A new ranked set sample estimator of variance

Summary. We develop an unbiased estimator of the variance of a population based on a ranked set sample. We show that this new estimator is better than estimating the variance based on a simple random sample and more efficient than the estimator based on a ranked set sample proposed by Stokes. Also, a test to determine the effectiveness of the judgment ordering process is proposed.     

方差已知的正态样本多个异常值的检验

针对检验异常值的奈尔方法,对出现多个异常值时检验效果不好,产生异常值遮蔽现象,修改其检验统计量。给出了修改后检验统计量的临界值,改进了这个重要的检验方法。     

ON A SHARED ALLELE TEST OF RANDOM MATING

A simple random sample is observed from a population with a large number‘K’ of alleles, to test for random mating. Of n couples, n_ijkl have female genotype ij and male genotype kl (i, j, k, l{1,…, A‘}). The large contingency table is collapsed into three counts, n₀, n₁ and n₂ where n_p is the number of couples with s alleles in common (s = 0,1, 2). The counts are estimated by np?_o where n₀, is the estimated probability of a couple having s alleles in common under the hypothesis of random mating. The usual chi-square goodness of fit statistic X² compares observed (n_s) with expected (np?) over the three categories, s = 0,1,2. An empirical observation has suggested that X² is close to having a chi-square distribution with two degrees of freedom (X) despite a large number of parameters implicitly estimated in _e. This paper gives two theorems which show that x is indeed the approximate distribution of X² for large n and K₁“, provided that no allele type over-dominates the others.     

一种改进的线性容差电路的k-故障诊断

提出了一种改进的线性容差电路的k-故障诊断方法。与现有方法相比,较多地利用了已知的统计特性,缩小了电路可能的故障范围。同时,还证明了故障诊断与信号解卷积模型的相似性,将信号处理领域的方法引入线性电路故障诊断中。计算机模拟实验证实了该方法的有效性。     

A Bayesian predictive approach to determining the number of components in a mixture distribution

This paper describes a Bayesian approach to mixture modelling and a method based on predictive distribution to determine the number of components in the mixtures. The implementation is done through the use of the Gibbs sampler. The method is described through the mixtures of normal and gamma distributions. Analysis is presented in one simulated and one real data example. The Bayesian results are then compared with the likelihood approach for the two examples.     

基于词频的风景道产品谱系--以美国蓝岭风景道为例

蓝岭风景道是"美国最长的一条乡村风景道"、"美国最受喜爱的一条驾车道",影响力巨大,产品谱系具有典型性和样板性。从宏观发展背景及条件,开发理念,以及产品谱系构成、特征、空间分布与成因分析等方面,对蓝岭风景道旅游产品谱系进行较深入分析,揭示风景道产品谱系规律和特征,得出蓝岭风景道旅游产品谱系宝贵的经验启示是:要从国家战略层面高度重视道路的交通、景观、文化和保护等复合功能的综合开发利用,要改变风景道产品开发仅仅是对道路本身开发的狭窄理念,在综合考虑区位、资源、客源和社会经济综合环境等因素的前提下,构建具有广谱性强和丰富度高的旅游产品谱系,以满足市场需求,带动区域经济社会发展。     

市场经济体制下统计监督的特点与对策

统计监督是调控、管理并保证经济运行的重要依据和条件 ,在市场经济体制下发挥着极为重要的作用 ,并且在目的、范围和传播方式上具有与传统体制所不同的鲜明特点。市场经济体制下统计监督应走向开放、与新体制接轨、提高结果的可信度、重视事前预测和控制     

On the distributions of multivariate sample skewness

In this paper, we consider the multivariate normality test based on measure of multivariate sample skewness defined by Srivastava (1984). Srivastava derived asymptotic expectation up to the order N⁻¹ for the multivariate sample skewness and approximate χ²${\chi }^2$ test statistic, where N   is sample size. Under normality, we derive another expectation and variance for Srivastava's multivariate sample skewness in order to obtain a better test statistic. From this result, improved approximate χ²${\chi }^2$ test statistic using the multivariate sample skewness is also given for assessing multivariate normality. Finally, the numerical result by Monte Carlo simulation is shown in order to evaluate accuracy of the obtained expectation, variance and improved approximate χ²${\chi }^2$ test statistic. Furthermore, upper and lower percentiles of χ²${\chi }^2$ test statistic derived in this paper are compared with those of χ²${\chi }^2$ test statistic derived by Mardia (1974) which is used multivariate sample skewness defined by Mardia (1970).     

Exact Tests of Significance in Higher Dimensional Tables

We describe methods used to provide an exact test of significance of the hypothesis that all factors are mutually independent of each other in 2³ and 2⁴ contingency tables. Several numerical examples demonstrate the advantages of exact tests over approximate significance levels. We give bounds on the number of tables needed to perform this exact significance test. In four or more dimensions the number of tables in this enumeration becomes astronomical with even modest sample sizes. Inverting the characteristic function of the exact distribution has proved useful in these situations.     

A note on empirical likelihoods derived from pairwise score functions

Pairwise likelihood functions are convenient surrogates for the ordinary likelihood, useful when the latter is too difficult or even impractical to compute. One drawback of pairwise likelihood inference is that, for a multidimensional parameter of interest, the pairwise likelihood analogue of the likelihood ratio statistic does not have the standard chi-square asymptotic distribution. Invoking the theory of unbiased estimating functions, this paper proposes and discusses a computationally and theoretically attractive approach based on the derivation of empirical likelihood functions from the pairwise scores. This approach produces alternatives to the pairwise likelihood ratio statistic, which allow reference to the usual asymptotic chi-square distribution and which are useful when the elements of the Godambe information are troublesome to evaluate or in the presence of large data sets with relative small sample sizes. Two Monte Carlo studies are performed in order to assess the finite-sample performance of the proposed empirical pairwise likelihoods.