Enriched multinormal priors revisited

In a 1974 paper, the author indicated how natural conjugate priors for multi-dimensional exponential family likelihoods could be enriched in certain cases through linear transformations of independent marginal priors. In particular, it was shown how the usual Normal-Wishart prior for the multinormal distribution with unknown mean vector and precision matrix could have the number of hyperparameters increased; the ‘thinness’ of the traditional prior is well- known. The new, linearly dependent prior leads to full-dimensional credibility prediction formulae for the observational mean vector and covariance matrix, as contrasted with the simpler, self-dimensional forecasts obtained in prior literature. However, there was an error made in the sufficient-statistics term of the covariance predictor which is corrected in this work. In addition, this paper explains in detail the properties of the enriched multinormal prior and why revised statistics are needed, and interprets the important relationship between the linear transformation matrix and the matrix of credibility time constants. An enumeration of the additional number of hyperparameters needed for the enriched prior shows its value in modelling multinormal problems; it is shown that the estimation of these hyperparameters can be carried out in a natural way, in the space of the observable variables.     

THE ECONOMY AT A TURNING POINT

In this Forecast Release we assess the evidence from the economic indicators and the latest official statistics for the view that the economy is at a turning point. We conclude that, while last year's rapid decline in UK output is coming to an end, a broadly-based recovery of the UK economy is unlikely until the world economy starts to grow again. The business surveys suggest that the upturn in European economy is less well established than the UK recovery. It may also be delayed further by high interest rates. The world turning point is thus likely to be some months later than die UK turning point, despite the strong upswing in the US. This implies that the UK recovery could be somewhat hesitant in the coming months.     

基于中国邮路问题的移动基站切换链路测方法研究

文章基于中国邮路问题,提出了移动基站切换链路测的新方法。根据基站与城市道路之间的关系以及交通规则,提出了移动基站切换链路测方法的有向图模型,使移动基站切换链路测问题成为了中国邮路问题。在移动基站切换链路测方法的有向图模型中,通过把单行道转化为双行道后,使该方法的有向图模型由非欧拉图转化成了欧拉图,经过这样特殊处理后,大大降低了求解移动基站切换链路测问题的复杂性。为了验证该方法的有效性,文章用一个具体的实例来证明了其有效性。     

上市公司审计委托关系的重构——加强审计独立性的路径

本文首先分析了我国上市公司现行审计委托模式的缺陷,指出由上市公司直接委托会计师事务所审计的现行审计委托模式容易造成审计独立性缺失。然后结合我国实际,提出实行在中国证监会下设立审计委员会统一管理上市公司财务报表审计的新的审计委托模式。通过重构上市公司审计委托关系,增强注册会计师审计独立性。     

GMM estimation of a maximum entropy distribution with interval data

We develop a generalized method of moments (GMM) estimator for the distribution of a variable where summary statistics are available only for intervals of the random variable. Without individual data, one cannot calculate the weighting matrix for the GMM estimator. Instead, we propose a simulated weighting matrix based on a first-step consistent estimate. When the functional form of the underlying distribution is unknown, we estimate it using a simple yet flexible maximum entropy density. Our Monte Carlo simulations show that the proposed maximum entropy density is able to approximate various distributions extremely well. The two-step GMM estimator with a simulated weighting matrix improves the efficiency of the one-step GMM considerably. We use this method to estimate the U.S. income distribution and compare these results with those based on the underlying raw income data.     

完善和落实社会物流统计制度促进现代物流产业的发展

社会物流统计指标体系和调查方式方法体系是社会物流统计制度的重要内容，而企业物流统计制度则是保证社会物流统计制度得以贯彻落实的前提条件。本文将社会物流统计和企业物流统计作为一个有机系统．从大系统的视角来分析社会物流统计制度存在的不足．并提出完善社会物流统计制度的建议。     

Measuring the Success of the Holland Hexagon

J. L. Holland's approach to personality (and careers that aresuitable for different personality types) involves scoring peopleon six personality measures and intercorrelating the six scores;there is a hypothesis about the relative sizes of the fifteencorrelations. In the present paper, some statistics are proposed fordescribing how well this hypothesis (and three variants of it) matches an observed correlation matrix. These statistics are analogousto a correlation coefficient. A variables-in-common model isgiven that justifies the most parsimonious of the hypotheses considered.     

Conditional distributions of generalized order statistics and some characterizations

Generalized order statistics have been introduced in Kamps (1995a). They enable a unified approach to several models of ordered random variables, e.g. (ordinary) order statistics, record values, sequential order statistics, record values from non-identical distributions. The purpose of this paper is to develop conditional distributions of one generalized order statistic given another and to characterize the underlying continuous distribution by different conditional expectations. Well-known results for ordinary order statistics and record values are extended to generalized order statistics. Received: July 1997     

“地面滑行时前轮跑偏”故障的分析

本文通过对737NG系列飞机前轮转弯系统原理介绍为出发点,结合作者在国航重庆维修基地工作多年的排故经验,针对经常出现的"地面滑行时前轮跑偏"这一故障信息,总结出了一套切实可行的快速排故方法,供大家研究讨论。     

浅谈概率统计课堂中的趣味教学法

为了推动概率统计课程的教学改革,提高学生学习概率统计课程的积极性,结合作者多年的教学经验,提出了趣味教学法,首先要培养学生的兴趣,在此基础上循序渐进引导学生掌握这门课的学习方法,寓教于乐,从而达到教学目的。     

