凉山彝区与欧美地区“外游”客源间的双向禁忌

凉山之“凉”、月城之幽蜚声中外,随着我国与全球大多数国家综合关系的不断改善,随着全球变暖和生态条件的日渐衰败,清凉秀美、民风独特的凉山彝族地区业已成为吸引全球客源的重要旅游目的地。凉山彝区与欧美地区超长距大跨度的自然地理、人文民风差别虽然是吸引国际旅游客源的重要因素,但也必然会在宗教背景、审美情趣、饮食起居、行为礼仪、民俗民风等方面出现相克相悖的现象。本文从“客源”（欧关）、“目的”（凉山）两地宗教、习俗等民族文化差异的角度切入,重点对欧美基督教区域游客在凉山彝区“外游”诸环节中的“双向禁忌”做出分析探讨。     

基于EM填补和加权秩和比的电力系统黑启动决策方法

电力系统大停电后需要安全可靠的黑启动方案进行电力快速恢复,如何从众多黑启动方案中进行优选是一个重要课题。不同于以往完全信息情况下的研究,本文对电力系统黑启动方案评估问题的研究是基于不完全信息情况下进行的,提出一种EM填补和加权秩和比相结合的黑启动决策方法。首先,采用EM算法填补黑启动方案评价空值,得到完备的黑启动评价矩阵;然后,计算指标间的差异性,利用差异性权重法得到各个指标的权重;最后,采用加权秩和比法确定每个方案的评分值,实现黑启动方案的分级和完全排序。本文方法基于广东电网黑启动数据集进行实验验证,实验结果表明,本文方法可以对不完全信息情况下的黑启动方案进行优劣排序,且具有较高准确性。     

Outsourcing: decision-making methods and criteria during design and engineering

Research to date for decision-making on outsourcing has almost exclusively focussed on strategic and operational levels. Consequently, we know relatively little about decision-making on outsourcing during design and engineering, i.e. the tactical level; that also means that the characteristics of design and engineering – incomplete and inaccurate information and progressive availability of data – are not incorporated in existing frameworks and methods at that level. To fill this gap, a first-of-its-kind framework, based on an extensive appraisal of the literature, is validated; to that purpose, a Delphi survey was undertaken gauging the opinions of two homogeneous groups of academic and industry experts. The analysis of the survey affirms the assumptions made about the role of the progressive availability of data during decision-making on outsourcing. The results from this study should not only inform further research into decision-making during design and engineering but potentially the framework might also have validity for purchasing at the tactical level and strategic decision-making on outsourcing.     

限制性定价策略中在位厂商的最优产量选择

Milgrom-Roberts模型及相关研究证明了不完全信息条件下限制性定价策略均衡的存在,但对存在的具体形式却没有说明。本文通过对Milgrom-Roberts限制性定价模型的进一步研究,指出不完全信息条件下不同成本类型的在位厂商阻止潜在竞争厂商进入的策略均衡可以在一个产量区间内存在;并且由于利润最大化原则,实际上形成在位厂商生产最优产量即阻止进入的均衡产量区间内的利润最大化产量、潜在竞争厂商不进入的唯一策略均衡结果。由于潜在的进入威胁,在位厂商要想成功实施限制性定价策略,其最优产量只能大于或等于垄断产量,而利润只能小于或等于垄断利润。     

信息披露时间不确定与风险债务评估

本文研究当公司信息披露时间不确定、而信息披露时投资者能完全真实地了解公司价值的情形下风险债务的评估问题,假设关于公司真实价值的信息流服从泊松过程,得到了公司债务安全条款的阈值和公司债务价值评估的表达式。分析表明,当信息流到达率增大时,债务安全条款的阈值降低的同时导致债务价值的损失,但若公司价值增大,债务价值的损失将逐渐减小。     

Minimum chi-square estimator and test for incomplete multidimensional contingency tables

A modified transformed chi-square statistic is defined for testing hypotheses of quasi-independence in the incomplete multi-dimensional contingency table and a simple method for determining degrees of freedom is given. A modified transformed chi-squareestimator of the expected cell frequencies is given in closed form for a general class of exact linear constraints. The co-variance matrix of estimated cell frequencies is derived under the assumption of a conditional Poisson distribution.     

Likelihood ratio test for independence with partial multivariate normal data

This article derives the likelihood ratio statistic to test the independence between (X ₁,…,X _r ) and (X _r+1,…,X _k ) under the assumption that (X ₁,…,X _k ) has a multivariate normal distribution and that a sample of size n is available, where for N observation vectors all components are available, while for M = (n + N) observation vectors, the data on the last q components, (X_k-q+1,…,X _k ) are missing (k+q≥r).     

Association Models for Multi-Dimensional Cross-Classifications of Ordinal Variables

Models are formulated for describing associations among ordinal variables in multidimensional tables.Uniform association and uniform interaction models occur as special cases in which equal-interval scores are assigned to levels of the variables.The models described are extensions of ones proposed by Goodman (1979).     

The effect of category choice on the odds ratio and several measures of association in case-control studies

In many case-control studies the risk factors are categorized in order to clarify the analysis and presentation of the data. However, inconsistent categorization of continuous risk factors may make interpretation difficult. This paper attempts to evaluate the effect of the categorization procedure on the odds ratio and several measures of association. Often the risk factor is dichotomized and the data linking the risk factor and the disease is presented in a 2 x 2 table. We show that the odds ratio obtained from the 2x2 table is usually considerably larger than the comparable statistic that would have been obtained had a large number of outpoints been used. Also, if 2 x 2, 2 x 3, or 2 x 4 tables are obtained by using a few outpoints on the risk factor, the measures of association for these tables are usually greater than the measure that would have been obtained had a large number of cntpoints been used. We propose an odds ratio measure that more closely approximates the odds ratio between the continuous risk factor and disease. A corresponding measure of association is also proposed for 2 x 2, 2x3, and 2x4 tables.     

The Maximum Probability 2 × c Contingency Tables and the Maximum Probability Points of the Multivariate Hypergeometric Distribution

Abstract

The problem of obtaining the maximum probability 2 × c contingency table with fixed marginal sums, R  = (R ₁, R ₂) and C  = (C ₁, … , C _c ), and row and column independence is equivalent to the problem of obtaining the maximum probability points (mode) of the multivariate hypergeometric distribution MH(R ₁; C ₁, … , C _c ). The most simple and general method for these problems is Joe's (Joe, H. (1988 Joe, H. 1988. Extreme probabilities for contingency tables under row and column independence with application to Fisher's exact test. Commun. Statist. Theory Meth., 17(11): 3677–3685. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). Extreme probabilities for contingency tables under row and column independence with application to Fisher's exact test. Commun. Statist. Theory Meth. 17(11):3677–3685.) In this article we study a family of MH's in which a connection relationship is defined between its elements. Based on this family and on a characterization of the mode described in Requena and Martín (Requena, F., Martín, N. (2000 Requena, F. and Martín, N. 2000. Characterization of maximum probability points in the multivariate hypergeometric distribution. Statist. Probab. Lett., 50: 39–47.  [Google Scholar]). Characterization of maximum probability points in the multivariate hypergeometric distribution. Statist. Probab. Lett. 50:39–47.), we develop a new method for the above problems, which is completely general, non recursive, very simple in practice and more efficient than the Joe's method. Also, under weak conditions (which almost always hold), the proposed method provides a simple explicit solution to these problems. In addition, the well-known expression for the mode of a hypergeometric distribution is just a particular case of the method in this article.