality for $\|F_n^{K}(h)-F\|_\infty$ , where F is the true distribution function. The exponential bound is also applied to show that an adaptive estimator can be constructed that efficiently estimates the true distribution function F in sup-norm loss, and, at the same time, estimates the density of F—if it exists (but without assuming it does)—at the best possible rate of convergence over Hölder-balls, again in sup-norm loss.     

Extension of the variance function of a steep exponential family

Let F={P(m,F); mM_F} be a multidimensional steep natural exponential family parameterized by its domain of the means M_F and let V_F(m) be its variance function. This paper studies the boundary behaviour of V_F. Necessary and sufficient conditions on a point of ∂M_F are given so that V_F admits a continuous extension to the point . It is also shown that the existence of implies the existence of a limit distribution concentrated on an exposed face of containing . The relation between and is established and some illustrating examples are given.     

A one-parameter family of stationary solutions in the Susceptible-Infected-Susceptible epidemic model

We study the uncorrelated Susceptible-Infected-Susceptible (SIS) model in epidemiology on top of a one parameter family of networks whose connectivity distribution ranges from scale free (SF) to exponential. For each network, the fraction of the population infected in the long term is a recursively defined hypergeometric function. For highly contagious diseases, with a high infection rate, the fraction of the population infected is lower when the network is SF. For less contagious diseases, the fraction of the population infected is lower when the network is exponential. This result points to an evolutionary advantage for a network being SF—namely an SF network is more resistant to the spread of a deadly disease.