Statistical Proofs of Some Matrix Theorems *

Books on linear models and multivariate analysis generally include a chapter on matrix algebra, quite rightly so, as matrix results are used in the discussion of statistical methods in these areas. During recent years a number of papers have appeared where statistical results derived without the use of matrix theorems have been used to prove some matrix results which are used to generate other statistical results. This may have some pedagogical value. It is not, however, suggested that prior knowledge of matrix theory is not necessary for studying statistics. It is intended to show that a judicious use of statistical and matrix results might be of help in providing elegant proofs of problems both in statistics and matrix algebra and make the study of both the subjects somewhat interesting. Some basic notions of vector spaces and matrices are, however, necessary and these are outlined in the introduction to this paper.     

浅谈市场适应背景下的体育统计学教学改革

体育统计学是社会体育专业学生必修课程之一,也是专业技能课程之一,在市场需求越来越看重应用型人才的现在,社会体育专业人才的培养也应该适应市场需求,在课程设置方面更趋于市场需求,笔者就新时期体育统计学的课程改革谈谈自己的看法。     

Formulating hypothetical scenarios in correlation stress testing via a Bayesian framework

Correlation stress testing refers to the correlation matrix adjustment to evaluate potential impact of the changes in correlations under financial crises. There are two categories, sensitivity tests and scenario tests. For a scenario test, the correlation matrix is adjusted to mimic the situation under an underlying stress event. It is only natural that when some correlations are altered, the other correlations (peripheral correlations) should vary as well. However, most existing methods ignore this potential change in peripheral correlations. In this paper, we propose a Bayesian correlation adjustment method to give a new correlation matrix for a scenario test based on the original correlation matrix and views on correlations such that peripheral correlations are altered according to the dependence structure of empirical correlations. The algorithm of posterior simulation is also extended so that two correlations can be updated in one Gibbs sampler step. This greatly enhances the rate of convergence. The proposed method is applied to an international stock portfolio dataset.     

Dating Business-Cycle turning points

This paper presents a logit model for dating business-cycle turning points. The regressors are monthly series from the Business Cycle Indicators database of the Conference Board. Dividing the sample period into a subset for model initialization (1959∶9–1970∶12) and a subset for testing (1971∶1–2003∶12) yields a chronology that is nearly identical to that established by the National Bureau of Economic Research (NBER). However, the recognition lag is less than four months, in contrast to an average of more than eleven months for the official chronology. (JEL E320) The author is grateful for comments by an anonymous referee.     

Reconstruction of previous failure times and records

For the sequences of independent identically distributed random variables with continuous distributions, we provide the optimal upper bounds for the increments of order and record statistics under condition that the values of future order statistics and records are known. The bounds are expressed in terms of quantiles and absolute moments centered about the quantiles of the parent distribution. We also describe the distributions which approach the bounds with arbitrary desired accuracy.The second author was supported by the Polish State Committee for Scientific Research (KBN) under Grant 5 P03A 012 20Received November 2003     

Likelihood Ratio Test for and Against Nonlinear Inequality Constraints

In applied statistics a finite dimensional parameter involved in the distribution function of the observed random variable is very often constrained by a number of nonlinear inequalities. This paper is devoted to studying the likelihood ratio test for and against the hypothesis that the parameter is restricted by some nonlinear inequalities. The asymptotic null distributions of the likelihood ratio statistics are derived by using the limits of the related optimization problems. The author also shows how to compute critical values for the tests.     

三角白化权函数灰色聚类决策下中小企业信用评价模型构建

在充分调研基础上,建立了中小企业信用评价指标体系,将灰色统计理论中的三角白化权函数聚类决策方法应用到中小企业信用评价工作中,并通过重新设计灰色聚类决策步骤,克服了三角白化权函数聚类系数不规范可能带来的聚类错误或影响类内排序问题。经实例分析表明,该方法可使评估结果更为客观、可靠,更有利于作出正确的决策。     

The inter-industry distribution of technological capabilities. A case study in the application of the Italian patenting in the U.S.A.

In this paper patent statistics are used as a technological indicator for the purpose of identifying the inter-industry distribution of technological capabilities. A matrix of Italian patents in the U.S.A. by industrial sectors and technological fields is discussed. This matrix, which is complementary to those devoted to inter-industry technology flows, is of interest to technology policy, since it indicates the sources of a given technological capability. The same matrix shows that the companies, and consequently the industrial sectors involved, are multi-technological in that they produce inventions in a wide range of technological fields. The present paper is an initial attempt to quantify this known fact.     

Minimum Distance Estimation and Testing of DSGE Models from Structural VARs*

The aim of this paper is to complement the minimum distance estimation–structural vector autoregression approach when the weighting matrix is not optimal. In empirical studies, this choice is motivated by stochastic singularity or collinearity problems associated with the covariance matrix of impulse response functions. Consequently, the asymptotic distribution cannot be used to test the economic model's fit. To circumvent this difficulty, we propose a simple simulation method to construct critical values for the test statistics. An empirical application with US data illustrates the proposed method.     

“长三角”旅游服务质量预警机制建立的研究

打造中国旅游的“金三角”,苏、浙、沪三地必须实现旅游资源的整合。而建立有效的旅游服务质量预警机制是实现旅游资源整合的基础。